Bug 532569. Support 'transparent' attribute on XUL IFRAMEs to integrate content documents into the chrome rendering hierarchy, with their background defaulting to transparent. r=mats,sr=bz

layout/base/nsDocumentViewer.cpp

@@ -2292,13 +2292,17 @@ DocumentViewerImpl::FindContainerView()
 {
   nsIView* containerView = nsnull;
 
+  nsCOMPtr<nsIContent> containerElement;
+  nsCOMPtr<nsIDocShellTreeItem> docShellItem = do_QueryReferent(mContainer);
+  nsCOMPtr<nsPIDOMWindow> pwin(do_GetInterface(docShellItem));
+  if (pwin) {
+    containerElement = do_QueryInterface(pwin->GetFrameElementInternal());
+  }
+        
   if (mParentWidget) {
     containerView = nsIView::GetViewFor(mParentWidget);
-  } else if (mContainer) {
-    nsCOMPtr<nsIDocShellTreeItem> docShellItem = do_QueryReferent(mContainer);
-    nsCOMPtr<nsPIDOMWindow> pwin(do_GetInterface(docShellItem));
-    if (pwin) {
-      nsCOMPtr<nsIContent> content = do_QueryInterface(pwin->GetFrameElementInternal());
+  } else {
+    if (mContainer) {
       nsCOMPtr<nsIPresShell> parentPresShell;
       if (docShellItem) {
         nsCOMPtr<nsIDocShellTreeItem> parentDocShellItem;
@@ -2308,12 +2312,12 @@ DocumentViewerImpl::FindContainerView()
           parentDocShell->GetPresShell(getter_AddRefs(parentPresShell));
         }
       }
-      if (!content) {
+      if (!containerElement) {
         NS_WARNING("Subdocument container has no content");
       } else if (!parentPresShell) {
         NS_WARNING("Subdocument container has no presshell");
       } else {
-        nsIFrame* f = parentPresShell->GetRealPrimaryFrameFor(content);
+        nsIFrame* f = parentPresShell->GetRealPrimaryFrameFor(containerElement);
         if (f) {
           nsIFrame* subdocFrame = f->GetContentInsertionFrame();
           // subdocFrame might not be a subdocument frame; the frame
@@ -2339,6 +2343,10 @@ DocumentViewerImpl::FindContainerView()
   if (!containerView)
     return nsnull;
 
+  if (containerElement &&
+      containerElement->HasAttr(kNameSpaceID_None, nsGkAtoms::transparent))
+    return containerView;
+
   nsIWidget* outerWidget = containerView->GetNearestWidget(nsnull);
   if (outerWidget &&
       outerWidget->GetTransparencyMode() == eTransparencyTransparent)

layout/base/tests/chrome/Makefile.in

@@ -55,6 +55,8 @@ _CHROME_FILES = \
 	test_printpreview.xul \
 	printpreview_helper.xul \
 	test_bug533845.xul \
+	chrome_content_integration_window.xul \
+	test_chrome_content_integration.xul \
     $(NULL)
 
 libs:: $(_CHROME_FILES)

layout/base/tests/chrome/chrome_content_integration_window.xul

@@ -0,0 +1,49 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<window title="Content/chrome integration subwindow"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        onload="runTests()"
+        style="background:black; -moz-appearance:none;">
+  <script type="text/javascript" src="chrome://mochikit/content/tests/SimpleTest/WindowSnapshot.js"></script>
+
+  <stack style="height:300px; width:200px;">
+    <!-- the bottom 100px is a strip of black that should be vixible through the content iframe -->
+    <vbox style="background:pink; border-bottom:100px solid black"/>
+    <!-- the middle 100px is a strip of black in the content iframe -->
+    <!-- the bottom 100px of the iframe is transparent, the top 100px is yellow -->
+    <iframe type="content" style="border:none;"
+            transparent="transparent"
+            src="data:text/html,&lt;div style='position:absolute;left:0;top:0;width:100%;height:100px;background:yellow;border-bottom:100px solid black'&gt;"/>
+    <!-- the top 100px is a strip of black above the content iframe -->
+    <vbox style="border-top:100px solid black;"/>
+  </stack>
+
+  <script type="application/javascript">
+    <![CDATA[
+    var imports = [ "SimpleTest", "is", "isnot", "ok" ];
+    for each (var import in imports) {
+      window[import] = window.opener.wrappedJSObject[import];
+    }
+    
+    var HTMLNS = "http://www.w3.org/1999/xhtml";
+
+    function runTests() {
+      var testCanvas = snapshotWindow(window);
+
+      var refCanvas = snapshotWindow(window);
+      var ctx = refCanvas.getContext('2d');
+      ctx.fillStyle = "black";
+      ctx.fillRect(0, 0, refCanvas.width, refCanvas.height);
+
+      var comparison = compareSnapshots(testCanvas, refCanvas, true);
+      ok(comparison[0], "Rendering OK, got " + comparison[1] + ", expected " + comparison[2]);
+      dump(comparison[1] + "\n");
+      dump(comparison[2] + "\n");
+
+      var tester = window.SimpleTest;
+      window.close();
+      tester.finish();
+    }
+    ]]>
+  </script>
+</window>

layout/base/tests/chrome/test_chrome_content_integration.xul

@@ -0,0 +1,23 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css"
+                 type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript"
+          src="chrome://mochikit/content/MochiKit/packed.js"></script>
+  <script type="application/javascript"
+          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+  <![CDATA[
+    SimpleTest.waitForExplicitFinish();
+    window.open("chrome_content_integration_window.xul", "chrome_content_integration",
+                "chrome,width=200,height=300");
+  ]]>
+  </script>
+</window>