--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebKit/chromium/src/DragScrollTimer.cpp	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,126 @@
+/*
+ * Copyright (C) 2010 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "DragScrollTimer.h"
+
+#include "FrameView.h"
+
+using namespace WebCore;
+
+namespace WebKit {
+
+// Computes the distance from a point outside a rect to the nearest edge of the rect.
+static IntSize distanceToRect(const IntPoint& point, const IntRect& rect)
+{
+    int dx = 0, dy = 0;
+    if (point.x() < rect.x())
+        dx = point.x() - rect.x();
+    else if (rect.right() < point.x())
+        dx = point.x() - rect.right();
+    if (point.y() < rect.y())
+        dy = point.y() - rect.y();
+    else if (rect.bottom() < point.y())
+        dy = point.y() - rect.bottom();
+    return IntSize(dx, dy);
+}
+
+DragScrollTimer::DragScrollTimer()
+    : m_timer(this, &DragScrollTimer::fired)
+    , m_view(0)
+    , m_scrolling(false)
+{
+}
+
+DragScrollTimer::~DragScrollTimer()
+{
+    // We do this for detecting dead object earlier
+    stop(); 
+}
+
+void DragScrollTimer::stop()
+{
+    m_timer.stop();
+    m_view = 0;
+    m_scrolling = false;
+}
+
+void DragScrollTimer::scroll()
+{
+    m_view->scrollBy(m_lastDistance);
+    m_scrolling = true;
+}
+
+void DragScrollTimer::update()
+{
+    if (shouldScroll())
+        scroll();
+    else
+        stop();
+}
+
+void DragScrollTimer::triggerScroll(FrameView* view, const WebPoint& location)
+{
+    if (!view)
+        return;
+
+    // Approximates Safari
+    static const double scrollStartDelay = 0.2;
+
+    m_view = view;
+    m_lastDistance = scrollDistanceFor(view, location);
+
+    if (m_scrolling)
+        update();
+    else if (shouldScroll() && !m_timer.isActive())
+        m_timer.startOneShot(scrollStartDelay);
+}
+
+IntSize DragScrollTimer::scrollDistanceFor(FrameView* view, const WebPoint& location) const
+{
+    static const int scrollMargin = 30;
+
+    IntRect bounds(0, 0, view->visibleWidth(), view->visibleHeight());
+    if (!bounds.contains(location))
+        return IntSize(0, 0); // The location is outside the border belt.
+
+    bounds.setY(bounds.y() + scrollMargin);
+    bounds.setHeight(bounds.height() - scrollMargin * 2);
+    bounds.setX(bounds.x() + scrollMargin);
+    bounds.setWidth(bounds.width() - scrollMargin * 2);
+
+    if (bounds.contains(location))
+        return IntSize(0, 0); // The location is inside the border belt.
+
+    // The location is over the border belt.
+    return distanceToRect(location, bounds);
+}
+
+} // namespace WebKit