scale image的方法

public static Bitmap scaleImg(Bitmap bm, int newWidth, int newHeight) {
// 获得图片的宽高
int width = bm.getWidth();
int height = bm.getHeight();
// 设置想要的大小
int newWidth1 = newWidth;
int newHeight1 = newHeight;
// 计算缩放比例
float scaleWidth = ((float) newWidth1) / width;
float scaleHeight = ((float) newHeight1) / height;


// 取得想要缩放的matrix参数
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
// 得到新的图片
Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,
true);

if (width != newWidth && height != newHeight) {
freeBitmap(bm);
}
return newbm;


}