Add bitmap overlay effect to transformer demo.

The new demo GlFrameProcessor is based on BitmapOverlayVideoProcessor
from the gl-demo. The demo-only GlFrameProcessor can be deleted once
Transformer supports this functionality.

PiperOrigin-RevId: 440059735

demos/transformer/src/main/assets/fragment_shader_bitmap_overlay_es2.glsl

@@ -0,0 +1,37 @@
+#version 100
+// 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.
+
+// ES 2 fragment shader that overlays the bitmap from uTexSampler1 over a video
+// frame from uTexSampler0.
+
+precision mediump float;
+// Texture containing an input video frame.
+uniform sampler2D uTexSampler0;
+// Texture containing the overlap bitmap.
+uniform sampler2D uTexSampler1;
+// Horizontal scaling factor for the overlap bitmap.
+uniform float uScaleX;
+// Vertical scaling factory for the overlap bitmap.
+uniform float uScaleY;
+varying vec2 vTexSamplingCoord;
+void main() {
+  vec4 videoColor = texture2D(uTexSampler0, vTexSamplingCoord);
+  vec4 overlayColor = texture2D(uTexSampler1,
+                                vec2(vTexSamplingCoord.x * uScaleX,
+                                     vTexSamplingCoord.y * uScaleY));
+  // Blend the video decoder output and the overlay bitmap.
+  gl_FragColor = videoColor * (1.0 - overlayColor.a)
+      + overlayColor * overlayColor.a;
+}

demos/transformer/src/main/java/androidx/media3/demo/transformer/BitmapOverlayFrameProcessor.java

@@ -0,0 +1,163 @@
+/*
+ * 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 androidx.media3.demo.transformer;
+
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
+
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Matrix;
+import android.graphics.Paint;
+import android.graphics.drawable.BitmapDrawable;
+import android.opengl.GLES20;
+import android.opengl.GLUtils;
+import android.util.Size;
+import androidx.media3.common.C;
+import androidx.media3.common.util.GlProgram;
+import androidx.media3.common.util.GlUtil;
+import androidx.media3.transformer.GlFrameProcessor;
+import java.io.IOException;
+import java.util.Locale;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+/**
+ * A {@link GlFrameProcessor} that overlays a bitmap with a logo and timer on each frame.
+ *
+ * <p>The bitmap is drawn using an Android {@link Canvas}.
+ */
+// TODO(b/227625365): Delete this class and use a frame processor from the Transformer library, once
+//  overlaying a bitmap and text is supported in Transformer.
+/* package */ final class BitmapOverlayFrameProcessor implements GlFrameProcessor {
+  static {
+    GlUtil.glAssertionsEnabled = true;
+  }
+
+  private static final String VERTEX_SHADER_PATH = "vertex_shader_copy_es2.glsl";
+  private static final String FRAGMENT_SHADER_PATH = "fragment_shader_bitmap_overlay_es2.glsl";
+
+  private static final int BITMAP_WIDTH_HEIGHT = 512;
+
+  private final Context context;
+  private final Paint paint;
+  private final Bitmap overlayBitmap;
+  private final Bitmap logoBitmap;
+  private final Canvas overlayCanvas;
+
+  private float bitmapScaleX;
+  private float bitmapScaleY;
+  private int bitmapTexId;
+  private @MonotonicNonNull Size outputSize;
+  private @MonotonicNonNull GlProgram glProgram;
+
+  public BitmapOverlayFrameProcessor(Context context) {
+    this.context = context;
+    paint = new Paint();
+    paint.setTextSize(64);
+    paint.setAntiAlias(true);
+    paint.setARGB(0xFF, 0xFF, 0xFF, 0xFF);
+    paint.setColor(Color.GRAY);
+    overlayBitmap =
+        Bitmap.createBitmap(BITMAP_WIDTH_HEIGHT, BITMAP_WIDTH_HEIGHT, Bitmap.Config.ARGB_8888);
+    overlayCanvas = new Canvas(overlayBitmap);
+    try {
+      logoBitmap =
+          ((BitmapDrawable)
+                  context.getPackageManager().getApplicationIcon(context.getPackageName()))
+              .getBitmap();
+    } catch (PackageManager.NameNotFoundException e) {
+      throw new IllegalStateException(e);
+    }
+  }
+
+  @Override
+  public void initialize(int inputTexId, int inputWidth, int inputHeight) throws IOException {
+    if (inputWidth > inputHeight) {
+      bitmapScaleX = inputWidth / (float) inputHeight;
+      bitmapScaleY = 1f;
+    } else {
+      bitmapScaleX = 1f;
+      bitmapScaleY = inputHeight / (float) inputWidth;
+    }
+    outputSize = new Size(inputWidth, inputHeight);
+
+    bitmapTexId = GlUtil.createTexture(BITMAP_WIDTH_HEIGHT, BITMAP_WIDTH_HEIGHT);
+    GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, /* level= */ 0, overlayBitmap, /* border= */ 0);
+
+    glProgram = new GlProgram(context, VERTEX_SHADER_PATH, FRAGMENT_SHADER_PATH);
+    // Draw the frame on the entire normalized device coordinate space, from -1 to 1, for x and y.
+    glProgram.setBufferAttribute(
+        "aFramePosition", GlUtil.getNormalizedCoordinateBounds(), GlUtil.RECTANGLE_VERTICES_COUNT);
+    glProgram.setBufferAttribute(
+        "aTexSamplingCoord", GlUtil.getTextureCoordinateBounds(), GlUtil.RECTANGLE_VERTICES_COUNT);
+    glProgram.setSamplerTexIdUniform("uTexSampler0", inputTexId, /* texUnitIndex= */ 0);
+    glProgram.setSamplerTexIdUniform("uTexSampler1", bitmapTexId, /* texUnitIndex= */ 1);
+    glProgram.setFloatUniform("uScaleX", bitmapScaleX);
+    glProgram.setFloatUniform("uScaleY", bitmapScaleY);
+  }
+
+  @Override
+  public Size getOutputSize() {
+    return checkStateNotNull(outputSize);
+  }
+
+  @Override
+  public void updateProgramAndDraw(long presentationTimeUs) {
+    checkStateNotNull(glProgram);
+    glProgram.use();
+
+    // Draw to the canvas and store it in a texture.
+    String text =
+        String.format(Locale.US, "%.02f", presentationTimeUs / (float) C.MICROS_PER_SECOND);
+    overlayBitmap.eraseColor(Color.TRANSPARENT);
+    overlayCanvas.drawBitmap(logoBitmap, /* left= */ 3, /* top= */ 378, paint);
+    overlayCanvas.drawText(text, /* x= */ 160, /* y= */ 466, paint);
+    GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, bitmapTexId);
+    GLUtils.texSubImage2D(
+        GLES20.GL_TEXTURE_2D,
+        /* level= */ 0,
+        /* xoffset= */ 0,
+        /* yoffset= */ 0,
+        flipBitmapVertically(overlayBitmap));
+    GlUtil.checkGlError();
+
+    glProgram.bindAttributesAndUniforms();
+    // The four-vertex triangle strip forms a quad.
+    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, /* first= */ 0, /* count= */ 4);
+  }
+
+  @Override
+  public void release() {
+    if (glProgram != null) {
+      glProgram.delete();
+    }
+  }
+
+  private static Bitmap flipBitmapVertically(Bitmap bitmap) {
+    Matrix flip = new Matrix();
+    flip.postScale(1f, -1f);
+    return Bitmap.createBitmap(
+        bitmap,
+        /* x= */ 0,
+        /* y= */ 0,
+        bitmap.getWidth(),
+        bitmap.getHeight(),
+        flip,
+        /* filter= */ true);
+  }
+}

demos/transformer/src/main/java/androidx/media3/demo/transformer/ConfigurationActivity.java

@@ -88,7 +88,7 @@ public final class ConfigurationActivity extends AppCompatActivity {
     "MP4 with HDR (HDR10) H265 video (encoding may fail)",
   };
   private static final String[] DEMO_FRAME_PROCESSORS = {
-    "Dizzy crop", "Periodic vignette", "3D spin", "Zoom in start"
+    "Dizzy crop", "Periodic vignette", "3D spin", "Overlay logo & timer", "Zoom in start"
   };
   private static final int PERIODIC_VIGNETTE_INDEX = 1;
   private static final String SAME_AS_INPUT_OPTION = "same as input";

demos/transformer/src/main/java/androidx/media3/demo/transformer/TransformerActivity.java

@@ -266,6 +266,9 @@ public final class TransformerActivity extends AppCompatActivity {
               AdvancedFrameProcessorFactory.createSpin3dFrameProcessor(/* context= */ this));
         }
         if (selectedFrameProcessors[3]) {
+          frameProcessors.add(new BitmapOverlayFrameProcessor(/* context= */ this));
+        }
+        if (selectedFrameProcessors[4]) {
           frameProcessors.add(
               AdvancedFrameProcessorFactory.createZoomInTransitionFrameProcessor(
                   /* context= */ this));