Bug 486200 - Need API to compute screen coordinates of DOM elements

r=roc,dbaron, sr=roc,jst

dom/base/nsGlobalWindow.cpp

@@ -170,6 +170,7 @@
 #ifdef MOZ_XUL
 #include "nsXULPopupManager.h"
 #endif
+#include "nsIFrame.h"
 
 #include "plbase64.h"
 
@@ -3406,6 +3407,72 @@ nsGlobalWindow::GetScreenX(PRInt32* aScreenX)
   return NS_OK;
 }
 
+nsRect
+nsGlobalWindow::GetInnerScreenRect()
+{
+  if (!mDocShell)
+    return nsRect();
+
+  nsGlobalWindow* rootWindow =
+    static_cast<nsGlobalWindow*>(GetPrivateRoot());
+  if (rootWindow) {
+    rootWindow->FlushPendingNotifications(Flush_Layout);
+  }
+
+  nsCOMPtr<nsIPresShell> presShell;
+  mDocShell->GetPresShell(getter_AddRefs(presShell));
+  if (!presShell)
+    return nsRect();
+  nsIFrame* rootFrame = presShell->GetRootFrame();
+  if (!rootFrame)
+    return nsRect();
+
+  return rootFrame->GetScreenRectInAppUnits();
+}
+
+NS_IMETHODIMP
+nsGlobalWindow::GetMozInnerScreenX(float* aScreenX)
+{
+  FORWARD_TO_OUTER(GetMozInnerScreenX, (aScreenX), NS_ERROR_NOT_INITIALIZED);
+
+  nsRect r = GetInnerScreenRect();
+  *aScreenX = nsPresContext::AppUnitsToFloatCSSPixels(r.x);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsGlobalWindow::GetMozInnerScreenY(float* aScreenY)
+{
+  FORWARD_TO_OUTER(GetMozInnerScreenY, (aScreenY), NS_ERROR_NOT_INITIALIZED);
+
+  nsRect r = GetInnerScreenRect();
+  *aScreenY = nsPresContext::AppUnitsToFloatCSSPixels(r.y);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsGlobalWindow::GetMozScreenPixelsPerCSSPixel(float* aScreenPixels)
+{
+  FORWARD_TO_OUTER(GetMozScreenPixelsPerCSSPixel,
+      (aScreenPixels), NS_ERROR_NOT_INITIALIZED);
+
+  *aScreenPixels = 1;
+
+  if (!nsContentUtils::IsCallerTrustedForRead())
+    return NS_ERROR_DOM_SECURITY_ERR;
+  if (!mDocShell)
+    return NS_OK;
+  nsCOMPtr<nsPresContext> presContext;
+  mDocShell->GetPresContext(getter_AddRefs(presContext));
+  if (!presContext)
+    return NS_OK;
+
+  *aScreenPixels = float(nsPresContext::AppUnitsPerCSSPixel())/
+      presContext->AppUnitsPerDevPixel();
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsGlobalWindow::SetScreenX(PRInt32 aScreenX)
 {

dom/base/nsGlobalWindow.h

@@ -90,6 +90,7 @@
 #include "nsIXPCScriptable.h"
 #include "nsPoint.h"
 #include "nsSize.h"
+#include "nsRect.h"
 #include "mozFlushType.h"
 #include "prclist.h"
 #include "nsIDOMStorageObsolete.h"
@@ -589,6 +590,7 @@ protected:
   
   nsresult GetOuterSize(nsIntSize* aSizeCSSPixels);
   nsresult SetOuterSize(PRInt32 aLengthCSSPixels, PRBool aIsWidth);
+  nsRect GetInnerScreenRect();
 
   PRBool IsFrame()
   {

dom/interfaces/base/nsIDOMWindowInternal.idl

@@ -44,7 +44,7 @@ interface nsIControllers;
 interface nsIDOMLocation;
 interface nsIVariant;
 
-[scriptable, uuid(3414EBC7-731F-4697-9F43-ACA6F5050875)]
+[scriptable, uuid(62579239-b619-4bf2-8d39-0b73e8663a85)]
 interface nsIDOMWindowInternal : nsIDOMWindow2
 {
   readonly attribute nsIDOMWindowInternal        window;
@@ -104,6 +104,9 @@ interface nsIDOMWindowInternal : nsIDOMWindow2
            attribute long                        outerHeight;
            attribute long                        screenX;
            attribute long                        screenY;
+  readonly attribute float                       mozInnerScreenX;
+  readonly attribute float                       mozInnerScreenY;
+  readonly attribute float                       mozScreenPixelsPerCSSPixel;
 
   /* The offset in pixels by which the window is scrolled */
   readonly attribute long                        pageXOffset;

dom/tests/mochitest/general/Makefile.in

@@ -44,7 +44,9 @@ relativesrcdir  = dom/tests/mochitest/general
 include $(DEPTH)/config/autoconf.mk
 include $(topsrcdir)/config/rules.mk
 
-_TEST_FILES = test_offsets.html \
+_TEST_FILES = \
+		test_innerScreen.xul \
+		test_offsets.html \
 		test_offsets.xul \
 		test_offsets.js \
 		test_domWindowUtils.html \

dom/tests/mochitest/general/test_innerScreen.xul

@@ -0,0 +1,79 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="/tests/SimpleTest/test.css" type="text/css"?>
+<!--
+  Tests for mozInnerScreenX/Y properties
+  -->
+<window title="Test mozInnerScreenX/Y Properties"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="text/javascript" src="/MochiKit/packed.js"/>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"/>
+
+  <!-- test resuls are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml" style="height: 300px; overflow: auto;"/>
+
+  <iframe id="f" style="margin:50px; width:200px; height:200px; border:none;"></iframe>
+
+  <!-- test code goes here -->
+  <script type="application/javascript"><![CDATA[
+
+function isRounded(a, b, msg) {
+  is(Math.round(a), Math.round(b), msg);
+}
+
+function doTests()
+{
+  var readable = false;
+  try
+  {
+    mozScreenPixelsPerCSSPixel;
+    readable = true;
+  }
+  catch(ex) { }
+  ok(!readable, "window pixels per css pixel shouldn't be readable to content");
+
+  netscape.security.PrivilegeManager.enablePrivilege('UniversalXPConnect');
+
+  var devPxPerCSSPx = window.mozScreenPixelsPerCSSPixel;
+  var windowBO = document.documentElement.boxObject;
+  isRounded(window.mozInnerScreenX*devPxPerCSSPx, windowBO.screenX,
+            "window screen X");
+  isRounded(window.mozInnerScreenY*devPxPerCSSPx, windowBO.screenY,
+            "window screen Y");
+
+  var f = document.getElementById("f");
+  var fBounds = f.getBoundingClientRect();
+
+  const CI = Components.interfaces;
+  var fshell = f.contentWindow.QueryInterface(CI.nsIInterfaceRequestor).getInterface(CI.nsIWebNavigation).QueryInterface(CI.nsIDocShell);
+  var fmudv = fshell.contentViewer.QueryInterface(CI.nsIMarkupDocumentViewer);
+
+  isRounded(f.contentWindow.mozInnerScreenX,
+            window.mozInnerScreenX + fBounds.left,
+            "frame screen X");
+  isRounded(f.contentWindow.mozInnerScreenY,
+            window.mozInnerScreenY + fBounds.top,
+            "frame screen Y");
+
+  fmudv.fullZoom *= 2;
+  is(f.contentWindow.mozScreenPixelsPerCSSPixel, 2*devPxPerCSSPx,
+     "frame screen pixels per CSS pixel");
+
+  isRounded(f.contentWindow.mozInnerScreenX*2,
+            window.mozInnerScreenX + fBounds.left,
+            "zoomed frame screen X");
+  isRounded(f.contentWindow.mozInnerScreenY*2,
+            window.mozInnerScreenY + fBounds.top,
+            "zoomed frame screen Y");
+  fmudv.fullZoom = 1.0;
+
+  SimpleTest.finish();
+}
+
+addLoadEvent(doTests);
+SimpleTest.waitForExplicitFinish();
+
+]]>
+</script>
+
+</window>