Ported the Snap Scroll example to Python.

1 files changed, 116 insertions, 0 deletions

diff --git a/snapscroll/snapscroll.py b/snapscroll/snapscroll.py
new file mode 100644
index 0000000..b80a168
--- /dev/null
+++ b/snapscroll/snapscroll.py
@@ -0,0 +1,116 @@
+#############################################################################
+##
+## 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.
+##
+#############################################################################
+
+import sys
+
+from PyQt4.QtCore import *
+from PyQt4.QtGui import *
+from PyQt4.QtWebKit import *
+
+if QT_VERSION < 0x0040500:
+    sys.stderr.write("You need Qt 4.5 or newer to run this example.\n")
+    sys.exit(1)
+
+SNAP_THRESHOLD = 10
+
+class SnapView(QWebView):
+
+    def __init__(self):
+    
+        QWebView.__init__(self)
+        self.snapEnabled = True
+        self.setWindowTitle(self.tr("Snap-scrolling is ON"))
+
+    # rects hit by the line, in main frame's view coordinate
+    def hitBoundingRects(self, line):
+    
+        hitRects = []
+
+        points = 8
+        delta = QPoint(line.dx() / points, line.dy() / points)
+
+        point = line.p1()
+        i = 0
+        while i < points - 1:
+            point += delta
+            hit = self.page().mainFrame().hitTestContent(point)
+            if not hit.boundingRect().isEmpty():
+                hitRects.append(hit.boundingRect())
+            i += 1
+        
+        return hitRects
+    
+    def keyPressEvent(self, event):
+
+        # toggle snapping
+        if event.key() == Qt.Key_F3:
+            self.snapEnabled = not self.snapEnabled
+            if self.snapEnabled:
+                self.setWindowTitle(self.tr("Snap-scrolling is ON"))
+            else:
+                self.setWindowTitle(self.tr("Snap-scrolling is OFF"))
+            event.accept()
+            return
+        
+        # no snapping? do not bother...
+        if not self.snapEnabled:
+            QWebView.keyReleaseEvent(self, event)
+            return
+        
+        previousOffset = self.page().mainFrame().scrollPosition()
+
+        QWebView.keyReleaseEvent(self, event)
+        if not event.isAccepted():
+            return
+
+        if event.key() == Qt.Key_Down:
+            ofs = self.page().mainFrame().scrollPosition()
+            jump = ofs.y() - previousOffset.y()
+            if jump == 0:
+                return
+
+            jump += SNAP_THRESHOLD
+
+            rects = self.hitBoundingRects(QLine(1, 1, self.width() - 1, 1))
+            i = 0
+            while i < len(rects):
+                j = rects[i].top() - previousOffset.y()
+                if j > SNAP_THRESHOLD and j < jump:
+                    jump = j
+                i += 1
+            
+            self.page().mainFrame().setScrollPosition(previousOffset + QPoint(0, jump))
+
+
+if __name__ == "__main__":
+
+    app = QApplication(sys.argv)
+    
+    view = SnapView()
+    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")
+    
+    sys.exit(app.exec_())