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(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   // 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
  35   // Find the rect within which we shouldn't snap, by expanding the track rect
  36   // in both dimensions.
  37   gfx::Rect noSnapRect(scrollbarRect);
  38   const int thickness = isHorizontal ? noSnapRect.height() : noSnapRect.width();
  39   noSnapRect.Inset(
  40       (isHorizontal ? kOffEndMultiplier : kOffSideMultiplier) * -thickness,
  41       (isHorizontal ? kOffSideMultiplier : kOffEndMultiplier) * -thickness);
  42
  43   // We should snap iff the event is outside our calculated rect.
  44   return !noSnapRect.Contains(eventPoint);
  45 }
  46
  47 }  // namespace content