由网友(敢毁她清白就敢给她未来)分享简介：我有，我想使用一个覆盖PNG文件 - 但是，这个文件必须镜像（并旋转180°），但为了节省空间，我不想把镜像文件在APK，但编程做这个动作。I have a PNG file that I want to use for an overlay - however, this file has to be mirror...

我有，我想使用一个覆盖PNG文件 - 但是，这个文件必须镜像（并旋转180°），但为了节省空间，我不想把镜像文件在APK，但编程做这个动作。

I have a PNG file that I want to use for an overlay - however, this file has to be mirrored (and rotated by 180°), but in order to save space, I don't want to place the mirrored file in the apk, but do this action programmatically.

我怎样才能做到这一点与升级Froyo或以上？

How can I do this with Froyo and above?

推荐答案

缩放由-1.0导致图像翻转。假设 BMP 是要镜像（这里的X轴），你可以做的位图：

Scaling by -1.0 causes the image to be flipped. Assuming bmp is the bitmap you want to mirror (here on the x axis) you can do :

Matrix matrix = new Matrix(); 
matrix.preScale(-1.0f, 1.0f); 
Bitmap mirroredBitmap = Bitmap.createBitmap(bmp, 0, 0, bmp.width(), bmp.height(), matrix, false);

如果您不希望创建第二个位图，你可以用 canvas.scale 做同样的：

If you don't want to create a second bitmap, you can do the same with canvas.scale :

canvas.save();
canvas.scale(-1.0f, 1.0f);
canvas.drawBitmap(bitmap, ...); // The bitmap is flipped
canvas.restore();