content/renderer/webscrollbarbehavior_impl_gtkoraura.cc

   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
  12 bool WebScrollbarBehaviorImpl::shouldCenterOnThumb(
  13       blink::WebScrollbarBehavior::Button mouseButton,
  14       bool shiftKeyPressed,
  15       bool altKeyPressed) {
  16 #if defined(TOOLKIT_GTK) || (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
  24 bool WebScrollbarBehaviorImpl::shouldSnapBackToDragOrigin(
  25     const blink::WebPoint& eventPoint,
  26     const blink::WebRect& scrollbarRect,
  27     bool isHorizontal) {
  28 #if defined(TOOLKIT_GTK)
  29   return false;
  30 #endif
  31
  32   // Constants used to figure the drag rect outside which we should snap the
  33   // scrollbar thumb back to its origin. These calculations are based on
  34   // observing the behavior of the MSVC8 main window scrollbar + some
  35   // guessing/extrapolation.
  36   static const int kOffEndMultiplier = 3;
  37   static const int kOffSideMultiplier = 8;
  38
  39   // Find the rect within which we shouldn't snap, by expanding the track rect
  40   // in both dimensions.
  41   gfx::Rect noSnapRect(scrollbarRect);
  42   const int thickness = isHorizontal ? noSnapRect.height() : noSnapRect.width();
  43   noSnapRect.Inset(
  44       (isHorizontal ? kOffEndMultiplier : kOffSideMultiplier) * -thickness,
  45       (isHorizontal ? kOffSideMultiplier : kOffEndMultiplier) * -thickness);
  46
  47   // We should snap iff the event is outside our calculated rect.
  48   return !noSnapRect.Contains(eventPoint);
  49 }
  50
  51 }  // namespace content