Merge pull request #6356 from elpaso/bugfix-17721-color-picker

[bugfix] Restore color picker from layer styling panel

src/gui/qgscolorbutton.cpp

@@ -231,20 +231,7 @@ void QgsColorButton::mouseMoveEvent( QMouseEvent *e )
 {
   if ( mPickingColor )
   {
-    //currently in color picker mode
-    if ( e->buttons() & Qt::LeftButton )
-    {
-      //if left button depressed, sample color under cursor and temporarily update button color
-      //to give feedback to user
-      QScreen *screen = findScreenAt( e->globalPos() );
-      if ( screen )
-      {
-        QPixmap snappedPixmap = screen->grabWindow( QApplication::desktop()->winId(), e->globalPos().x(), e->globalPos().y(), 1, 1 );
-        QImage snappedImage = snappedPixmap.toImage();
-        QColor hoverColor = snappedImage.pixel( 0, 0 );
-        setButtonBackground( hoverColor );
-      }
-    }
+    setButtonBackground( sampleColor( e->globalPos() ) );
     e->accept();
     return;
   }
@@ -286,26 +273,23 @@ void QgsColorButton::mouseReleaseEvent( QMouseEvent *e )
   QToolButton::mouseReleaseEvent( e );
 }
 
-void QgsColorButton::stopPicking( QPointF eventPos, bool sampleColor )
+void QgsColorButton::stopPicking( QPoint eventPos, bool samplingColor )
 {
   //release mouse and keyboard, and reset cursor
   releaseMouse();
   releaseKeyboard();
-  unsetCursor();
+  QgsApplication::restoreOverrideCursor();
   setMouseTracking( false );
   mPickingColor = false;
 
-  if ( !sampleColor )
+  if ( !samplingColor )
   {
-    //not sampling color, nothing more to do
+    //not sampling color, restore old color
+    setButtonBackground( mCurrentColor );
     return;
   }
 
-  //grab snapshot of pixel under mouse cursor
-  QPixmap snappedPixmap = QApplication::desktop()->screen()->grab( QRect( eventPos.x(), eventPos.y(), 1, 1 ) );
-  QImage snappedImage = snappedPixmap.toImage();
-  //extract color from pixel and set color
-  setColor( snappedImage.pixel( 0, 0 ) );
+  setColor( sampleColor( eventPos ) );
   addRecentColor( mColor );
 }
 
@@ -356,6 +340,19 @@ void QgsColorButton::dropEvent( QDropEvent *e )
   }
 }
 
+QColor QgsColorButton::sampleColor( QPoint point ) const
+{
+
+  QScreen *screen = findScreenAt( point );
+  if ( ! screen )
+  {
+    return QColor();
+  }
+  QPixmap snappedPixmap = screen->grabWindow( QApplication::desktop()->winId(), point.x(), point.y(), 1, 1 );
+  QImage snappedImage = snappedPixmap.toImage();
+  return snappedImage.pixel( 0, 0 );
+}
+
 QScreen *QgsColorButton::findScreenAt( QPoint pos )
 {
   for ( QScreen *screen : QGuiApplication::screens() )
@@ -680,7 +677,9 @@ void QgsColorButton::pasteColor()
 void QgsColorButton::activatePicker()
 {
   //activate picker color
-  setCursor( QgsApplication::getThemeCursor( QgsApplication::Cursor::Sampler ) );
+  // Store current color
+  mCurrentColor = mColor;
+  QApplication::setOverrideCursor( QgsApplication::getThemeCursor( QgsApplication::Cursor::Sampler ) );
   grabMouse();
   grabKeyboard();
   mPickingColor = true;

src/gui/qgscolorbutton.h

@@ -399,6 +399,9 @@ class GUI_EXPORT QgsColorButton : public QToolButton
 
   private:
 
+
+    QColor sampleColor( QPoint point ) const;
+
     static QScreen *findScreenAt( QPoint pos );
     Behavior mBehavior = QgsColorButton::ShowDialog;
     QString mColorDialogTitle;
@@ -408,6 +411,10 @@ class GUI_EXPORT QgsColorButton : public QToolButton
     QgsColorSchemeRegistry *mColorSchemeRegistry = nullptr;
 
     QColor mDefaultColor;
+
+    //! Store current color when start picking
+    QColor mCurrentColor;
+
     QString mContext;
     bool mAllowOpacity = false;
     bool mColorSet = false;
@@ -436,10 +443,10 @@ class GUI_EXPORT QgsColorButton : public QToolButton
     /**
      * Ends a color picking operation
      * \param eventPos global position of pixel to sample color from
-     * \param sampleColor set to true to actually sample the color, false to just cancel
+     * \param samplingColor set to true to actually sample the color, false to just cancel
      * the color picking operation
      */
-    void stopPicking( QPointF eventPos, bool sampleColor = true );
+    void stopPicking( QPoint eventPos, bool samplingColor = true );
 
     /**
      * Create a color icon for display in the drop-down menu