Test: Use unpremultiplied alpha for GL output.

In addition to this being how Alpha should be handled, tests do fail under
API 29 without this CL. Unfortunately while these tests do fail under API 29
without this CL, we currently only run this test on API 33 emulators, so we
didn't catch this failure earlier (until compositor tests on mh failed on all
devices under API 29 and succeeded on all at or over 29).

PiperOrigin-RevId: 557781757

libraries/effect/src/androidTest/java/androidx/media3/effect/AlphaScaleShaderProgramPixelTest.java

@@ -17,11 +17,11 @@ package androidx.media3.effect;
 
 import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE;
-import static androidx.media3.test.utils.BitmapPixelTestUtil.createArgb8888BitmapFromFocusedGlFramebuffer;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.createGlTextureFromBitmap;
+import static androidx.media3.test.utils.BitmapPixelTestUtil.createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.getBitmapAveragePixelAbsoluteDifferenceArgb8888;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.maybeSaveTestBitmap;
-import static androidx.media3.test.utils.BitmapPixelTestUtil.readBitmap;
+import static androidx.media3.test.utils.BitmapPixelTestUtil.readBitmapUnpremultipliedAlpha;
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static com.google.common.truth.Truth.assertThat;
 
@@ -86,7 +86,7 @@ public final class AlphaScaleShaderProgramPixelTest {
     eglContext = GlUtil.createEglContext(eglDisplay);
     placeholderEglSurface = GlUtil.createFocusedPlaceholderEglSurface(eglContext, eglDisplay);
 
-    Bitmap inputBitmap = readBitmap(ORIGINAL_PNG_ASSET_PATH);
+    Bitmap inputBitmap = readBitmapUnpremultipliedAlpha(ORIGINAL_PNG_ASSET_PATH);
     inputWidth = inputBitmap.getWidth();
     inputHeight = inputBitmap.getHeight();
     inputTexId = createGlTextureFromBitmap(inputBitmap);
@@ -123,12 +123,13 @@ public final class AlphaScaleShaderProgramPixelTest {
   public void noOpAlpha_matchesGoldenFile() throws Exception {
     alphaScaleShaderProgram = new AlphaScale(1.0f).toGlShaderProgram(context, /* useHdr= */ false);
     Size outputSize = alphaScaleShaderProgram.configure(inputWidth, inputHeight);
-    Bitmap expectedBitmap = readBitmap(ORIGINAL_PNG_ASSET_PATH);
+    Bitmap expectedBitmap = readBitmapUnpremultipliedAlpha(ORIGINAL_PNG_ASSET_PATH);
     maybeSaveTestBitmap(testId, /* bitmapLabel= */ "input", expectedBitmap, /* path= */ null);
 
     alphaScaleShaderProgram.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
     Bitmap actualBitmap =
-        createArgb8888BitmapFromFocusedGlFramebuffer(outputSize.getWidth(), outputSize.getHeight());
+        createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+            outputSize.getWidth(), outputSize.getHeight());
 
     // TODO(b/207848601): Switch to using proper tooling for testing against golden data.
     maybeSaveTestBitmap(testId, /* bitmapLabel= */ "actual", actualBitmap, /* path= */ null);
@@ -142,11 +143,12 @@ public final class AlphaScaleShaderProgramPixelTest {
   public void zeroAlpha_matchesGoldenFile() throws Exception {
     alphaScaleShaderProgram = new AlphaScale(0.0f).toGlShaderProgram(context, /* useHdr= */ false);
     Size outputSize = alphaScaleShaderProgram.configure(inputWidth, inputHeight);
-    Bitmap expectedBitmap = readBitmap(ZERO_ALPHA_PNG_ASSET_PATH);
+    Bitmap expectedBitmap = readBitmapUnpremultipliedAlpha(ZERO_ALPHA_PNG_ASSET_PATH);
 
     alphaScaleShaderProgram.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
     Bitmap actualBitmap =
-        createArgb8888BitmapFromFocusedGlFramebuffer(outputSize.getWidth(), outputSize.getHeight());
+        createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+            outputSize.getWidth(), outputSize.getHeight());
 
     // TODO(b/207848601): Switch to using proper tooling for testing against golden data.
     maybeSaveTestBitmap(testId, /* bitmapLabel= */ "actual", actualBitmap, /* path= */ null);
@@ -160,11 +162,12 @@ public final class AlphaScaleShaderProgramPixelTest {
   public void decreaseAlpha_matchesGoldenFile() throws Exception {
     alphaScaleShaderProgram = new AlphaScale(0.5f).toGlShaderProgram(context, /* useHdr= */ false);
     Size outputSize = alphaScaleShaderProgram.configure(inputWidth, inputHeight);
-    Bitmap expectedBitmap = readBitmap(DECREASE_ALPHA_PNG_ASSET_PATH);
+    Bitmap expectedBitmap = readBitmapUnpremultipliedAlpha(DECREASE_ALPHA_PNG_ASSET_PATH);
 
     alphaScaleShaderProgram.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
     Bitmap actualBitmap =
-        createArgb8888BitmapFromFocusedGlFramebuffer(outputSize.getWidth(), outputSize.getHeight());
+        createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+            outputSize.getWidth(), outputSize.getHeight());
 
     // TODO(b/207848601): Switch to using proper tooling for testing against golden data.
     maybeSaveTestBitmap(testId, /* bitmapLabel= */ "actual", actualBitmap, /* path= */ null);
@@ -178,16 +181,17 @@ public final class AlphaScaleShaderProgramPixelTest {
   public void increaseAlpha_matchesGoldenFile() throws Exception {
     alphaScaleShaderProgram = new AlphaScale(1.5f).toGlShaderProgram(context, /* useHdr= */ false);
     Size outputSize = alphaScaleShaderProgram.configure(inputWidth, inputHeight);
-    Bitmap expectedBitmap = readBitmap(INCREASE_ALPHA_PNG_ASSET_PATH);
+    Bitmap expectedBitmap = readBitmapUnpremultipliedAlpha(INCREASE_ALPHA_PNG_ASSET_PATH);
 
     alphaScaleShaderProgram.drawFrame(inputTexId, /* presentationTimeUs= */ 0);
     Bitmap actualBitmap =
-        createArgb8888BitmapFromFocusedGlFramebuffer(outputSize.getWidth(), outputSize.getHeight());
+        createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+            outputSize.getWidth(), outputSize.getHeight());
 
     // TODO(b/207848601): Switch to using proper tooling for testing against golden data.
     maybeSaveTestBitmap(testId, /* bitmapLabel= */ "actual", actualBitmap, /* path= */ null);
     float averagePixelAbsoluteDifference =
         getBitmapAveragePixelAbsoluteDifferenceArgb8888(expectedBitmap, actualBitmap, testId);
-    assertThat(averagePixelAbsoluteDifference).isAtMost(0);
+    assertThat(averagePixelAbsoluteDifference).isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE);
   }
 }

libraries/test_utils/src/main/java/androidx/media3/test/utils/BitmapPixelTestUtil.java

@@ -17,6 +17,7 @@ package androidx.media3.test.utils;
 
 import static androidx.media3.common.util.Assertions.checkNotNull;
 import static androidx.media3.common.util.Assertions.checkState;
+import static androidx.media3.common.util.Util.SDK_INT;
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static com.google.common.truth.Truth.assertThat;
 import static java.lang.Math.abs;
@@ -48,6 +49,7 @@ import java.io.OutputStream;
 import java.lang.reflect.Method;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
+import org.junit.AssumptionViolatedException;
 
 /** Utilities for pixel tests. */
 // TODO(b/263395272): After the bug is fixed and dependent tests are moved back to media3.effect,
@@ -123,6 +125,8 @@ public class BitmapPixelTestUtil {
    * @return A {@link Bitmap}.
    * @throws IOException If the bitmap can't be read.
    */
+  // TODO: b/295523484 - Update all tests using readBitmap to instead use
+  //  readBitmapUnpremultipliedAlpha, and rename readBitmapUnpremultipliedAlpha back to readBitmap.
   public static Bitmap readBitmap(String assetString) throws IOException {
     Bitmap bitmap;
     try (InputStream inputStream = getApplicationContext().getAssets().open(assetString)) {
@@ -131,6 +135,25 @@ public class BitmapPixelTestUtil {
     return bitmap;
   }
 
+  /**
+   * Reads a bitmap with unpremultiplied alpha from the specified asset location.
+   *
+   * @param assetString Relative path to the asset within the assets directory.
+   * @return A {@link Bitmap}.
+   * @throws IOException If the bitmap can't be read.
+   */
+  @RequiresApi(19) // BitmapFactory.Options#inPremultiplied.
+  public static Bitmap readBitmapUnpremultipliedAlpha(String assetString) throws IOException {
+    Bitmap bitmap;
+    try (InputStream inputStream = getApplicationContext().getAssets().open(assetString)) {
+      // Media3 expected bitmaps are generated from OpenGL, which uses non-premultiplied colors.
+      BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
+      bitmapOptions.inPremultiplied = false;
+      bitmap = BitmapFactory.decodeStream(inputStream, /* outPadding= */ null, bitmapOptions);
+    }
+    return checkNotNull(bitmap);
+  }
+
   /**
    * Returns a bitmap with the same information as the provided alpha/red/green/blue 8-bits per
    * component image.
@@ -360,8 +383,8 @@ public class BitmapPixelTestUtil {
       Class<?> testStorageClass = Class.forName("androidx.test.services.storage.TestStorage");
       Method method = testStorageClass.getMethod("openOutputFile", String.class);
       Object testStorage = testStorageClass.getDeclaredConstructor().newInstance();
-      OutputStream outputStream = (OutputStream) method.invoke(testStorage, fileName);
-      bitmap.compress(Bitmap.CompressFormat.PNG, /* quality= */ 100, checkNotNull(outputStream));
+      OutputStream outputStream = checkNotNull((OutputStream) method.invoke(testStorage, fileName));
+      bitmap.compress(Bitmap.CompressFormat.PNG, /* quality= */ 100, outputStream);
     } catch (ClassNotFoundException e) {
       // Do nothing
     } catch (Exception e) {
@@ -375,22 +398,56 @@ public class BitmapPixelTestUtil {
    *
    * <p>This method may block until any previously called OpenGL commands are complete.
    *
+   * <p>This method incorrectly marks the output Bitmap as {@link Bitmap#isPremultiplied()
+   * premultiplied}, even though OpenGL typically outputs only non-premultiplied alpha. Use {@link
+   * #createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer} to properly handle alpha.
+   *
    * @param width The width of the pixel rectangle to read.
    * @param height The height of the pixel rectangle to read.
    * @return A {@link Bitmap} with the framebuffer's values.
    */
+  // TODO: b/295523484 - Update all tests using createArgb8888BitmapFromFocusedGlFramebuffer to
+  //  instead use createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer, and rename
+  //  createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer back to
+  //  createArgb8888BitmapFromFocusedGlFramebuffer. Also, apply
+  //  setPremultiplied(false) to createBitmapFromFocusedGlFrameBuffer.
+  @RequiresApi(17) // #flipBitmapVertically.
   public static Bitmap createArgb8888BitmapFromFocusedGlFramebuffer(int width, int height)
       throws GlUtil.GlException {
     return createBitmapFromFocusedGlFrameBuffer(
         width, height, /* pixelSize= */ 4, GLES20.GL_UNSIGNED_BYTE, Bitmap.Config.ARGB_8888);
   }
 
+  /**
+   * Creates a {@link Bitmap.Config#ARGB_8888} bitmap with the values of the focused OpenGL
+   * framebuffer.
+   *
+   * <p>This method may block until any previously called OpenGL commands are complete.
+   *
+   * @param width The width of the pixel rectangle to read.
+   * @param height The height of the pixel rectangle to read.
+   * @return A {@link Bitmap} with the framebuffer's values.
+   */
+  @RequiresApi(19) // Bitmap#setPremultiplied.
+  public static Bitmap createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+      int width, int height) throws GlUtil.GlException {
+    Bitmap bitmap =
+        createBitmapFromFocusedGlFrameBuffer(
+            width, height, /* pixelSize= */ 4, GLES20.GL_UNSIGNED_BYTE, Bitmap.Config.ARGB_8888);
+    bitmap.setPremultiplied(false); // OpenGL represents colors as unpremultiplied.
+    return bitmap;
+  }
+
   /**
    * Creates a {@link Bitmap.Config#RGBA_F16} bitmap with the values of the focused OpenGL
    * framebuffer.
    *
    * <p>This method may block until any previously called OpenGL commands are complete.
    *
+   * <p>This method incorrectly marks the output Bitmap as {@link Bitmap#isPremultiplied()
+   * premultiplied}, even though OpenGL typically outputs only non-premultiplied alpha. Call {@link
+   * Bitmap#setPremultiplied} with {@code false} on the output bitmap to properly handle alpha.
+   *
    * @param width The width of the pixel rectangle to read.
    * @param height The height of the pixel rectangle to read.
    * @return A {@link Bitmap} with the framebuffer's values.
@@ -402,6 +459,7 @@ public class BitmapPixelTestUtil {
         width, height, /* pixelSize= */ 8, GLES30.GL_HALF_FLOAT, Bitmap.Config.RGBA_F16);
   }
 
+  @RequiresApi(17) // #flipBitmapVertically.
   private static Bitmap createBitmapFromFocusedGlFrameBuffer(
       int width, int height, int pixelSize, int glReadPixelsFormat, Bitmap.Config bitmapConfig)
       throws GlUtil.GlException {
@@ -424,6 +482,7 @@ public class BitmapPixelTestUtil {
    * @param bitmap A {@link Bitmap}.
    * @return The identifier of the newly created texture.
    */
+  @RequiresApi(17) // #flipBitmapVertically.
   public static int createGlTextureFromBitmap(Bitmap bitmap) throws GlUtil.GlException {
     int texId =
         GlUtil.createTexture(
@@ -436,10 +495,25 @@ public class BitmapPixelTestUtil {
     return texId;
   }
 
+  @RequiresApi(17) // Bitmap#isPremultiplied.
   public static Bitmap flipBitmapVertically(Bitmap bitmap) {
+    boolean wasPremultiplied = bitmap.isPremultiplied();
+    if (!wasPremultiplied) {
+      if (SDK_INT >= 19) {
+        // Bitmap.createBitmap must be called on a premultiplied bitmap.
+        bitmap.setPremultiplied(true);
+      } else {
+        throw new AssumptionViolatedException(
+            "bitmap is not premultiplied and Bitmap.setPremultiplied is not supported under API 19."
+                + " unpremultiplied bitmaps cannot be flipped");
+      }
+    }
+
     Matrix flip = new Matrix();
     flip.postScale(1f, -1f);
-    return Bitmap.createBitmap(
+
+    Bitmap flippedBitmap =
+        Bitmap.createBitmap(
             bitmap,
             /* x= */ 0,
             /* y= */ 0,
@@ -447,6 +521,10 @@ public class BitmapPixelTestUtil {
             bitmap.getHeight(),
             flip,
             /* filter= */ true);
+    if (SDK_INT >= 19) {
+      flippedBitmap.setPremultiplied(wasPremultiplied);
+    }
+    return flippedBitmap;
   }
 
   private BitmapPixelTestUtil() {}

libraries/test_utils/src/main/java/androidx/media3/test/utils/TextureBitmapReader.java

@@ -16,12 +16,14 @@
 
 package androidx.media3.test.utils;
 
+import static androidx.media3.common.util.Assertions.checkState;
 import static androidx.media3.common.util.Assertions.checkStateNotNull;
 
 import android.graphics.Bitmap;
 import android.os.Build;
 import android.view.Surface;
 import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
 import androidx.media3.common.GlTextureInfo;
 import androidx.media3.common.VideoFrameProcessingException;
 import androidx.media3.common.util.GlUtil;
@@ -35,6 +37,10 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
  * {@inheritDoc}
  *
  * <p>Reads from an OpenGL texture. Only for use on physical devices.
+ *
+ * <p>For images with alpha, this method incorrectly marks the output Bitmap as {@link
+ * Bitmap#isPremultiplied() premultiplied}, even though OpenGL typically outputs only
+ * non-premultiplied alpha.
  */
 @UnstableApi
 public final class TextureBitmapReader implements VideoFrameProcessorTestRunner.BitmapReader {
@@ -75,8 +81,18 @@ public final class TextureBitmapReader implements VideoFrameProcessorTestRunner.
   /**
    * Reads the given {@code outputTexture}.
    *
-   * <p>The read result can be fetched by calling one of me {@link #getBitmap} methods.
+   * <p>The read result can be fetched by calling one of the {@link #getBitmap} methods.
+   *
+   * <p>This implementation incorrectly marks the output Bitmap as {@link Bitmap#isPremultiplied()
+   * premultiplied}, even though OpenGL typically outputs only non-premultiplied alpha. Use {@link
+   * #readBitmapUnpremultipliedAlpha} to properly handle alpha.
    */
+  // TODO: b/295523484 - In createBitmapFromCurrentGlFrameBuffer, call
+  //  createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer instead of
+  //  createArgb8888BitmapFromFocusedGlFramebuffer, so that TextureBitmapReader always reads bitmaps
+  //  as unpremultiplied alpha. Then, remove this method (as we'll already be using premultiplied
+  //  alpha).
+  @RequiresApi(17) // BitmapPixelTestUtil#createArgb8888BitmapFromFocusedGlFramebuffer.
   public void readBitmap(GlTextureInfo outputTexture, long presentationTimeUs)
       throws VideoFrameProcessingException {
     try {
@@ -91,6 +107,28 @@ public final class TextureBitmapReader implements VideoFrameProcessorTestRunner.
     }
   }
 
+  /**
+   * Reads the given {@code outputTexture} as one with unpremultiplied alpha.
+   *
+   * <p>The read result can be fetched by calling one of the {@link #getBitmap} methods.
+   */
+  @RequiresApi(19) // BitmapPixelTestUtil#createArgb8888BitmapFromFocusedGlFramebuffer.
+  public void readBitmapUnpremultipliedAlpha(GlTextureInfo outputTexture, long presentationTimeUs)
+      throws VideoFrameProcessingException {
+    checkState(!useHighPrecisionColorComponents);
+    try {
+      GlUtil.focusFramebufferUsingCurrentContext(
+          outputTexture.fboId, outputTexture.width, outputTexture.height);
+      outputBitmap =
+          BitmapPixelTestUtil.createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
+              outputTexture.width, outputTexture.height);
+      outputTimestampsToBitmaps.put(presentationTimeUs, outputBitmap);
+    } catch (GlUtil.GlException e) {
+      throw new VideoFrameProcessingException(e);
+    }
+  }
+
+  @RequiresApi(17) // BitmapPixelTestUtil#createArgb8888BitmapFromFocusedGlFramebuffer.
   private static Bitmap createBitmapFromCurrentGlFrameBuffer(
       int width, int height, boolean useHighPrecisionColorComponents) throws GlUtil.GlException {
     if (!useHighPrecisionColorComponents) {

libraries/transformer/src/androidTest/java/androidx/media3/transformer/DefaultVideoCompositorPixelTest.java

@@ -18,7 +18,7 @@ package androidx.media3.transformer;
 import static androidx.media3.common.util.Util.SDK_INT;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE;
 import static androidx.media3.test.utils.BitmapPixelTestUtil.maybeSaveTestBitmap;
-import static androidx.media3.test.utils.BitmapPixelTestUtil.readBitmap;
+import static androidx.media3.test.utils.BitmapPixelTestUtil.readBitmapUnpremultipliedAlpha;
 import static androidx.media3.test.utils.VideoFrameProcessorTestRunner.VIDEO_FRAME_PROCESSING_WAIT_MS;
 import static androidx.test.core.app.ApplicationProvider.getApplicationContext;
 import static com.google.common.truth.Truth.assertThat;
@@ -474,7 +474,7 @@ public final class DefaultVideoCompositorPixelTest {
                 }
                 outputTimestampsToBitmaps.put(
                     presentationTimeUs,
-                    BitmapPixelTestUtil.createArgb8888BitmapFromFocusedGlFramebuffer(
+                    BitmapPixelTestUtil.createUnpremultipliedArgb8888BitmapFromFocusedGlFramebuffer(
                         outputTexture.width, outputTexture.height));
                 releaseOutputTextureCallback.release(presentationTimeUs);
               },
@@ -519,7 +519,7 @@ public final class DefaultVideoCompositorPixelTest {
       inputVideoFrameProcessorTestRunners
           .get(inputId)
           .queueInputBitmap(
-              readBitmap(ORIGINAL_PNG_ASSET_PATH),
+              readBitmapUnpremultipliedAlpha(ORIGINAL_PNG_ASSET_PATH),
               /* durationUs= */ durationSec * C.MICROS_PER_SECOND,
               /* offsetToAddUs= */ offsetToAddSec * C.MICROS_PER_SECOND,
               /* frameRate= */ frameRate);
@@ -613,7 +613,8 @@ public final class DefaultVideoCompositorPixelTest {
                           releaseOutputTextureCallback,
                       long syncObject) -> {
                     GlUtil.awaitSyncObject(syncObject);
-                    textureBitmapReader.readBitmap(outputTexture, presentationTimeUs);
+                    textureBitmapReader.readBitmapUnpremultipliedAlpha(
+                        outputTexture, presentationTimeUs);
                     videoCompositor.queueInputTexture(
                         inputId, outputTexture, presentationTimeUs, releaseOutputTextureCallback);
                   },
@@ -703,7 +704,7 @@ public final class DefaultVideoCompositorPixelTest {
     maybeSaveTestBitmap(testId, actualBitmapLabel, actualBitmap, /* path= */ null);
     float averagePixelAbsoluteDifference =
         BitmapPixelTestUtil.getBitmapAveragePixelAbsoluteDifferenceArgb8888(
-            readBitmap(expectedBitmapAssetPath), actualBitmap, testId);
+            readBitmapUnpremultipliedAlpha(expectedBitmapAssetPath), actualBitmap, testId);
     assertWithMessage("Pixel difference for bitmapLabel = " + actualBitmapLabel)
         .that(averagePixelAbsoluteDifference)
         .isAtMost(MAXIMUM_AVERAGE_PIXEL_ABSOLUTE_DIFFERENCE_WITH_OVERLAY);