https://bugs.webkit.org/show_bug.cgi?id=79751

Reviewed by Tony Chang.

Source/WebCore:

This patch implements rendering functionality for a given text track,
following closer the exact WebVTT specification. There are two new classes
which have been added in order to succesfully cover rendering when of a text
track cue.

RenderTextTrackCue handles the specific rendering algorithm required,
by checking for overlaps with other boxes that are in the same
container (these can be any other boxes, not necessarily other cues,
the video controls, for example).

TextTrackCueBox extends HTMLDivElement and is an intermediate layer
between the renderer class and the actual cue object. Its purpose is
to instantiate the particular renderer and cover all the default CSS
styling that needs to be applied to the cue.

The layout is done in two steps:
  - Step 1: Layout the TextTrackCue with default CSS properties set (this is
the TextTrackCueBox decorated with the respective CSS elements)
  - Step 2: RenderTextTrackCue adjusts the box position depending on the
parameters of the TextTrackCue object and the overlaps that may occur with
previously positioned cues.

Tests: media/track/track-cue-rendering-horizontal.html
       media/track/track-cue-rendering-vertical.html

* CMakeLists.txt: Updated to include RenderTextTrackCue.
* GNUmakefile.list.am: Updated to include RenderTextTrackCue.
* Target.pri: Updated to include RenderTextTrackCue.
* WebCore.gypi: Updated to include RenderTextTrackCue.
* WebCore.vcproj/WebCore.vcproj: Updated to include RenderTextTrackCue.
* WebCore.xcodeproj/project.pbxproj: Updated to include RenderTextTrackCue.
* css/mediaControls.css: Removed unreliable CSS.
(video::-webkit-media-text-track-display): Removed properties.
* html/shadow/MediaControlElements.cpp: Updated to not use the new class.
(RenderTextTrackContainerElement):
(WebCore::MediaControlTextTrackContainerElement::updateDisplay): Simplified
the function by moving the check if track is rendered in TextTrack and used
the TextTrackCueBox for cues.
* html/track/TextTrack.cpp: Added a new method.
(WebCore::TextTrack::isRendered): Method that returns whether the track should
be rendered or not.
(WebCore):
* html/track/TextTrack.h: Added the isRendered method.
(TextTrack):
* html/track/TextTrackCue.cpp: Added several helper methods and
the TextTrackCueBox.
(WebCore):
(WebCore::TextTrackCueBox::TextTrackCueBox): The TextTrackCueBox extends
the HTMLDivElement and represents a bridge class between RenderTextTrackCue
and TextTrackCue. This is required as the layout is done in two steps, as
explained on top of the ChangeLog entry.
(WebCore::TextTrackCueBox::getCue): Returns the associated TextTrackCue object.
(WebCore::TextTrackCueBox::applyCSSProperties): Applies a part of the default CSS
properties, as defined by section 3.5.1 of the WebVTT specification.
(WebCore::TextTrackCueBox::shadowPseudoId): Moved the shadow pseudo id.
(WebCore::TextTrackCueBox::createRenderer): Creates the particular renderer.
(WebCore::TextTrackCue::TextTrackCue): Corrected the internal writing mode map.
(WebCore::TextTrackCue::calculateComputedLinePosition): Updated the compute line
position algorithm. This requires, however, a method to consider only rendered
tracks (and therefore will be addressed completely in subsequent changeset).
(WebCore::TextTrackCue::calculateDisplayParameters): Updated and corrected the
computed display parameters to match the current specification.
(WebCore::TextTrackCue::getDisplayTree): Update to use the TextTrackCueBox class
and moved CSS application to the respective class.
(WebCore::TextTrackCue::getPositionCoordinates): Added comment to specify in which
situation this method is used and change visibility to private.
(WebCore::TextTrackCue::getCSSWritingMode): Returns the CSS writing mode corresponding
to the cue writing mode.
(WebCore::TextTrackCue::getCSSSize): Returns the cue width / height (depending on the
writing direction.
(WebCore::TextTrackCue::getCSSPosition): Returns the default display position, that is
used in the first layout step.
* html/track/TextTrackCue.h:
(WebCore):
(TextTrackCueBox):
(WebCore::TextTrackCueBox::create): Initialization method.
(TextTrackCue):
(WebCore::TextTrackCue::getWritingDirection): Helper method to return the internal
values used to represent the writing direction.
* rendering/RenderTextTrackCue.cpp: Added.
(WebCore):
(WebCore::RenderTextTrackCue::RenderTextTrackCue):
(WebCore::RenderTextTrackCue::layout): The rendering steps, as mentioned in
the WebVTT rendering rules. Currently, this treats only the snap-to-lines set
case. It is implemented following closely the spec, and might be subject to
change as discussions on various bugs evolve.
(WebCore::RenderTextTrackCue::initializeLayoutParameters): Steps 1 - 7.
(WebCore::RenderTextTrackCue::placeBoxInDefaultPosition): Steps 8 - 10.
(WebCore::RenderTextTrackCue::isOutside): Inline method to check if the cue is outside.
(WebCore::RenderTextTrackCue::isOverlapping): Inline method to check if the cue overlaps other boxes.
(WebCore::RenderTextTrackCue::shouldSwitchDirection): Step 12.
(WebCore::RenderTextTrackCue::moveBoxesByStep): Step 13.
(WebCore::RenderTextTrackCue::switchDirection): Steps 15 - 18.
(WebCore::RenderTextTrackCue::repositionCueSnapToLinesSet): Cue repositioning
for text track cue when the snap to lines flag is set.
(WebCore::RenderTextTrackCue::repositionCueSnapToLinesNotSet): Cue repositioning
for text track cue when the snap to lines flag is not set. Not implemented yet.
* rendering/RenderTextTrackCue.h: Added.
(WebCore):
(RenderTextTrackCue): Rendering class, handling the display of cues.

LayoutTests:

Test cases covering snap-to-lines horizontal and vertical positioning of cues.

* media/track/captions-webvtt/captions-snap-to-lines-set.vtt: Added.
* media/track/track-cue-rendering-horizontal.html: Added.
* media/track/track-cue-rendering-snap-to-lines-not-set-expected.txt: Updated.
* media/track/track-cue-rendering-vertical.html: Added.
* media/video-test.js: Updated to support pixel test dumps.
* platform/chromium-linux/media/track/track-cue-rendering-horizontal-expected.png: Added.
* platform/chromium-linux/media/track/track-cue-rendering-horizontal-expected.txt: Added.
* platform/chromium-linux/media/track/track-cue-rendering-vertical-expected.png: Added.
* platform/chromium-linux/media/track/track-cue-rendering-vertical-expected.txt: Added.
* platform/chromium/TestExpectations: Marking these temporarily as IMAGE fail, as they will
anyway require new baselines.
* platform/mac/media/track/track-cue-rendering-horizontal-expected.png: Added.
* platform/mac/media/track/track-cue-rendering-horizontal-expected.txt: Added.
* platform/mac/media/track/track-cue-rendering-vertical-expected.png: Added.
* platform/mac/media/track/track-cue-rendering-vertical-expected.txt: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@126372 268f45cc-cd09-0410-ab3c-d52691b4dbfc