bitmap等比例缩小

//图片缩小
public static Bitmap small(Bitmap bitmap) {
    Matrix matrix = new Matrix();
    matrix.postScale(0.5f,0.5f); //长和宽放大缩小的比例
    Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
    return resizeBmp;
}