1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "content/renderer/webscrollbarbehavior_impl_gtkoraura.h"
6
7 #include "third_party/WebKit/public/platform/WebPoint.h"
8 #include "third_party/WebKit/public/platform/WebRect.h"
9
10 namespace content {
11
shouldCenterOnThumb(blink::WebScrollbarBehavior::Button mouseButton,bool shiftKeyPressed,bool altKeyPressed)12 bool WebScrollbarBehaviorImpl::shouldCenterOnThumb(
13 blink::WebScrollbarBehavior::Button mouseButton,
14 bool shiftKeyPressed,
15 bool altKeyPressed) {
16 #if (defined(OS_LINUX) && !defined(OS_CHROMEOS))
17 if (mouseButton == blink::WebScrollbarBehavior::ButtonMiddle)
18 return true;
19 #endif
20 return (mouseButton == blink::WebScrollbarBehavior::ButtonLeft) &&
21 shiftKeyPressed;
22 }
23
shouldSnapBackToDragOrigin(const blink::WebPoint & eventPoint,const blink::WebRect & scrollbarRect,bool isHorizontal)24 bool WebScrollbarBehaviorImpl::shouldSnapBackToDragOrigin(
25 const blink::WebPoint& eventPoint,
26 const blink::WebRect& scrollbarRect,
27 bool isHorizontal) {
28 // Constants used to figure the drag rect outside which we should snap the
29 // scrollbar thumb back to its origin. These calculations are based on
30 // observing the behavior of the MSVC8 main window scrollbar + some
31 // guessing/extrapolation.
32 static const int kOffEndMultiplier = 3;
33 static const int kOffSideMultiplier = 8;
34 static const int kDefaultWinScrollbarThickness = 17;
35
36 // Find the rect within which we shouldn't snap, by expanding the track rect
37 // in both dimensions.
38 gfx::Rect noSnapRect(scrollbarRect);
39 int thickness = isHorizontal ? noSnapRect.height() : noSnapRect.width();
40 // Even if the platform's scrollbar is narrower than the default Windows one,
41 // we still want to provide at least as much slop area, since a slightly
42 // narrower scrollbar doesn't necessarily imply that users will drag
43 // straighter.
44 thickness = std::max(thickness, kDefaultWinScrollbarThickness);
45 noSnapRect.Inset(
46 (isHorizontal ? kOffEndMultiplier : kOffSideMultiplier) * -thickness,
47 (isHorizontal ? kOffSideMultiplier : kOffEndMultiplier) * -thickness);
48
49 // On most platforms, we should snap iff the event is outside our calculated
50 // rect. On Linux, however, we should not snap for events off the ends, but
51 // not the sides, of the rect.
52 #if (defined(OS_LINUX) && !defined(OS_CHROMEOS))
53 return isHorizontal ?
54 (eventPoint.y < noSnapRect.y() || eventPoint.y >= noSnapRect.bottom()) :
55 (eventPoint.x < noSnapRect.x() || eventPoint.x >= noSnapRect.right());
56 #else
57 return !noSnapRect.Contains(eventPoint);
58 #endif
59 }
60
61 } // namespace content
62