From 04b3a3176a6b753b8d65820a3a738b01501a6d50 Mon Sep 17 00:00:00 2001
From: Wuzzy <almikes@aol.com>
Date: Thu, 8 Oct 2015 23:20:42 +0200
Subject: [PATCH] Implement zooming with menu and mouse wheel

---
 mainwindow.cpp |  2 ++
 svgviewer.cpp  | 18 ++++++++++++++++++
 svgviewer.h    | 12 ++++++++++++
 3 files changed, 32 insertions(+)

diff --git a/mainwindow.cpp b/mainwindow.cpp
index 00aeff5..103ae61 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -47,6 +47,8 @@ MainWindow::MainWindow(QWidget *parent)
     /* Signals and slots */
     connect(actionQuit, SIGNAL(triggered()), this, SLOT(close()));
     connect(actionOpen, SIGNAL(triggered()), this, SLOT(openFileDialog()));
+    connect(actionZoomIn, SIGNAL(triggered()), svgViewer, SLOT(zoomIn()));
+    connect(actionZoomOut, SIGNAL(triggered()), svgViewer, SLOT(zoomOut()));
 }
 
 void MainWindow::openFileDialog() {
diff --git a/svgviewer.cpp b/svgviewer.cpp
index c3b26c3..f9e0dc2 100644
--- a/svgviewer.cpp
+++ b/svgviewer.cpp
@@ -30,3 +30,21 @@ void SVGViewer::openFile(QString fileName) {
 
     gScene->addItem(svgItem);
 }
+
+void SVGViewer::zoomIn() {
+    zoomChange(2);
+}
+void SVGViewer::zoomOut() {
+    zoomChange(0.5);
+}
+
+void SVGViewer::zoomChange(qreal factor) {
+    scale(factor, factor);
+}
+
+void SVGViewer::wheelEvent(QWheelEvent *event)
+{
+    qreal factor = qPow(1.2, event->delta() / 240.0);
+    zoomChange(factor);
+    event->accept();
+}
diff --git a/svgviewer.h b/svgviewer.h
index b2fe16c..c6fb8ee 100644
--- a/svgviewer.h
+++ b/svgviewer.h
@@ -4,15 +4,27 @@
 #include <QSvgRenderer>
 #include <QGraphicsView>
 #include <QGraphicsSvgItem>
+#include <QWheelEvent>
+#include <qmath.h>
 
 class SVGViewer : public QGraphicsView
 {
+    Q_OBJECT
+
 public:
     SVGViewer(QWidget *parent = 0);
     void openFile(QString fileName);
 
+public slots:
+    void zoomIn();
+    void zoomOut();
+
 protected:
     void paintEvent(QPaintEvent* event);
+    void wheelEvent(QWheelEvent* event);
+
+private slots:
+    void zoomChange(qreal factor);
 
 private:
     QGraphicsSvgItem* svgItem;
-- 
2.11.4.GIT