Bug 681192. Part 13: Make nsDOMWindowUtils event coordinate calculations more accurate. r=matspal

--HG--
extra : rebase_source : fef4ef568baf1a67038aeb0e187511771fe0d565

dom/base/nsDOMWindowUtils.cpp

@@ -524,6 +524,16 @@ nsDOMWindowUtils::SendMouseEventToWindow(const nsAString& aType,
                               aIgnoreRootScrollFrame, true);
 }
 
+static nsIntPoint
+ToWidgetPoint(float aX, float aY, const nsPoint& aOffset,
+              nsPresContext* aPresContext)
+{
+  double appPerDev = aPresContext->AppUnitsPerDevPixel();
+  nscoord appPerCSS = nsPresContext::AppUnitsPerCSSPixel();
+  return nsIntPoint(NSToIntRound((aX*appPerCSS + aOffset.x)/appPerDev),
+                    NSToIntRound((aY*appPerCSS + aOffset.y)/appPerDev));
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::SendMouseEventCommon(const nsAString& aType,
                                        float aX,
@@ -577,13 +587,7 @@ nsDOMWindowUtils::SendMouseEventCommon(const nsAString& aType,
   if (!presContext)
     return NS_ERROR_FAILURE;
 
-  PRInt32 appPerDev = presContext->AppUnitsPerDevPixel();
+  event.refPoint = ToWidgetPoint(aX, aY, offset, presContext);
-  event.refPoint.x =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aX) + offset.x,
-                          appPerDev);
-  event.refPoint.y =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aY) + offset.y,
-                          appPerDev);
   event.ignoreRootScrollFrame = aIgnoreRootScrollFrame;
 
   nsEventStatus status;
@@ -644,13 +648,7 @@ nsDOMWindowUtils::SendMouseScrollEvent(const nsAString& aType,
   if (!presContext)
     return NS_ERROR_FAILURE;
 
-  PRInt32 appPerDev = presContext->AppUnitsPerDevPixel();
+  event.refPoint = ToWidgetPoint(aX, aY, offset, presContext);
-  event.refPoint.x =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aX) + offset.x,
-                          appPerDev);
-  event.refPoint.y =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aY) + offset.y,
-                          appPerDev);
 
   nsEventStatus status;
   return widget->DispatchEvent(&event, status);
@@ -703,15 +701,8 @@ nsDOMWindowUtils::SendTouchEvent(const nsAString& aType,
     return NS_ERROR_FAILURE;
   }
   event.touches.SetCapacity(aCount);
-  PRInt32 appPerDev = presContext->AppUnitsPerDevPixel();
   for (PRUint32 i = 0; i < aCount; ++i) {
-    nsIntPoint pt(0, 0);
+    nsIntPoint pt = ToWidgetPoint(aXs[i], aYs[i], offset, presContext);
-    pt.x =
-      NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aXs[i]) + offset.x,
-                            appPerDev);
-    pt.y =
-      NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aYs[i]) + offset.y,
-                            appPerDev);
     nsCOMPtr<nsIDOMTouch> t(new nsDOMTouch(aIdentifiers[i],
                                            pt,
                                            nsIntPoint(aRxs[i], aRys[i]),
@@ -1081,13 +1072,7 @@ nsDOMWindowUtils::SendSimpleGestureEvent(const nsAString& aType,
   if (!presContext)
     return NS_ERROR_FAILURE;
 
-  PRInt32 appPerDev = presContext->AppUnitsPerDevPixel();
+  event.refPoint = ToWidgetPoint(aX, aY, offset, presContext);
-  event.refPoint.x =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aX) + offset.x,
-                          appPerDev);
-  event.refPoint.y =
-    NSAppUnitsToIntPixels(nsPresContext::CSSPixelsToAppUnits(aY) + offset.y,
-                          appPerDev);
 
   nsEventStatus status;
   return widget->DispatchEvent(&event, status);