Allow notification to be dragged and dropped (#473)

* Set x-kde-urls for notifications

The x-kde-urls field in the hints map allows us to provide a direct URL
to the saved screenshot. The notification server may then use this hint
to provide extra functionality, such as drag and drop support and
thumbnails.

For more information see https://community.kde.org/Plasma/Notifications#File_Path

Fixes #256

Note that other notification servers may ignore this hint.

* Avoid branching twice for ok

src/utils/systemnotification.cpp

@@ -1,6 +1,7 @@
 #include "systemnotification.h"
 #include "src/utils/confighandler.h"
 #include <QApplication>
+#include <QUrl>
 
 #ifndef Q_OS_WIN
 #include <QDBusConnection>
@@ -24,13 +25,14 @@ SystemNotification::SystemNotification(QObject *parent) : QObject(parent) {
 }
 #endif
 
-void SystemNotification::sendMessage(const QString &text) {
-    sendMessage(text, tr("Flameshot Info"));
+void SystemNotification::sendMessage(const QString &text, const QString &savePath) {
+    sendMessage(text, tr("Flameshot Info"), savePath);
 }
 
 void SystemNotification::sendMessage(
         const QString &text,
         const QString &title,
+        const QString &savePath,
         const int timeout)
 {
     if(!ConfigHandler().desktopNotificationValue()) {
@@ -39,13 +41,19 @@ void SystemNotification::sendMessage(
 
 #ifndef Q_OS_WIN
     QList<QVariant> args;
+    QVariantMap hintsMap;
+    if (!savePath.isEmpty()) {
+        QUrl fullPath = QUrl::fromLocalFile(savePath);
+        // allows the notification to be dragged and dropped
+        hintsMap[QStringLiteral("x-kde-urls")] = QStringList({fullPath.toString()});
+    }
     args << (qAppName())                 //appname
          << static_cast<unsigned int>(0) //id
          << "flameshot"                  //icon
          << title                        //summary
          << text                         //body
          << QStringList()                //actions
-         << QVariantMap()                //hints
+         << hintsMap                     //hints
          << timeout;                     //timeout
     m_interface->callWithArgumentList(QDBus::AutoDetect, QStringLiteral("Notify"), args);
 #else