AlphaScale.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
*
* https://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.effect;
import static androidx.media3.common.util.Assertions.checkArgument;
import android.content.Context;
import androidx.annotation.FloatRange;
import androidx.media3.common.VideoFrameProcessingException;
import androidx.media3.common.util.UnstableApi;
/** Scales the alpha value (i.e. the translucency) of a frame. */
@UnstableApi
public final class AlphaScale implements GlEffect {
private final float alphaScale;
/**
* Creates a new instance to scale the entire frame's alpha values by {@code alphaScale}, to
* modify translucency.
*
* <p>An {@code alphaScale} value of {@code 1} means no change is applied. A value below {@code 1}
* increases translucency, and a value above {@code 1} reduces translucency.
*/
public AlphaScale(@FloatRange(from = 0) float alphaScale) {
checkArgument(0 <= alphaScale);
this.alphaScale = alphaScale;
}
@Override
public AlphaScaleShaderProgram toGlShaderProgram(Context context, boolean useHdr)
throws VideoFrameProcessingException {
return new AlphaScaleShaderProgram(context, useHdr, alphaScale);
}
@Override
public boolean isNoOp(int inputWidth, int inputHeight) {
return alphaScale == 1f;
}
}