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/*
* Copyright (C) 2016 The Android Open Source Project
*
* 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.
*/
package org.mozilla.thirdparty.com.google.android.exoplayer2.text.tx3g;
import android.graphics.Color;
import android.graphics.Typeface;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.style.ForegroundColorSpan;
import android.text.style.StyleSpan;
import android.text.style.TypefaceSpan;
import android.text.style.UnderlineSpan;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.text.Cue;
import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SimpleSubtitleDecoder;
import org.mozilla.thirdparty.com.google.android.exoplayer2.text.Subtitle;
import org.mozilla.thirdparty.com.google.android.exoplayer2.text.SubtitleDecoderException;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
import org.mozilla.thirdparty.com.google.android.exoplayer2.util.Util;
import java.nio.charset.Charset;
import java.util.List;
/**
* A {@link SimpleSubtitleDecoder} for tx3g.
* <p>
* Currently supports parsing of a single text track with embedded styles.
*/
public final class Tx3gDecoder extends SimpleSubtitleDecoder {
private static final char BOM_UTF16_BE = '\uFEFF';
private static final char BOM_UTF16_LE = '\uFFFE';
private static final int TYPE_STYL = 0x7374796c;
private static final int TYPE_TBOX = 0x74626f78;
private static final String TX3G_SERIF = "Serif";
private static final int SIZE_ATOM_HEADER = 8;
private static final int SIZE_SHORT = 2;
private static final int SIZE_BOM_UTF16 = 2;
private static final int SIZE_STYLE_RECORD = 12;
private static final int FONT_FACE_BOLD = 0x0001;
private static final int FONT_FACE_ITALIC = 0x0002;
private static final int FONT_FACE_UNDERLINE = 0x0004;
private static final int SPAN_PRIORITY_LOW = 0xFF << Spanned.SPAN_PRIORITY_SHIFT;
private static final int SPAN_PRIORITY_HIGH = 0;
private static final int DEFAULT_FONT_FACE = 0;
private static final int DEFAULT_COLOR = Color.WHITE;
private static final String DEFAULT_FONT_FAMILY = C.SANS_SERIF_NAME;
private static final float DEFAULT_VERTICAL_PLACEMENT = 0.85f;
private final ParsableByteArray parsableByteArray;
private boolean customVerticalPlacement;
private int defaultFontFace;
private int defaultColorRgba;
private String defaultFontFamily;
private float defaultVerticalPlacement;
private int calculatedVideoTrackHeight;
/**
* Sets up a new {@link Tx3gDecoder} with default values.
*
* @param initializationData Sample description atom ('stsd') data with default subtitle styles.
*/
public Tx3gDecoder(List<byte[]> initializationData) {
super("Tx3gDecoder");
parsableByteArray = new ParsableByteArray();
if (initializationData != null && initializationData.size() == 1
&& (initializationData.get(0).length == 48 || initializationData.get(0).length == 53)) {
byte[] initializationBytes = initializationData.get(0);
defaultFontFace = initializationBytes[24];
defaultColorRgba = ((initializationBytes[26] & 0xFF) << 24)
| ((initializationBytes[27] & 0xFF) << 16)
| ((initializationBytes[28] & 0xFF) << 8)
| (initializationBytes[29] & 0xFF);
String fontFamily =
Util.fromUtf8Bytes(initializationBytes, 43, initializationBytes.length - 43);
defaultFontFamily = TX3G_SERIF.equals(fontFamily) ? C.SERIF_NAME : C.SANS_SERIF_NAME;
//font size (initializationBytes[25]) is 5% of video height
calculatedVideoTrackHeight = 20 * initializationBytes[25];
customVerticalPlacement = (initializationBytes[0] & 0x20) != 0;
if (customVerticalPlacement) {
int requestedVerticalPlacement = ((initializationBytes[10] & 0xFF) << 8)
| (initializationBytes[11] & 0xFF);
defaultVerticalPlacement = (float) requestedVerticalPlacement / calculatedVideoTrackHeight;
defaultVerticalPlacement = Util.constrainValue(defaultVerticalPlacement, 0.0f, 0.95f);
} else {
defaultVerticalPlacement = DEFAULT_VERTICAL_PLACEMENT;
}
} else {
defaultFontFace = DEFAULT_FONT_FACE;
defaultColorRgba = DEFAULT_COLOR;
defaultFontFamily = DEFAULT_FONT_FAMILY;
customVerticalPlacement = false;
defaultVerticalPlacement = DEFAULT_VERTICAL_PLACEMENT;
}
}
@Override
protected Subtitle decode(byte[] bytes, int length, boolean reset)
throws SubtitleDecoderException {
parsableByteArray.reset(bytes, length);
String cueTextString = readSubtitleText(parsableByteArray);
if (cueTextString.isEmpty()) {
return Tx3gSubtitle.EMPTY;
}
// Attach default styles.
SpannableStringBuilder cueText = new SpannableStringBuilder(cueTextString);
attachFontFace(cueText, defaultFontFace, DEFAULT_FONT_FACE, 0, cueText.length(),
SPAN_PRIORITY_LOW);
attachColor(cueText, defaultColorRgba, DEFAULT_COLOR, 0, cueText.length(),
SPAN_PRIORITY_LOW);
attachFontFamily(cueText, defaultFontFamily, DEFAULT_FONT_FAMILY, 0, cueText.length(),
SPAN_PRIORITY_LOW);
float verticalPlacement = defaultVerticalPlacement;
// Find and attach additional styles.
while (parsableByteArray.bytesLeft() >= SIZE_ATOM_HEADER) {
int position = parsableByteArray.getPosition();
int atomSize = parsableByteArray.readInt();
int atomType = parsableByteArray.readInt();
if (atomType == TYPE_STYL) {
assertTrue(parsableByteArray.bytesLeft() >= SIZE_SHORT);
int styleRecordCount = parsableByteArray.readUnsignedShort();
for (int i = 0; i < styleRecordCount; i++) {
applyStyleRecord(parsableByteArray, cueText);
}
} else if (atomType == TYPE_TBOX && customVerticalPlacement) {
assertTrue(parsableByteArray.bytesLeft() >= SIZE_SHORT);
int requestedVerticalPlacement = parsableByteArray.readUnsignedShort();
verticalPlacement = (float) requestedVerticalPlacement / calculatedVideoTrackHeight;
verticalPlacement = Util.constrainValue(verticalPlacement, 0.0f, 0.95f);
}
parsableByteArray.setPosition(position + atomSize);
}
return new Tx3gSubtitle(
new Cue(
cueText,
/* textAlignment= */ null,
verticalPlacement,
Cue.LINE_TYPE_FRACTION,
Cue.ANCHOR_TYPE_START,
Cue.DIMEN_UNSET,
Cue.TYPE_UNSET,
Cue.DIMEN_UNSET));
}
private static String readSubtitleText(ParsableByteArray parsableByteArray)
throws SubtitleDecoderException {
assertTrue(parsableByteArray.bytesLeft() >= SIZE_SHORT);
int textLength = parsableByteArray.readUnsignedShort();
if (textLength == 0) {
return "";
}
if (parsableByteArray.bytesLeft() >= SIZE_BOM_UTF16) {
char firstChar = parsableByteArray.peekChar();
if (firstChar == BOM_UTF16_BE || firstChar == BOM_UTF16_LE) {
return parsableByteArray.readString(textLength, Charset.forName(C.UTF16_NAME));
}
}
return parsableByteArray.readString(textLength, Charset.forName(C.UTF8_NAME));
}
private void applyStyleRecord(ParsableByteArray parsableByteArray,
SpannableStringBuilder cueText) throws SubtitleDecoderException {
assertTrue(parsableByteArray.bytesLeft() >= SIZE_STYLE_RECORD);
int start = parsableByteArray.readUnsignedShort();
int end = parsableByteArray.readUnsignedShort();
parsableByteArray.skipBytes(2); // font identifier
int fontFace = parsableByteArray.readUnsignedByte();
parsableByteArray.skipBytes(1); // font size
int colorRgba = parsableByteArray.readInt();
attachFontFace(cueText, fontFace, defaultFontFace, start, end, SPAN_PRIORITY_HIGH);
attachColor(cueText, colorRgba, defaultColorRgba, start, end, SPAN_PRIORITY_HIGH);
}
private static void attachFontFace(SpannableStringBuilder cueText, int fontFace,
int defaultFontFace, int start, int end, int spanPriority) {
if (fontFace != defaultFontFace) {
final int flags = Spanned.SPAN_EXCLUSIVE_EXCLUSIVE | spanPriority;
boolean isBold = (fontFace & FONT_FACE_BOLD) != 0;
boolean isItalic = (fontFace & FONT_FACE_ITALIC) != 0;
if (isBold) {
if (isItalic) {
cueText.setSpan(new StyleSpan(Typeface.BOLD_ITALIC), start, end, flags);
} else {
cueText.setSpan(new StyleSpan(Typeface.BOLD), start, end, flags);
}
} else if (isItalic) {
cueText.setSpan(new StyleSpan(Typeface.ITALIC), start, end, flags);
}
boolean isUnderlined = (fontFace & FONT_FACE_UNDERLINE) != 0;
if (isUnderlined) {
cueText.setSpan(new UnderlineSpan(), start, end, flags);
}
if (!isUnderlined && !isBold && !isItalic) {
cueText.setSpan(new StyleSpan(Typeface.NORMAL), start, end, flags);
}
}
}
private static void attachColor(SpannableStringBuilder cueText, int colorRgba,
int defaultColorRgba, int start, int end, int spanPriority) {
if (colorRgba != defaultColorRgba) {
int colorArgb = ((colorRgba & 0xFF) << 24) | (colorRgba >>> 8);
cueText.setSpan(new ForegroundColorSpan(colorArgb), start, end,
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE | spanPriority);
}
}
@SuppressWarnings("ReferenceEquality")
private static void attachFontFamily(SpannableStringBuilder cueText, String fontFamily,
String defaultFontFamily, int start, int end, int spanPriority) {
if (fontFamily != defaultFontFamily) {
cueText.setSpan(new TypefaceSpan(fontFamily), start, end,
Spanned.SPAN_EXCLUSIVE_EXCLUSIVE | spanPriority);
}
}
private static void assertTrue(boolean checkValue) throws SubtitleDecoderException {
if (!checkValue) {
throw new SubtitleDecoderException("Unexpected subtitle format.");
}
}
}
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