From 1787f95f5727a20a4f0871736ad987fcfdf0f3c6 Mon Sep 17 00:00:00 2001
From: Friedemann Kleint <Friedemann.Kleint@qt.io>
Date: Wed, 28 Feb 2018 15:47:23 +0100
Subject: SVG viewer example: Improve zoom facility

Add a label displaying the current zoom with
a tooltip.

Add menu actions for ZoomIn/ZoomOut and Reset.

Task-number: QTBUG-60653
Change-Id: I7569427345737024b7a3191677e54c83673bb40e
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
---
 examples/svg/svgviewer/mainwindow.cpp | 20 ++++++++++++++++++++
 examples/svg/svgviewer/mainwindow.h   |  5 +++++
 examples/svg/svgviewer/svgview.cpp    | 34 ++++++++++++++++++++++++++++++++--
 examples/svg/svgviewer/svgview.h      | 10 ++++++++++
 4 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/examples/svg/svgviewer/mainwindow.cpp b/examples/svg/svgviewer/mainwindow.cpp
index 8cb94d2..7dd240a 100644
--- a/examples/svg/svgviewer/mainwindow.cpp
+++ b/examples/svg/svgviewer/mainwindow.cpp
@@ -64,6 +64,7 @@ static inline QString picturesLocation()
 MainWindow::MainWindow()
     : QMainWindow()
     , m_view(new SvgView)
+    , m_zoomLabel(new QLabel)
 {
     QToolBar *toolBar = new QToolBar(this);
     addToolBar(Qt::TopToolBarArea, toolBar);
@@ -94,6 +95,14 @@ MainWindow::MainWindow()
     m_outlineAction->setChecked(true);
     connect(m_outlineAction, &QAction::toggled, m_view, &SvgView::setViewOutline);
 
+    viewMenu->addSeparator();
+    QAction *zoomAction = viewMenu->addAction(tr("Zoom &In"), m_view, &SvgView::zoomIn);
+    zoomAction->setShortcut(QKeySequence::ZoomIn);
+    zoomAction = viewMenu->addAction(tr("Zoom &Out"), m_view, &SvgView::zoomOut);
+    zoomAction->setShortcut(QKeySequence::ZoomOut);
+    zoomAction = viewMenu->addAction(tr("Reset Zoom"), m_view, &SvgView::resetZoom);
+    zoomAction->setShortcut(Qt::CTRL + Qt::Key_0);
+
     QMenu *rendererMenu = menuBar()->addMenu(tr("&Renderer"));
     m_nativeAction = rendererMenu->addAction(tr("&Native"));
     m_nativeAction->setCheckable(true);
@@ -134,6 +143,11 @@ MainWindow::MainWindow()
     help->addAction(tr("About Qt"), qApp, &QApplication::aboutQt);
 
     setCentralWidget(m_view);
+
+    m_zoomLabel->setToolTip(tr("Use the mouse wheel to zoom"));
+    statusBar()->addPermanentWidget(m_zoomLabel);
+    updateZoomLabel();
+    connect(m_view, &SvgView::zoomChanged, this, &MainWindow::updateZoomLabel);
 }
 
 void MainWindow::openFile()
@@ -221,3 +235,9 @@ void MainWindow::exportImage()
         }
     }
 }
+
+void MainWindow::updateZoomLabel()
+{
+    const int percent = qRound(m_view->zoomFactor() * qreal(100));
+    m_zoomLabel->setText(QString::number(percent) + QLatin1Char('%'));
+}
diff --git a/examples/svg/svgviewer/mainwindow.h b/examples/svg/svgviewer/mainwindow.h
index 3d18fd1..6c2af7e 100644
--- a/examples/svg/svgviewer/mainwindow.h
+++ b/examples/svg/svgviewer/mainwindow.h
@@ -61,6 +61,7 @@ class QAction;
 class QGraphicsView;
 class QGraphicsScene;
 class QGraphicsRectItem;
+class QLabel;
 QT_END_NAMESPACE
 
 class MainWindow : public QMainWindow
@@ -77,6 +78,9 @@ public slots:
     void exportImage();
     void setRenderer(int renderMode);
 
+private slots:
+    void updateZoomLabel();
+
 private:
     QAction *m_nativeAction;
     QAction *m_glAction;
@@ -86,6 +90,7 @@ private:
     QAction *m_outlineAction;
 
     SvgView *m_view;
+    QLabel *m_zoomLabel;
 
     QString m_currentPath;
 };
diff --git a/examples/svg/svgviewer/svgview.cpp b/examples/svg/svgviewer/svgview.cpp
index bbc853c..ecc8409 100644
--- a/examples/svg/svgviewer/svgview.cpp
+++ b/examples/svg/svgviewer/svgview.cpp
@@ -178,6 +178,29 @@ void SvgView::setViewOutline(bool enable)
     m_outlineItem->setVisible(enable);
 }
 
+qreal SvgView::zoomFactor() const
+{
+    return transform().m11();
+}
+
+void SvgView::zoomIn()
+{
+    zoomBy(2);
+}
+
+void SvgView::zoomOut()
+{
+    zoomBy(0.5);
+}
+
+void SvgView::resetZoom()
+{
+    if (!qFuzzyCompare(zoomFactor(), qreal(1))) {
+        resetTransform();
+        emit zoomChanged();
+    }
+}
+
 void SvgView::paintEvent(QPaintEvent *event)
 {
     if (m_renderer == Image) {
@@ -199,9 +222,16 @@ void SvgView::paintEvent(QPaintEvent *event)
 
 void SvgView::wheelEvent(QWheelEvent *event)
 {
-    qreal factor = qPow(1.2, event->delta() / 240.0);
+    zoomBy(qPow(1.2, event->delta() / 240.0));
+}
+
+void SvgView::zoomBy(qreal factor)
+{
+    const qreal currentZoom = zoomFactor();
+    if ((factor < 1 && currentZoom < 0.1) || (factor > 1 && currentZoom > 10))
+        return;
     scale(factor, factor);
-    event->accept();
+    emit zoomChanged();
 }
 
 QSvgRenderer *SvgView::renderer() const
diff --git a/examples/svg/svgviewer/svgview.h b/examples/svg/svgviewer/svgview.h
index 2a1a5ed..1b6b33e 100644
--- a/examples/svg/svgviewer/svgview.h
+++ b/examples/svg/svgviewer/svgview.h
@@ -76,16 +76,26 @@ public:
     QSize svgSize() const;
     QSvgRenderer *renderer() const;
 
+    qreal zoomFactor() const;
+
 public slots:
     void setHighQualityAntialiasing(bool highQualityAntialiasing);
     void setViewBackground(bool enable);
     void setViewOutline(bool enable);
+    void zoomIn();
+    void zoomOut();
+    void resetZoom();
+
+signals:
+    void zoomChanged();
 
 protected:
     void wheelEvent(QWheelEvent *event) override;
     void paintEvent(QPaintEvent *event) override;
 
 private:
+    void zoomBy(qreal factor);
+
     RendererType m_renderer;
 
     QGraphicsSvgItem *m_svgItem;
-- 
cgit v1.2.1