Overlay: fix the overlay anchor translation

Makes OverlayFrameAnchor works as described in the OverlaySettings documentation. Currently the code does the opposite e.g setting the anchor to (+1,-1) makes the code anchor to the top left rather than the bottom right.

PiperOrigin-RevId: 621585558

RELEASENOTES.md

@@ -102,6 +102,11 @@
     *   Add support for EGL_GL_COLORSPACE_BT2020_HLG_EXT, which improves HLG
         surface output in ExoPlayer.setVideoEffect and Transformer's Debug
         SurfaceView.
+    *   Update Overlay matrix implementation to make it consistent with the
+        documentation by flipping the x and y values applied in
+        `setOverlayFrameAnchor()`. If using
+        `OverlaySettings.Builder.setOverlayFrameAnchor()`, please flip their x
+        and y values by multiplying them by `-1`.
 *   Muxers:
 *   IMA extension:
 *   Session:

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

@@ -38,7 +38,7 @@ import java.util.Locale;
         new OverlaySettings.Builder()
             // Place the timer in the bottom left corner of the screen with some padding from the
             // edges.
-            .setOverlayFrameAnchor(/* x= */ 1f, /* y= */ 1f)
+            .setOverlayFrameAnchor(/* x= */ -1f, /* y= */ -1f)
             .setBackgroundFrameAnchor(/* x= */ -0.7f, /* y= */ -0.95f)
             .build();
   }

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

@@ -623,7 +623,7 @@ public final class TransformerActivity extends AppCompatActivity {
           new OverlaySettings.Builder()
               // Place the logo in the bottom left corner of the screen with some padding from the
               // edges.
-              .setOverlayFrameAnchor(/* x= */ 1f, /* y= */ 1f)
+              .setOverlayFrameAnchor(/* x= */ -1f, /* y= */ -1f)
               .setBackgroundFrameAnchor(/* x= */ -0.95f, /* y= */ -0.95f)
               .build();
       Drawable logo;

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

@@ -171,7 +171,7 @@ public class OverlayShaderProgramPixelTest {
     Bitmap overlayBitmap = readBitmap(OVERLAY_PNG_ASSET_PATH);
     OverlaySettings overlaySettings =
         new OverlaySettings.Builder()
-            .setOverlayFrameAnchor(/* x= */ 1f, /* y= */ -1f)
+            .setOverlayFrameAnchor(/* x= */ -1f, /* y= */ 1f)
             .setBackgroundFrameAnchor(/* x= */ -1f, /* y= */ 1f)
             .build();
     BitmapOverlay staticBitmapOverlay =
@@ -199,7 +199,7 @@ public class OverlayShaderProgramPixelTest {
           throws Exception {
     Bitmap overlayBitmap = readBitmap(OVERLAY_PNG_ASSET_PATH);
     OverlaySettings overlaySettings =
-        new OverlaySettings.Builder().setOverlayFrameAnchor(/* x= */ 1f, /* y= */ -1f).build();
+        new OverlaySettings.Builder().setOverlayFrameAnchor(/* x= */ -1f, /* y= */ 1f).build();
     BitmapOverlay staticBitmapOverlay =
         BitmapOverlay.createStaticBitmapOverlay(overlayBitmap, overlaySettings);
     overlayShaderProgram =

libraries/effect/src/main/java/androidx/media3/effect/SamplerOverlayMatrixProvider.java

@@ -33,23 +33,13 @@ import androidx.media3.common.util.Size;
 
   @Override
   public float[] getTransformationMatrix(Size overlaySize, OverlaySettings overlaySettings) {
-    // When sampling from a (for example, texture) sampler, the overlay anchor's x and y coordinates
-    // are flipped.
-    OverlaySettings samplerOverlaySettings =
-        overlaySettings
-            .buildUpon()
-            .setOverlayFrameAnchor(
-                /* x= */ -1 * overlaySettings.overlayFrameAnchor.first,
-                /* y= */ -1 * overlaySettings.overlayFrameAnchor.second)
-            .build();
-
     // When sampling from a (for example, texture) sampler, the transformation matrix applied to a
     // sampler's coordinate should be the inverse of the transformation matrix that would otherwise
     // be applied to a vertex.
     Matrix.invertM(
         transformationMatrixInv,
         MATRIX_OFFSET,
-        super.getTransformationMatrix(overlaySize, samplerOverlaySettings),
+        super.getTransformationMatrix(overlaySize, overlaySettings),
         MATRIX_OFFSET);
     return transformationMatrixInv;
   }