#601: empty img behaviour M1196668 M1616537 M1506592 (see also M1549742)

dom/base/nsIImageLoadingContent.idl

@@ -60,7 +60,7 @@ interface nsIImageLoadingContent : imgINotificationObserver
    * the image was blocked.  This status always refers to the
    * CURRENT_REQUEST load.
    */
-  readonly attribute short imageBlockingStatus;
+  [infallible] readonly attribute short imageBlockingStatus;
 
   /**
    * Used to register an image decoder observer.  Typically, this will

layout/generic/nsImageFrame.cpp

@@ -115,7 +115,7 @@ static bool HaveSpecifiedSize(const nsStylePosition* aStylePosition)
 
 // Decide whether we can optimize away reflows that result from the
 // image's intrinsic size changing.
-inline bool HaveFixedSize(const nsHTMLReflowState& aReflowState)
+static bool HaveFixedSize(const nsHTMLReflowState& aReflowState)
 {
   NS_ASSERTION(aReflowState.mStylePosition, "crappy reflowState - null stylePosition");
   // Don't try to make this optimization when an image has percentages
@@ -437,8 +437,23 @@ nsImageFrame::SourceRectToDest(const nsIntRect& aRect)
     (!(_state).HasAtLeastOneOfStates(NS_EVENT_STATE_BROKEN | NS_EVENT_STATE_USERDISABLED) && \
      (_state).HasState(NS_EVENT_STATE_LOADING) && (_loadingOK)))
 
-/* static */
-bool
+static bool HasAltText(Element* aElement)
+{
+  // We always return some alternate text for <input>, see
+  // nsCSSFrameConstructor::GetAlternateTextFor.
+  if (aElement->IsHTMLElement(nsGkAtoms::input)) {
+    return true;
+  }
+
+  MOZ_ASSERT(aElement->IsHTMLElement(nsGkAtoms::img));
+  nsAutoString altText;
+  return aElement->GetAttr(kNameSpaceID_None, nsGkAtoms::alt, altText) && !altText.IsEmpty();
+}
+
+// Check if we want to use an image frame or just let the frame constructor make
+// us into an inline.
+
+/* static */ bool
 nsImageFrame::ShouldCreateImageFrameFor(Element* aElement,
                                         nsStyleContext* aStyleContext)
 {
@@ -449,44 +464,26 @@ nsImageFrame::ShouldCreateImageFrameFor(Element* aElement,
     return true;
   }
 
-  // Check if we want to use a placeholder box with an icon or just
-  // let the presShell make us into inline text.  Decide as follows:
-  //
-  //  - if our special "force icons" style is set, show an icon
-  //  - else if our "do not show placeholders" pref is set, skip the icon
-  //  - else:
-  //  - if there is a src attribute, there is no alt attribute,
-  //    and this is not an <object> (which could not possibly have
-  //    such an attribute), show an icon.
-  //  - if QuirksMode, and the IMG has a size show an icon.
-  //  - otherwise, skip the icon
-  bool useSizedBox;
-  
+  // If our special "force icons" style is set, show an icon
   if (aStyleContext->StyleUIReset()->mForceBrokenImageIcon) {
-    useSizedBox = true;
-  }
-  else if (gIconLoad && gIconLoad->mPrefForceInlineAltText) {
-    useSizedBox = false;
-  }
-  else if (aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::src) &&
-           !aElement->HasAttr(kNameSpaceID_None, nsGkAtoms::alt) &&
-           !aElement->IsHTMLElement(nsGkAtoms::object) &&
-           !aElement->IsHTMLElement(nsGkAtoms::input)) {
-    // Use a sized box if we have no alt text.  This means no alt attribute
-    // and the node is not an object or an input (since those always have alt
-    // text).
-    useSizedBox = true;
-  }
-  else if (aStyleContext->PresContext()->CompatibilityMode() !=
-           eCompatibility_NavQuirks) {
-    useSizedBox = false;
-  }
-  else {
-    // check whether we have specified size
-    useSizedBox = HaveSpecifiedSize(aStyleContext->StylePosition());
+    return true;
   }
 
-  return useSizedBox;
+  // If our "do not show placeholders" pref is set, skip the icon
+  if (gIconLoad && gIconLoad->mPrefForceInlineAltText) {
+    return false;
+  }
+
+  // If there is no Alt text, always create an image frame (regardless of src)
+  if (!HasAltText(aElement)) {
+    return true;
+  }
+
+  if (aStyleContext->PresContext()->CompatibilityMode() == eCompatibility_NavQuirks) {
+    return HaveSpecifiedSize(aStyleContext->StylePosition());
+  }
+
+  return false;
 }
 
 nsresult
@@ -767,6 +764,34 @@ nsImageFrame::PredictedDestRect(const nsRect& aFrameContentBox)
                                               StylePosition());
 }
 
+bool nsImageFrame::ShouldShowBrokenImageIcon() const
+{
+  bool imageBroken = false;
+  // Check for broken images. valid null images (eg. img src="") are
+  // not considered broken because they have no image requests
+  nsCOMPtr<nsIImageLoadingContent> imageLoader = do_QueryInterface(mContent);
+  if (imageLoader) {
+    // <img alt=""> is special, and it shouldn't draw the broken image icon,
+    // unlike the no-alt attribute or non-empty-alt-attribute case.
+    if (mContent->HasAttr(kNameSpaceID_None, nsGkAtoms::alt)) {
+      nsAutoString altText;
+      mContent->GetAttr(kNameSpaceID_None, nsGkAtoms::alt, altText);
+      if (altText.IsEmpty())
+        return false;
+    }
+
+    nsCOMPtr<imgIRequest> currentRequest;
+    imageLoader->GetRequest(nsIImageLoadingContent::CURRENT_REQUEST,
+                            getter_AddRefs(currentRequest));
+    uint32_t imageStatus;
+    imageBroken =
+      currentRequest &&
+      NS_SUCCEEDED(currentRequest->GetImageStatus(&imageStatus)) &&
+      (imageStatus & imgIRequest::STATUS_ERROR);
+  }
+  return imageBroken;
+}
+
 void
 nsImageFrame::EnsureIntrinsicSizeAndRatio()
 {
@@ -776,22 +801,21 @@ nsImageFrame::EnsureIntrinsicSizeAndRatio()
       mIntrinsicSize.width.GetCoordValue() == 0 &&
       mIntrinsicSize.height.GetUnit() == eStyleUnit_Coord &&
       mIntrinsicSize.height.GetCoordValue() == 0) {
-
     if (mImage) {
       UpdateIntrinsicSize(mImage);
       UpdateIntrinsicRatio(mImage);
     } else {
-      // image request is null or image size not known, probably an
-      // invalid image specified
-      // - make the image big enough for the icon (it may not be
-      // used if inline alt expansion is used instead)
+      // Image request is null or image size not known.
       if (!(GetStateBits() & NS_FRAME_GENERATED_CONTENT)) {
-        nscoord edgeLengthToUse =
-          nsPresContext::CSSPixelsToAppUnits(
-            ICON_SIZE + (2 * (ICON_PADDING + ALT_BORDER_WIDTH)));
-        mIntrinsicSize.width.SetCoordValue(edgeLengthToUse);
-        mIntrinsicSize.height.SetCoordValue(edgeLengthToUse);
-        mIntrinsicRatio.SizeTo(1, 1);
+        // Likely an invalid image. Check if we should display it as broken.
+        if (ShouldShowBrokenImageIcon()) {
+          nscoord edgeLengthToUse =
+            nsPresContext::CSSPixelsToAppUnits(
+              ICON_SIZE + (2 * (ICON_PADDING + ALT_BORDER_WIDTH)));
+          mIntrinsicSize.width.SetCoordValue(edgeLengthToUse);
+          mIntrinsicSize.height.SetCoordValue(edgeLengthToUse);
+          mIntrinsicRatio.SizeTo(1, 1);
+        }
       }
     }
   }
@@ -1362,7 +1386,8 @@ nsImageFrame::DisplayAltFeedback(nsRenderingContext& aRenderingContext,
   DrawResult result = DrawResult::NOT_READY;
 
   // Check if we should display image placeholders
-  if (!gIconLoad->mPrefShowPlaceholders ||
+  if (!ShouldShowBrokenImageIcon() ||
+      !gIconLoad->mPrefShowPlaceholders ||
       (isLoading && !gIconLoad->mPrefShowLoadingPlaceholder)) {
     result = DrawResult::SUCCESS;
   } else {

layout/generic/nsImageFrame.h

@@ -104,6 +104,8 @@ public:
                                     nsIAtom* aAttribute,
                                     int32_t aModType) override;
 
+  bool ShouldShowBrokenImageIcon() const;
+
 #ifdef ACCESSIBILITY
   virtual mozilla::a11y::AccType AccessibleType() override;
 #endif