ImageMetadata.java 文件源码

private Bitmap readBitmap (final int scalePercentage, final Rect cropRect) throws IOException {
    if (100 % scalePercentage != 0) throw new IllegalArgumentException("scalePercentage " + scalePercentage + " is not a int ratio.");
    final Options opts = new Options();
    opts.inPurgeable = true;
    opts.inInputShareable = true;
    opts.inSampleSize = 100 / scalePercentage;

    if (cropRect != null) {
        final BitmapRegionDecoder dec = BitmapRegionDecoder.newInstance(openFileDescriptor().getFileDescriptor(), true);
        try {
            return dec.decodeRegion(cropRect, opts);
        }
        finally {
            dec.recycle();
        }
    }

    return BitmapFactory.decodeFileDescriptor(openFileDescriptor().getFileDescriptor(), null, opts);
}