Bug 1082486 - Part 3 - Refactor UpdatePosition(). r=roc

GetTouchCaretPosition() is needed in a later patch.

layout/base/TouchCaret.cpp

@@ -430,14 +430,18 @@ TouchCaret::UpdatePosition()
 {
   MOZ_ASSERT(mVisible);
 
+  nsPoint pos = GetTouchCaretPosition();
+  pos = ClampPositionToScrollFrame(pos);
+  SetTouchFramePos(pos);
+}
+
+nsPoint
+TouchCaret::GetTouchCaretPosition()
+{
   nsRect focusRect;
   nsIFrame* focusFrame = GetCaretFocusFrame(&focusRect);
   nsIFrame* canvasFrame = GetCanvasFrame();
 
-  if (!focusFrame || !canvasFrame || focusRect.IsEmpty()) {
-    return;
-  }
-
   // Position of the touch caret relative to focusFrame.
   nsPoint pos = nsPoint(focusRect.x + (focusRect.width / 2),
                         focusRect.y + focusRect.height);
@@ -445,6 +449,16 @@ TouchCaret::UpdatePosition()
   // Transform the position to make it relative to canvas frame.
   nsLayoutUtils::TransformPoint(focusFrame, canvasFrame, pos);
 
+  return pos;
+}
+
+nsPoint
+TouchCaret::ClampPositionToScrollFrame(const nsPoint& aPosition)
+{
+  nsPoint pos = aPosition;
+  nsIFrame* focusFrame = GetCaretFocusFrame();
+  nsIFrame* canvasFrame = GetCanvasFrame();
+
   // Clamp the touch caret position to the scrollframe boundary.
   nsIFrame* closestScrollFrame =
     nsLayoutUtils::GetClosestFrameOfType(focusFrame, nsGkAtoms::scrollFrame);
@@ -462,7 +476,7 @@ TouchCaret::UpdatePosition()
                                            nsGkAtoms::scrollFrame);
   }
 
-  SetTouchFramePos(pos);
+  return pos;
 }
 
 /* static */void

layout/base/TouchCaret.h

@@ -111,6 +111,18 @@ private:
    */
   nscoord GetCaretYCenterPosition();
 
+  /**
+   * Retrieve the position of the touch caret.
+   * The returned point is relative to the canvas frame.
+   */
+  nsPoint GetTouchCaretPosition();
+
+  /**
+   * Clamp the position of the touch caret to the scroll frame boundary.
+   * The returned point is relative to the canvas frame.
+   */
+  nsPoint ClampPositionToScrollFrame(const nsPoint& aPosition);
+
   /**
    * Set the position of the touch caret.
    * Touch caret is an absolute positioned div.