Use a pixmap instead of an image in the tablet example

The transformations QImage->QPixmap are killing the performance of the
tablet example. This is noticeable because of the number of events sent
by the tablet (painting MUST be fast in tabletEvent()).

Reviewed-by: David Boddie

2 files changed, 19 insertions, 19 deletions

diff --git a/examples/widgets/tablet/tabletcanvas.cpp b/examples/widgets/tablet/tabletcanvas.cpp
index 130498b..20b0d1e 100644
--- a/examples/widgets/tablet/tabletcanvas.cpp
+++ b/examples/widgets/tablet/tabletcanvas.cpp
@@ -50,7 +50,7 @@ TabletCanvas::TabletCanvas()
     resize(500, 500);
     myBrush = QBrush();
     myPen = QPen();
-    initImage();
+    initPixmap();
     setAutoFillBackground(true);
     deviceDown = false;
     myColor = Qt::red;
@@ -60,29 +60,29 @@ TabletCanvas::TabletCanvas()
     lineWidthType = LineWidthPressure;
 }
 
-void TabletCanvas::initImage()
+void TabletCanvas::initPixmap()
 {
-    QImage newImage = QImage(width(), height(), QImage::Format_ARGB32);
-    QPainter painter(&newImage);
-    painter.fillRect(0, 0, newImage.width(), newImage.height(), Qt::white);
-    if (!image.isNull())
-        painter.drawImage(0, 0, image);
+    QPixmap newPixmap = QPixmap(width(), height());
+    newPixmap.fill(Qt::white);
+    QPainter painter(&newPixmap);
+    if (!pixmap.isNull())
+        painter.drawPixmap(0, 0, pixmap);
     painter.end();
-    image = newImage;
+    pixmap = newPixmap;
 }
 //! [0]
 
 //! [1]
 bool TabletCanvas::saveImage(const QString &file)
 {
-    return image.save(file);
+    return pixmap.save(file);
 }
 //! [1]
 
 //! [2]
 bool TabletCanvas::loadImage(const QString &file)
 {
-    bool success = image.load(file);
+    bool success = pixmap.load(file);
 
     if (success) {
         update();
@@ -114,8 +114,8 @@ void TabletCanvas::tabletEvent(QTabletEvent *event)
 
             if (deviceDown) {
                 updateBrush(event);
-                QPainter painter(&image);
-                paintImage(painter, event);
+                QPainter painter(&pixmap);
+                paintPixmap(painter, event);
             }
             break;
         default:
@@ -129,12 +129,12 @@ void TabletCanvas::tabletEvent(QTabletEvent *event)
 void TabletCanvas::paintEvent(QPaintEvent *)
 {
     QPainter painter(this);
-    painter.drawImage(QPoint(0, 0), image);
+    painter.drawPixmap(0, 0, pixmap);
 }
 //! [4]
 
 //! [5]
-void TabletCanvas::paintImage(QPainter &painter, QTabletEvent *event)
+void TabletCanvas::paintPixmap(QPainter &painter, QTabletEvent *event)
 {
     QPoint brushAdjust(10, 10);
 
@@ -271,6 +271,6 @@ void TabletCanvas::updateBrush(QTabletEvent *event)
 
 void TabletCanvas::resizeEvent(QResizeEvent *)
 {
-    initImage();
+    initPixmap();
     polyLine[0] = polyLine[1] = polyLine[2] = QPoint();
 }
diff --git a/examples/widgets/tablet/tabletcanvas.h b/examples/widgets/tablet/tabletcanvas.h
index 02b8794..5a2fb1d 100644
--- a/examples/widgets/tablet/tabletcanvas.h
+++ b/examples/widgets/tablet/tabletcanvas.h
@@ -43,7 +43,7 @@
 #define TABLETCANVAS_H
 
 #include <QWidget>
-#include <QImage>
+#include <QPixmap>
 #include <QPoint>
 #include <QTabletEvent>
 #include <QColor>
@@ -92,8 +92,8 @@ protected:
     void resizeEvent(QResizeEvent *event);
 
 private:
-    void initImage();
-    void paintImage(QPainter &painter, QTabletEvent *event);
+    void initPixmap();
+    void paintPixmap(QPainter &painter, QTabletEvent *event);
     Qt::BrushStyle brushPattern(qreal value);
     void updateBrush(QTabletEvent *event);
 
@@ -104,7 +104,7 @@ private:
     QTabletEvent::TabletDevice myTabletDevice;
     QColor myColor;
 
-    QImage image;
+    QPixmap pixmap;
     QBrush myBrush;
     QPen myPen;
     bool deviceDown;