shaka-player
Version:
DASH/EME video player library
426 lines (368 loc) • 10.2 kB
JavaScript
/*! @license
* Shaka Player
* Copyright 2016 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
goog.provide('shaka.cea.Cea708Window');
goog.require('shaka.cea.CeaUtils');
goog.require('shaka.cea.CeaUtils.StyledChar');
goog.require('shaka.text.Cue');
goog.require('shaka.util.Functional');
/**
* CEA-708 Window. Each CEA-708 service owns 8 of these.
*/
shaka.cea.Cea708Window = class {
/**
* @param {number} windowNum
*/
constructor(windowNum) {
/**
* A number from 0 - 7 indicating the window number in the
* service that owns this window.
* @private {number}
*/
this.windowNum_ = windowNum;
/**
* Indicates whether this window is visible.
* @private {boolean}
*/
this.visible_ = false;
/**
* Indicates whether the horizontal and vertical anchors coordinates specify
* a percentage of the screen, or physical coordinates on the screen.
* @private {boolean}
*/
this.relativeToggle_ = false;
/**
* Horizontal anchor. Loosely corresponds to a WebVTT viewport X anchor.
* @private {number}
*/
this.horizontalAnchor_ = 0;
/**
* Vertical anchor. Loosely corresponds to a WebVTT viewport Y anchor.
* @private {number}
*/
this.verticalAnchor_ = 0;
/**
* If valid, ranges from 0 to 8, specifying one of 9 locations on window:
* 0________1________2
* | | |
* 3________4________5
* | | |
* 6________7________8
* Diagram is valid as per CEA-708-E section 8.4.4.
* Each of these locations corresponds to a WebVTT region's "region anchor".
* @private {number}
*/
this.anchorId_ = 0;
/**
* Indicates the number of rows in this window's buffer/memory.
* @private {number}
*/
this.rowCount_ = 0;
/**
* Indicates the number of columns in this window's buffer/memory.
* @private {number}
*/
this.colCount_ = 0;
/**
* Center by default.
* @private {!shaka.cea.Cea708Window.TextJustification}
*/
this.justification_ = shaka.cea.Cea708Window.TextJustification.CENTER;
/**
* An array of rows of styled characters, representing the
* current text and styling of text in this window.
* @private {!Array<!Array<?shaka.cea.CeaUtils.StyledChar>>}
*/
this.memory_ = [];
/**
* @private {number}
*/
this.startTime_ = 0;
/**
* Row that the current pen is pointing at.
* @private {number}
*/
this.row_ = 0;
/**
* Column that the current pen is pointing at.
* @private {number}
*/
this.col_ = 0;
/**
* Indicates whether the current pen position is italicized.
* @private {boolean}
*/
this.italics_ = false;
/**
* Indicates whether the current pen position is underlined.
* @private {boolean}
*/
this.underline_ = false;
/**
* Indicates the text color at the current pen position.
* @private {string}
*/
this.textColor_ = shaka.cea.CeaUtils.DEFAULT_TXT_COLOR;
/**
* Indicates the background color at the current pen position.
* @private {string}
*/
this.backgroundColor_ = shaka.cea.CeaUtils.DEFAULT_BG_COLOR;
this.resetMemory();
// TODO Support window positioning by mapping them to Regions.
// https://dvcs.w3.org/hg/text-tracks/raw-file/default/608toVTT/608toVTT.html#positioning-in-cea-708
shaka.util.Functional.ignored(this.verticalAnchor_, this.relativeToggle_,
this.horizontalAnchor_, this.anchorId_, this.windowNum_);
}
/**
* @param {boolean} visible
* @param {number} verticalAnchor
* @param {number} horizontalAnchor
* @param {number} anchorId
* @param {boolean} relativeToggle
* @param {number} rowCount
* @param {number} colCount
*/
defineWindow(visible, verticalAnchor, horizontalAnchor, anchorId,
relativeToggle, rowCount, colCount) {
this.visible_ = visible;
this.verticalAnchor_ = verticalAnchor;
this.horizontalAnchor_ = horizontalAnchor;
this.anchorId_ = anchorId;
this.relativeToggle_ = relativeToggle;
this.rowCount_ = rowCount;
this.colCount_ = colCount;
}
/**
* Resets the memory buffer.
*/
resetMemory() {
this.memory_ = [];
for (let i = 0; i < shaka.cea.Cea708Window.MAX_ROWS; i++) {
this.memory_.push(this.createNewRow_());
}
}
/**
* Allocates and returns a new row.
* @return {!Array<?shaka.cea.CeaUtils.StyledChar>}
* @private
*/
createNewRow_() {
const row = [];
for (let j = 0; j < shaka.cea.Cea708Window.MAX_COLS; j++) {
row.push(null);
}
return row;
}
/**
* Sets the unicode value for a char at the current pen location.
* @param {string} char
*/
setCharacter(char) {
// Check if the pen is out of bounds.
if (!this.isPenInBounds_()) {
return;
}
const cea708Char = new shaka.cea.CeaUtils.StyledChar(
char, this.underline_, this.italics_,
this.backgroundColor_, this.textColor_);
this.memory_[this.row_][this.col_] = cea708Char;
// Increment column
this.col_ ++;
}
/**
* Erases a character from the buffer and moves the pen back.
*/
backspace() {
if (!this.isPenInBounds_()) {
return;
}
// Check if a backspace can be done.
if (this.col_ <= 0 && this.row_ <= 0) {
return;
}
if (this.col_ <= 0) {
// Move pen back a row.
this.col_ = this.colCount_ - 1;
this.row_--;
} else {
// Move pen back a column.
this.col_--;
}
// Erase the character occupied at that position.
this.memory_[this.row_][this.col_] = null;
}
/**
* @private
*/
isPenInBounds_() {
const inRowBounds = this.row_ < this.rowCount_ && this.row_ >= 0;
const inColBounds = this.col_ < this.colCount_ && this.col_ >= 0;
return inRowBounds && inColBounds;
}
/**
* @return {boolean}
*/
isVisible() {
return this.visible_;
}
/**
* Moves up <count> rows in the buffer.
* @param {number} count
* @private
*/
moveUpRows_(count) {
let dst = 0; // Row each row should be moved to.
// Move existing rows up by <count>.
for (let i = count; i < shaka.cea.Cea708Window.MAX_ROWS; i++, dst++) {
this.memory_[dst] = this.memory_[i];
}
// Create <count> new rows at the bottom.
for (let i = 0; i < count; i++, dst++) {
this.memory_[dst] = this.createNewRow_();
}
}
/**
* Handles CR. Increments row - if last row, "roll up" all rows by one.
*/
carriageReturn() {
if (this.row_ + 1 >= this.rowCount_) {
this.moveUpRows_(1);
this.col_ = 0;
return;
}
this.row_++;
this.col_ = 0;
}
/**
* Handles HCR. Moves the pen to the beginning of the cur. row and clears it.
*/
horizontalCarriageReturn() {
this.memory_[this.row_] = this.createNewRow_();
this.col_ = 0;
}
/**
* @param {number} endTime
* @param {number} serviceNumber Number of the service emitting this caption.
* @return {?shaka.extern.ICaptionDecoder.ClosedCaption}
*/
forceEmit(endTime, serviceNumber) {
const stream = `svc${serviceNumber}`;
const TextJustification = shaka.cea.Cea708Window.TextJustification;
const topLevelCue = new shaka.text.Cue(
this.startTime_, endTime, /* payload= */ '');
if (this.justification_ === TextJustification.LEFT) {
// LEFT justified.
topLevelCue.textAlign = shaka.text.Cue.textAlign.LEFT;
} else if (this.justification_ === TextJustification.RIGHT) {
// RIGHT justified.
topLevelCue.textAlign = shaka.text.Cue.textAlign.RIGHT;
} else {
// CENTER justified. Both FULL and CENTER are handled as CENTER justified.
topLevelCue.textAlign = shaka.text.Cue.textAlign.CENTER;
}
const caption = shaka.cea.CeaUtils.getParsedCaption(
topLevelCue, stream, this.memory_, this.startTime_, endTime);
if (caption) {
// If a caption is being emitted, then the next caption's start time
// should be no less than this caption's end time.
this.setStartTime(endTime);
}
return caption;
}
/**
* @param {number} row
* @param {number} col
*/
setPenLocation(row, col) {
this.row_ = row;
this.col_ = col;
}
/**
* @param {string} backgroundColor
*/
setPenBackgroundColor(backgroundColor) {
this.backgroundColor_ = backgroundColor;
}
/**
* @param {string} textColor
*/
setPenTextColor(textColor) {
this.textColor_ = textColor;
}
/**
* @param {boolean} underline
*/
setPenUnderline(underline) {
this.underline_ = underline;
}
/**
* @param {boolean} italics
*/
setPenItalics(italics) {
this.italics_ = italics;
}
/** Reset the pen to 0,0 with default styling. */
resetPen() {
this.row_ = 0;
this.col_ = 0;
this.underline_ = false;
this.italics_ = false;
this.textColor_ = shaka.cea.CeaUtils.DEFAULT_TXT_COLOR;
this.backgroundColor_ = shaka.cea.CeaUtils.DEFAULT_BG_COLOR;
}
/**
* @param {!shaka.cea.Cea708Window.TextJustification} justification
*/
setJustification(justification) {
this.justification_ = justification;
}
/**
* Sets the window to visible.
*/
display() {
this.visible_ = true;
}
/**
* Sets the window to invisible.
*/
hide() {
this.visible_ = false;
}
/**
* Toggles the visibility of the window.
*/
toggle() {
this.visible_ = !this.visible_;
}
/**
* Sets the start time for the cue to be emitted.
* @param {number} pts
*/
setStartTime(pts) {
this.startTime_ = pts;
}
};
/**
* Caption type.
* @const @enum {number}
*/
shaka.cea.Cea708Window.TextJustification = {
LEFT: 0,
RIGHT: 1,
CENTER: 2,
FULL: 3,
};
/**
* Can be indexed 0-31 for 4:3 format, and 0-41 for 16:9 formats.
* Thus the absolute maximum is 42 columns for the 16:9 format.
* @private @const {number}
*/
shaka.cea.Cea708Window.MAX_COLS = 42;
/**
* Maximum of 16 rows that can be indexed from 0 to 15.
* @private @const {number}
*/
shaka.cea.Cea708Window.MAX_ROWS = 16;