1 files changed, 259 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/subrip/SubripDecoder.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/subrip/SubripDecoder.java
new file mode 100644
index 0000000000..36ebf6ead0
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/text/subrip/SubripDecoder.java
@@ -0,0 +1,259 @@
+/*
+ * 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.subrip;
+
+import android.text.Html;
+import android.text.Spanned;
+import android.text.TextUtils;
+import androidx.annotation.Nullable;
+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.util.Log;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.LongArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import java.util.ArrayList;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * A {@link SimpleSubtitleDecoder} for SubRip.
+ */
+public final class SubripDecoder extends SimpleSubtitleDecoder {
+
+  // Fractional positions for use when alignment tags are present.
+  private static final float START_FRACTION = 0.08f;
+  private static final float END_FRACTION = 1 - START_FRACTION;
+  private static final float MID_FRACTION = 0.5f;
+
+  private static final String TAG = "SubripDecoder";
+
+  // Some SRT files don't include hours or milliseconds in the timecode, so we use optional groups.
+  private static final String SUBRIP_TIMECODE = "(?:(\\d+):)?(\\d+):(\\d+)(?:,(\\d+))?";
+  private static final Pattern SUBRIP_TIMING_LINE =
+      Pattern.compile("\\s*(" + SUBRIP_TIMECODE + ")\\s*-->\\s*(" + SUBRIP_TIMECODE + ")\\s*");
+
+  // NOTE: Android Studio's suggestion to simplify '\\}' is incorrect [internal: b/144480183].
+  private static final Pattern SUBRIP_TAG_PATTERN = Pattern.compile("\\{\\\\.*?\\}");
+  private static final String SUBRIP_ALIGNMENT_TAG = "\\{\\\\an[1-9]\\}";
+
+  // Alignment tags for SSA V4+.
+  private static final String ALIGN_BOTTOM_LEFT = "{\\an1}";
+  private static final String ALIGN_BOTTOM_MID = "{\\an2}";
+  private static final String ALIGN_BOTTOM_RIGHT = "{\\an3}";
+  private static final String ALIGN_MID_LEFT = "{\\an4}";
+  private static final String ALIGN_MID_MID = "{\\an5}";
+  private static final String ALIGN_MID_RIGHT = "{\\an6}";
+  private static final String ALIGN_TOP_LEFT = "{\\an7}";
+  private static final String ALIGN_TOP_MID = "{\\an8}";
+  private static final String ALIGN_TOP_RIGHT = "{\\an9}";
+
+  private final StringBuilder textBuilder;
+  private final ArrayList<String> tags;
+
+  public SubripDecoder() {
+    super("SubripDecoder");
+    textBuilder = new StringBuilder();
+    tags = new ArrayList<>();
+  }
+
+  @Override
+  protected Subtitle decode(byte[] bytes, int length, boolean reset) {
+    ArrayList<Cue> cues = new ArrayList<>();
+    LongArray cueTimesUs = new LongArray();
+    ParsableByteArray subripData = new ParsableByteArray(bytes, length);
+
+    @Nullable String currentLine;
+    while ((currentLine = subripData.readLine()) != null) {
+      if (currentLine.length() == 0) {
+        // Skip blank lines.
+        continue;
+      }
+
+      // Parse the index line as a sanity check.
+      try {
+        Integer.parseInt(currentLine);
+      } catch (NumberFormatException e) {
+        Log.w(TAG, "Skipping invalid index: " + currentLine);
+        continue;
+      }
+
+      // Read and parse the timing line.
+      currentLine = subripData.readLine();
+      if (currentLine == null) {
+        Log.w(TAG, "Unexpected end");
+        break;
+      }
+
+      Matcher matcher = SUBRIP_TIMING_LINE.matcher(currentLine);
+      if (matcher.matches()) {
+        cueTimesUs.add(parseTimecode(matcher, /* groupOffset= */ 1));
+        cueTimesUs.add(parseTimecode(matcher, /* groupOffset= */ 6));
+      } else {
+        Log.w(TAG, "Skipping invalid timing: " + currentLine);
+        continue;
+      }
+
+      // Read and parse the text and tags.
+      textBuilder.setLength(0);
+      tags.clear();
+      currentLine = subripData.readLine();
+      while (!TextUtils.isEmpty(currentLine)) {
+        if (textBuilder.length() > 0) {
+          textBuilder.append("<br>");
+        }
+        textBuilder.append(processLine(currentLine, tags));
+        currentLine = subripData.readLine();
+      }
+
+      Spanned text = Html.fromHtml(textBuilder.toString());
+
+      @Nullable String alignmentTag = null;
+      for (int i = 0; i < tags.size(); i++) {
+        String tag = tags.get(i);
+        if (tag.matches(SUBRIP_ALIGNMENT_TAG)) {
+          alignmentTag = tag;
+          // Subsequent alignment tags should be ignored.
+          break;
+        }
+      }
+      cues.add(buildCue(text, alignmentTag));
+      cues.add(Cue.EMPTY);
+    }
+
+    Cue[] cuesArray = new Cue[cues.size()];
+    cues.toArray(cuesArray);
+    long[] cueTimesUsArray = cueTimesUs.toArray();
+    return new SubripSubtitle(cuesArray, cueTimesUsArray);
+  }
+
+  /**
+   * Trims and removes tags from the given line. The removed tags are added to {@code tags}.
+   *
+   * @param line The line to process.
+   * @param tags A list to which removed tags will be added.
+   * @return The processed line.
+   */
+  private String processLine(String line, ArrayList<String> tags) {
+    line = line.trim();
+
+    int removedCharacterCount = 0;
+    StringBuilder processedLine = new StringBuilder(line);
+    Matcher matcher = SUBRIP_TAG_PATTERN.matcher(line);
+    while (matcher.find()) {
+      String tag = matcher.group();
+      tags.add(tag);
+      int start = matcher.start() - removedCharacterCount;
+      int tagLength = tag.length();
+      processedLine.replace(start, /* end= */ start + tagLength, /* str= */ "");
+      removedCharacterCount += tagLength;
+    }
+
+    return processedLine.toString();
+  }
+
+  /**
+   * Build a {@link Cue} based on the given text and alignment tag.
+   *
+   * @param text The text.
+   * @param alignmentTag The alignment tag, or {@code null} if no alignment tag is available.
+   * @return Built cue
+   */
+  private Cue buildCue(Spanned text, @Nullable String alignmentTag) {
+    if (alignmentTag == null) {
+      return new Cue(text);
+    }
+
+    // Horizontal alignment.
+    @Cue.AnchorType int positionAnchor;
+    switch (alignmentTag) {
+      case ALIGN_BOTTOM_LEFT:
+      case ALIGN_MID_LEFT:
+      case ALIGN_TOP_LEFT:
+        positionAnchor = Cue.ANCHOR_TYPE_START;
+        break;
+      case ALIGN_BOTTOM_RIGHT:
+      case ALIGN_MID_RIGHT:
+      case ALIGN_TOP_RIGHT:
+        positionAnchor = Cue.ANCHOR_TYPE_END;
+        break;
+      case ALIGN_BOTTOM_MID:
+      case ALIGN_MID_MID:
+      case ALIGN_TOP_MID:
+      default:
+        positionAnchor = Cue.ANCHOR_TYPE_MIDDLE;
+        break;
+    }
+
+    // Vertical alignment.
+    @Cue.AnchorType int lineAnchor;
+    switch (alignmentTag) {
+      case ALIGN_BOTTOM_LEFT:
+      case ALIGN_BOTTOM_MID:
+      case ALIGN_BOTTOM_RIGHT:
+        lineAnchor = Cue.ANCHOR_TYPE_END;
+        break;
+      case ALIGN_TOP_LEFT:
+      case ALIGN_TOP_MID:
+      case ALIGN_TOP_RIGHT:
+        lineAnchor = Cue.ANCHOR_TYPE_START;
+        break;
+      case ALIGN_MID_LEFT:
+      case ALIGN_MID_MID:
+      case ALIGN_MID_RIGHT:
+      default:
+        lineAnchor = Cue.ANCHOR_TYPE_MIDDLE;
+        break;
+    }
+
+    return new Cue(
+        text,
+        /* textAlignment= */ null,
+        getFractionalPositionForAnchorType(lineAnchor),
+        Cue.LINE_TYPE_FRACTION,
+        lineAnchor,
+        getFractionalPositionForAnchorType(positionAnchor),
+        positionAnchor,
+        Cue.DIMEN_UNSET);
+  }
+
+  private static long parseTimecode(Matcher matcher, int groupOffset) {
+    @Nullable String hours = matcher.group(groupOffset + 1);
+    long timestampMs = hours != null ? Long.parseLong(hours) * 60 * 60 * 1000 : 0;
+    timestampMs += Long.parseLong(matcher.group(groupOffset + 2)) * 60 * 1000;
+    timestampMs += Long.parseLong(matcher.group(groupOffset + 3)) * 1000;
+    @Nullable String millis = matcher.group(groupOffset + 4);
+    if (millis != null) {
+      timestampMs += Long.parseLong(millis);
+    }
+    return timestampMs * 1000;
+  }
+
+  /* package */ static float getFractionalPositionForAnchorType(@Cue.AnchorType int anchorType) {
+    switch (anchorType) {
+      case Cue.ANCHOR_TYPE_START:
+        return SubripDecoder.START_FRACTION;
+      case Cue.ANCHOR_TYPE_MIDDLE:
+        return SubripDecoder.MID_FRACTION;
+      case Cue.ANCHOR_TYPE_END:
+        return SubripDecoder.END_FRACTION;
+      case Cue.TYPE_UNSET:
+      default:
+        // Should never happen.
+        throw new IllegalArgumentException();
+    }
+  }
+}