/**
* Creates a centered bitmap of the desired size.
*
* @param source original bitmap source
* @param width targeted width
* @param height targeted height
*/
public static Bitmap extractThumbnail(
Bitmap source, int width, int height) {
return extractThumbnail(source, width, height, OPTIONS_NONE);
}
/**
* Creates a centered bitmap of the desired size.
*
* @param source original bitmap source
* @param width targeted width
* @param height targeted height
* @param options options used during thumbnail extraction
*/
public static Bitmap extractThumbnail(
Bitmap source, int width, int height, int options) {
if (source == null) {
return null;
}
float scale;
if (source.getWidth() < source.getHeight()) {
scale = width / (float) source.getWidth();
} else {
scale = height / (float) source.getHeight();
}
Matrix matrix = new Matrix();
matrix.setScale(scale, scale);
Bitmap thumbnail = transform(matrix, source, width, height,
OPTIONS_SCALE_UP | options);
return thumbnail;
}
/*
* Compute the sample size as a function of minSideLength
* and maxNumOfPixels.
* minSideLength is used to specify that minimal width or height of a
* bitmap.
* maxNumOfPixels is used to specify the maximal size in pixels that is
* tolerable in terms of memory usage.
*
* The function returns a sample size based on the constraints.
* Both size and minSideLength can be passed in as IImage.UNCONSTRAINED,
* which indicates no care of the corresponding constraint.
* The functions prefers returning a sample size that
* generates a smaller bitmap, unless minSideLength = IImage.UNCONSTRAINED.
*
* Also, the function rounds up the sample size to a power of 2 or multiple
* of 8 because BitmapFactory only honors sample size this way.
* For example, BitmapFactory downsamples an image by 2 even though the
* request is 3. So we round up the sample size to avoid OOM.
*/
private static int computeSampleSize(BitmapFactory.Options options,
int minSideLength, int maxNumOfPixels) {
int initialSize = computeInitialSampleSize(options, minSideLength,
maxNumOfPixels);
int roundedSize;
if (initialSize <= 8 ) {
roundedSize = 1;
while (roundedSize < initialSize) {
roundedSize <<= 1;
}
} else {
roundedSize = (initialSize + 7) / 8 * 8;
}
return roundedSize;
}