Support pinch zoom gesture in the Mandelbrot example

Used QGesture for this as per the gesture example.
Moved the help and info text to separate lines.
Enabled word wrap to prevent text going off screen.

As a drive-by, the code to center the window at a size that's a fraction
of the screen is replaced with a simple sizeHint() override. The user
should have control over placement, particularly now that it should be
placed manually onto a touchscreen if the user has one.

Done-with: Shawn Rutledge
Fixes: QTBUG-96702
Pick-to: 6.4
Change-Id: I8dba8b09bed474f585341e9a7a8c71fb60293eee
Reviewed-by: Rami Potinkara <rami.potinkara@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 8 insertions, 0 deletions

diff --git a/examples/corelib/threads/mandelbrot/mandelbrotwidget.h b/examples/corelib/threads/mandelbrot/mandelbrotwidget.h
index 68c4a6f4f7..23c3a2bf40 100644
--- a/examples/corelib/threads/mandelbrot/mandelbrotwidget.h
+++ b/examples/corelib/threads/mandelbrot/mandelbrotwidget.h
@@ -4,6 +4,7 @@
 #ifndef MANDELBROTWIDGET_H
 #define MANDELBROTWIDGET_H
 
+#include <QGestureEvent>
 #include <QPixmap>
 #include <QWidget>
 #include "renderthread.h"
@@ -18,6 +19,7 @@ public:
     MandelbrotWidget(QWidget *parent = nullptr);
 
 protected:
+    QSize sizeHint() const override { return {1024, 768}; };
     void paintEvent(QPaintEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;
     void keyPressEvent(QKeyEvent *event) override;
@@ -27,6 +29,9 @@ protected:
     void mousePressEvent(QMouseEvent *event) override;
     void mouseMoveEvent(QMouseEvent *event) override;
     void mouseReleaseEvent(QMouseEvent *event) override;
+#ifndef QT_NO_GESTURES
+    bool event(QEvent *event) override;
+#endif
 
 private slots:
     void updatePixmap(const QImage &image, double scaleFactor);
@@ -34,6 +39,9 @@ private slots:
 
 private:
     void scroll(int deltaX, int deltaY);
+#ifndef QT_NO_GESTURES
+    bool gestureEvent(QGestureEvent *event);
+#endif
 
     RenderThread thread;
     QPixmap pixmap;