Zoom support

imagescrollarea.cpp

@@ -2,8 +2,10 @@
 #include <QMouseEvent>
 #include <QScrollBar>
 #include <QKeyEvent>
+#include <QDebug>
 
-ImageScrollArea::ImageScrollArea(QWidget *parent) : QScrollArea(parent)
+ImageScrollArea::ImageScrollArea(QWidget *parent) : QScrollArea(parent),
+    m_scale(-1)
 {
     m_label = new QLabel(this);
     setWidget(m_label);
@@ -12,9 +14,54 @@ ImageScrollArea::ImageScrollArea(QWidget *parent) : QScrollArea(parent)
 void ImageScrollArea::setImage(const QPixmap &img)
 {
     m_pixmap = img;
-    QPixmap pix = img.scaled(size(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
+    QPixmap pix;
+    if(m_scale < 0)
+        pix = img.scaled(size(), Qt::KeepAspectRatio, Qt::SmoothTransformation);
+    else
+        pix = img.scaled(img.size() * m_scale, Qt::KeepAspectRatio, Qt::SmoothTransformation);
+
     m_label->setPixmap(pix);
     m_label->resize(pix.size());
+
+    horizontalScrollBar()->setValue(horizontalScrollBar()->maximum() / 2);
+    verticalScrollBar()->setValue(verticalScrollBar()->maximum() / 2);
+}
+
+void ImageScrollArea::setScale(float scale)
+{
+    if(scale > 4 || (scale < 0.2 && scale > 0))
+        return;
+
+    m_scale = scale;
+    QSize newSize = m_scale < 0 ? size() : m_pixmap.size()*scale;
+    m_label->setPixmap(m_pixmap.scaled(newSize, Qt::KeepAspectRatio, Qt::SmoothTransformation));
+    m_label->resize(newSize);
+}
+
+void ImageScrollArea::zoomIn()
+{
+    if(m_scale < 0)
+        m_scale = (float)size().width()/m_pixmap.size().width();
+
+    setScale(m_scale + 0.1);
+}
+
+void ImageScrollArea::zoomOut()
+{
+    if(m_scale < 0)
+        m_scale = (float)size().width()/m_pixmap.size().width();
+
+    setScale(m_scale - 0.1);
+}
+
+void ImageScrollArea::bestFit()
+{
+    setScale(-1);
+}
+
+void ImageScrollArea::oneToOne()
+{
+    setScale(1);
 }
 
 void ImageScrollArea::keyPressEvent(QKeyEvent *event)
@@ -42,7 +89,30 @@ void ImageScrollArea::mousePressEvent(QMouseEvent *event)
 
 void ImageScrollArea::resizeEvent(QResizeEvent *event)
 {
-    m_label->setPixmap(m_pixmap.scaled(event->size(), Qt::KeepAspectRatio, Qt::SmoothTransformation));
-    m_label->resize(event->size());
+    if(m_scale < 0)
+    {
+        m_label->setPixmap(m_pixmap.scaled(event->size(), Qt::KeepAspectRatio, Qt::SmoothTransformation));
+        m_label->resize(event->size());
+    }
     QScrollArea::resizeEvent(event);
 }
+
+void ImageScrollArea::wheelEvent(QWheelEvent *event)
+{
+    if(m_scale < 0)
+        m_scale = (float)size().width()/m_pixmap.size().width();
+
+    QPointF top(horizontalScrollBar()->value(), verticalScrollBar()->value());
+    QPointF mousePos = (top + event->posF()) / m_scale;
+
+    QPoint delta = event->angleDelta();
+    if(delta.y() > 0)
+        setScale(m_scale + 0.1);
+    else
+        setScale(m_scale - 0.1);
+
+    mousePos *= m_scale;
+    top = mousePos - event->posF();
+    horizontalScrollBar()->setValue(top.x());
+    verticalScrollBar()->setValue(top.y());
+}

imagescrollarea.h

@@ -6,18 +6,27 @@
 
 class ImageScrollArea : public QScrollArea
 {
+    Q_OBJECT
     QPoint m_lastPos;
     QLabel *m_label;
     QPixmap m_pixmap;
+    float m_scale;
 public:
     explicit ImageScrollArea(QWidget *parent = 0);
     void setImage(const QPixmap &img);
+    void setScale(float scale);
+public slots:
+    void zoomIn();
+    void zoomOut();
+    void bestFit();
+    void oneToOne();
 protected:
     void keyPressEvent(QKeyEvent *event);
     void keyReleaseEvent(QKeyEvent *event);
     void mouseMoveEvent(QMouseEvent *event);
     void mousePressEvent(QMouseEvent *event);
     void resizeEvent(QResizeEvent *event);
+    void wheelEvent(QWheelEvent *event);
 };
 
 #endif // IMAGESCROLLAREA_H

mainwindow.cpp

@@ -25,7 +25,12 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent),
     fileMenu->addAction(tr("Exit"), this, SLOT(close()));
     menuBar()->addMenu(fileMenu);
 
-    m_ringList->setDir("/home/nou/Obrázky/jap/dusan-jpg");
+    QMenu *viewMenu = new QMenu(tr("View"), this);
+    viewMenu->addAction(tr("Zoom In"), m_image, SLOT(zoomIn()), QKeySequence::ZoomIn);
+    viewMenu->addAction(tr("Zoom Out"), m_image, SLOT(zoomOut()), QKeySequence::ZoomOut);
+    viewMenu->addAction(tr("Best Fit"), m_image, SLOT(bestFit()), QKeySequence("Ctrl+1"));
+    viewMenu->addAction(tr("1:1"), m_image, SLOT(oneToOne()));
+    menuBar()->addMenu(viewMenu);
 }
 
 MainWindow::~MainWindow()