SVG with zero intrinsic size should be respected always

third_party/WebKit/Source/core/layout/LayoutReplaced.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011-2012. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 264 matching lines @@
 
     // 10.3.2 Inline, replaced elements: http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-width
     double intrinsicRatio = 0;
     FloatSize constrainedSize;
     computeAspectRatioInformationForLayoutBox(contentLayoutObject, constrainedSize, intrinsicRatio);
 
     if (style()->logicalWidth().isAuto()) {
         bool computedHeightIsAuto = hasAutoHeightOrContainingBlockWithAutoHeight();
         bool hasIntrinsicWidth = constrainedSize.width() > 0;
 
+        if (!hasIntrinsicWidth && contentLayoutObject)
+            hasIntrinsicWidth = contentLayoutObject->style()->logicalWidth().isFixed();

[davve, 2016/01/18 15:52:48]

You rely on the (logical) intrinsic width being collected as
presentation attribute, thus ending up in
style()->logicalWidth(). Then you use style()->logicalWidth() as
indication whether there is an intrinsic (logical) width or not.

A weakness of this trick is that there can be "proper" style on the
SVG that shouldn't indicate intrinsic width (or height respectively).

The example below gives a 300x150 green rect in Firefox and Chrome and
I think that's correct. With your patch we would think there is a
(zero) intrinsic width and render nothing.

html:

<object style="background: green" data="some-svg.svg"></object>

some-svg.svg:

<svg xmlns="http://www.w3.org/2000/svg" style="width: 0"></svg>

I think we need something more elaborate here, preferable by
propagating enough information from
SVGSVGElement::intrinsicWidth/Height to make the correct
hasIntrinsicWidth/Height judgement in
LayoutReplaced::computeReplacedLogicalWidth/Height().

[Shanmuga Pandi, 2016/01/20 06:09:34]

Instead of LogicalWidth()/Height(), getting hasIntrinsicWidth()/Height() to
detect whether SVG has intrisic width/height. 

This solve the above the problem and the bug reported.

+
         // If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width, then that intrinsic width is the used value of 'width'.
         if (computedHeightIsAuto && hasIntrinsicWidth)
             return computeReplacedLogicalWidthRespectingMinMaxWidth(constrainedSize.width(), shouldComputePreferred);
 
         bool hasIntrinsicHeight = constrainedSize.height() > 0;
         if (intrinsicRatio) {
             // If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width, but does have an intrinsic height and intrinsic ratio;
             // or if 'width' has a computed value of 'auto', 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value
             // of 'width' is: (used height) * (intrinsic ratio)
             if (intrinsicRatio && ((computedHeightIsAuto && !hasIntrinsicWidth && hasIntrinsicHeight) || !computedHeightIsAuto)) {
@@ skipping 42 matching lines @@
     LayoutBox* contentLayoutObject = embeddedContentBox();
 
     // 10.6.2 Inline, replaced elements: http://www.w3.org/TR/CSS21/visudet.html#inline-replaced-height
     double intrinsicRatio = 0;
     FloatSize constrainedSize;
     computeAspectRatioInformationForLayoutBox(contentLayoutObject, constrainedSize, intrinsicRatio);
 
     bool widthIsAuto = style()->logicalWidth().isAuto();
     bool hasIntrinsicHeight = constrainedSize.height() > 0;
 
+    if (!hasIntrinsicHeight && contentLayoutObject)
+        hasIntrinsicHeight = contentLayoutObject->style()->logicalHeight().isFixed();
+
     // If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic height, then that intrinsic height is the used value of 'height'.
     if (widthIsAuto && hasIntrinsicHeight)
         return computeReplacedLogicalHeightRespectingMinMaxHeight(constrainedSize.height());
 
     // Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic ratio then the used value of 'height' is:
     // (used width) / (intrinsic ratio)
     if (intrinsicRatio)
         return computeReplacedLogicalHeightRespectingMinMaxHeight(availableLogicalWidth() / intrinsicRatio);
 
     // Otherwise, if 'height' has a computed value of 'auto', and the element has an intrinsic height, then that intrinsic height is the used value of 'height'.
@@ skipping 113 matching lines @@
     // We only include the space below the baseline in our layer's cached paint invalidation rect if the
     // image is selected. Since the selection state has changed update the rect.
     if (hasLayer())
         setPreviousPaintInvalidationRect(boundsRectForPaintInvalidation(containerForPaintInvalidation()));
 
     if (canUpdateSelectionOnRootLineBoxes())
         inlineBoxWrapper()->root().setHasSelectedChildren(state != SelectionNone);
 }
 
 }