GaussianBlur.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 androidx.media3.effect;
import androidx.annotation.FloatRange;
import androidx.annotation.RequiresApi;
import androidx.media3.common.util.UnstableApi;
/**
* A {@link SeparableConvolution} to apply a Gaussian blur on image data.
*
* <p>The width of the blur is specified in pixels and applied symmetrically.
*/
@UnstableApi
@RequiresApi(26) // See SeparableConvolution.
public final class GaussianBlur extends SeparableConvolution {
private final float sigma;
private final float numStandardDeviations;
/**
* Creates an instance.
*
* @param sigma The half-width of 1 standard deviation, in pixels.
* @param numStandardDeviations The size of function domain, measured in the number of standard
* deviations.
*/
public GaussianBlur(
@FloatRange(from = 0.0, fromInclusive = false) float sigma,
@FloatRange(from = 0.0, fromInclusive = false) float numStandardDeviations) {
this.sigma = sigma;
this.numStandardDeviations = numStandardDeviations;
}
/**
* Creates an instance with {@code numStandardDeviations} set to {@code 2.0f}.
*
* @param sigma The half-width of 1 standard deviation, in pixels.
*/
public GaussianBlur(float sigma) {
this(sigma, /* numStandardDeviations= */ 2.0f);
}
@Override
public ConvolutionFunction1D getConvolution(long presentationTimeUs) {
return new GaussianFunction(sigma, numStandardDeviations);
}
}