BitmapUtils.java 文件源码

public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int
        reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int halfHeight = height / 2;
        final int halfWidth = width / 2;

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while ((halfHeight / inSampleSize) >= reqHeight && (halfWidth / inSampleSize) >=
                reqWidth) {
            inSampleSize *= 2;
        }
    }

    return inSampleSize;
}