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/*
* Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
* Copyright (C) 2012 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "third_party/blink/renderer/core/html/track/text_track_container.h"
#include "third_party/blink/renderer/core/html/media/html_video_element.h"
#include "third_party/blink/renderer/core/html/track/cue_timeline.h"
#include "third_party/blink/renderer/core/html/track/text_track.h"
#include "third_party/blink/renderer/core/layout/layout_block_flow.h"
#include "third_party/blink/renderer/core/layout/layout_video.h"
#include "third_party/blink/renderer/core/resize_observer/resize_observer.h"
#include "third_party/blink/renderer/core/resize_observer/resize_observer_entry.h"
namespace blink {
namespace {
class VideoElementResizeDelegate final : public ResizeObserver::Delegate {
public:
VideoElementResizeDelegate(TextTrackContainer& container)
: ResizeObserver::Delegate(), text_track_container_(container) {}
void OnResize(
const HeapVector<Member<ResizeObserverEntry>>& entries) override {
DCHECK_EQ(entries.size(), 1u);
DCHECK(IsHTMLVideoElement(entries[0]->target()));
text_track_container_->UpdateDefaultFontSize(
entries[0]->target()->GetLayoutObject());
}
void Trace(blink::Visitor* visitor) override {
visitor->Trace(text_track_container_);
ResizeObserver::Delegate::Trace(visitor);
}
private:
Member<TextTrackContainer> text_track_container_;
};
} // namespace
TextTrackContainer::TextTrackContainer(Document& document)
: HTMLDivElement(document), default_font_size_(0) {}
void TextTrackContainer::Trace(blink::Visitor* visitor) {
visitor->Trace(video_size_observer_);
HTMLDivElement::Trace(visitor);
}
TextTrackContainer* TextTrackContainer::Create(
HTMLMediaElement& media_element) {
TextTrackContainer* element =
new TextTrackContainer(media_element.GetDocument());
element->SetShadowPseudoId(
AtomicString("-webkit-media-text-track-container"));
if (IsHTMLVideoElement(media_element))
element->ObserveSizeChanges(media_element);
return element;
}
LayoutObject* TextTrackContainer::CreateLayoutObject(const ComputedStyle&) {
return new LayoutBlockFlow(this);
}
void TextTrackContainer::ObserveSizeChanges(Element& element) {
video_size_observer_ = ResizeObserver::Create(
GetDocument(), new VideoElementResizeDelegate(*this));
video_size_observer_->observe(&element);
}
void TextTrackContainer::UpdateDefaultFontSize(
LayoutObject* media_layout_object) {
if (!media_layout_object || !media_layout_object->IsVideo())
return;
// FIXME: The video size is used to calculate the font size (a workaround
// for lack of per-spec vh/vw support) but the whole media element is used
// for cue rendering. This is inconsistent. See also the somewhat related
// spec bug: https://www.w3.org/Bugs/Public/show_bug.cgi?id=28105
LayoutSize video_size =
ToLayoutVideo(*media_layout_object).ReplacedContentRect().Size();
LayoutUnit smallest_dimension =
std::min(video_size.Height(), video_size.Width());
float font_size = smallest_dimension * 0.05f;
// Avoid excessive FP precision issue.
// C11 5.2.4.2.2:9 requires assignment and cast to remove extra precision, but
// the behavior is currently not portable. fontSize may have precision higher
// than m_fontSize thus straight comparison can fail despite they cast to the
// same float value.
volatile float& current_font_size = default_font_size_;
float old_font_size = current_font_size;
current_font_size = font_size;
if (current_font_size == old_font_size)
return;
SetInlineStyleProperty(CSSPropertyFontSize, default_font_size_,
CSSPrimitiveValue::UnitType::kPixels);
}
void TextTrackContainer::UpdateDisplay(HTMLMediaElement& media_element,
ExposingControls exposing_controls) {
if (!media_element.TextTracksVisible()) {
RemoveChildren();
return;
}
// http://dev.w3.org/html5/webvtt/#dfn-rules-for-updating-the-display-of-webvtt-text-tracks
// 1. If the media element is an audio element, or is another playback
// mechanism with no rendering area, abort these steps. There is nothing to
// render.
if (IsHTMLAudioElement(media_element))
return;
// 2. Let video be the media element or other playback mechanism.
HTMLVideoElement& video = ToHTMLVideoElement(media_element);
// 3. Let output be an empty list of absolutely positioned CSS block boxes.
// Note: This is a layout algorithm, expressed terms of appending CSS block
// boxes to output, and the "apply WebVTT cue settings" part is implemented
// in LayoutVTTCue. Here we merely create the DOM tree from which the layout
// tree is built and append it to this TextTrackContainer.
// 4. If the user agent is exposing a user interface for video, add to
// output one or more completely transparent positioned CSS block boxes that
// cover the same region as the user interface.
// Note: Overlap checking for the controls is implemented in LayoutVTTCue
// without a placeholder box (element or layout object).
// 5. If the last time these rules were run, the user agent was not exposing
// a user interface for video, but now it is, optionally let reset be true.
// Otherwise, let reset be false.
bool reset = exposing_controls == kDidStartExposingControls;
// 6. Let tracks be the subset of video's list of text tracks that have as
// their rules for updating the text track rendering these rules for
// updating the display of WebVTT text tracks, and whose text track mode is
// showing or showing by default.
// 7. Let cues be an empty list of text track cues.
// 8. For each track track in tracks, append to cues all the cues from
// track's list of cues that have their text track cue active flag set.
const CueList& active_cues = video.GetCueTimeline().CurrentlyActiveCues();
// 9. If reset is false, then, for each text track cue cue in cues: if cue's
// text track cue display state has a set of CSS boxes, then add those boxes
// to output, and remove cue from cues.
// Note: Removing all children will cause them to be re-inserted below,
// invalidating the layout.
// effect
if (reset)
RemoveChildren();
// 10. For each text track cue cue in cues that has not yet had
// corresponding CSS boxes added to output, in text track cue order, run the
// following substeps:
double movie_time = video.currentTime();
for (const auto& active_cue : active_cues) {
TextTrackCue* cue = active_cue.Data();
DCHECK(cue->IsActive());
if (!cue->track() || !cue->track()->IsRendered() || !cue->IsActive())
continue;
cue->UpdateDisplay(*this);
cue->UpdatePastAndFutureNodes(movie_time);
}
// 11. Return output.
// See the note for step 3 for why there is no output to return.
}
} // namespace blink