Implement text and drawable overlays

Implements milestone 1.2 of the [overlays implementation plan](https://docs.google.com/document/d/1EcP2GN8k8N74hHZyD0KTqm9oQo5-W1dZMqIVyqVGtlo/edit#bookmark=id.76uzcie1dg9d)

PiperOrigin-RevId: 493282868

library/effect/src/androidTest/java/com/google/android/exoplayer2/effect/OverlayTextureProcessorPixelTest.java

@@ -27,10 +27,14 @@ import static com.google.common.truth.Truth.assertThat;
 
 import android.content.Context;
 import android.graphics.Bitmap;
+import android.graphics.Color;
 import android.opengl.EGLContext;
 import android.opengl.EGLDisplay;
 import android.opengl.EGLSurface;
 import android.opengl.Matrix;
+import android.text.Spannable;
+import android.text.SpannableString;
+import android.text.style.ForegroundColorSpan;
 import android.util.Pair;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.android.exoplayer2.util.FrameProcessingException;
@@ -60,6 +64,10 @@ public class OverlayTextureProcessorPixelTest {
       "media/bitmap/sample_mp4_first_frame/electrical_colors/overlay_bitmap_default.png";
   public static final String OVERLAY_BITMAP_SCALED =
       "media/bitmap/sample_mp4_first_frame/electrical_colors/overlay_bitmap_scaled.png";
+  public static final String OVERLAY_TEXT_DEFAULT =
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/overlay_text_default.png";
+  public static final String OVERLAY_TEXT_TRANSLATE =
+      "media/bitmap/sample_mp4_first_frame/electrical_colors/overlay_text_translate.png";
 
   private final Context context = getApplicationContext();
 
@@ -159,6 +167,65 @@ public class OverlayTextureProcessorPixelTest {
     assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
   }
 
+  @Test
+  public void drawFrame_textOverlay_blendsTextIntoFrame() throws Exception {
+    String testId = "drawFrame_textOverlay";
+    SpannableString overlayText = new SpannableString(/* source= */ "Text styling");
+    overlayText.setSpan(
+        new ForegroundColorSpan(Color.GRAY),
+        /* start= */ 0,
+        /* end= */ 4,
+        Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+    TextOverlay staticTextOverlay = TextOverlay.createStaticTextOverlay(overlayText);
+    overlayTextureProcessor =
+        new OverlayEffect(ImmutableList.of(staticTextOverlay))
+            .toGlTextureProcessor(context, /* useHdr= */ false);
+    Pair<Integer, Integer> outputSize = overlayTextureProcessor.configure(inputWidth, inputHeight);
+    setupOutputTexture(outputSize.first, outputSize.second);
+    Bitmap expectedBitmap = readBitmap(OVERLAY_TEXT_DEFAULT);
+
+    overlayTextureProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        createArgb8888BitmapFromCurrentGlFramebuffer(outputSize.first, outputSize.second);
+
+    maybeSaveTestBitmapToCacheDirectory(testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        getBitmapAveragePixelAbsoluteDifferenceArgb8888(expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
+  @Test
+  public void drawFrame_translatedTextOverlay_blendsTextIntoFrame() throws Exception {
+    String testId = "drawFrame_translatedTextOverlay";
+    float[] translateMatrix = GlUtil.create4x4IdentityMatrix();
+    Matrix.translateM(translateMatrix, /* mOffset= */ 0, /* x= */ 0.5f, /* y= */ 0.5f, /* z= */ 1);
+    SpannableString overlayText = new SpannableString(/* source= */ "Text styling");
+    overlayText.setSpan(
+        new ForegroundColorSpan(Color.GRAY),
+        /* start= */ 0,
+        /* end= */ 4,
+        Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
+    OverlaySettings overlaySettings =
+        new OverlaySettings.Builder().setMatrix(translateMatrix).build();
+    TextOverlay staticTextOverlay =
+        TextOverlay.createStaticTextOverlay(overlayText, overlaySettings);
+    overlayTextureProcessor =
+        new OverlayEffect(ImmutableList.of(staticTextOverlay))
+            .toGlTextureProcessor(context, /* useHdr= */ false);
+    Pair<Integer, Integer> outputSize = overlayTextureProcessor.configure(inputWidth, inputHeight);
+    setupOutputTexture(outputSize.first, outputSize.second);
+    Bitmap expectedBitmap = readBitmap(OVERLAY_TEXT_TRANSLATE);
+
+    overlayTextureProcessor.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
+    Bitmap actualBitmap =
+        createArgb8888BitmapFromCurrentGlFramebuffer(outputSize.first, outputSize.second);
+
+    maybeSaveTestBitmapToCacheDirectory(testId, /* bitmapLabel= */ "actual", actualBitmap);
+    float averagePixelAbsoluteDifference =
+        getBitmapAveragePixelAbsoluteDifferenceArgb8888(expectedBitmap, actualBitmap, testId);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
+  }
+
   private void setupOutputTexture(int outputWidth, int outputHeight) throws GlUtil.GlException {
     int outputTexId =
         GlUtil.createTexture(

library/effect/src/main/java/com/google/android/exoplayer2/effect/DrawableOverlay.java

+/*
+ * Copyright 2022 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 com.google.android.exoplayer2.effect;
+
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.drawable.Drawable;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * Creates a {@link TextureOverlay} from {@link Drawable}.
+ *
+ * <p>Uses a canvas to draw {@link DrawableOverlay} onto {@link BitmapOverlay}, which is then
+ * displayed on each frame.
+ */
+public abstract class DrawableOverlay extends BitmapOverlay {
+  private @MonotonicNonNull Bitmap lastBitmap;
+  private @MonotonicNonNull Drawable lastDrawable;
+
+  /**
+   * Returns the overlay {@link Drawable} displayed at the specified timestamp.
+   *
+   * @param presentationTimeUs The presentation timestamp of the current frame, in microseconds.
+   */
+  public abstract Drawable getDrawable(long presentationTimeUs);
+
+  @Override
+  public Bitmap getBitmap(long presentationTimeUs) {
+    Drawable overlayDrawable = getDrawable(presentationTimeUs);
+    // TODO(b/227625365): Drawable doesn't implement the equals method, so investigate other methods
+    // of
+    //  detecting the need to redraw the bitmap.
+    if (!overlayDrawable.equals(lastDrawable)) {
+      lastDrawable = overlayDrawable;
+      lastBitmap =
+          Bitmap.createBitmap(
+              lastDrawable.getIntrinsicWidth(),
+              lastDrawable.getIntrinsicHeight(),
+              Bitmap.Config.ARGB_8888);
+      Canvas canvas = new Canvas(lastBitmap);
+      lastDrawable.draw(canvas);
+    }
+    return checkNotNull(lastBitmap);
+  }
+
+  /**
+   * Creates a {@link TextOverlay} that shows the {@code overlayDrawable} with the same {@link
+   * OverlaySettings} throughout the whole video.
+   *
+   * @param overlaySettings The {@link OverlaySettings} configuring how the overlay is displayed on
+   *     the frames.
+   */
+  public static DrawableOverlay createStaticDrawableOverlay(
+      Drawable drawable, OverlaySettings overlaySettings) {
+    return new DrawableOverlay() {
+      @Override
+      public Drawable getDrawable(long presentationTimeUs) {
+        return drawable;
+      }
+    };
+  }
+}

library/effect/src/main/java/com/google/android/exoplayer2/effect/TextOverlay.java

+/*
+ * Copyright 2022 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 com.google.android.exoplayer2.effect;
+
+import static com.google.android.exoplayer2.util.Assertions.checkNotNull;
+import static com.google.android.exoplayer2.util.Util.SDK_INT;
+
+import android.annotation.SuppressLint;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.text.Layout;
+import android.text.SpannableString;
+import android.text.StaticLayout;
+import android.text.TextPaint;
+import androidx.annotation.DoNotInline;
+import androidx.annotation.RequiresApi;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * Creates a {@link TextureOverlay} from text.
+ *
+ * <p>Uses a {@link SpannableString} store the text and support advanced per-character text styling.
+ */
+public abstract class TextOverlay extends BitmapOverlay {
+  public static final int TEXT_SIZE_PIXELS = 100;
+
+  private @MonotonicNonNull Bitmap lastBitmap;
+  private @MonotonicNonNull SpannableString lastText;
+
+  /**
+   * Returns the overlay text displayed at the specified timestamp.
+   *
+   * @param presentationTimeUs The presentation timestamp of the current frame, in microseconds.
+   */
+  public abstract SpannableString getText(long presentationTimeUs);
+
+  @SuppressLint("InlinedApi") // Inlined Layout constants.
+  @Override
+  public Bitmap getBitmap(long presentationTimeUs) {
+    SpannableString overlayText = getText(presentationTimeUs);
+    if (!overlayText.equals(lastText)) {
+      lastText = overlayText;
+      TextPaint textPaint = new TextPaint();
+      textPaint.setTextSize(TEXT_SIZE_PIXELS);
+      StaticLayout staticLayout;
+      int width = (int) textPaint.measureText(overlayText, /* start= */ 0, overlayText.length());
+      if (SDK_INT >= 23) {
+        staticLayout = Api23.getStaticLayout(overlayText, textPaint, width);
+      } else {
+        staticLayout =
+            new StaticLayout(
+                overlayText,
+                textPaint,
+                width,
+                Layout.Alignment.ALIGN_NORMAL,
+                Layout.DEFAULT_LINESPACING_MULTIPLIER,
+                Layout.DEFAULT_LINESPACING_ADDITION,
+                /* includepad= */ true);
+      }
+      lastBitmap =
+          Bitmap.createBitmap(
+              staticLayout.getWidth(), staticLayout.getHeight(), Bitmap.Config.ARGB_8888);
+      Canvas canvas = new Canvas(checkNotNull(lastBitmap));
+      staticLayout.draw(canvas);
+    }
+    return checkNotNull(lastBitmap);
+  }
+
+  /**
+   * Creates a {@link TextOverlay} that shows the {@code overlayText} with the same default settings
+   * in {@link OverlaySettings} throughout the whole video.
+   */
+  public static TextOverlay createStaticTextOverlay(SpannableString overlayText) {
+    return new TextOverlay() {
+      @Override
+      public SpannableString getText(long presentationTimeUs) {
+        return overlayText;
+      }
+    };
+  }
+
+  /**
+   * Creates a {@link TextOverlay} that shows the {@code overlayText} with the same {@link
+   * OverlaySettings} throughout the whole video.
+   *
+   * @param overlaySettings The {@link OverlaySettings} configuring how the overlay is displayed on
+   *     the frames.
+   */
+  public static TextOverlay createStaticTextOverlay(
+      SpannableString overlayText, OverlaySettings overlaySettings) {
+    return new TextOverlay() {
+      @Override
+      public SpannableString getText(long presentationTimeUs) {
+        return overlayText;
+      }
+
+      @Override
+      public OverlaySettings getOverlaySettings(long presentationTimeUs) {
+        return overlaySettings;
+      }
+    };
+  }
+
+  @RequiresApi(23)
+  private static final class Api23 {
+    @DoNotInline
+    public static StaticLayout getStaticLayout(
+        SpannableString text, TextPaint textPaint, int width) {
+      return StaticLayout.Builder.obtain(
+              text, /* start= */ 0, /* end= */ text.length(), textPaint, width)
+          .build();
+    }
+  }
+}