Implement config checking (#1859)

* Add error handling functions to ConfigHandler

Refurbished functions setValue and value which were previously unused.
These functions now set/get a setting with error handling.
Currently recognizes only errors recognizable by QSettings.

* Make use of value and setValue in ConfigHandler

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add checker for unrecognized general options

Extraneous config options in [General] will be reported as errors.
Added some placeholder functions to be implemented in future commits.

* Introduce keysFromGroup function

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Check shortcut names for duplicates

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix notification spam

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Implement shortcut conflict checking

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix reading of fallbacks on error

If there is a config error, some values would not be loaded correctly.
Using the newly implemented function ConfigHandler::contains instead of
QSettings::contains solves this issue.

These changes reveal u bug that causes a crash on startup.

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix crashes introduced in previous commit

Because ConfigHandler is a dependency of most other classes,
calling functions from those classes inside ConfigHandler caused
infinite recursions in some cases.

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add config file watcher

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add missing config options

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix bug in shortcut conflict detection

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add error resolved notification

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add GUI error message overlay

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add indicator in config window

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Use ConfigHandler::fileChanged in ConfigWindow

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix watcher sometimes not firing

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Improve config file watching performance

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add new way to handle config

This is only a fundamental implementation. Future commits will replace
everything with this new paradigm.

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix getButtons and related functions

Also refactored related code to use QList instead of QVector because
QSettings does not work well with QVector.

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Make good use of the new way

* Implement proper checking for basic types

Everything is covered, apart from KeySequence.

* Move fallback path to ExistingDir value handler

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Use consistent naming scheme in ConfigHandler

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Implement config getters/setters via macro

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Surround text with tr and clang-format

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix colors being saved obfuscated

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add ValueHandler::represenation

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Move ValueHandler to separate files

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* confighandler.cpp: rename macro CUSTOM to OPTION

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix bug with shortcut conflict checker

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Update docs and fix setAllTheButtons

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Handle filenamePattern properly

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix failing build due to wrong function name

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix QSet error due to Qt version mismatch

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Replace QSharedPointer::get with data for older Qt versions

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix failing build on MacOS and ubuntu 18.04

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add column headers to recognizedGeneralOptions map

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix ubuntu 18.04 error

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix false positive when shortcuts empty

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix wrong shortcut group prefix

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Implement proper shortcut checking

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add shortcut map in ConfigHandler

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Move ConfigShortcuts functions to ShortcutsWidget

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix minor bugs

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add fallback scheme: Pictures, HOME, TMP

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add config --check CLI option

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Add config error log to GUI

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Rename ValueHandler::description to expected

* Convert Qt's #AARRGGBB to #RRGGBBAA and vice versa

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Remove obsolete `saveAfterCopyPath`

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Fix errors in example config

Also added an additional ; in front of actual comments to differentiate
them from commented options.

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Allow special value 'picker' in userColors

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

* Allow only name, #RRGGBB, and #RRGGBBAA color formats

Signed-off-by: Haris Gušić <harisgusic.dev@gmail.com>

flameshot.example.ini

@@ -1,73 +1,73 @@
-[General]
+;[General]
-; Configure which buttons to show after drawing a selection
+;; Configure which buttons to show after drawing a selection
-; Not easy to set by hand
+;; Not easy to set by hand
 ;buttons=@Variant(\0\0\0\x7f\0\0\0\vQList<int>\0\0\0\0\x14\0\0\0\0\0\0\0\x1\0\0\0\x2\0\0\0\x3\0\0\0\x4\0\0\0\x5\0\0\0\x6\0\0\0\x12\0\0\0\xf\0\0\0\x13\0\0\0\a\0\0\0\b\0\0\0\t\0\0\0\x10\0\0\0\n\0\0\0\v\0\0\0\f\0\0\0\r\0\0\0\xe\0\0\0\x11)
-
+;
-; List of colors for color picker
+;; List of colors for color picker
-; The colors are arranged counter-clockwise with the first being set to the right of the cursor
+;; The colors are arranged counter-clockwise with the first being set to the right of the cursor
-; Colors are any valid hex code or W3C color name
+;; Colors are any valid hex code or W3C color name
-; "picker" adds a custom color picker
+;; "picker" adds a custom color picker
 ;userColors=#800000, #ff0000, #ffff00, #00ff00, #008000, #00ffff, #0000ff, #ff00ff, #800080, picker
-
+;
-; Image Save Path
+;; Image Save Path
-;savePath=
+;savePath=/tmp
-
+;
-; Whether the savePath is a fixed path (bool)
+;; Whether the savePath is a fixed path (bool)
 ;savePathFixed=false
-
+;
-; Main UI color
+;; Main UI color
-; Color is any valid hex code or W3C color name
+;; Color is any valid hex code or W3C color name
 ;uiColor=#740096
-
+;
-; Contrast UI color
+;; Contrast UI color
-; Color is any valid hex code or W3C color name
+;; Color is any valid hex code or W3C color name
 ;contrastUiColor=#270032
-
+;
-; Last used color
+;; Last used color
-; Color is any valid hex code or W3C color name
+;; Color is any valid hex code or W3C color name
-;drawColor=
+;drawColor=#ff0000
-
+;
-; Show the help screen on startup (bool)
+;; Show the help screen on startup (bool)
 ;showHelp=true
-
+;
-; Show the side panel button (bool)
+;; Show the side panel button (bool)
 ;showSidePanelButton=true
-
+;
-; Ignore updates to versions less than this value
+;; Ignore updates to versions less than this value
 ;ignoreUpdateToVersion=
-
+;
-; Show desktop notifications (bool)
+;; Show desktop notifications (bool)
 ;showDesktopNotification=true
-
+;
-; Filename pattern using C++ strftime formatting
+;; Filename pattern using C++ strftime formatting
 ;filenamePattern=%F_%H-%M
-
+;
-; Whether the tray icon is disabled (bool)
+;; Whether the tray icon is disabled (bool)
 ;disabledTrayIcon=false
-
+;
-; Last used tool thickness (int)
+;; Last used tool thickness (int)
-;drawThickness=0
+;drawThickness=1
-
+;
-; Keep the App Launcher open after selecting an app (bool)
+;; Keep the App Launcher open after selecting an app (bool)
 ;keepOpenAppLauncher=false
-
+;
-; Launch at startup (bool)
+;; Launch at startup (bool)
-;startupLaunch=
+;startupLaunch=true
-
+;
-; Opacity of area outside selection (int in range 0-255)
+;; Opacity of area outside selection (int in range 0-255)
 ;contrastOpacity=190
-
+;
-; Save image after copy (bool)
+;; Save image after copy (bool)
 ;saveAfterCopy=false
-
+;
-; Copy path to image after save (bool)
+;; Copy path to image after save (bool)
 ;copyPathAfterSave=false
-
+;
-; Use JPG format instead of PNG (bool)
+;; Use JPG format instead of PNG (bool)
 ;useJpgForClipboard=false
-
+;
-; Shortcut Settings for all tools
+;; Shortcut Settings for all tools
-[Shortcuts]
+;[Shortcuts]
 ;TYPE_ARROW=A
 ;TYPE_CIRCLE=C
 ;TYPE_CIRCLECOUNT=

src/config/buttonlistview.cpp

@@ -59,7 +59,7 @@ void ButtonListView::updateActiveButtons(QListWidgetItem* item)
                    CaptureToolButton::getPriorityByButton(b);
         });
     } else {
-        m_listButtons.remove(m_listButtons.indexOf(bType));
+        m_listButtons.removeOne(bType);
     }
     ConfigHandler().setButtons(m_listButtons);
 }
@@ -85,7 +85,7 @@ void ButtonListView::selectAll()
 
 void ButtonListView::updateComponents()
 {
-    m_listButtons = ConfigHandler().getButtons();
+    m_listButtons = ConfigHandler().buttons();
     auto listTypes = CaptureToolButton::getIterableButtonTypes();
     for (int i = 0; i < this->count(); ++i) {
         QListWidgetItem* item = this->item(i);

src/config/buttonlistview.h

@@ -22,7 +22,7 @@ protected:
     void initButtonList();
 
 private:
-    QVector<CaptureToolButton::ButtonType> m_listButtons;
+    QList<CaptureToolButton::ButtonType> m_listButtons;
     QMap<QString, CaptureToolButton::ButtonType> m_buttonTypeByName;
 
     void updateActiveButtons(QListWidgetItem*);

src/config/configwindow.cpp

@@ -11,10 +11,17 @@
 #include "src/utils/confighandler.h"
 #include "src/utils/globalvalues.h"
 #include "src/utils/pathinfo.h"
+#include <QApplication>
+#include <QDialog>
+#include <QDialogButtonBox>
 #include <QFileSystemWatcher>
 #include <QIcon>
 #include <QKeyEvent>
+#include <QLabel>
+#include <QSizePolicy>
 #include <QTabBar>
+#include <QTextEdit>
+#include <QTextStream>
 #include <QVBoxLayout>
 
 // ConfigWindow contains the menus where you can configure the application
@@ -24,25 +31,18 @@ ConfigWindow::ConfigWindow(QWidget* parent)
 {
     // We wrap QTabWidget in a QWidget because of a Qt bug
     auto layout = new QVBoxLayout(this);
-    m_tabs = new QTabWidget(this);
+    m_tabWidget = new QTabWidget(this);
-    m_tabs->tabBar()->setUsesScrollButtons(false);
+    m_tabWidget->tabBar()->setUsesScrollButtons(false);
-    layout->addWidget(m_tabs);
+    layout->addWidget(m_tabWidget);
 
     setAttribute(Qt::WA_DeleteOnClose);
     setWindowIcon(QIcon(":img/app/flameshot.svg"));
     setWindowTitle(tr("Configuration"));
 
-    auto changedSlot = [this](QString s) {
+    connect(ConfigHandler::getInstance(),
-        QStringList files = m_configWatcher->files();
+            &ConfigHandler::fileChanged,
-        if (!files.contains(s)) {
+            this,
-            this->m_configWatcher->addPath(s);
+            &ConfigWindow::updateChildren);
-        }
-        emit updateChildren();
-    };
-    m_configWatcher = new QFileSystemWatcher(this);
-    m_configWatcher->addPath(ConfigHandler().configFilePath());
-    connect(
-      m_configWatcher, &QFileSystemWatcher::fileChanged, this, changedSlot);
 
     QColor background = this->palette().window().color();
     bool isDark = ColorUtils::colorIsDark(background);
@@ -51,24 +51,40 @@ ConfigWindow::ConfigWindow(QWidget* parent)
 
     // visuals
     m_visuals = new VisualsEditor();
-    m_tabs->addTab(
+    m_visualsTab = new QWidget();
-      m_visuals, QIcon(modifier + "graphics.svg"), tr("Interface"));
+    QVBoxLayout* visualsLayout = new QVBoxLayout(m_visualsTab);
+    m_visualsTab->setLayout(visualsLayout);
+    visualsLayout->addWidget(m_visuals);
+    m_tabWidget->addTab(
+      m_visualsTab, QIcon(modifier + "graphics.svg"), tr("Interface"));
 
     // filename
     m_filenameEditor = new FileNameEditor();
-    m_tabs->addTab(m_filenameEditor,
+    m_filenameEditorTab = new QWidget();
-                   QIcon(modifier + "name_edition.svg"),
+    QVBoxLayout* filenameEditorLayout = new QVBoxLayout(m_filenameEditorTab);
-                   tr("Filename Editor"));
+    m_filenameEditorTab->setLayout(filenameEditorLayout);
+    filenameEditorLayout->addWidget(m_filenameEditor);
+    m_tabWidget->addTab(m_filenameEditorTab,
+                        QIcon(modifier + "name_edition.svg"),
+                        tr("Filename Editor"));
 
     // general
     m_generalConfig = new GeneralConf();
-    m_tabs->addTab(
+    m_generalConfigTab = new QWidget();
-      m_generalConfig, QIcon(modifier + "config.svg"), tr("General"));
+    QVBoxLayout* generalConfigLayout = new QVBoxLayout(m_generalConfigTab);
+    m_generalConfigTab->setLayout(generalConfigLayout);
+    generalConfigLayout->addWidget(m_generalConfig);
+    m_tabWidget->addTab(
+      m_generalConfigTab, QIcon(modifier + "config.svg"), tr("General"));
 
     // shortcuts
     m_shortcuts = new ShortcutsWidget();
-    m_tabs->addTab(
+    m_shortcutsTab = new QWidget();
-      m_shortcuts, QIcon(modifier + "shortcut.svg"), tr("Shortcuts"));
+    QVBoxLayout* shortcutsLayout = new QVBoxLayout(m_shortcutsTab);
+    m_shortcutsTab->setLayout(shortcutsLayout);
+    shortcutsLayout->addWidget(m_shortcuts);
+    m_tabWidget->addTab(
+      m_shortcutsTab, QIcon(modifier + "shortcut.svg"), tr("Shortcuts"));
 
     // connect update sigslots
     connect(this,
@@ -83,6 +99,12 @@ ConfigWindow::ConfigWindow(QWidget* parent)
             &ConfigWindow::updateChildren,
             m_generalConfig,
             &GeneralConf::updateComponents);
+
+    // Error indicator (this must come last)
+    initErrorIndicator(m_visualsTab, m_visuals);
+    initErrorIndicator(m_filenameEditorTab, m_filenameEditor);
+    initErrorIndicator(m_generalConfigTab, m_generalConfig);
+    initErrorIndicator(m_shortcutsTab, m_shortcuts);
 }
 
 void ConfigWindow::keyPressEvent(QKeyEvent* e)
@@ -91,3 +113,84 @@ void ConfigWindow::keyPressEvent(QKeyEvent* e)
         close();
     }
 }
+
+void ConfigWindow::initErrorIndicator(QWidget* tab, QWidget* widget)
+{
+    QLabel* label = new QLabel(tab);
+    QPushButton* btnShowErrors = new QPushButton("Show errors", tab);
+    QHBoxLayout* btnLayout = new QHBoxLayout(tab);
+
+    // Set up label
+    label->setText(tr(
+      "<b>Configuration file has errors. Resolve them before continuing.</b>"));
+    label->setStyleSheet(QStringLiteral(":disabled { color: %1; }")
+                           .arg(qApp->palette().color(QPalette::Text).name()));
+    label->setVisible(ConfigHandler().hasError());
+
+    // Set up "Show errors" button
+    btnShowErrors->setSizePolicy(QSizePolicy::Maximum, QSizePolicy::Fixed);
+    btnLayout->addWidget(btnShowErrors);
+    btnShowErrors->setVisible(ConfigHandler().hasError());
+
+    widget->setEnabled(!ConfigHandler().hasError());
+
+    // Add label and button to the parent widget's layout
+    QBoxLayout* layout = static_cast<QBoxLayout*>(tab->layout());
+    if (layout != nullptr) {
+        layout->insertWidget(0, label);
+        layout->insertLayout(1, btnLayout);
+    } else {
+        widget->layout()->addWidget(label);
+        widget->layout()->addWidget(btnShowErrors);
+    }
+
+    // Sigslots
+    connect(ConfigHandler::getInstance(), &ConfigHandler::error, widget, [=]() {
+        widget->setEnabled(false);
+        label->show();
+        btnShowErrors->show();
+    });
+    connect(ConfigHandler::getInstance(),
+            &ConfigHandler::errorResolved,
+            widget,
+            [=]() {
+                widget->setEnabled(true);
+                label->hide();
+                btnShowErrors->hide();
+            });
+    connect(btnShowErrors, &QPushButton::clicked, this, [this]() {
+        // Generate error log message
+        QString str;
+        QTextStream stream(&str);
+        ConfigHandler().checkForErrors(&stream);
+
+        // Set up dialog
+        QDialog dialog;
+        dialog.setWindowTitle(QStringLiteral("Configuration errors"));
+        dialog.setLayout(new QVBoxLayout(&dialog));
+
+        // Add text display
+        QTextEdit* textDisplay = new QTextEdit(&dialog);
+        textDisplay->setPlainText(str);
+        textDisplay->setReadOnly(true);
+        dialog.layout()->addWidget(textDisplay);
+
+        // Add Ok button
+        using BBox = QDialogButtonBox;
+        BBox* buttons = new BBox(BBox::Ok);
+        dialog.layout()->addWidget(buttons);
+        connect(buttons, &QDialogButtonBox::clicked, this, [&dialog]() {
+            dialog.close();
+        });
+
+        dialog.show();
+
+        qApp->processEvents();
+        QPoint center = dialog.geometry().center();
+        QRect dialogRect(0, 0, 400, 400);
+        dialogRect.moveCenter(center);
+        dialog.setGeometry(dialogRect);
+
+        dialog.exec();
+    });
+}

src/config/configwindow.h

@@ -10,6 +10,7 @@ class ShortcutsWidget;
 class GeneralConf;
 class QFileSystemWatcher;
 class VisualsEditor;
+class QWidget;
 
 class ConfigWindow : public QWidget
 {
@@ -24,10 +25,19 @@ protected:
     void keyPressEvent(QKeyEvent*);
 
 private:
-    QTabWidget* m_tabs;
+    QTabWidget* m_tabWidget;
+
     FileNameEditor* m_filenameEditor;
+    QWidget* m_filenameEditorTab;
+
     ShortcutsWidget* m_shortcuts;
+    QWidget* m_shortcutsTab;
+
     GeneralConf* m_generalConfig;
+    QWidget* m_generalConfigTab;
+
     VisualsEditor* m_visuals;
-    QFileSystemWatcher* m_configWatcher;
+    QWidget* m_visualsTab;
+
+    void initErrorIndicator(QWidget* tab, QWidget* widget);
 };

src/config/filenameeditor.cpp

@@ -103,7 +103,7 @@ void FileNameEditor::showParsedPattern(const QString& p)
 
 void FileNameEditor::resetName()
 {
-    m_nameEditor->setText(ConfigHandler().filenamePatternValue());
+    m_nameEditor->setText(ConfigHandler().filenamePattern());
 }
 
 void FileNameEditor::addToNameEditor(QString s)
@@ -114,6 +114,6 @@ void FileNameEditor::addToNameEditor(QString s)
 
 void FileNameEditor::updateComponents()
 {
-    m_nameEditor->setText(ConfigHandler().filenamePatternValue());
+    m_nameEditor->setText(ConfigHandler().filenamePattern());
     m_outputLabel->setText(m_nameHandler->parsedPattern());
 }

src/config/generalconf.cpp

@@ -42,7 +42,7 @@ GeneralConf::GeneralConf(QWidget* parent)
     initCopyPathAfterSave();
     initUseJpgForClipboard();
     initSaveAfterCopy();
-    initUploadHistoryMaxSize();
+    inituploadHistoryMax();
     initUndoLimit();
 
     m_layout->addStretch();
@@ -55,31 +55,27 @@ GeneralConf::GeneralConf(QWidget* parent)
 void GeneralConf::_updateComponents(bool allowEmptySavePath)
 {
     ConfigHandler config;
-    m_helpMessage->setChecked(config.showHelpValue());
+    m_helpMessage->setChecked(config.showHelp());
-    m_sidePanelButton->setChecked(config.showSidePanelButtonValue());
+    m_sidePanelButton->setChecked(config.showSidePanelButton());
-    m_sysNotifications->setChecked(config.desktopNotificationValue());
+    m_sysNotifications->setChecked(config.showDesktopNotification());
-    m_autostart->setChecked(config.startupLaunchValue());
+    m_autostart->setChecked(config.startupLaunch());
-    m_copyAndCloseAfterUpload->setChecked(
+    m_copyAndCloseAfterUpload->setChecked(config.copyAndCloseAfterUpload());
-      config.copyAndCloseAfterUploadEnabled());
+    m_saveAfterCopy->setChecked(config.saveAfterCopy());
-    m_saveAfterCopy->setChecked(config.saveAfterCopyValue());
+    m_copyPathAfterSave->setChecked(config.copyPathAfterSave());
-    m_copyPathAfterSave->setChecked(config.copyPathAfterSaveEnabled());
     m_useJpgForClipboard->setChecked(config.useJpgForClipboard());
     m_historyConfirmationToDelete->setChecked(
       config.historyConfirmationToDelete());
     m_checkForUpdates->setChecked(config.checkForUpdates());
     m_showStartupLaunchMessage->setChecked(config.showStartupLaunchMessage());
     m_screenshotPathFixedCheck->setChecked(config.savePathFixed());
-    m_uploadHistoryMaxSize->setValue(config.uploadHistoryMaxSizeValue());
+    m_uploadHistoryMax->setValue(config.uploadHistoryMax());
     m_undoLimit->setValue(config.undoLimit());
 
     if (allowEmptySavePath || !config.savePath().isEmpty()) {
         m_savePath->setText(config.savePath());
-    } else {
-        ConfigHandler().setSavePath(
-          QStandardPaths::writableLocation(QStandardPaths::PicturesLocation));
     }
 #if defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
-    m_showTray->setChecked(!config.disabledTrayIconValue());
+    m_showTray->setChecked(!config.disabledTrayIcon());
 #endif
 }
 
@@ -100,7 +96,7 @@ void GeneralConf::showSidePanelButtonChanged(bool checked)
 
 void GeneralConf::showDesktopNotificationChanged(bool checked)
 {
-    ConfigHandler().setDesktopNotification(checked);
+    ConfigHandler().setShowDesktopNotification(checked);
 }
 
 void GeneralConf::showTrayIconChanged(bool checked)
@@ -344,7 +340,7 @@ void GeneralConf::initCopyAndCloseAfterUpload()
     m_scrollAreaLayout->addWidget(m_copyAndCloseAfterUpload);
 
     connect(m_copyAndCloseAfterUpload, &QCheckBox::clicked, [](bool checked) {
-        ConfigHandler().setCopyAndCloseAfterUploadEnabled(checked);
+        ConfigHandler().setCopyAndCloseAfterUpload(checked);
     });
 }
 
@@ -368,10 +364,6 @@ void GeneralConf::initSaveAfterCopy()
     QHBoxLayout* pathLayout = new QHBoxLayout();
 
     QString path = ConfigHandler().savePath();
-    if (path.isEmpty()) {
-        path =
-          QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);
-    }
     m_savePath = new QLineEdit(path, this);
     m_savePath->setDisabled(true);
     QString foreground = this->palette().windowText().color().name();
@@ -401,7 +393,7 @@ void GeneralConf::historyConfirmationToDelete(bool checked)
     ConfigHandler().setHistoryConfirmationToDelete(checked);
 }
 
-void GeneralConf::initUploadHistoryMaxSize()
+void GeneralConf::inituploadHistoryMax()
 {
     QGroupBox* box = new QGroupBox(tr("Latest Uploads Max Size"));
     box->setFlat(true);
@@ -410,22 +402,22 @@ void GeneralConf::initUploadHistoryMaxSize()
     QVBoxLayout* vboxLayout = new QVBoxLayout();
     box->setLayout(vboxLayout);
 
-    m_uploadHistoryMaxSize = new QSpinBox(this);
+    m_uploadHistoryMax = new QSpinBox(this);
-    m_uploadHistoryMaxSize->setMaximum(50);
+    m_uploadHistoryMax->setMaximum(50);
     QString foreground = this->palette().windowText().color().name();
-    m_uploadHistoryMaxSize->setStyleSheet(
+    m_uploadHistoryMax->setStyleSheet(
       QStringLiteral("color: %1").arg(foreground));
 
-    connect(m_uploadHistoryMaxSize,
+    connect(m_uploadHistoryMax,
             SIGNAL(valueChanged(int)),
             this,
-            SLOT(uploadHistoryMaxSizeChanged(int)));
+            SLOT(uploadHistoryMaxChanged(int)));
-    vboxLayout->addWidget(m_uploadHistoryMaxSize);
+    vboxLayout->addWidget(m_uploadHistoryMax);
 }
 
-void GeneralConf::uploadHistoryMaxSizeChanged(int max)
+void GeneralConf::uploadHistoryMaxChanged(int max)
 {
-    ConfigHandler().setUploadHistoryMaxSize(max);
+    ConfigHandler().setUploadHistoryMax(max);
 }
 
 void GeneralConf::initUndoLimit()
@@ -479,10 +471,6 @@ void GeneralConf::saveAfterCopyChanged(bool checked)
 void GeneralConf::changeSavePath()
 {
     QString path = ConfigHandler().savePath();
-    if (path.isEmpty()) {
-        path =
-          QStandardPaths::writableLocation(QStandardPaths::PicturesLocation);
-    }
     path = chooseFolder(path);
     if (!path.isEmpty()) {
         m_savePath->setText(path);
@@ -496,7 +484,7 @@ void GeneralConf::initCopyPathAfterSave()
     m_copyPathAfterSave->setToolTip(tr("Copy file path after save"));
     m_scrollAreaLayout->addWidget(m_copyPathAfterSave);
     connect(m_copyPathAfterSave, &QCheckBox::clicked, [](bool checked) {
-        ConfigHandler().setCopyPathAfterSaveEnabled(checked);
+        ConfigHandler().setCopyPathAfterSave(checked);
     });
 }
 

src/config/generalconf.h

@@ -30,7 +30,7 @@ private slots:
     void checkForUpdatesChanged(bool checked);
     void autostartChanged(bool checked);
     void historyConfirmationToDelete(bool checked);
-    void uploadHistoryMaxSizeChanged(int max);
+    void uploadHistoryMaxChanged(int max);
     void undoLimit(int limit);
     void saveAfterCopyChanged(bool checked);
     void changeSavePath();
@@ -49,7 +49,7 @@ private:
     void initShowDesktopNotification();
     void initShowTrayIcon();
     void initHistoryConfirmationToDelete();
-    void initUploadHistoryMaxSize();
+    void inituploadHistoryMax();
     void initUndoLimit();
     void initConfigButtons();
     void initCheckForUpdates();
@@ -84,6 +84,6 @@ private:
     QCheckBox* m_screenshotPathFixedCheck;
     QCheckBox* m_historyConfirmationToDelete;
     QCheckBox* m_useJpgForClipboard;
-    QSpinBox* m_uploadHistoryMaxSize;
+    QSpinBox* m_uploadHistoryMax;
     QSpinBox* m_undoLimit;
 };

src/config/shortcutswidget.cpp

@@ -2,9 +2,9 @@
 // SPDX-FileCopyrightText: 2020 Yurii Puchkov at Namecheap & Contributors
 
 #include "shortcutswidget.h"
+#include "capturetool.h"
 #include "setshortcutwidget.h"
 #include "src/core/qguiappcurrentscreen.h"
-#include "src/utils/configshortcuts.h"
 #include <QHeaderView>
 #include <QIcon>
 #include <QKeyEvent>
@@ -37,13 +37,12 @@ ShortcutsWidget::ShortcutsWidget(QWidget* parent)
     m_layout = new QVBoxLayout(this);
     m_layout->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
 
-    m_shortcuts = ConfigShortcuts().captureShortcutsDefault(
+    initShortcuts();
-      CaptureToolButton::getIterableButtonTypes());
     initInfoTable();
     show();
 }
 
-const QVector<QStringList>& ShortcutsWidget::shortcuts()
+const QList<QStringList>& ShortcutsWidget::shortcuts()
 {
     return m_shortcuts;
 }
@@ -158,6 +157,71 @@ void ShortcutsWidget::slotShortcutCellClicked(int row, int col)
     }
 }
 
+void ShortcutsWidget::initShortcuts()
+{
+    auto buttons = CaptureToolButton::getIterableButtonTypes();
+
+    // get shortcuts names from capture buttons
+    for (const CaptureToolButton::ButtonType& t : buttons) {
+        CaptureToolButton* b = new CaptureToolButton(t, nullptr);
+        QString shortcutName = QVariant::fromValue(t).toString();
+        if (shortcutName != "TYPE_IMAGEUPLOADER") {
+            appendShortcut(shortcutName, b->tool()->description());
+        }
+        delete b;
+    }
+
+    // additional tools that don't have their own buttons
+    appendShortcut("TYPE_TOGGLE_PANEL", "Toggle side panel");
+    appendShortcut("TYPE_RESIZE_LEFT", "Resize selection left 1px");
+    appendShortcut("TYPE_RESIZE_RIGHT", "Resize selection right 1px");
+    appendShortcut("TYPE_RESIZE_UP", "Resize selection up 1px");
+    appendShortcut("TYPE_RESIZE_DOWN", "Resize selection down 1px");
+    appendShortcut("TYPE_SELECT_ALL", "Select entire screen");
+    appendShortcut("TYPE_MOVE_LEFT", "Move selection left 1px");
+    appendShortcut("TYPE_MOVE_RIGHT", "Move selection right 1px");
+    appendShortcut("TYPE_MOVE_UP", "Move selection up 1px");
+    appendShortcut("TYPE_MOVE_DOWN", "Move selection down 1px");
+    appendShortcut("TYPE_COMMIT_CURRENT_TOOL", "Commit text in text area");
+    appendShortcut("TYPE_DELETE_CURRENT_TOOL", "Delete current tool");
+
+    // non-editable shortcuts have an empty shortcut name
+
+    m_shortcuts << (QStringList() << "" << QObject::tr("Quit capture")
+                                  << QKeySequence(Qt::Key_Escape).toString());
+
+    // Global hotkeys
+#if defined(Q_OS_MACOS)
+    m_shortcuts << (QStringList()
+                    << "" << QObject::tr("Screenshot history") << "⇧⌘⌥H");
+    m_shortcuts << (QStringList()
+                    << "" << QObject::tr("Capture screen") << "⇧⌘⌥4");
+#elif defined(Q_OS_WIN)
+    m_shortcuts << (QStringList() << "" << QObject::tr("Screenshot history")
+                                  << "Shift+Print Screen");
+    m_shortcuts << (QStringList()
+                    << "" << QObject::tr("Capture screen") << "Print Screen");
+#else
+    // TODO - Linux doesn't support global shortcuts for (XServer and Wayland),
+    // possibly it will be solved in the QHotKey library later. So it is
+    // disabled for now.
+#endif
+    m_shortcuts << (QStringList()
+                    << "" << QObject::tr("Show color picker") << "Right Click");
+    m_shortcuts << (QStringList()
+                    << "" << QObject::tr("Change the tool's thickness")
+                    << "Mouse Wheel");
+}
+
+void ShortcutsWidget::appendShortcut(const QString& shortcutName,
+                                     const QString& description)
+{
+    m_shortcuts << (QStringList()
+                    << shortcutName
+                    << QObject::tr(description.toStdString().c_str())
+                    << ConfigHandler().shortcut(shortcutName));
+}
+
 #if defined(Q_OS_MACOS)
 const QString& ShortcutsWidget::nativeOSHotKeyText(const QString& text)
 {

src/config/shortcutswidget.h

@@ -18,7 +18,7 @@ class ShortcutsWidget : public QWidget
     Q_OBJECT
 public:
     explicit ShortcutsWidget(QWidget* parent = nullptr);
-    const QVector<QStringList>& shortcuts();
+    const QList<QStringList>& shortcuts();
 
 private:
     void initInfoTable();
@@ -38,7 +38,11 @@ private:
     ConfigHandler m_config;
     QTableWidget* m_table;
     QVBoxLayout* m_layout;
-    QVector<QStringList> m_shortcuts;
+    QList<QStringList> m_shortcuts;
+
+    void initShortcuts();
+    void appendShortcut(const QString& shortcutName,
+                        const QString& description);
 };
 
 #endif // HOTKEYSCONFIG_H

src/config/uicoloreditor.cpp

@@ -37,8 +37,8 @@ UIcolorEditor::UIcolorEditor(QWidget* parent)
 void UIcolorEditor::updateComponents()
 {
     ConfigHandler config;
-    m_uiColor = config.uiMainColorValue();
+    m_uiColor = config.uiColor();
-    m_contrastColor = config.uiContrastColorValue();
+    m_contrastColor = config.contrastUiColor();
     m_buttonContrast->setColor(m_contrastColor);
     m_buttonMainColor->setColor(m_uiColor);
     if (m_lastButtonPressed == m_buttonMainColor) {
@@ -53,9 +53,9 @@ void UIcolorEditor::updateUIcolor()
 {
     ConfigHandler config;
     if (m_lastButtonPressed == m_buttonMainColor) {
-        config.setUIMainColor(m_uiColor);
+        config.setUiColor(m_uiColor);
     } else {
-        config.setUIContrastColor(m_contrastColor);
+        config.setContrastUiColor(m_contrastColor);
     }
 }
 

src/config/visualseditor.cpp

@@ -21,7 +21,7 @@ void VisualsEditor::updateComponents()
 {
     m_buttonList->updateComponents();
     m_colorEditor->updateComponents();
-    int opacity = ConfigHandler().contrastOpacityValue();
+    int opacity = ConfigHandler().contrastOpacity();
     m_opacitySlider->setMapedValue(0, opacity, 255);
 }
 
@@ -50,7 +50,7 @@ void VisualsEditor::initOpacitySlider()
     m_layout->addWidget(label);
     m_layout->addLayout(localLayout);
 
-    int opacity = ConfigHandler().contrastOpacityValue();
+    int opacity = ConfigHandler().contrastOpacity();
     m_opacitySlider->setMapedValue(0, opacity, 255);
 }
 

src/core/controller.cpp

@@ -66,7 +66,7 @@ Controller::Controller()
 
     // init tray icon
 #if defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
-    if (!ConfigHandler().disabledTrayIconValue()) {
+    if (!ConfigHandler().disabledTrayIcon()) {
         enableTrayIcon();
     }
 #elif defined(Q_OS_WIN)

src/main.cpp

@@ -165,6 +165,8 @@ int main(int argc, char* argv[])
       { "a", "autostart" },
       QObject::tr("Enable or disable run at startup"),
       QStringLiteral("bool"));
+    CommandOption checkOption(
+      "check", QObject::tr("Check the configuration for errors"));
     CommandOption showHelpOption(
       { "s", "showhelp" },
       QObject::tr("Show the help message in the capture mode"),
@@ -270,7 +272,8 @@ int main(int argc, char* argv[])
                         trayOption,
                         showHelpOption,
                         mainColorOption,
-                        contrastColorOption },
+                        contrastColorOption,
+                        checkOption },
                       configArgument);
     // Parse
     if (!parser.parse(app.arguments())) {
@@ -447,8 +450,19 @@ int main(int argc, char* argv[])
         bool help = parser.isSet(showHelpOption);
         bool mainColor = parser.isSet(mainColorOption);
         bool contrastColor = parser.isSet(contrastColorOption);
+        bool check = parser.isSet(checkOption);
         bool someFlagSet =
-          (filename || tray || help || mainColor || contrastColor);
+          (filename || tray || help || mainColor || contrastColor || check);
+        if (check) {
+            QTextStream stream(stderr);
+            bool ok = ConfigHandler(true).checkForErrors(&stream);
+            if (ok) {
+                stream << QStringLiteral("No errors detected.\n");
+                goto finish;
+            } else {
+                return 1;
+            }
+        }
         ConfigHandler config;
         if (autostart) {
             QDBusMessage m = QDBusMessage::createMethodCall(
@@ -506,12 +520,12 @@ int main(int argc, char* argv[])
         if (mainColor) {
             QString colorCode = parser.value(mainColorOption);
             QColor parsedColor(colorCode);
-            config.setUIMainColor(parsedColor);
+            config.setUiColor(parsedColor);
         }
         if (contrastColor) {
             QString colorCode = parser.value(contrastColorOption);
             QColor parsedColor(colorCode);
-            config.setUIContrastColor(parsedColor);
+            config.setContrastUiColor(parsedColor);
         }
 
         // Open gui when no options

src/tools/imgur/imguruploader.cpp

@@ -47,7 +47,7 @@ ImgurUploader::ImgurUploader(const QPixmap& capture, QWidget* parent)
 #endif
 
     m_spinner = new LoadSpinner(this);
-    m_spinner->setColor(ConfigHandler().uiMainColorValue());
+    m_spinner->setColor(ConfigHandler().uiColor());
     m_spinner->start();
 
     m_infoLabel = new QLabel(tr("Uploading Image"));
@@ -94,7 +94,7 @@ void ImgurUploader::handleReply(QNetworkReply* reply)
         imageName = history.packFileName("imgur", deleteToken, imageName);
         history.save(m_pixmap, imageName);
 
-        if (ConfigHandler().copyAndCloseAfterUploadEnabled()) {
+        if (ConfigHandler().copyAndCloseAfterUpload()) {
             SystemNotification().sendMessage(
               QObject::tr("URL copied to clipboard."));
             QApplication::clipboard()->setText(m_imageURL.toString());

src/tools/launcher/applauncherwidget.cpp

@@ -42,7 +42,7 @@ AppLauncherWidget::AppLauncherWidget(const QPixmap& p, QWidget* parent)
     setWindowIcon(QIcon(":img/app/flameshot.svg"));
     setWindowTitle(tr("Open With"));
 
-    m_keepOpen = ConfigHandler().keepOpenAppLauncherValue();
+    m_keepOpen = ConfigHandler().keepOpenAppLauncher();
 
     QString dirLocal = QDir::homePath() + "/.local/share/applications/";
     QDir appsDirLocal(dirLocal);
@@ -57,7 +57,7 @@ AppLauncherWidget::AppLauncherWidget(const QPixmap& p, QWidget* parent)
 
     m_terminalCheckbox = new QCheckBox(tr("Launch in terminal"), this);
     m_keepOpenCheckbox = new QCheckBox(tr("Keep open after selection"), this);
-    m_keepOpenCheckbox->setChecked(ConfigHandler().keepOpenAppLauncherValue());
+    m_keepOpenCheckbox->setChecked(ConfigHandler().keepOpenAppLauncher());
     connect(m_keepOpenCheckbox,
             &QCheckBox::clicked,
             this,

src/tools/pin/pinwidget.cpp

@@ -19,8 +19,8 @@ PinWidget::PinWidget(const QPixmap& pixmap, QWidget* parent)
     setAttribute(Qt::WA_TranslucentBackground);
 
     ConfigHandler conf;
-    m_baseColor = conf.uiMainColorValue();
+    m_baseColor = conf.uiColor();
-    m_hoverColor = conf.uiContrastColorValue();
+    m_hoverColor = conf.contrastUiColor();
 
     m_layout = new QVBoxLayout(this);
     const int margin = this->margin();

src/utils/CMakeLists.txt

@@ -5,7 +5,7 @@ target_sources(
           filenamehandler.h
           screengrabber.h
           systemnotification.h
-          configshortcuts.h
+          valuehandler.h
           request.h
           strfparse.h
 )
@@ -16,6 +16,7 @@ target_sources(
           screengrabber.cpp
           confighandler.cpp
           systemnotification.cpp
+          valuehandler.cpp
           screenshotsaver.cpp
           dbusutils.cpp
           globalvalues.cpp
@@ -24,7 +25,6 @@ target_sources(
           pathinfo.cpp
           colorutils.cpp
           history.cpp
-          configshortcuts.cpp
           strfparse.cpp
         request.cpp
 )

src/utils/confighandler.h

@@ -9,121 +9,141 @@
 #include <QVariant>
 #include <QVector>
 
-class ConfigHandler
+class QFileSystemWatcher;
+class ValueHandler;
+template<class T>
+class QSharedPointer;
+class QTextStream;
+
+/**
+ * Declare and implement a getter for a config option. `KEY` is the option key
+ * as it appears in the config file, `TYPE` is the C++ type. At the same time
+ * `KEY` is the name of the generated getter function.
+ */
+#define CONFIG_GETTER(KEY, TYPE)                                               \
+    TYPE KEY() { return value(QStringLiteral(#KEY)).value<TYPE>(); }
+
+/**
+ * Declare and implement a setter for a config option. `FUNC` is the name of the
+ * generated function, `KEY` is the option key as it appears in the config file
+ * and `TYPE` is the C++ type.
+ */
+#define CONFIG_SETTER(FUNC, KEY, TYPE)                                         \
+    void FUNC(const TYPE& value)                                               \
+    {                                                                          \
+        setValue(QStringLiteral(#KEY), QVariant::fromValue(value));            \
+    }
+
+/**
+ * Combines the functionality of `CONFIG_GETTER` and `CONFIG_SETTER`. `GETFUNC`
+ * is simultaneously the name of the getter function and the option key as it
+ * appears in the config file. `SETFUNC` is the name of the setter function.
+ * `TYPE` is the C++ type of the value.
+ */
+#define CONFIG_GETTER_SETTER(GETFUNC, SETFUNC, TYPE)                           \
+    CONFIG_GETTER(GETFUNC, TYPE)                                               \
+    CONFIG_SETTER(SETFUNC, GETFUNC, TYPE)
+
+class ConfigHandler : public QObject
 {
+    Q_OBJECT
+
 public:
-    explicit ConfigHandler();
+    explicit ConfigHandler(bool skipInitialErrorCheck = false);
 
-    QVector<CaptureToolButton::ButtonType> getButtons();
+    static ConfigHandler* getInstance();
-    void setButtons(const QVector<CaptureToolButton::ButtonType>&);
 
-    QVector<QColor> getUserColors();
+    // Definitions of getters and setters for config options
+    // Some special cases are implemented regularly, without the macro
+    // NOTE: When adding new options, make sure to add an entry in
+    // recognizedGeneralOptions in the cpp file.
+    CONFIG_GETTER_SETTER(userColors, setUserColors, QVector<QColor>);
+    CONFIG_GETTER_SETTER(savePath, setSavePath, QString)
+    CONFIG_GETTER_SETTER(savePathFixed, setSavePathFixed, bool)
+    CONFIG_GETTER_SETTER(uiColor, setUiColor, QColor)
+    CONFIG_GETTER_SETTER(contrastUiColor, setContrastUiColor, QColor)
+    CONFIG_GETTER_SETTER(drawColor, setDrawColor, QColor)
+    CONFIG_GETTER_SETTER(fontFamily, setFontFamily, QString)
+    CONFIG_GETTER_SETTER(showHelp, setShowHelp, bool)
+    CONFIG_GETTER_SETTER(showSidePanelButton, setShowSidePanelButton, bool)
+    CONFIG_GETTER_SETTER(showDesktopNotification,
+                         setShowDesktopNotification,
+                         bool)
+    CONFIG_GETTER_SETTER(filenamePattern, setFilenamePattern, QString)
+    CONFIG_GETTER_SETTER(disabledTrayIcon, setDisabledTrayIcon, bool)
+    CONFIG_GETTER_SETTER(drawThickness, setDrawThickness, int)
+    CONFIG_GETTER_SETTER(drawFontSize, setDrawFontSize, int)
+    CONFIG_GETTER_SETTER(keepOpenAppLauncher, setKeepOpenAppLauncher, bool)
+    CONFIG_GETTER_SETTER(checkForUpdates, setCheckForUpdates, bool)
+    CONFIG_GETTER_SETTER(showStartupLaunchMessage,
+                         setShowStartupLaunchMessage,
+                         bool)
+    CONFIG_GETTER_SETTER(contrastOpacity, setContrastOpacity, int)
+    CONFIG_GETTER_SETTER(copyAndCloseAfterUpload,
+                         setCopyAndCloseAfterUpload,
+                         bool)
+    CONFIG_GETTER_SETTER(historyConfirmationToDelete,
+                         setHistoryConfirmationToDelete,
+                         bool)
+    CONFIG_GETTER_SETTER(uploadHistoryMax, setUploadHistoryMax, int)
+    CONFIG_GETTER_SETTER(saveAfterCopy, setSaveAfterCopy, bool)
+    CONFIG_GETTER_SETTER(copyPathAfterSave, setCopyPathAfterSave, bool)
+    CONFIG_GETTER_SETTER(useJpgForClipboard, setUseJpgForClipboard, bool)
+    CONFIG_GETTER_SETTER(ignoreUpdateToVersion,
+                         setIgnoreUpdateToVersion,
+                         QString)
+    CONFIG_GETTER_SETTER(undoLimit, setUndoLimit, int)
+    CONFIG_GETTER_SETTER(buttons,
+                         setButtons,
+                         QList<CaptureToolButton::ButtonType>)
 
-    QString savePath();
+    // SPECIAL CASES
-    void setSavePath(const QString&);
+    bool startupLaunch();
-
-    bool savePathFixed();
-    void setSavePathFixed(bool);
-
-    QColor uiMainColorValue();
-    void setUIMainColor(const QColor&);
-
-    QColor uiContrastColorValue();
-    void setUIContrastColor(const QColor&);
-
-    QColor drawColorValue();
-    void setDrawColor(const QColor&);
-
-    void setFontFamily(const QString&);
-    const QString& fontFamily();
-
-    bool showHelpValue();
-    void setShowHelp(const bool);
-
-    bool showSidePanelButtonValue();
-    void setShowSidePanelButton(const bool);
-
-    bool desktopNotificationValue();
-    void setDesktopNotification(const bool);
-
-    QString filenamePatternDefault();
-    QString filenamePatternValue();
-    void setFilenamePattern(const QString&);
-
-    bool disabledTrayIconValue();
-    void setDisabledTrayIcon(const bool);
-
-    int drawThicknessValue();
-    void setDrawThickness(const int);
-
-    int drawFontSizeValue();
-    void setDrawFontSize(const int);
-
-    bool keepOpenAppLauncherValue();
-    void setKeepOpenAppLauncher(const bool);
-
-    bool checkForUpdates();
-    void setCheckForUpdates(const bool);
-
-    bool verifyLaunchFile();
-    bool startupLaunchValue();
     void setStartupLaunch(const bool);
-
+    QString saveAsFileExtension();
-    bool showStartupLaunchMessage();
+    CONFIG_SETTER(setSaveAsFileExtension, setSaveAsFileExtension, QString)
-    void setShowStartupLaunchMessage(const bool);
-
-    int contrastOpacityValue();
-    void setContrastOpacity(const int);
-
-    bool copyAndCloseAfterUploadEnabled();
-    void setCopyAndCloseAfterUploadEnabled(const bool);
-
-    bool historyConfirmationToDelete();
-    void setHistoryConfirmationToDelete(const bool save);
-
-    int uploadHistoryMaxSizeValue();
-    void setUploadHistoryMaxSize(const int);
-
-    bool saveAfterCopyValue();
-    void setSaveAfterCopy(const bool);
-
-    bool copyPathAfterSaveEnabled();
-    void setCopyPathAfterSaveEnabled(const bool);
-
-    bool useJpgForClipboard() const;
-    void setUseJpgForClipboard(const bool);
-    void setSaveAsFileExtension(const QString& extension);
-    QString getSaveAsFileExtension();
-
-    void setDefaultSettings();
     void setAllTheButtons();
 
-    void setIgnoreUpdateToVersion(const QString& text);
+    // DEFAULTS
-    QString ignoreUpdateToVersion();
+    QString filenamePatternDefault();
-
+    void setDefaultSettings();
-    void setUndoLimit(int value);
-    int undoLimit();
-
-    bool setShortcut(const QString&, const QString&);
-    const QString& shortcut(const QString&);
-
     QString configFilePath() const;
 
-    void setValue(const QString& group,
+    // GENERIC GETTERS AND SETTERS
-                  const QString& key,
+    bool setShortcut(const QString&, const QString&);
-                  const QVariant& value);
+    QString shortcut(const QString&);
-    QVariant& value(const QString& group, const QString& key);
+    void setValue(const QString& key, const QVariant& value);
+    QVariant value(const QString& key) const;
+
+    // INFO
+    const QSet<QString>& recognizedGeneralOptions() const;
+    const QSet<QString>& recognizedShortcutNames() const;
+    QSet<QString> keysFromGroup(const QString& group) const;
+
+    // ERROR HANDLING
+    bool checkForErrors(QTextStream* log = nullptr) const;
+    bool checkUnrecognizedSettings(QTextStream* log = nullptr) const;
+    bool checkShortcutConflicts(QTextStream* log = nullptr) const;
+    bool checkSemantics(QTextStream* log = nullptr) const;
+    void checkAndHandleError() const;
+    void setErrorState(bool error) const;
+    bool hasError() const;
+    QString errorMessage() const;
+
+signals:
+    void error() const;
+    void errorResolved() const;
+    void fileChanged() const;
 
 private:
-    QString m_strRes;
+    mutable QSettings m_settings;
-    QVariant m_varRes;
-    QSettings m_settings;
-    QVector<QStringList> m_shortcuts;
 
-    bool normalizeButtons(QVector<int>&);
+    static bool m_hasError, m_errorCheckPending, m_skipNextErrorCheck;
+    static QSharedPointer<QFileSystemWatcher> m_configWatcher;
 
-    QVector<CaptureToolButton::ButtonType> fromIntToButton(
+    void ensureFileWatched() const;
-      const QVector<int>& l);
+    QSharedPointer<ValueHandler> valueHandler(const QString& key) const;
-    QVector<int> fromButtonToInt(
+    void assertKeyRecognized(const QString& key) const;
-      const QVector<CaptureToolButton::ButtonType>& l);
+    bool isShortcut(const QString& key) const;
+    QString baseName(QString key) const;
 };

src/utils/configshortcuts.h

@@ -1,26 +0,0 @@
-#ifndef CONFIGSHORTCUTS_H
-#define CONFIGSHORTCUTS_H
-
-#include "src/widgets/capture/capturetoolbutton.h"
-#include <QKeySequence>
-#include <QString>
-#include <QStringList>
-#include <QVector>
-
-class ConfigShortcuts
-{
-public:
-    ConfigShortcuts();
-
-    const QVector<QStringList>& captureShortcutsDefault(
-      const QVector<CaptureToolButton::ButtonType>& buttons);
-    const QKeySequence& captureShortcutDefault(const QString& buttonType);
-
-private:
-    QVector<QStringList> m_shortcuts;
-    QKeySequence m_ks;
-
-    void addShortcut(const QString& shortcutName, const QString& description);
-};
-
-#endif // CONFIGSHORTCUTS_H

src/utils/filenamehandler.cpp

@@ -27,7 +27,7 @@ FileNameHandler::FileNameHandler(QObject* parent)
 
 QString FileNameHandler::parsedPattern()
 {
-    return parseFilename(ConfigHandler().filenamePatternValue());
+    return parseFilename(ConfigHandler().filenamePattern());
 }
 
 QString FileNameHandler::parseFilename(const QString& name)

src/utils/history.cpp

@@ -57,7 +57,7 @@ const QList<QString>& History::history()
                                              QDir::Files,
                                              QDir::Time);
     int cnt = 0;
-    int max = ConfigHandler().uploadHistoryMaxSizeValue();
+    int max = ConfigHandler().uploadHistoryMax();
     m_thumbs.clear();
     foreach (QString fileName, images) {
         if (++cnt <= max) {

src/utils/screenshotsaver.cpp

@@ -58,7 +58,7 @@ void ScreenshotSaver::saveToClipboard(const QPixmap& capture)
 {
     // If we are able to properly save the file, save the file and copy to
     // clipboard.
-    if ((ConfigHandler().saveAfterCopyValue()) &&
+    if ((ConfigHandler().saveAfterCopy()) &&
         (!ConfigHandler().savePath().isEmpty())) {
         saveToFilesystem(capture,
                          ConfigHandler().savePath(),
@@ -126,7 +126,7 @@ QString ScreenshotSaver::ShowSaveFileDialog(QWidget* parent,
         mimeTypeList.append(mimeType);
     dialog.setMimeTypeFilters(mimeTypeList);
 
-    QString suffix = ConfigHandler().getSaveAsFileExtension();
+    QString suffix = ConfigHandler().saveAsFileExtension();
     QString defaultMimeType =
       QMimeDatabase().mimeTypeForFile("image" + suffix).name();
     dialog.selectMimeTypeFilter(defaultMimeType);
@@ -179,7 +179,7 @@ bool ScreenshotSaver::saveToFilesystemGUI(const QPixmap& capture)
 
         QString msg = QObject::tr("Capture saved as ") + savePath;
 
-        if (config.copyPathAfterSaveEnabled()) {
+        if (config.copyPathAfterSave()) {
             msg =
               QObject::tr("Capture is saved and copied to the clipboard as ") +
               savePath;
@@ -190,7 +190,7 @@ bool ScreenshotSaver::saveToFilesystemGUI(const QPixmap& capture)
         Controller::getInstance()->sendCaptureSaved(
           m_id, QFileInfo(savePath).canonicalFilePath());
 
-        if (config.copyPathAfterSaveEnabled()) {
+        if (config.copyPathAfterSave()) {
             QApplication::clipboard()->setText(savePath);
         }
 

src/utils/systemnotification.cpp

@@ -35,7 +35,7 @@ void SystemNotification::sendMessage(const QString& text,
                                      const QString& savePath,
                                      const int timeout)
 {
-    if (!ConfigHandler().desktopNotificationValue()) {
+    if (!ConfigHandler().showDesktopNotification()) {
         return;
     }
 

src/utils/valuehandler.cpp

@@ -0,0 +1,413 @@
+#include "valuehandler.h"
+#include "confighandler.h"
+#include <QColor>
+#include <QFileInfo>
+#include <QStandardPaths>
+#include <QVariant>
+
+// VALUE HANDLER
+
+QVariant ValueHandler::value(const QVariant& val)
+{
+    if (!val.isValid() || !check(val)) {
+        return fallback();
+    } else {
+        return process(val);
+    }
+}
+
+QVariant ValueHandler::fallback()
+{
+    return QVariant();
+}
+
+QVariant ValueHandler::representation(const QVariant& val)
+{
+    return val.toString();
+}
+
+QString ValueHandler::expected()
+{
+    return {};
+}
+
+QVariant ValueHandler::process(const QVariant& val)
+{
+    return val;
+}
+
+// BOOL
+
+Bool::Bool(bool def)
+  : m_def(def)
+{}
+
+bool Bool::check(const QVariant& val)
+{
+    QString str = val.toString();
+    if (str != "true" && str != "false") {
+        return false;
+    }
+    return true;
+}
+
+QVariant Bool::fallback()
+{
+    return m_def;
+}
+
+QString Bool::expected()
+{
+    return QStringLiteral("true or false");
+}
+
+// STRING
+
+String::String(const QString& def)
+  : m_def(def)
+{}
+
+bool String::check(const QVariant&)
+{
+    return true;
+}
+
+QVariant String::fallback()
+{
+    return m_def;
+}
+
+QString String::expected()
+{
+    return QStringLiteral("string");
+}
+
+// COLOR
+
+Color::Color(const QColor& def)
+  : m_def(def)
+{}
+
+bool Color::check(const QVariant& val)
+{
+    QString str = val.toString();
+    // Disable #RGB, #RRRGGGBBB and #RRRRGGGGBBBB formats that QColor supports
+    return QColor::isValidColor(str) &&
+           (str[0] != '#' ||
+            (str.length() != 4 && str.length() != 10 && str.length() != 13));
+}
+
+QVariant Color::process(const QVariant& val)
+{
+    QString str = val.toString();
+    QColor color(str);
+    if (str.length() == 9 && str[0] == '#') {
+        // Convert #RRGGBBAA (flameshot) to #AARRGGBB (QColor)
+        int blue = color.blue();
+        color.setBlue(color.green());
+        color.setGreen(color.red());
+        color.setRed(color.alpha());
+        color.setAlpha(blue);
+    }
+    return color;
+}
+
+QVariant Color::fallback()
+{
+    return m_def;
+}
+
+QVariant Color::representation(const QVariant& val)
+{
+    QString str = val.toString();
+    QColor color(str);
+    if (str.length() == 9 && str[0] == '#') {
+        // Convert #AARRGGBB (QColor) to #RRGGBBAA (flameshot)
+        int alpha = color.alpha();
+        color.setAlpha(color.red());
+        color.setRed(color.green());
+        color.setGreen(color.blue());
+        color.setBlue(alpha);
+    }
+    return color.name();
+}
+
+QString Color::expected()
+{
+    return QStringLiteral("color name or hex value");
+}
+
+// BOUNDED INT
+
+BoundedInt::BoundedInt(int min, int max, int def)
+  : m_min(min)
+  , m_max(max)
+  , m_def(def)
+{}
+
+bool BoundedInt::check(const QVariant& val)
+{
+    QString str = val.toString();
+    bool conversionOk;
+    int num = str.toInt(&conversionOk);
+    return conversionOk && (m_max < m_min || num <= m_max);
+}
+
+QVariant BoundedInt::fallback()
+{
+    return m_def;
+}
+
+QString BoundedInt::expected()
+{
+    return QStringLiteral("number between %1 and %2").arg(m_min).arg(m_max);
+}
+
+// LOWER BOUNDED INT
+
+LowerBoundedInt::LowerBoundedInt(int min, int def)
+  : m_min(min)
+  , m_def(def)
+{}
+
+bool LowerBoundedInt::check(const QVariant& val)
+{
+    QString str = val.toString();
+    bool conversionOk;
+    int num = str.toInt(&conversionOk);
+    return conversionOk && num >= m_min;
+}
+
+QVariant LowerBoundedInt::fallback()
+{
+    return m_def;
+}
+
+QString LowerBoundedInt::expected()
+{
+    return QStringLiteral("number >= %1").arg(m_min);
+}
+
+// KEY SEQUENCE
+
+KeySequence::KeySequence(const QKeySequence& fallback)
+  : m_fallback(fallback)
+{}
+
+bool KeySequence::check(const QVariant& val)
+{
+    QString str = val.toString();
+    if (!str.isEmpty() && QKeySequence(str).toString().isEmpty()) {
+        return false;
+    }
+    return true;
+}
+
+QVariant KeySequence::fallback()
+{
+    return m_fallback;
+}
+
+QString KeySequence::expected()
+{
+    return QStringLiteral("keyboard shortcut");
+}
+
+// EXISTING DIR
+
+bool ExistingDir::check(const QVariant& val)
+{
+    if (!val.canConvert(QVariant::String) || val.toString().isEmpty()) {
+        return false;
+    }
+    QFileInfo info(val.toString());
+    return info.isDir() && info.exists();
+}
+
+QVariant ExistingDir::fallback()
+{
+    using SP = QStandardPaths;
+    for (auto location :
+         { SP::PicturesLocation, SP::HomeLocation, SP::TempLocation }) {
+        QString path = SP::writableLocation(location);
+        if (QFileInfo(path).isDir()) {
+            return path;
+        }
+    }
+    return {};
+}
+
+QString ExistingDir::expected()
+{
+    return QStringLiteral("existing directory");
+}
+
+// FILENAME PATTERN
+
+bool FilenamePattern::check(const QVariant&)
+{
+    return true;
+}
+
+QVariant FilenamePattern::fallback()
+{
+    return ConfigHandler().filenamePatternDefault();
+}
+
+QVariant FilenamePattern::process(const QVariant& val)
+{
+    QString str = val.toString();
+    return !str.isEmpty() ? val : fallback();
+}
+
+QString FilenamePattern::expected()
+{
+    return QStringLiteral("please edit using the GUI");
+}
+
+// BUTTON LIST
+
+using BType = CaptureToolButton::ButtonType;
+using BList = QList<BType>;
+
+bool ButtonList::check(const QVariant& val)
+{
+    using CTB = CaptureToolButton;
+    auto allButtons = CTB::getIterableButtonTypes();
+    for (int btn : val.value<QList<int>>()) {
+        if (!allButtons.contains(static_cast<CTB::ButtonType>(btn))) {
+            return false;
+        }
+    }
+    return true;
+}
+
+// Helper
+void sortButtons(BList& buttons)
+{
+    std::sort(buttons.begin(), buttons.end(), [](BType a, BType b) {
+        return CaptureToolButton::getPriorityByButton(a) <
+               CaptureToolButton::getPriorityByButton(b);
+    });
+}
+
+QVariant ButtonList::process(const QVariant& val)
+{
+    QList<int> intButtons = val.value<QList<int>>();
+    auto buttons = ButtonList::fromIntList(intButtons);
+    sortButtons(buttons);
+    return QVariant::fromValue(buttons);
+}
+
+QVariant ButtonList::fallback()
+{
+    auto buttons = CaptureToolButton::getIterableButtonTypes();
+    buttons.removeOne(CaptureToolButton::TYPE_SIZEDECREASE);
+    buttons.removeOne(CaptureToolButton::TYPE_SIZEINCREASE);
+    sortButtons(buttons);
+    return QVariant::fromValue(buttons);
+}
+
+QVariant ButtonList::representation(const QVariant& val)
+{
+    auto intList = toIntList(val.value<BList>());
+    normalizeButtons(intList);
+    return QVariant::fromValue(intList);
+}
+
+QString ButtonList::expected()
+{
+    return QStringLiteral("please don't edit by hand");
+}
+
+QList<CaptureToolButton::ButtonType> ButtonList::fromIntList(
+  const QList<int>& l)
+{
+    QList<CaptureToolButton::ButtonType> buttons;
+    buttons.reserve(l.size());
+    for (auto const i : l)
+        buttons << static_cast<CaptureToolButton::ButtonType>(i);
+    return buttons;
+}
+
+QList<int> ButtonList::toIntList(const QList<CaptureToolButton::ButtonType>& l)
+{
+    QList<int> buttons;
+    buttons.reserve(l.size());
+    for (auto const i : l)
+        buttons << static_cast<int>(i);
+    return buttons;
+}
+
+bool ButtonList::normalizeButtons(QList<int>& buttons)
+{
+    QList<int> listTypesInt =
+      toIntList(CaptureToolButton::getIterableButtonTypes());
+
+    bool hasChanged = false;
+    for (int i = 0; i < buttons.size(); i++) {
+        if (!listTypesInt.contains(buttons.at(i))) {
+            buttons.removeAt(i);
+            hasChanged = true;
+        }
+    }
+    return hasChanged;
+}
+
+// USER COLORS
+
+bool UserColors::check(const QVariant& val)
+{
+    if (!val.isValid()) {
+        return true;
+    }
+    if (!val.canConvert(QVariant::StringList)) {
+        return false;
+    }
+    for (const QString& str : val.toStringList()) {
+        if (!QColor::isValidColor(str) && str != "picker") {
+            return false;
+        }
+    }
+    return true;
+}
+
+QVariant UserColors::process(const QVariant& val)
+{
+    QStringList strColors = val.toStringList();
+    if (strColors.isEmpty()) {
+        return fallback();
+    }
+
+    QVector<QColor> colors;
+    colors.reserve(strColors.size());
+
+    for (const QString& str : strColors) {
+        if (str != "picker") {
+            colors.append(QColor(str));
+        } else {
+            colors.append(QColor());
+        }
+    }
+
+    return QVariant::fromValue(colors);
+}
+
+QVariant UserColors::fallback()
+{
+    return QVariant::fromValue(QVector<QColor>{ Qt::darkRed,
+                                                Qt::red,
+                                                Qt::yellow,
+                                                Qt::green,
+                                                Qt::darkGreen,
+                                                Qt::cyan,
+                                                Qt::blue,
+                                                Qt::magenta,
+                                                Qt::darkMagenta,
+                                                QColor() });
+}
+
+QString UserColors::expected()
+{
+    return QStringLiteral("list of colors separated by comma");
+}

src/utils/valuehandler.h

@@ -0,0 +1,197 @@
+#pragma once
+
+#include "src/widgets/capture/capturetoolbutton.h"
+
+#include <QColor>
+#include <QList>
+#include <QString>
+
+class QVariant;
+
+/**
+ * @brief Handles the value of a configuration option (abstract class).
+ *
+ * Each configuration option is represented as a `QVariant`. If the option was
+ * not specified in a config file, the `QVariant` will be invalid.
+ *
+ * Each option will usually be handled in three different ways:
+ * - have its value checked for semantic errors (type, format, etc).
+ *   @see ValueHandler::check
+ * - have its value (that was taken from the config file) adapted for proper
+ * use.
+ *   @see ValueHandler::value
+ * - provided a fallback value in case: the config does not explicitly specify
+ *   it, or the config contains an error and is globally falling back to
+ *   defaults.
+ *   @see ValueHandler::fallback.
+ * - some options may want to be stored in the config file in a different way
+ *   than the default one provided by `QVariant`.
+ *   @see ValueHandler::representation
+ *
+ * @note Please see the documentation of the functions to learn when you should
+ * override each.
+ *
+ */
+class ValueHandler
+{
+public:
+    /**
+     * @brief Check the value semantically.
+     * @param val The value that was read from the config file
+     * @return Whether the value is correct
+     * @note The function should presume that `val.isValid()` is true.
+     */
+    virtual bool check(const QVariant& val) = 0;
+    /**
+     * @brief Adapt the value for proper use.
+     * @param val The value that was read from the config file
+     * @return The modified value
+     *
+     * If the value is invalid (unspecified in the config) or does not pass
+     * `check`, the fallback will be returned. Otherwise the value is processed
+     * by `process` and then returned.
+     *
+     * @note Cannot be overriden
+     * @see fallback, process
+     */
+    QVariant value(const QVariant& val);
+    /**
+     * @brief Fallback value (default value).
+     */
+    virtual QVariant fallback();
+    /**
+     * @brief Return the representaion of the value in the config file.
+     *
+     * Override this if you want to write the value in a different format than
+     * the one provided by `QVariant`.
+     */
+    virtual QVariant representation(const QVariant& val);
+    /**
+     * @brief The expected value (descriptive).
+     * Used when reporting configuration errors.
+     */
+    virtual QString expected();
+
+protected:
+    /**
+     * @brief Process a value, presuming it is a valid `QVariant`.
+     * @param val The value that was read from the config file
+     * @return The processed value
+     * @note You will usually want to override this. In rare cases, you may want
+     * to override `value`.
+     */
+    virtual QVariant process(const QVariant& val);
+};
+
+class Bool : public ValueHandler
+{
+public:
+    Bool(bool def);
+    bool check(const QVariant& val) override;
+    QVariant fallback() override;
+    QString expected() override;
+
+private:
+    bool m_def;
+};
+
+class String : public ValueHandler
+{
+public:
+    String(const QString& def);
+    bool check(const QVariant&) override;
+    QVariant fallback() override;
+    QString expected() override;
+
+private:
+    QString m_def;
+};
+
+class Color : public ValueHandler
+{
+public:
+    Color(const QColor& def);
+    bool check(const QVariant& val) override;
+    QVariant process(const QVariant& val) override;
+    QVariant fallback() override;
+    QVariant representation(const QVariant& val) override;
+    QString expected() override;
+
+private:
+    QColor m_def;
+};
+
+class BoundedInt : public ValueHandler
+{
+public:
+    BoundedInt(int min, int max, int def);
+
+    bool check(const QVariant& val) override;
+    virtual QVariant fallback() override;
+    QString expected() override;
+
+private:
+    int m_min, m_max, m_def;
+};
+
+class LowerBoundedInt : public ValueHandler
+{
+public:
+    LowerBoundedInt(int min, int def);
+    bool check(const QVariant& val) override;
+    QVariant fallback() override;
+    QString expected() override;
+
+private:
+    int m_min, m_def;
+};
+
+class KeySequence : public ValueHandler
+{
+public:
+    KeySequence(const QKeySequence& fallback = {});
+    bool check(const QVariant& val) override;
+    QVariant fallback() override;
+    QString expected() override;
+
+private:
+    QKeySequence m_fallback;
+};
+
+class ExistingDir : public ValueHandler
+{
+    bool check(const QVariant& val) override;
+    QVariant fallback() override;
+    QString expected() override;
+};
+
+class FilenamePattern : public ValueHandler
+{
+    bool check(const QVariant&) override;
+    QVariant fallback() override;
+    QVariant process(const QVariant&) override;
+    QString expected() override;
+};
+
+class ButtonList : public ValueHandler
+{
+public:
+    bool check(const QVariant& val) override;
+    QVariant process(const QVariant& val) override;
+    QVariant fallback() override;
+    QVariant representation(const QVariant& val) override;
+    QString expected() override;
+
+    // UTILITY FUNCTIONS
+    static QList<CaptureToolButton::ButtonType> fromIntList(const QList<int>&);
+    static QList<int> toIntList(const QList<CaptureToolButton::ButtonType>& l);
+    static bool normalizeButtons(QList<int>& buttons);
+};
+
+class UserColors : public ValueHandler
+{
+    bool check(const QVariant& val) override;
+    QVariant process(const QVariant& val) override;
+    QVariant fallback() override;
+    QString expected() override;
+};

src/widgets/capture/capturebutton.cpp

@@ -72,4 +72,4 @@ void CaptureButton::setColor(const QColor& c)
     setStyleSheet(styleSheet());
 }
 
-QColor CaptureButton::m_mainColor = ConfigHandler().uiMainColorValue();
+QColor CaptureButton::m_mainColor = ConfigHandler().uiColor();

src/widgets/capture/capturetoolbutton.cpp

@@ -81,8 +81,7 @@ void CaptureToolButton::updateIcon()
     setIconSize(size() * 0.6);
 }
 
-QVector<CaptureToolButton::ButtonType>
+QList<CaptureToolButton::ButtonType> CaptureToolButton::getIterableButtonTypes()
-CaptureToolButton::getIterableButtonTypes()
 {
     return iterableButtonTypes;
 }
@@ -123,7 +122,7 @@ void CaptureToolButton::setColor(const QColor& c)
     updateIcon();
 }
 
-QColor CaptureToolButton::m_mainColor = ConfigHandler().uiMainColorValue();
+QColor CaptureToolButton::m_mainColor = ConfigHandler().uiColor();
 
 static std::map<CaptureToolButton::ButtonType, int> buttonTypeOrder
 {
@@ -163,31 +162,30 @@ int CaptureToolButton::getPriorityByButton(CaptureToolButton::ButtonType b)
                                         : it->second;
 }
 
-QVector<CaptureToolButton::ButtonType>
+QList<CaptureToolButton::ButtonType> CaptureToolButton::iterableButtonTypes = {
-  CaptureToolButton::iterableButtonTypes = {
+    CaptureToolButton::TYPE_PENCIL,
-      CaptureToolButton::TYPE_PENCIL,
+    CaptureToolButton::TYPE_DRAWER,
-      CaptureToolButton::TYPE_DRAWER,
+    CaptureToolButton::TYPE_ARROW,
-      CaptureToolButton::TYPE_ARROW,
+    CaptureToolButton::TYPE_SELECTION,
-      CaptureToolButton::TYPE_SELECTION,
+    CaptureToolButton::TYPE_RECTANGLE,
-      CaptureToolButton::TYPE_RECTANGLE,
+    CaptureToolButton::TYPE_CIRCLE,
-      CaptureToolButton::TYPE_CIRCLE,
+    CaptureToolButton::TYPE_MARKER,
-      CaptureToolButton::TYPE_MARKER,
+    CaptureToolButton::TYPE_TEXT,
-      CaptureToolButton::TYPE_TEXT,
+    CaptureToolButton::TYPE_PIXELATE,
-      CaptureToolButton::TYPE_PIXELATE,
+    CaptureToolButton::TYPE_INVERT,
-      CaptureToolButton::TYPE_INVERT,
+    CaptureToolButton::TYPE_SELECTIONINDICATOR,
-      CaptureToolButton::TYPE_CIRCLECOUNT,
+    CaptureToolButton::TYPE_MOVESELECTION,
-      CaptureToolButton::TYPE_SELECTIONINDICATOR,
+    CaptureToolButton::TYPE_UNDO,
-      CaptureToolButton::TYPE_MOVESELECTION,
+    CaptureToolButton::TYPE_REDO,
-      CaptureToolButton::TYPE_UNDO,
+    CaptureToolButton::TYPE_COPY,
-      CaptureToolButton::TYPE_REDO,
+    CaptureToolButton::TYPE_SAVE,
-      CaptureToolButton::TYPE_COPY,
+    CaptureToolButton::TYPE_EXIT,
-      CaptureToolButton::TYPE_SAVE,
+    CaptureToolButton::TYPE_IMAGEUPLOADER,
-      CaptureToolButton::TYPE_EXIT,
-      CaptureToolButton::TYPE_IMAGEUPLOADER,
 #if !defined(Q_OS_MACOS)
-      CaptureToolButton::TYPE_OPEN_APP,
+    CaptureToolButton::TYPE_OPEN_APP,
 #endif
-      CaptureToolButton::TYPE_PIN,
+    CaptureToolButton::TYPE_PIN,
-      CaptureToolButton::TYPE_SIZEINCREASE,
+    CaptureToolButton::TYPE_CIRCLECOUNT,
-      CaptureToolButton::TYPE_SIZEDECREASE,
+    CaptureToolButton::TYPE_SIZEINCREASE,
-  };
+    CaptureToolButton::TYPE_SIZEDECREASE,
+};

src/widgets/capture/capturetoolbutton.h

@@ -51,7 +51,7 @@ public:
     explicit CaptureToolButton(const ButtonType, QWidget* parent = nullptr);
     ~CaptureToolButton();
 
-    static QVector<CaptureToolButton::ButtonType> getIterableButtonTypes();
+    static QList<CaptureToolButton::ButtonType> getIterableButtonTypes();
     static int getPriorityByButton(CaptureToolButton::ButtonType);
 
     QString name() const;
@@ -64,7 +64,7 @@ public:
 
 protected:
     void mousePressEvent(QMouseEvent* e) override;
-    static QVector<ButtonType> iterableButtonTypes;
+    static QList<ButtonType> iterableButtonTypes;
 
     CaptureTool* m_tool;
 

src/widgets/capture/capturewidget.cpp

@@ -29,6 +29,8 @@
 #include <QApplication>
 #include <QDateTime>
 #include <QDesktopWidget>
+#include <QFontMetrics>
+#include <QLabel>
 #include <QPaintEvent>
 #include <QPainter>
 #include <QScreen>
@@ -56,6 +58,8 @@ CaptureWidget::CaptureWidget(uint id,
   , m_captureDone(false)
   , m_previewEnabled(true)
   , m_adjustmentButtonPressed(false)
+  , m_configError(false)
+  , m_configErrorResolved(false)
   , m_activeButton(nullptr)
   , m_activeTool(nullptr)
   , m_toolWidget(nullptr)
@@ -85,9 +89,9 @@ CaptureWidget::CaptureWidget(uint id,
             this,
             &CaptureWidget::childLeave);
     setAttribute(Qt::WA_DeleteOnClose);
-    m_opacity = m_config.contrastOpacityValue();
+    m_opacity = m_config.contrastOpacity();
-    m_uiColor = m_config.uiMainColorValue();
+    m_uiColor = m_config.uiColor();
-    m_contrastUiColor = m_config.uiContrastColorValue();
+    m_contrastUiColor = m_config.contrastUiColor();
     setMouseTracking(true);
     initContext(savePath, fullScreen);
     initShortcuts();
@@ -200,10 +204,25 @@ CaptureWidget::CaptureWidget(uint id,
 
     initPanel();
 
+    m_config.checkAndHandleError();
+    if (m_config.hasError()) {
+        m_configError = true;
+    }
+    connect(ConfigHandler::getInstance(), &ConfigHandler::error, this, [=]() {
+        m_configError = true;
+        m_configErrorResolved = false;
+        update();
+    });
+    connect(
+      ConfigHandler::getInstance(), &ConfigHandler::errorResolved, this, [=]() {
+          m_configError = false;
+          m_configErrorResolved = true;
+          update();
+      });
     OverlayMessage::init(this,
                          QGuiAppCurrentScreen().currentScreen()->geometry());
 
-    if (m_config.showHelpValue()) {
+    if (m_config.showHelp()) {
         OverlayMessage::push(
           tr("Select an area with the mouse, or press Esc to exit."
              "\nPress Enter to capture the screen."
@@ -225,7 +244,7 @@ CaptureWidget::~CaptureWidget()
 void CaptureWidget::initButtons()
 {
     auto allButtonTypes = CaptureToolButton::getIterableButtonTypes();
-    auto visibleButtonTypes = m_config.getButtons();
+    auto visibleButtonTypes = m_config.buttons();
     QVector<CaptureToolButton*> vectorButtons;
 
     // Add all buttons but hide those that were disabled in the Interface config
@@ -376,6 +395,10 @@ void CaptureWidget::paintEvent(QPaintEvent* paintEvent)
 
     // draw inactive region
     drawInactiveRegion(&painter);
+
+    if (m_configError || m_configErrorResolved) {
+        drawConfigErrorMessage(&painter);
+    }
 }
 
 void CaptureWidget::showColorPicker(const QPoint& pos)
@@ -683,8 +706,7 @@ void CaptureWidget::mouseMoveEvent(QMouseEvent* e)
                 m_buttonHandler->show();
             }
         }
-    } else if (m_activeButton && m_activeButton->tool() &&
+    } else if (m_activeButton && m_activeButton->tool()) {
-               m_activeButton->tool()->showMousePreview()) {
         update();
     } else {
         if (!m_selection->isVisible()) {
@@ -705,7 +727,7 @@ void CaptureWidget::mouseReleaseEvent(QMouseEvent* e)
         }
         m_colorPicker->hide();
         if (!m_context.color.isValid()) {
-            m_context.color = ConfigHandler().drawColorValue();
+            m_context.color = ConfigHandler().drawColor();
             m_panel->show();
         }
     } else if (m_mouseIsClicked) {
@@ -907,11 +929,11 @@ void CaptureWidget::moveEvent(QMoveEvent* e)
 
 void CaptureWidget::initContext(const QString& savePath, bool fullscreen)
 {
-    m_context.color = m_config.drawColorValue();
+    m_context.color = m_config.drawColor();
     m_context.savePath = savePath;
     m_context.widgetOffset = mapToGlobal(QPoint(0, 0));
     m_context.mousePos = mapFromGlobal(QCursor::pos());
-    m_context.thickness = m_config.drawThicknessValue();
+    m_context.thickness = m_config.drawThickness();
     m_context.fullscreen = fullscreen;
 }
 
@@ -934,7 +956,7 @@ void CaptureWidget::initPanel()
 #endif
     }
 
-    if (ConfigHandler().showSidePanelButtonValue()) {
+    if (ConfigHandler().showSidePanelButton()) {
         auto* panelToggleButton =
           new OrientablePushButton(tr("Tool Settings"), this);
         makeChild(panelToggleButton);
@@ -1107,9 +1129,9 @@ void CaptureWidget::loadDrawThickness()
     if ((m_activeButton && m_activeButton->tool() &&
          m_activeButton->tool()->type() == ToolType::TEXT) ||
         (m_activeTool && m_activeTool->type() == ToolType::TEXT)) {
-        m_context.thickness = m_config.drawFontSizeValue();
+        m_context.thickness = m_config.drawFontSize();
     } else {
-        m_context.thickness = m_config.drawThicknessValue();
+        m_context.thickness = m_config.drawThickness();
     }
     emit m_sidePanel->thicknessChanged(m_context.thickness);
 }
@@ -1670,6 +1692,28 @@ QRect CaptureWidget::extendedRect(const QRect& r) const
                  r.height() * devicePixelRatio);
 }
 
+void CaptureWidget::drawConfigErrorMessage(QPainter* painter)
+{
+    QString msg;
+    if (m_configError) {
+        msg = ConfigHandler().errorMessage();
+    } else if (m_configErrorResolved) {
+        msg = tr("Configuration error resolved. Launch `flameshot "
+                 "gui` again to apply it.");
+    }
+
+    auto textRect = painter->fontMetrics().boundingRect(msg);
+    int w = textRect.width(), h = textRect.height();
+    textRect = { size().width() - w, size().height() - h, w + 100, h + 100 };
+    QScreen* currentScreen = QGuiAppCurrentScreen().currentScreen();
+
+    if (!textRect.contains(QCursor::pos(currentScreen))) {
+        QColor textColor(Qt::white);
+        painter->setPen(textColor);
+        painter->drawText(textRect, msg);
+    }
+}
+
 void CaptureWidget::drawInactiveRegion(QPainter* painter)
 {
     QColor overlayColor(0, 0, 0, m_opacity);

src/widgets/capture/capturewidget.h

@@ -22,6 +22,7 @@
 #include <QUndoStack>
 #include <QWidget>
 
+class QLabel;
 class QPaintEvent;
 class QResizeEvent;
 class QMouseEvent;
@@ -131,6 +132,7 @@ private:
 
     QRect extendedSelection() const;
     QRect extendedRect(const QRect& r) const;
+    void drawConfigErrorMessage(QPainter* painter);
     void drawInactiveRegion(QPainter* painter);
     void drawToolsData(bool updateLayersPanel = true,
                        bool drawSelection = false);
@@ -161,6 +163,8 @@ private:
     bool m_captureDone;
     bool m_previewEnabled;
     bool m_adjustmentButtonPressed;
+    bool m_configError;
+    bool m_configErrorResolved;
 
     UpdateNotificationWidget* m_updateNotificationWidget;
     quint64 m_lastMouseWheel;

src/widgets/capture/colorpicker.cpp

@@ -11,12 +11,12 @@ ColorPicker::ColorPicker(QWidget* parent)
   : QWidget(parent)
 {
     ConfigHandler config;
-    m_colorList = config.getUserColors();
+    m_colorList = config.userColors();
     m_colorAreaSize = GlobalValues::buttonBaseSize() * 0.6;
     setMouseTracking(true);
     // save the color values in member variables for faster access
-    m_uiColor = config.uiMainColorValue();
+    m_uiColor = config.uiColor();
-    m_drawColor = config.drawColorValue();
+    m_drawColor = config.drawColor();
     // extraSize represents the extra space needed for the highlight of the
     // selected color.
     const int extraSize = 6;

src/widgets/capture/notifierbox.cpp

@@ -16,7 +16,7 @@ NotifierBox::NotifierBox(QWidget* parent)
     m_timer->setSingleShot(true);
     m_timer->setInterval(600);
     connect(m_timer, &QTimer::timeout, this, &NotifierBox::hide);
-    m_bgColor = ConfigHandler().uiMainColorValue();
+    m_bgColor = ConfigHandler().uiColor();
     m_foregroundColor =
       (ColorUtils::colorIsDark(m_bgColor) ? Qt::white : Qt::black);
     m_bgColor.setAlpha(180);

src/widgets/capture/overlaymessage.cpp

@@ -66,7 +66,7 @@ void OverlayMessage::paintEvent(QPaintEvent*)
     QRectF bRect = boundingRect();
     bRect.moveTo(0, 0);
 
-    QColor rectColor(ConfigHandler().uiMainColorValue());
+    QColor rectColor(ConfigHandler().uiColor());
     rectColor.setAlpha(180);
     QColor textColor(
       (ColorUtils::colorIsDark(rectColor) ? Qt::white : Qt::black));