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;
}

性能测试：

1. 手机

CPU : MTK6575 ,1G Hz

MEM : 512MB

OS : andoid 2.3.7

2.图片尺寸1632 * 1224

结果：

1. 方法1在280 - 350毫秒间，方法2在110毫秒左右。

2. 方法2优于方法1

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