/**
* @license
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
goog.provide('shaka.text.SimpleTextDisplayer');
goog.require('goog.asserts');
goog.require('shaka.log');
goog.require('shaka.text.Cue');
/**
* <p>
* This defines the default text displayer plugin. An instance of this
* class is used when no custom displayer is given.
* </p>
* <p>
* This class simply converts shaka.text.Cue objects to
* TextTrackCues and feeds them to the browser.
* </p>
*
* @param {HTMLMediaElement} video
* @constructor
* @struct
* @implements {shaka.extern.TextDisplayer}
* @export
*/
shaka.text.SimpleTextDisplayer = function(video) {
/** @private {TextTrack} */
this.textTrack_ = null;
// TODO: Test that in all cases, the built-in CC controls in the video element
// are toggling our TextTrack.
// If the video element has TextTracks, disable them. If we see one that
// was created by a previous instance of Shaka Player, reuse it.
for (let i = 0; i < video.textTracks.length; ++i) {
let track = video.textTracks[i];
track.mode = 'disabled';
if (track.label == shaka.text.SimpleTextDisplayer.TextTrackLabel_) {
this.textTrack_ = track;
}
}
if (!this.textTrack_) {
// As far as I can tell, there is no observable difference between setting
// kind to 'subtitles' or 'captions' when creating the TextTrack object.
// The individual text tracks from the manifest will still have their own
// kinds which can be displayed in the app's UI.
this.textTrack_ = video.addTextTrack(
'subtitles', shaka.text.SimpleTextDisplayer.TextTrackLabel_);
}
this.textTrack_.mode = 'hidden';
};
/**
* @override
* @export
*/
shaka.text.SimpleTextDisplayer.prototype.remove = function(start, end) {
// Check that the displayer hasn't been destroyed.
if (!this.textTrack_) return false;
let removeInRange = (cue) => {
const inside = cue.startTime < end && cue.endTime > start;
return inside;
};
shaka.text.SimpleTextDisplayer.removeWhere_(this.textTrack_, removeInRange);
return true;
};
/**
* @override
* @export
*/
shaka.text.SimpleTextDisplayer.prototype.append = function(cues) {
const convertToTextTrackCue =
shaka.text.SimpleTextDisplayer.convertToTextTrackCue_;
// Convert cues.
let textTrackCues = [];
for (let i = 0; i < cues.length; i++) {
let cue = convertToTextTrackCue(cues[i]);
if (cue) {
textTrackCues.push(cue);
}
}
// Sort the cues based on start/end times. Make a copy of the array so
// we can get the index in the original ordering. Out of order cues are
// rejected by IE/Edge. See https://bit.ly/2K9VX3s
let sortedCues = textTrackCues.slice().sort(function(a, b) {
if (a.startTime != b.startTime) {
return a.startTime - b.startTime;
} else if (a.endTime != b.endTime) {
return a.endTime - b.startTime;
} else {
// The browser will display cues with identical time ranges from the
// bottom up. Reversing the order of equal cues means the first one
// parsed will be at the top, as you would expect.
// See https://github.com/google/shaka-player/issues/848 for more info.
return textTrackCues.indexOf(b) - textTrackCues.indexOf(a);
}
});
sortedCues.forEach(function(cue) {
this.textTrack_.addCue(cue);
}.bind(this));
};
/**
* @override
* @export
*/
shaka.text.SimpleTextDisplayer.prototype.destroy = function() {
if (this.textTrack_) {
let removeIt = (cue) => true;
shaka.text.SimpleTextDisplayer.removeWhere_(this.textTrack_, removeIt);
}
this.textTrack_ = null;
return Promise.resolve();
};
/**
* @override
* @export
*/
shaka.text.SimpleTextDisplayer.prototype.isTextVisible = function() {
return this.textTrack_.mode == 'showing';
};
/**
* @override
* @export
*/
shaka.text.SimpleTextDisplayer.prototype.setTextVisibility = function(on) {
this.textTrack_.mode = on ? 'showing' : 'hidden';
};
/**
* @param {!shaka.extern.Cue} shakaCue
* @return {TextTrackCue}
* @private
*/
shaka.text.SimpleTextDisplayer.convertToTextTrackCue_ = function(shakaCue) {
if (shakaCue.startTime >= shakaCue.endTime) {
// IE/Edge will throw in this case.
// See issue #501
shaka.log.warning('Invalid cue times: ' + shakaCue.startTime +
' - ' + shakaCue.endTime);
return null;
}
const Cue = shaka.text.Cue;
/** @type {VTTCue} */
let vttCue = new VTTCue(shakaCue.startTime,
shakaCue.endTime,
shakaCue.payload);
// NOTE: positionAlign and lineAlign settings are not supported by Chrome
// at the moment, so setting them will have no effect.
// The bug on chromium to implement them:
// https://bugs.chromium.org/p/chromium/issues/detail?id=633690
vttCue.lineAlign = shakaCue.lineAlign;
vttCue.positionAlign = shakaCue.positionAlign;
vttCue.size = shakaCue.size;
try {
// Safari 10 seems to throw on align='center'.
vttCue.align = shakaCue.textAlign;
} catch (exception) {}
if (shakaCue.textAlign == 'center' && vttCue.align != 'center') {
// We want vttCue.position = 'auto'. By default, |position| is set to
// "auto". If we set it to "auto" safari will throw an exception, so we
// must rely on the default value.
vttCue.align = 'middle';
}
if (shakaCue.writingMode ==
Cue.writingMode.VERTICAL_LEFT_TO_RIGHT) {
vttCue.vertical = 'lr';
} else if (shakaCue.writingMode ==
Cue.writingMode.VERTICAL_RIGHT_TO_LEFT) {
vttCue.vertical = 'rl';
}
// snapToLines flag is true by default
if (shakaCue.lineInterpretation == Cue.lineInterpretation.PERCENTAGE) {
vttCue.snapToLines = false;
}
if (shakaCue.line != null) {
vttCue.line = shakaCue.line;
}
if (shakaCue.position != null) {
vttCue.position = shakaCue.position;
}
return vttCue;
};
/**
* Iterate over all the cues in a text track and remove all those for which
* |predicate(cue)| returns true.
*
* @param {!TextTrack} track
* @param {function(!TextTrackCue):boolean} predicate
* @private
*/
shaka.text.SimpleTextDisplayer.removeWhere_ = function(track, predicate) {
// Since |track.cues| can be null if |track.mode| is "disabled", force it to
// something other than "disabled".
//
// If the track is already showing, then we should keep it as showing. But if
// it something else, we will use hidden so that we don't "flash" cues on the
// screen.
let oldState = track.mode;
let tempState = oldState == 'showing' ? 'showing' : 'hidden';
track.mode = tempState;
goog.asserts.assert(
track.cues,
'Cues should be accessible when mode is set to "' + tempState + '".');
// Go backward so that if a removal is done, it should not cause problems
// with future indexing. In the case that the underlying implementation
// returns a copy (and not a shared instance) cache a copy of the tracks.
let cues = track.cues;
for (let i = cues.length - 1; i >= 0; i--) {
let cue = cues[i];
if (cue && predicate(cue)) {
track.removeCue(cue);
}
}
track.mode = oldState;
};
/**
* @const {string}
* @private
*/
shaka.text.SimpleTextDisplayer.TextTrackLabel_ = 'Shaka Player TextTrack';