Finds the Bitmap optimal sampleSize for loading the picture - Android Graphics

Android examples for Graphics:Bitmap Sample Size

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Description

Finds the Bitmap optimal sampleSize for loading the picture

Demo Code

/*//  ww  w .j  a v a2s .  c o m
 * Copyright (C) 2012 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.java2s;

public class Main {
    /**
     * Finds the optimal sampleSize for loading the picture
     * @param originalSmallerExtent Width or height of the picture, whichever is smaller
     * @param targetExtent Width or height of the target view, whichever is bigger.
     *
     * If either one of the parameters is 0 or smaller, no sampling is applied
     */
    public static int findOptimalSampleSize(int originalSmallerExtent,
            int targetExtent) {
        // If we don't know sizes, we can't do sampling.
        if (targetExtent < 1)
            return 1;
        if (originalSmallerExtent < 1)
            return 1;

        // Test what the best sample size is. To do that, we find the sample size that gives us
        // the best trade-off between resulting image size and memory requirement. We allow
        // the down-sampled image to be 20% smaller than the target size. That way we can get around
        // unfortunate cases where e.g. a 720 picture is requested for 362 and not down-sampled at
        // all. Why 20%? Why not. Prove me wrong.
        int extent = originalSmallerExtent;
        int sampleSize = 1;
        while ((extent >> 1) >= targetExtent * 0.8f) {
            sampleSize <<= 1;
            extent >>= 1;
        }

        return sampleSize;
    }
}

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