New example on how to do simple snap-scrolling on QWebView.

2 files changed, 125 insertions, 0 deletions

diff --git a/snapscroll/snapscroll.cpp b/snapscroll/snapscroll.cpp
new file mode 100644
index 0000000..41a73c3
--- /dev/null
+++ b/snapscroll/snapscroll.cpp
@@ -0,0 +1,123 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the Graphics Dojo project on Qt Labs.
+**
+** This file may be used under the terms of the GNU General Public
+** License version 2.0 or 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of
+** this file.  Please review the following information to ensure GNU
+** General Public Licensing requirements will be met:
+** http://www.fsf.org/licensing/licenses/info/GPLv2.html and
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+**
+** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+**
+****************************************************************************/
+
+#include <QtCore>
+#include <QtGui>
+#include <QtWebKit>
+
+#if QT_VERSION < 0x0040500
+#error You need Qt 4.5 or newer
+#endif
+
+#define SNAP_THRESHOLD 10
+
+class SnapView: public QWebView
+{
+public:
+
+    SnapView(): QWebView(), snapEnabled(true) {
+        setWindowTitle("Snap-scrolling is ON");
+    }
+
+private:
+
+    bool snapEnabled;
+
+    // rects hit by the line, in main frame's view coordinate
+    QList<QRect> hitBoundingRects(const QLine &line) {
+        QList<QRect> hitRects;
+
+        const int points = 8;
+        QPoint delta(line.dx() / points, line.dy() / points);
+
+        QPoint point = line.p1();
+        for (int i = 0; i < points - 1; ++i) {
+            point += delta;
+            QWebHitTestResult hit = page()->mainFrame()->hitTestContent(point);
+            if (!hit.boundingRect().isEmpty())
+                hitRects += hit.boundingRect();
+        }
+
+        return hitRects;
+    }
+
+    void keyPressEvent(QKeyEvent *event) {
+
+        // toggle snapping
+        if (event->key() == Qt::Key_F3) {
+            snapEnabled = !snapEnabled;
+            if (snapEnabled)
+                setWindowTitle("Snap-scrolling is ON");
+            else
+                setWindowTitle("Snap-scrolling is OFF");
+            event->accept();
+            return;
+        }
+
+        // no snapping? do not bother...
+        if (!snapEnabled) {
+            QWebView::keyReleaseEvent(event);
+            return;
+        }
+
+        QPoint previousOffset = page()->mainFrame()->scrollPosition();
+
+        QWebView::keyReleaseEvent(event);
+        if (!event->isAccepted())
+            return;
+
+        if (event->key() == Qt::Key_Down) {
+            QPoint ofs = page()->mainFrame()->scrollPosition();
+            int jump = ofs.y() - previousOffset.y();
+            if (jump == 0)
+                return;
+
+            jump += SNAP_THRESHOLD;
+
+            QList<QRect> rects = hitBoundingRects(QLine(1, 1, width() - 1, 1));
+            for (int i = 0; i < rects.count(); ++i) {
+                int j = rects[i].top() - previousOffset.y();
+                if (j > SNAP_THRESHOLD && j < jump)
+                    jump = j;
+            }
+
+            page()->mainFrame()->setScrollPosition(previousOffset + QPoint(0, jump));
+        }
+    }
+};
+
+int main(int argc, char **argv)
+{
+    QApplication app(argc, argv);
+
+    SnapView view;
+    view.load(QUrl("http://news.bbc.co.uk/text_only.stm"));
+    view.resize(320, 500);
+    view.show();
+
+    QMessageBox::information(&view, "Hint", "Use F3 to toggle snapping on and off");
+
+    return app.exec();
+}
+
+
diff --git a/snapscroll/snapscroll.pro b/snapscroll/snapscroll.pro
new file mode 100644
index 0000000..4291b80
--- /dev/null
+++ b/snapscroll/snapscroll.pro
@@ -0,0 +1,2 @@
+SOURCES = snapscroll.cpp
+QT += webkit network