原文地址：https://www.cnblogs.com/exmyth/p/4632700.html
旋转有两种方案，一种是旋转控件，还有一种是在旋转bitmap
旋转bitmap有两种方式
Android两种 旋转Bitmap方法
方法1. 利用Bitmap.createBitmap
Bitmap adjustPhotoRotation(Bitmap bm, final int orientationDegree) {
Matrix m = new Matrix();
m.setRotate(orientationDegree, (float) bm.getWidth() / 2, (float) bm.getHeight() / 2);
try {
Bitmap bm1 = Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), m, true);
return bm1;
} catch (OutOfMemoryError ex) {
}
return null;
}
方法2. 利用Canvas.drawBitmap
Bitmap adjustPhotoRotation(Bitmap bm, final int orientationDegree) {
Matrix m = new Matrix();
m.setRotate(orientationDegree, (float) bm.getWidth() / 2, (float) bm.getHeight() / 2);
float targetX, targetY;
if (orientationDegree == 90) {
targetX = bm.getHeight();
targetY = 0;
} else {
targetX = bm.getHeight();
targetY = bm.getWidth();
}
final float[] values = new float[9];
m.getValues(values);
float x1 = values[Matrix.MTRANS_X];
float y1 = values[Matrix.MTRANS_Y];
m.postTranslate(targetX - x1, targetY - y1);
Bitmap bm1 = Bitmap.createBitmap(bm.getHeight(), bm.getWidth(), Bitmap.Config.ARGB_8888);
Paint paint = new Paint();
Canvas canvas = new Canvas(bm1);
canvas.drawBitmap(bm, m, paint);
return bm1;
}