1 /*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions are
6 * met:
7 *
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above
11 * copyright notice, this list of conditions and the following disclaimer
12 * in the documentation and/or other materials provided with the
13 * distribution.
14 * * Neither the name of Google Inc. nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 */
30
31 #include "config.h"
32 #include "DragScrollTimer.h"
33
34 #include "FrameView.h"
35
36 using namespace WebCore;
37
38 namespace WebKit {
39
40 // Computes the distance from a point outside a rect to the nearest edge of the rect.
distanceToRect(const IntPoint & point,const IntRect & rect)41 static IntSize distanceToRect(const IntPoint& point, const IntRect& rect)
42 {
43 int dx = 0, dy = 0;
44 if (point.x() < rect.x())
45 dx = point.x() - rect.x();
46 else if (rect.maxX() < point.x())
47 dx = point.x() - rect.maxX();
48 if (point.y() < rect.y())
49 dy = point.y() - rect.y();
50 else if (rect.maxY() < point.y())
51 dy = point.y() - rect.maxY();
52 return IntSize(dx, dy);
53 }
54
DragScrollTimer()55 DragScrollTimer::DragScrollTimer()
56 : m_timer(this, &DragScrollTimer::fired)
57 , m_view(0)
58 , m_scrolling(false)
59 {
60 }
61
~DragScrollTimer()62 DragScrollTimer::~DragScrollTimer()
63 {
64 // We do this for detecting dead object earlier
65 stop();
66 }
67
stop()68 void DragScrollTimer::stop()
69 {
70 m_timer.stop();
71 m_view = 0;
72 m_scrolling = false;
73 }
74
scroll()75 void DragScrollTimer::scroll()
76 {
77 m_view->scrollBy(m_lastDistance);
78 m_scrolling = true;
79 }
80
update()81 void DragScrollTimer::update()
82 {
83 if (shouldScroll())
84 scroll();
85 else
86 stop();
87 }
88
triggerScroll(FrameView * view,const WebPoint & location)89 void DragScrollTimer::triggerScroll(FrameView* view, const WebPoint& location)
90 {
91 if (!view)
92 return;
93
94 // Approximates Safari
95 static const double scrollStartDelay = 0.2;
96
97 m_view = view;
98 m_lastDistance = scrollDistanceFor(view, location);
99
100 if (m_scrolling)
101 update();
102 else if (shouldScroll() && !m_timer.isActive())
103 m_timer.startOneShot(scrollStartDelay);
104 }
105
scrollDistanceFor(FrameView * view,const WebPoint & location) const106 IntSize DragScrollTimer::scrollDistanceFor(FrameView* view, const WebPoint& location) const
107 {
108 static const int scrollMargin = 30;
109
110 IntRect bounds(0, 0, view->visibleWidth(), view->visibleHeight());
111 if (!bounds.contains(location))
112 return IntSize(0, 0); // The location is outside the border belt.
113
114 bounds.setY(bounds.y() + scrollMargin);
115 bounds.setHeight(bounds.height() - scrollMargin * 2);
116 bounds.setX(bounds.x() + scrollMargin);
117 bounds.setWidth(bounds.width() - scrollMargin * 2);
118
119 if (bounds.contains(location))
120 return IntSize(0, 0); // The location is inside the border belt.
121
122 // The location is over the border belt.
123 return distanceToRect(location, bounds);
124 }
125
126 } // namespace WebKit
127