Added inertial to the browser demo.

2 files changed, 29 insertions, 3 deletions

diff --git a/examples/gestures/browser/webview.cpp b/examples/gestures/browser/webview.cpp
index 38fb43d..95a96e7 100644
--- a/examples/gestures/browser/webview.cpp
+++ b/examples/gestures/browser/webview.cpp
@@ -316,10 +316,34 @@ bool WebView::event(QEvent *event)
 void WebView::gestureEvent(QGestureEvent *event)
 {
     if (const QGesture *g = event->gesture(Qt::PanGesture)) {
-        if (QWebFrame *frame = page()->mainFrame()) {
-            QPoint offset = g->pos() - g->lastPos();
-            frame->setScrollPosition(frame->scrollPosition() - offset);
+        if (g->state() == Qt::GestureUpdated) {
+            if (QWebFrame *frame = page()->mainFrame()) {
+                QPoint offset = g->pos() - g->lastPos();
+                frame->setScrollPosition(frame->scrollPosition() - offset);
+            }
+            speed = g->pos() - g->lastPos();
+        } else if (g->state() == Qt::GestureStarted) {
+            startTimer(20);
+        } else {
         }
         event->accept();
     }
 }
+
+static QPoint deaccelerate(const QPoint &speed, int a = 1, int max = 64)
+{
+    int x = qBound(-max, speed.x(), max);
+    int y = qBound(-max, speed.y(), max);
+    x = (x == 0) ? x : (x > 0) ? qMax(0, x - a) : qMin(0, x + a);
+    y = (y == 0) ? y : (y > 0) ? qMax(0, y - a) : qMin(0, y + a);
+    return QPoint(x, y);
+}
+
+void WebView::timerEvent(QTimerEvent *event)
+{
+    speed = deaccelerate(speed);
+    if (speed.isNull())
+        killTimer(event->timerId());
+    if (QWebFrame *frame = page()->mainFrame())
+        frame->setScrollPosition(frame->scrollPosition() - speed);
+}
diff --git a/examples/gestures/browser/webview.h b/examples/gestures/browser/webview.h
index 037d117..15fb40c 100644
--- a/examples/gestures/browser/webview.h
+++ b/examples/gestures/browser/webview.h
@@ -99,6 +99,7 @@ public:
 protected:
     bool event(QEvent *event);
     void gestureEvent(QGestureEvent *event);
+    void timerEvent(QTimerEvent *event);
     void mousePressEvent(QMouseEvent *event);
     void mouseReleaseEvent(QMouseEvent *event);
     void contextMenuEvent(QContextMenuEvent *event);
@@ -116,6 +117,7 @@ private:
     QUrl m_initialUrl;
     int m_progress;
     WebPage *m_page;
+    QPoint speed;
 };
 
 #endif