Add scrolling with keyboard arrow keys

Author: AlienCowEatCake

src/ImageViewer/src/GUI/ImageViewerWidget.cpp

@@ -21,6 +21,7 @@
 
 #include <QGraphicsScene>
 #include <QGraphicsItem>
+#include <QScrollBar>
 #include <QGraphicsPixmapItem>
 #include <QStyleOptionGraphicsItem>
 #include <QMatrix>
@@ -41,8 +42,11 @@ class QPinchGesture {};
 
 namespace {
 
+const int SCROLL_STEP = 10;
+const qreal ZOOM_STEP = 1.1;
 const qreal ZOOM_CHANGE_EPSILON = 1e-5;
 const int ZOOM_FIT_SIZE_CORRECTION = 1;
+const qreal ROTATION_TRESHOLD = 30;
 
 } // namespace
 
@@ -145,20 +149,20 @@ struct ImageViewerWidget::Impl
         if(changeFlags.testFlag(QPinchGesture::RotationAngleChanged))
         {
             const qreal rotationAngle = gesture->rotationAngle();
-            const qreal rotationTreshhold = 30;
-            if(rotationAngle > rotationTreshhold)
+            if(rotationAngle > ROTATION_TRESHOLD)
             {
                 imageViewerWidget->rotateClockwise();
                 gesture->setRotationAngle(0);
             }
-            if(rotationAngle < -rotationTreshhold)
+            if(rotationAngle < -ROTATION_TRESHOLD)
             {
                 imageViewerWidget->rotateCounterclockwise();
                 gesture->setRotationAngle(0);
             }
         }
 #else
         Q_UNUSED(gesture);
+        Q_UNUSED(ROTATION_TRESHOLD);
 #endif
     }
 
@@ -317,12 +321,12 @@ void ImageViewerWidget::flipVertical()
 
 void ImageViewerWidget::zoomIn()
 {
-    setZoomLevel(m_impl->currentZoomLevel * 1.1);
+    setZoomLevel(m_impl->currentZoomLevel * ZOOM_STEP);
 }
 
 void ImageViewerWidget::zoomOut()
 {
-    setZoomLevel(m_impl->currentZoomLevel / 1.1);
+    setZoomLevel(m_impl->currentZoomLevel / ZOOM_STEP);
 }
 
 void ImageViewerWidget::resetZoom()
@@ -331,6 +335,30 @@ void ImageViewerWidget::resetZoom()
     m_impl->updateTransformations();
 }
 
+void ImageViewerWidget::scrollLeft()
+{
+    QScrollBar* scrollBar = horizontalScrollBar();
+    scrollBar->setValue(scrollBar->value() - SCROLL_STEP);
+}
+
+void ImageViewerWidget::scrollRight()
+{
+    QScrollBar* scrollBar = horizontalScrollBar();
+    scrollBar->setValue(scrollBar->value() + SCROLL_STEP);
+}
+
+void ImageViewerWidget::scrollUp()
+{
+    QScrollBar* scrollBar = verticalScrollBar();
+    scrollBar->setValue(scrollBar->value() - SCROLL_STEP);
+}
+
+void ImageViewerWidget::scrollDown()
+{
+    QScrollBar* scrollBar = verticalScrollBar();
+    scrollBar->setValue(scrollBar->value() + SCROLL_STEP);
+}
+
 void ImageViewerWidget::setBackgroundColor(const QColor &color)
 {
     setBackgroundBrush(QBrush(color));

src/ImageViewer/src/GUI/ImageViewerWidget.h

@@ -80,6 +80,11 @@ public slots:
     void zoomOut();
     void resetZoom();
 
+    void scrollLeft();
+    void scrollRight();
+    void scrollUp();
+    void scrollDown();
+
     void setBackgroundColor(const QColor &color);
 
     void setSmoothTransformation(bool enabled);

src/ImageViewer/src/GUI/MainWindow.cpp

@@ -789,6 +789,18 @@ void MainWindow::keyPressEvent(QKeyEvent *event)
         if(m_impl->isFullScreenMode)
             switchFullScreenMode();
         break;
+    case Qt::Key_Up:
+        m_ui->imageViewerWidget->scrollUp();
+        break;
+    case Qt::Key_Down:
+        m_ui->imageViewerWidget->scrollDown();
+        break;
+    case Qt::Key_Left:
+        m_ui->imageViewerWidget->scrollLeft();
+        break;
+    case Qt::Key_Right:
+        m_ui->imageViewerWidget->scrollRight();
+        break;
     default:
         break;
     }