android - 如何将位图旋转45度

Question

如何旋转 位图 45度？

Matrix matrix = new Matrix();
matrix.postRotate(degrees);
mBitmapFirst = Bitmap.createBitmap(mBitmapFirst, 0, 0, mBitmapFirst.getWidth(), mBitmapFirst.getHeight());
mImageFirstView.setImageBitmap(mBitmapFirst);

我使用了这个方法，但只有当 rotation 90 degrees

时它才有效

Answer 1

你可以用这个例子旋转 45 度:

Matrix minMatrix = new Matrix();
//height and width are set earlier.
Bitmap minBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas minCanvas = new Canvas(minBitmap);

int minwidth = bitmapMin.getWidth();  
int minheight = bitmapMin.getHeight();
int centrex = minwidth/2;
int centrey = minheight/2;

minMatrix.setRotate(mindegrees, centrex, centrey);
Bitmap newmin = Bitmap.createBitmap(minBitmap, 0, 0, (int) minwidth, (int) minheight, minMatrix, true);

minCanvas.drawBitmap(newmin, (centrex - newmin.getWidth()/2), (centrey - newmin.getHeight()/2), null);
minCanvas.setBitmap(minBitmap);

其中 mindegree 是你的旋转度数，

希望对你有帮助