From 24c35a21858aac6ca23dcd775376ce07fc06fa50 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Fri, 13 Nov 2015 20:17:58 -0700
Subject: [PATCH] Draw layers that are under sub-displaylists.

Fixes #8325
---
 components/gfx/paint_task.rs                  | 41 +++++++++++++++----
 tests/wpt/mozilla/meta/MANIFEST.json          | 26 +++++++++++-
 .../tests/css/transform_scroll_layer.html     | 12 ++++++
 .../tests/css/transform_scroll_layer_ref.html |  5 +++
 4 files changed, 74 insertions(+), 10 deletions(-)
 create mode 100644 tests/wpt/mozilla/tests/css/transform_scroll_layer.html
 create mode 100644 tests/wpt/mozilla/tests/css/transform_scroll_layer_ref.html

diff --git a/components/gfx/paint_task.rs b/components/gfx/paint_task.rs
index 926aa2fe123..a44e1bd4d54 100644
--- a/components/gfx/paint_task.rs
+++ b/components/gfx/paint_task.rs
@@ -474,15 +474,38 @@ impl<C> PaintTask<C> where C: PaintListener + Send + 'static {
                                                                perspective,
                                                                parent_id));
 
-            if let PaintLayerContents::StackingContext(ref context) = paint_layer.contents {
-                // When there is a new layer, the transforms and origin are handled by the compositor,
-                // so the new transform and perspective matrices are just the identity.
-                continue_walking_stacking_context(properties,
-                                                  &context,
-                                                  &paint_layer.origin_for_child_layers(),
-                                                  &Matrix4::identity(),
-                                                  &Matrix4::identity(),
-                                                  Some(paint_layer.id));
+            match paint_layer.contents {
+                PaintLayerContents::StackingContext(ref context) => {
+                    // When there is a new layer, the transforms and origin are handled by the compositor,
+                    // so the new transform and perspective matrices are just the identity.
+                    continue_walking_stacking_context(properties,
+                                                      &context,
+                                                      &paint_layer.origin_for_child_layers(),
+                                                      &Matrix4::identity(),
+                                                      &Matrix4::identity(),
+                                                      Some(paint_layer.id));
+                },
+                PaintLayerContents::DisplayList(ref display_list) => {
+                    for kid in display_list.positioned_content.iter() {
+                        if let &DisplayItem::StackingContextClass(ref stacking_context) = kid {
+                            build_from_stacking_context(properties,
+                                                        &stacking_context,
+                                                        &parent_origin,
+                                                        &transform,
+                                                        &perspective,
+                                                        parent_id)
+
+                        }
+                    }
+                    for kid in display_list.layered_children.iter() {
+                        build_from_paint_layer(properties,
+                                               &kid,
+                                               &parent_origin,
+                                               &transform,
+                                               &perspective,
+                                               parent_id)
+                    }
+                },
             }
         }
 
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 40aabbdb3f6..2dd0440ad73 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -4023,6 +4023,18 @@
             "url": "/_mozilla/css/transform_optimization.html"
           }
         ],
+        "css/transform_scroll_layer.html": [
+          {
+            "path": "css/transform_scroll_layer.html",
+            "references": [
+              [
+                "/_mozilla/css/transform_scroll_layer_ref.html",
+                "=="
+              ]
+            ],
+            "url": "/_mozilla/css/transform_scroll_layer.html"
+          }
+        ],
         "css/transform_simple_a.html": [
           {
             "path": "css/transform_simple_a.html",
@@ -9202,6 +9214,18 @@
           "url": "/_mozilla/css/transform_optimization.html"
         }
       ],
+      "css/transform_scroll_layer.html": [
+        {
+          "path": "css/transform_scroll_layer.html",
+          "references": [
+            [
+              "/_mozilla/css/transform_scroll_layer_ref.html",
+              "=="
+            ]
+          ],
+          "url": "/_mozilla/css/transform_scroll_layer.html"
+        }
+      ],
       "css/transform_simple_a.html": [
         {
           "path": "css/transform_simple_a.html",
@@ -9772,4 +9796,4 @@
   "rev": null,
   "url_base": "/_mozilla/",
   "version": 2
-}
+}
\ No newline at end of file
diff --git a/tests/wpt/mozilla/tests/css/transform_scroll_layer.html b/tests/wpt/mozilla/tests/css/transform_scroll_layer.html
new file mode 100644
index 00000000000..a48d8fe749e
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/transform_scroll_layer.html
@@ -0,0 +1,12 @@
+<!doctype html>
+<meta charset="utf-8">
+<title></title>
+<link rel="match" href="transform_scroll_layer_ref.html">
+<div style="transform: translateX(0)">
+    <div style="width:400px;height:400px;background:#f00;overflow:scroll">
+    </div>
+</div>
+<div style="transform: translateX(0)">
+    <div style="width:400px;height:400px;background:#0f0;overflow:scroll">
+    </div>
+</div>
diff --git a/tests/wpt/mozilla/tests/css/transform_scroll_layer_ref.html b/tests/wpt/mozilla/tests/css/transform_scroll_layer_ref.html
new file mode 100644
index 00000000000..44953c3e7e2
--- /dev/null
+++ b/tests/wpt/mozilla/tests/css/transform_scroll_layer_ref.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<div style="width:400px;height:400px;background:#f00;overflow:scroll">
+</div>
+<div style="width:400px;height:400px;background:#0f0;overflow:scroll">
+</div>