https://bugs.webkit.org/show_bug.cgi?id=110252

Patch by Romain Perier <romain.perier@gmail.com> on 2013-08-01
Reviewed by Dean Jackson.

Source/WebCore:

Tests: fast/hidpi/image-srcset-simple.html
       fast/hidpi/image-srcset-src-selection.html
       fast/hidpi/image-srcset-simple.html
       fast/hidpi/image-srcset-src-selection.html
       fast/hidpi/image-srcset-only-src-attribute.html
       fast/hidpi/image-srcset-same-alternative-for-both-attributes.html
       fast/hidpi/image-srcset-invalid-inputs.html
       fast/hidpi/image-srcset-invalid-inputs-except-one.html
       fast/hidpi/image-srcset-invalid-inputs-correct-src.html
       fast/hidpi/image-srcset-change-dynamically-from-js.html
       fast/hidpi/image-srcset-remove-dynamically-from-js.html

* html/HTMLAttributeNames.in: Add srcset attribute.
* html/HTMLImageElement.cpp:
(WebCore::HTMLImageElement::HTMLImageElement):
Adding initialization for new variables member.
(WebCore::HTMLImageElement::imageSourceURL):
Override this method to return the choosen image transparently to the ImageLoader.
(WebCore::HTMLImageElement::updateBestImageForScaleFactor):
New method to select the good image candidate dependending on the scale factor. This method is separated from
parsing because it will be useful for selecting a new image candidate on the fly if the device scale factor changes.
(WebCore::HTMLImageElement::updateImagesFromSrcSet):
New method for parsing the srcset attribute and build a list of images with the corresponding scale factor.
(WebCore::HTMLImageElement::parseAttribute):
Adding support for processing the image candidates, select the good one and call ImageLoader for rendering.
* html/HTMLImageElement.h:
- Adding new methods declarations.
- Adding new type definition.
- Adding new variable member to store the URL of the choosen image.
- Adding new variable member to store the index of the src image.
- Adding new Vector to store the list of images after parsing.
* html/HTMLImageElement.idl: Adding srcset attribute for the differents existing bidings.

LayoutTests:

* fast/hidpi/image-srcset-simple.html: Ensures that the good image
is selected from srcset by the user agent according to the choosen scale factor.
* fast/hidpi/image-srcset-src-selection.html: Ensures that the image
from the src attribute is collected by the parsing algorithm and selected by the user agent
when no other candidate matches the scale factor.
* fast/hidpi/image-srcset-only-src-attribute.html: Ensures that the algorithms used for srcset
does not change the behaviour of the src attribute when the srcset attribute is not defined,
even using scale factor greater than 1.
* fast/hidpi/image-srcset-same-alternative-for-both-attributes.html: Ensures that the good image
is selected by the user agent when src and srcset contain an image with a scale factor of 1.
* fast/hidpi/image-srcset-invalid-inputs.html: Ensures that the parsing and the selection
algorithms support invalid inputs. Theses ones are simply ignored.
* fast/hidpi/image-srcset-invalid-inputs-except-one.html: Ensures that a valid image
is selected even if this one is part of a set containing invalid inputs.
* fast/hidpi/image-srcset-invalid-inputs-correct-src.html: Ensures that the image from
the src attribute is choosen when srcset contains only invalid inputs, this selection
should not depend on the scale factor.
* fast/hidpi/image-srcset-change-dynamically-from-js.html: Ensures that src and srcset attributes
can be changed dynamically from javascript.
* fast/hidpi/image-srcset-remove-dynamically-from-js.html: Ensures that src attribute
can be removed dynamically from javascript.
* platform/mac/fast/hidpi/image-srcset-simple-expected.png:
* platform/mac/fast/hidpi/image-srcset-simple-expected.txt:
* platform/mac/fast/hidpi/image-srcset-src-selection-expected.png:
* platform/mac/fast/hidpi/image-srcset-src-selection-expected.txt:
* platform/mac/fast/hidpi/image-srcset-only-src-attribute-expected.png:
* platform/mac/fast/hidpi/image-srcset-only-src-attribute-expected.txt:
* platform/mac/fast/hidpi/image-srcset-same-alternative-for-both-attributes-expected.png:
* platform/mac/fast/hidpi/image-srcset-same-alternative-for-both-attributes-expected.txt:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-expected.png:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-expected.txt:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-except-one-expected.png:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-except-one-expected.txt:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-correct-src-expected.png:
* platform/mac/fast/hidpi/image-srcset-invalid-inputs-correct-src-expected.txt:
* platform/mac/fast/hidpi/image-srcset-change-dynamically-from-js-expected.png:
* platform/mac/fast/hidpi/image-srcset-change-dynamically-from-js-expected.txt:
* platform/mac/fast/hidpi/image-srcset-remove-dynamically-from-js-expected.png:
* platform/mac/fast/hidpi/image-srcset-remove-dynamically-from-js-expected.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153624 268f45cc-cd09-0410-ab3c-d52691b4dbfc