Effect: Implement brightness convenience class.

It can be confusing how to use RgbMatrix for app devs not comfortable with image
manipulation, so add a helper class that simply translates rgb values the same
constant brightness value, to update the brightness values.

PiperOrigin-RevId: 509287229

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

@@ -373,13 +373,8 @@ public final class GlEffectsFrameProcessorPixelTest {
   @Test
   public void increaseBrightness_matchesGoldenFile() throws Exception {
     String testId = "increaseBrightness_matchesGoldenFile";
-    ImmutableList<Effect> increaseBrightness =
-        ImmutableList.of(
-            new RgbAdjustment.Builder().setRedScale(5).build(),
-            new RgbAdjustment.Builder().setGreenScale(5).build(),
-            new RgbAdjustment.Builder().setBlueScale(5).build());
     frameProcessorTestRunner =
-        getDefaultFrameProcessorTestRunnerBuilder(testId).setEffects(increaseBrightness).build();
+        getDefaultFrameProcessorTestRunnerBuilder(testId).setEffects(new Brightness(0.5f)).build();
     Bitmap expectedBitmap = readBitmap(INCREASE_BRIGHTNESS_PNG_ASSET_PATH);
 
     Bitmap actualBitmap = frameProcessorTestRunner.processFirstFrameAndEnd();

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

+/*
+ * Copyright 2023 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.checkArgument;
+
+import android.opengl.Matrix;
+import androidx.annotation.FloatRange;
+import com.google.android.exoplayer2.util.GlUtil;
+
+/** Modifies brightness of an input frame. */
+public class Brightness implements RgbMatrix {
+
+  private final float[] rgbMatrix;
+
+  /**
+   * Modifies brightness by adding a constant value to red, green, and blue values.
+   *
+   * @param brightness The constant value to add to red, green, and blue values. Should be greater
+   *     than or equal to -1f, and less than or equal to 1f.
+   */
+  public Brightness(@FloatRange(from = -1, to = 1) float brightness) {
+    checkArgument(
+        brightness >= -1f && brightness <= 1f,
+        "brightness value outside of range from -1f to 1f, inclusive");
+    rgbMatrix = GlUtil.create4x4IdentityMatrix();
+    Matrix.translateM(
+        rgbMatrix,
+        /* smOffset= */ 0,
+        /* x= */ brightness,
+        /* y= */ brightness,
+        /* z= */ brightness);
+  }
+
+  @Override
+  public float[] getMatrix(long presentationTimeUs, boolean useHdr) {
+    checkArgument(!useHdr, "HDR is not supported.");
+    return rgbMatrix;
+  }
+}