From 60dc6f547465df77eb3f6b8a44f6d257e78c03e5 Mon Sep 17 00:00:00 2001
From: Botond Ballo <botond@mozilla.com>
Date: Fri, 5 Sep 2014 18:42:03 -0400
Subject: [PATCH] Bug 1063224 - Add a PanStart() method to
 AsyncPanZoomController. r=kats

--HG--
extra : source : c26cacfcd1998dddd2982062c844e10bc5736541
---
 gfx/layers/apz/src/AsyncPanZoomController.cpp |  4 ++++
 gfx/layers/apz/src/AsyncPanZoomController.h   | 10 ++++++++++
 gfx/layers/apz/src/Axis.cpp                   |  4 ++++
 gfx/layers/apz/src/Axis.h                     | 11 ++++++++---
 4 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/gfx/layers/apz/src/AsyncPanZoomController.cpp b/gfx/layers/apz/src/AsyncPanZoomController.cpp
index d598190858c..1e2a3c98430 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -1726,6 +1726,10 @@ float AsyncPanZoomController::PanDistance() const {
   return NS_hypot(mX.PanDistance(), mY.PanDistance());
 }
 
+ScreenPoint AsyncPanZoomController::PanStart() const {
+  return ScreenPoint(mX.PanStart(), mY.PanStart());
+}
+
 const ScreenPoint AsyncPanZoomController::GetVelocityVector() {
   return ScreenPoint(mX.GetVelocity(), mY.GetVelocity());
 }
diff --git a/gfx/layers/apz/src/AsyncPanZoomController.h b/gfx/layers/apz/src/AsyncPanZoomController.h
index d194bd8f1a8..0160adcc846 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.h
+++ b/gfx/layers/apz/src/AsyncPanZoomController.h
@@ -488,6 +488,16 @@ protected:
    */
   float PanDistance() const;
 
+  /**
+   * Gets the start point of the current touch.
+   * Like PanDistance(), this only makes sense if a touch is currently
+   * happening and OnTouchMove() or the equivalent for pan gestures is
+   * being invoked.
+   * Unlikely PanDistance(), this function returns a point in local screen
+   * coordinates.
+   */
+  ScreenPoint PanStart() const;
+
   /**
    * Gets a vector of the velocities of each axis.
    */
diff --git a/gfx/layers/apz/src/Axis.cpp b/gfx/layers/apz/src/Axis.cpp
index ffecca597b6..0c627178dbf 100644
--- a/gfx/layers/apz/src/Axis.cpp
+++ b/gfx/layers/apz/src/Axis.cpp
@@ -207,6 +207,10 @@ void Axis::ClearOverscroll() {
   mOverscroll = 0;
 }
 
+ScreenCoord Axis::PanStart() const {
+  return mStartPos;
+}
+
 ScreenCoord Axis::PanDistance() const {
   return fabs(mPos - mStartPos);
 }
diff --git a/gfx/layers/apz/src/Axis.h b/gfx/layers/apz/src/Axis.h
index 0dc262243f7..d4800cf4a20 100644
--- a/gfx/layers/apz/src/Axis.h
+++ b/gfx/layers/apz/src/Axis.h
@@ -118,16 +118,21 @@ public:
    */
   void ClearOverscroll();
 
+  /**
+   * Gets the starting position of the touch supplied in StartTouch().
+   */
+  ScreenCoord PanStart() const;
+
   /**
    * Gets the distance between the starting position of the touch supplied in
-   * startTouch() and the current touch from the last
-   * updateWithTouchAtDevicePoint().
+   * StartTouch() and the current touch from the last
+   * UpdateWithTouchAtDevicePoint().
    */
   ScreenCoord PanDistance() const;
 
   /**
    * Gets the distance between the starting position of the touch supplied in
-   * startTouch() and the supplied position.
+   * StartTouch() and the supplied position.
    */
   ScreenCoord PanDistance(ScreenCoord aPos) const;