gfx/layers/apz/src/DragTracker.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "DragTracker.h"
   8
   9 #include "InputData.h"
  10 #include "mozilla/Logging.h"
  11
  12 static mozilla::LazyLogModule sApzDrgLog("apz.drag");
  13 #define DRAG_LOG(...) MOZ_LOG(sApzDrgLog, LogLevel::Debug, (__VA_ARGS__))
  14
  15 namespace mozilla {
  16 namespace layers {
  17
  18 DragTracker::DragTracker() : mInDrag(false) {}
  19
  20 /*static*/
  21 bool DragTracker::StartsDrag(const MouseInput& aInput) {
  22   return aInput.IsLeftButton() && aInput.mType == MouseInput::MOUSE_DOWN;
  23 }
  24
  25 /*static*/
  26 bool DragTracker::EndsDrag(const MouseInput& aInput) {
  27   // On Windows, we don't receive a MOUSE_UP at the end of a drag if an
  28   // actual drag session took place. As a backup, we detect the end of the
  29   // drag using the MOUSE_DRAG_END event, which normally is routed directly
  30   // to content, but we're specially routing to APZ for this purpose. Bug
  31   // 1265105 tracks a solution to this at the Windows widget layer; once
  32   // that is implemented, this workaround can be removed.
  33   return (aInput.IsLeftButton() && aInput.mType == MouseInput::MOUSE_UP) ||
  34          aInput.mType == MouseInput::MOUSE_DRAG_END;
  35 }
  36
  37 void DragTracker::Update(const MouseInput& aInput) {
  38   if (StartsDrag(aInput)) {
  39     DRAG_LOG("Starting drag\n");
  40     mInDrag = true;
  41   } else if (EndsDrag(aInput)) {
  42     DRAG_LOG("Ending drag\n");
  43     mInDrag = false;
  44     mOnScrollbar = Nothing();
  45   }
  46 }
  47
  48 bool DragTracker::InDrag() const { return mInDrag; }
  49
  50 bool DragTracker::IsOnScrollbar(bool aOnScrollbar) {
  51   if (!mOnScrollbar) {
  52     DRAG_LOG("Setting hitscrollbar %d\n", aOnScrollbar);
  53     mOnScrollbar = Some(aOnScrollbar);
  54   }
  55   return mOnScrollbar.value();
  56 }
  57
  58 }  // namespace layers
  59 }  // namespace mozilla