Bug 1259482 - Ensure that image loads are never dropped on the floor when queued for later. r=johns

2016-03-30 12:39:59 -04:00 · 2016-03-30 12:39:59 -04:00 · d43f85cd2a
--- a/dom/html/HTMLImageElement.cpp
+++ b/dom/html/HTMLImageElement.cpp
@ -98,6 +98,10 @@ public:
    return NS_OK;
  }

+  bool AlwaysLoad() {
+    return mAlwaysLoad;
+  }
+
 private:
  ~ImageLoadTask() {}
  RefPtr<HTMLImageElement> mElement;
@ -899,7 +903,13 @@ HTMLImageElement::QueueImageLoadTask(bool aAlwaysLoad)
    return;
  }

-  nsCOMPtr<nsIRunnable> task = new ImageLoadTask(this, aAlwaysLoad);
+  // Ensure that we don't overwrite a previous load request that requires
+  // a complete load to occur.
+  bool alwaysLoad = aAlwaysLoad;
+  if (mPendingImageLoadTask) {
+    alwaysLoad = alwaysLoad || mPendingImageLoadTask->AlwaysLoad();
+  }
+  RefPtr<ImageLoadTask> task = new ImageLoadTask(this, alwaysLoad);
  // The task checks this to determine if it was the last
  // queued event, and so earlier tasks are implicitly canceled.
  mPendingImageLoadTask = task;
--- a/dom/html/HTMLImageElement.h
+++ b/dom/html/HTMLImageElement.h
@ -22,6 +22,8 @@ namespace mozilla {
 class EventChainPreVisitor;
 namespace dom {

+class ImageLoadTask;
+
 class ResponsiveImageSelector;
 class HTMLImageElement final : public nsGenericHTMLElement,
                               public nsImageLoadingContent,
@ -362,7 +364,7 @@ private:
                                    nsRuleData* aData);

  bool mInDocResponsiveContent;
-  nsCOMPtr<nsIRunnable> mPendingImageLoadTask;
+  RefPtr<ImageLoadTask> mPendingImageLoadTask;
 };

 } // namespace dom
--- a/dom/html/reftests/reftest.list
+++ b/dom/html/reftests/reftest.list
@ -34,6 +34,8 @@ skip-if(Android||B2G) == 649134-2.html 649134-2-ref.html
 == bug448564-4a.html          bug448564-4b.html
 == bug502168-1_malformed.html bug502168-1_well-formed.html

+== responsive-image-load-shortcircuit.html responsive-image-load-shortcircuit-ref.html
+
 # Test that image documents taken into account CSS properties like
 # image-orientation when determining the size of the image.
 # (Fuzzy necessary due to pixel-wise comparison of different JPEGs.
--- a/dom/html/reftests/responsive-image-load-shortcircuit-ref.html
+++ b/dom/html/reftests/responsive-image-load-shortcircuit-ref.html
@ -0,0 +1 @@
+<iframe srcdoc="<img src=pass.png>" width="300px"></iframe>
--- a/dom/html/reftests/responsive-image-load-shortcircuit.html
+++ b/dom/html/reftests/responsive-image-load-shortcircuit.html
@ -0,0 +1,15 @@
+<html class="reftest-wait">
+<iframe srcdoc="<img srcset=red.png>" width="150px"></iframe>
+<script>
+  var iframe = document.querySelector('iframe');
+  iframe.onload = function() {
+    var doc = iframe.contentDocument;
+    var img = doc.querySelector('img');
+    img.srcset = "pass.png";
+    iframe.width = "300px";
+    img.onload = function() {
+      document.documentElement.classList.remove('reftest-wait');
+    };
+  }
+</script>
+</html>
				`@ -0,0 +1 @@`
				`<iframe srcdoc="<img src=pass.png>" width="300px"></iframe>`