Add 45-multiple degree adjustment for line, arrow and marker tools (#439)

* Add 45-multiple degree adjustment for line, arrow and marker tools

* Adjustment: Ctrl press is checked + widened functionality for two-point tools

src/tools/abstracttwopointtool.cpp

@@ -16,6 +16,29 @@
 //     along with Flameshot.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "abstracttwopointtool.h"
+#include <cmath>
+
+namespace {
+
+const double ADJ_UNIT = std::atan(1.0);
+const int DIRS_NUMBER = 4;
+
+enum UNIT {
+    HORIZ_DIR = 0,
+    DIAG1_DIR = 1,
+    VERT_DIR = 2,
+    DIAG2_DIR = 3
+};
+
+const double ADJ_DIAG_UNIT = 2 * ADJ_UNIT;
+const int DIAG_DIRS_NUMBER = 2;
+
+enum DIAG_UNIT {
+    DIR1 = 0,
+    DIR2 = 1
+};
+
+}
 
 AbstractTwoPointTool::AbstractTwoPointTool(QObject *parent) :
     CaptureTool(parent), m_thickness(0), m_padding(0)
@@ -52,6 +75,10 @@ void AbstractTwoPointTool::drawMove(const QPoint &p) {
     m_points.second = p;
 }
 
+void AbstractTwoPointTool::drawMoveWithAdjustment(const QPoint &p) {
+    m_points.second = m_points.first + adjustedVector(p - m_points.first);
+}
+
 void AbstractTwoPointTool::colorChanged(const QColor &c) {
     m_color = c;
 }
@@ -70,3 +97,39 @@ QRect AbstractTwoPointTool::backupRect(const QRect &limits) const {
     r += QMargins(val, val, val, val);
     return r.intersected(limits);
 }
+
+QPoint AbstractTwoPointTool::adjustedVector(QPoint v) const {
+    if (m_supportsOrthogonalAdj && m_supportsDiagonalAdj) {
+        int dir = ( static_cast<int>(round(atan2(-v.y(), v.x()) / ADJ_UNIT)) + DIRS_NUMBER ) % DIRS_NUMBER;
+        if (dir == UNIT::HORIZ_DIR) {
+            v.setY(0);
+        } else if (dir == UNIT::VERT_DIR) {
+            v.setX(0);
+        } else if (dir == UNIT::DIAG1_DIR) {
+            int newX = (v.x() - v.y()) / 2;
+            int newY = -newX;
+            v.setX(newX);
+            v.setY(newY);
+        } else {
+            int newX = (v.x() + v.y()) / 2;
+            int newY = newX;
+            v.setX(newX);
+            v.setY(newY);
+        }
+    } else if (m_supportsDiagonalAdj) {
+        int dir = ( static_cast<int>(round((atan2(-v.y(), v.x()) - ADJ_DIAG_UNIT / 2) / ADJ_DIAG_UNIT))
+                    + DIAG_DIRS_NUMBER ) % DIAG_DIRS_NUMBER;
+        if (dir == DIAG_UNIT::DIR1) {
+            int newX = (v.x() - v.y()) / 2;
+            int newY = -newX;
+            v.setX(newX);
+            v.setY(newY);
+        } else {
+            int newX = (v.x() + v.y()) / 2;
+            int newY = newX;
+            v.setX(newX);
+            v.setY(newY);
+        }
+    }
+    return v;
+}

src/tools/abstracttwopointtool.h

@@ -34,6 +34,7 @@ public:
 public slots:
     void drawEnd(const QPoint &p) override;
     void drawMove(const QPoint &p) override;
+    void drawMoveWithAdjustment(const QPoint &p) override;
     void colorChanged(const QColor &c) override;
     void thicknessChanged(const int th) override;
 
@@ -48,4 +49,9 @@ protected:
     // use m_padding to extend the area of the backup
     int m_padding;
 
+    bool m_supportsOrthogonalAdj = false;
+    bool m_supportsDiagonalAdj = false;
+
+private:
+    QPoint adjustedVector(QPoint v) const;
 };

src/tools/arrow/arrowtool.cpp

@@ -70,6 +70,8 @@ QLine getShorterLine(QPoint p1, QPoint p2, const int thickness) {
 
 ArrowTool::ArrowTool(QObject *parent) : AbstractTwoPointTool(parent) {
     m_padding = ArrowWidth / 2;
+    m_supportsOrthogonalAdj = true;
+    m_supportsDiagonalAdj = true;
 }
 
 QIcon ArrowTool::icon(const QColor &background, bool inEditor) const {

src/tools/capturetool.h

@@ -135,6 +135,11 @@ public slots:
     virtual void drawEnd(const QPoint &p) = 0;
     // Mouse pressed and moving, called once a pixel.
     virtual void drawMove(const QPoint &p) = 0;
+    // Called when drawMove is needed with an adjustment;
+    // should be overridden in case an adjustment is applicable.
+    virtual void drawMoveWithAdjustment(const QPoint &p) {
+        drawMove(p);
+    }
     // Called when the tool is activated.
     virtual void drawStart(const CaptureContext &context) = 0;
     // Called right after pressign the button which activates the tool.

src/tools/circle/circletool.cpp

@@ -23,7 +23,7 @@ namespace {
 }
 
 CircleTool::CircleTool(QObject *parent) : AbstractTwoPointTool(parent) {
-
+    m_supportsDiagonalAdj = true;
 }
 
 QIcon CircleTool::icon(const QColor &background, bool inEditor) const {

src/tools/line/linetool.cpp

@@ -20,18 +20,13 @@
 
 namespace {
 
-#define ADJ_VALUE 13
 #define PADDING_VALUE 2
 
-// Have to force horizontal position
-bool needsAdjustment(const QPoint &p0, const QPoint &p1) {
-    return (p1.y() >= p0.y() - ADJ_VALUE) && (p1.y() <= p0.y() + ADJ_VALUE);
-}
-
 }
 
 LineTool::LineTool(QObject *parent) : AbstractTwoPointTool(parent) {
-
+    m_supportsOrthogonalAdj = true;
+    m_supportsDiagonalAdj = true;
 }
 
 QIcon LineTool::icon(const QColor &background, bool inEditor) const {
@@ -67,13 +62,6 @@ void LineTool::paintMousePreview(QPainter &painter, const CaptureContext &contex
     painter.drawLine(context.mousePos, context.mousePos);
 }
 
-void LineTool::drawMove(const QPoint &p) {
-    m_points.second = p;
-    if (needsAdjustment(m_points.first, m_points.second)) {
-        m_points.second.setY(m_points.first.y());
-    }
-}
-
 void LineTool::drawStart(const CaptureContext &context) {
     m_color = context.color;
     m_thickness = context.thickness + PADDING_VALUE;

src/tools/line/linetool.h

@@ -35,7 +35,6 @@ public:
     void paintMousePreview(QPainter &painter, const CaptureContext &context) override;
 
 public slots:
-    void drawMove(const QPoint &p) override;
     void drawStart(const CaptureContext &context) override;
     void pressed(const CaptureContext &context) override;
 };

src/tools/marker/markertool.cpp

@@ -20,18 +20,13 @@
 
 namespace {
 
-#define ADJ_VALUE 14
 #define PADDING_VALUE 14
 
-// Have to force horizontal position
-bool needsAdjustment(const QPoint &p0, const QPoint &p1) {
-    return (p1.y() >= p0.y() - ADJ_VALUE) && (p1.y() <= p0.y() + ADJ_VALUE);
-}
-
 }
 
 MarkerTool::MarkerTool(QObject *parent) : AbstractTwoPointTool(parent) {
-
+    m_supportsOrthogonalAdj = true;
+    m_supportsDiagonalAdj = true;
 }
 
 QIcon MarkerTool::icon(const QColor &background, bool inEditor) const {
@@ -71,13 +66,6 @@ void MarkerTool::paintMousePreview(QPainter &painter, const CaptureContext &cont
     painter.drawLine(context.mousePos, context.mousePos);
 }
 
-void MarkerTool::drawMove(const QPoint &p) {
-    m_points.second = p;
-    if (needsAdjustment(m_points.first, m_points.second)) {
-        m_points.second.setY(m_points.first.y());
-    }
-}
-
 void MarkerTool::drawStart(const CaptureContext &context) {
     m_color = context.color;
     m_thickness = context.thickness + PADDING_VALUE;

src/tools/marker/markertool.h

@@ -35,7 +35,6 @@ public:
     void paintMousePreview(QPainter &painter, const CaptureContext &context) override;
 
 public slots:
-    void drawMove(const QPoint &p) override;
     void drawStart(const CaptureContext &context) override;
     void pressed(const CaptureContext &context) override;
     void thicknessChanged(const int th) override;

src/tools/rectangle/rectangletool.cpp

@@ -23,7 +23,7 @@ namespace {
 }
 
 RectangleTool::RectangleTool(QObject *parent) : AbstractTwoPointTool(parent) {
-
+    m_supportsDiagonalAdj = true;
 }
 
 QIcon RectangleTool::icon(const QColor &background, bool inEditor) const {

src/tools/selection/selectiontool.cpp

@@ -23,7 +23,7 @@ namespace {
 }
 
 SelectionTool::SelectionTool(QObject *parent) : AbstractTwoPointTool(parent) {
-
+    m_supportsDiagonalAdj = true;
 }
 
 bool SelectionTool::closeOnButtonPressed() const {

src/widgets/capture/capturewidget.cpp

@@ -52,7 +52,7 @@ CaptureWidget::CaptureWidget(const uint id, const QString &savePath,
                              bool fullScreen, QWidget *parent) :
     QWidget(parent), m_mouseIsClicked(false), m_rightClick(false),
     m_newSelection(false), m_grabbing(false), m_captureDone(false),
-    m_previewEnabled(true), m_activeButton(nullptr),
+    m_previewEnabled(true), m_adjustmentButtonPressed(false), m_activeButton(nullptr),
     m_activeTool(nullptr), m_toolWidget(nullptr),
     m_mouseOverHandle(SelectionWidget::NO_SIDE), m_id(id)
 {
@@ -398,7 +398,11 @@ void CaptureWidget::mouseMoveEvent(QMouseEvent *e) {
         }
     } else if (m_mouseIsClicked && m_activeTool) {
         // drawing with a tool
-        m_activeTool->drawMove(e->pos());
+        if (m_adjustmentButtonPressed) {
+            m_activeTool->drawMoveWithAdjustment(e->pos());
+        } else {
+            m_activeTool->drawMove(e->pos());
+        }
         update();
         // Hides the buttons under the mouse. If the mouse leaves, it shows them.
         if (m_buttonHandler->buttonsAreInside()) {
@@ -494,6 +498,14 @@ void CaptureWidget::keyPressEvent(QKeyEvent *e) {
         m_context.selection = extendedRect(&newGeometry);
         m_buttonHandler->updatePosition(m_selection->geometry());
         update();
+    } else if (e->key() == Qt::Key_Control) {
+        m_adjustmentButtonPressed = true;
+    }
+}
+
+void CaptureWidget::keyReleaseEvent(QKeyEvent *e) {
+    if (e->key() == Qt::Key_Control) {
+        m_adjustmentButtonPressed = false;
     }
 }
 

src/widgets/capture/capturewidget.h

@@ -97,6 +97,7 @@ protected:
     void mouseMoveEvent(QMouseEvent *);
     void mouseReleaseEvent(QMouseEvent *);
     void keyPressEvent(QKeyEvent *);
+    void keyReleaseEvent(QKeyEvent *);
     void wheelEvent(QWheelEvent *);
     void resizeEvent(QResizeEvent *);
     void moveEvent(QMoveEvent *);
@@ -119,6 +120,7 @@ protected:
     bool m_showInitialMsg;
     bool m_captureDone;
     bool m_previewEnabled;
+    bool m_adjustmentButtonPressed;
 
 private:
     void initContext(const QString &savePath, bool fullscreen);