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The source code is released under:
Apache License
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/* * Copyright 2014 Google Inc./*from ww w . j av a 2 s .co m*/ * * 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.apps.muzei.render; import android.graphics.Bitmap; import android.graphics.Color; public class ImageUtil { // Make sure input images are very small! public static float calculateDarkness(Bitmap bitmap) { if (bitmap == null) { return 0; } int width = bitmap.getWidth(); int height = bitmap.getHeight(); int totalLum = 0; int n = 0; int x, y, color; for (y = 0; y < height; y++) { for (x = 0; x < width; x++) { ++n; color = bitmap.getPixel(x, y); totalLum += (0.21f * Color.red(color) + 0.71f * Color.green(color) + 0.07f * Color.blue(color)); } } return (totalLum / n) / 256f; } private ImageUtil() { } public static int calculateSampleSize(int rawSize, int targetSize) { int sampleSize = 1; while (rawSize / (sampleSize << 1) > targetSize) { sampleSize <<= 1; } return sampleSize; } }