From c4d5846ffe4669d540a2f3c740f4cfa05d99f2dd Mon Sep 17 00:00:00 2001
From: Scott Johnson <sjohnson@mozilla.com>
Date: Mon, 3 Oct 2011 13:39:05 -0700
Subject: [PATCH] Bug 666446, Part 7/18 - Change nsImageLoader to utilize new
 refresh driver animations to overcome performance issues with animated
 background images. [r=roc]

---
 layout/base/nsImageLoader.cpp | 39 ++++++++++++++++++++++++++++++++---
 layout/base/nsImageLoader.h   |  8 +++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/layout/base/nsImageLoader.cpp b/layout/base/nsImageLoader.cpp
index bd711a155dd5..d02ca7d5de5e 100644
--- a/layout/base/nsImageLoader.cpp
+++ b/layout/base/nsImageLoader.cpp
@@ -57,6 +57,7 @@
 
 #include "nsStyleContext.h"
 #include "nsGkAtoms.h"
+#include "nsLayoutUtils.h"
 
 // Paint forcing
 #include "prenv.h"
@@ -67,7 +68,8 @@ nsImageLoader::nsImageLoader(nsIFrame *aFrame, PRUint32 aActions,
                              nsImageLoader *aNextLoader)
   : mFrame(aFrame),
     mActions(aActions),
-    mNextLoader(aNextLoader)
+    mNextLoader(aNextLoader),
+    mRequestRegistered(false)
 {
 }
 
@@ -105,12 +107,15 @@ nsImageLoader::Destroy()
     todestroy->Destroy();
   }
 
-  mFrame = nsnull;
-
   if (mRequest) {
+    nsPresContext* presContext = mFrame->PresContext();
+
+    nsLayoutUtils::DeregisterImageRequest(presContext, mRequest,
+                                          &mRequestRegistered);
     mRequest->CancelAndForgetObserver(NS_ERROR_FAILURE);
   }
 
+  mFrame = nsnull;
   mRequest = nsnull;
 }
 
@@ -269,3 +274,31 @@ nsImageLoader::DoRedraw(const nsRect* aDamageRect)
     mFrame->Invalidate(bounds);
   }
 }
+
+NS_IMETHODIMP
+nsImageLoader::OnStartDecode(imgIRequest *aRequest)
+{
+  // Register our image request with the refresh driver.
+  nsPresContext* presContext = mFrame->PresContext();
+  if (!presContext) {
+    return NS_OK;
+  }
+
+  nsLayoutUtils::RegisterImageRequest(presContext, aRequest,
+                                      &mRequestRegistered);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsImageLoader::OnStopDecode(imgIRequest *aRequest, nsresult status,
+                            const PRUnichar *statusArg)
+{
+  // Deregister the imgIRequest with the refresh driver if the
+  // image is not animated.
+  nsLayoutUtils::DeregisterImageRequestIfNotAnimated(mFrame->PresContext(),
+                                                     mRequest,
+                                                     &mRequestRegistered);
+
+  return NS_OK;
+}
diff --git a/layout/base/nsImageLoader.h b/layout/base/nsImageLoader.h
index de5287b5243e..8a2667631536 100644
--- a/layout/base/nsImageLoader.h
+++ b/layout/base/nsImageLoader.h
@@ -82,6 +82,10 @@ public:
 
   // imgIDecoderObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
+  NS_IMETHOD OnStartDecode(imgIRequest *aRequest);
+  NS_IMETHOD OnStopDecode(imgIRequest *aRequest,
+                          nsresult status,
+                          const PRUnichar *statusArg);
   NS_IMETHOD OnStopFrame(imgIRequest *aRequest, PRUint32 aFrame);
   NS_IMETHOD OnStopRequest(imgIRequest *aRequest, bool aLastPart);
   // Do not override OnDataAvailable since background images are not
@@ -109,4 +113,8 @@ private:
   nsCOMPtr<imgIRequest> mRequest;
   PRUint32 mActions;
   nsRefPtr<nsImageLoader> mNextLoader;
+
+  // This is a boolean flag indicating whether or not the current image request
+  // has been registered with the refresh driver.
+  bool mRequestRegistered;
 };