Add a basic custom painting facility to Sky

sky/engine/core/dom/Element.cpp

Index: sky/engine/core/dom/Element.cpp
diff --git a/sky/engine/core/dom/Element.cpp b/sky/engine/core/dom/Element.cpp
index 78d958c9d31c2020761e7fe64a2f3fc8ef43ded8..7f5c889f401940e91fb6dec051288f8ac6291011 100644
--- a/sky/engine/core/dom/Element.cpp
+++ b/sky/engine/core/dom/Element.cpp
@@ -26,6 +26,7 @@
 #include "sky/engine/config.h"
 #include "sky/engine/core/dom/Element.h"
 
+#include "base/bind.h"
 #include "gen/sky/core/CSSValueKeywords.h"
 #include "gen/sky/core/HTMLNames.h"
 #include "gen/sky/platform/RuntimeEnabledFeatures.h"
@@ -49,6 +50,7 @@
 #include "sky/engine/core/dom/ElementRareData.h"
 #include "sky/engine/core/dom/ElementTraversal.h"
 #include "sky/engine/core/dom/ExceptionCode.h"
+#include "sky/engine/core/dom/Microtask.h"
 #include "sky/engine/core/dom/MutationObserverInterestGroup.h"
 #include "sky/engine/core/dom/MutationRecord.h"
 #include "sky/engine/core/dom/NodeRenderStyle.h"
@@ -75,6 +77,8 @@
 #include "sky/engine/core/page/ChromeClient.h"
 #include "sky/engine/core/page/FocusController.h"
 #include "sky/engine/core/page/Page.h"
+#include "sky/engine/core/painting/PaintingContext.h"
+#include "sky/engine/core/painting/PaintingCallback.h"
 #include "sky/engine/core/rendering/RenderLayer.h"
 #include "sky/engine/core/rendering/RenderView.h"
 #include "sky/engine/platform/EventDispatchForbiddenScope.h"
@@ -413,6 +417,38 @@ PassRefPtr<ClientRect> Element::getBoundingClientRect()
     return ClientRect::create(result);
 }
 
+// TODO(abarth): We should schedule this work at a more reasonable time.
+static void handlePaintingCommit(RefPtr<Element> element, RefPtr<PaintingContext> context)
+{
+    if (!element->document().isActive())
+        return;
+    element->document().updateLayout();

[ojan, 2015/03/19 22:30:04]

We should not need to do this. I guess that falls out from scheduling the work
at a more reasonable time? We'll need to figure out how to get these callbacks
to not be able to change the tree structure.

+    RenderObject* renderer = element->renderer();
+    if (!renderer || !renderer->isBox())
+        return;
+    toRenderBox(renderer)->setCustomPainting(context->takeDisplayList());
+    element->document().scheduleVisualUpdate();
+}
+
+// TODO(abarth): We should schedule this work at a more reasonable time.
+static void runPaintingCallback(RefPtr<Element> element, PassOwnPtr<PaintingCallback> callback)
+{
+    if (!element->document().isActive())
+        return;
+    element->document().updateLayout();
+    RenderObject* renderer = element->renderer();
+    if (!renderer || !renderer->isBox())
+        return;
+    RefPtr<PaintingContext> context = PaintingContext::create(
+        toRenderBox(renderer)->size(), base::Bind(&handlePaintingCommit, element));
+    callback->handleEvent(context.get());
+}
+
+void Element::requestPaint(PassOwnPtr<PaintingCallback> callback)
+{
+    Microtask::enqueueMicrotask(base::Bind(&runPaintingCallback, this, callback));
+}
+
 void Element::setAttribute(const AtomicString& localName, const AtomicString& value, ExceptionState& exceptionState)
 {
     if (!Document::isValidName(localName)) {