java 在android中旋转保存的位图
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Rotate a saved bitmap in android
提问by prometheuspk
I am saving an image from the camera that was in landscape mode. so it gets saved in landscape mode and then i apply an overlay onto it that too is in landscape mode. I want to rotate that image and then save. e.g. if i have this
我正在从处于横向模式的相机中保存图像。所以它以横向模式保存，然后我在它上面应用一个覆盖层，它也是横向模式。我想旋转那个图像然后保存。例如，如果我有这个
I want to rotate clockwise by 90 degrees once and make it this and save it to sdcard:
我想顺时针旋转 90 度一次并将其保存到 SD 卡：
How is this to be accomplished?
这将如何实现？
回答by MAC
void rotate(float x)
{
Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),R.drawable.tedd);
int width = bitmapOrg.getWidth();
int height = bitmapOrg.getHeight();
int newWidth = 200;
int newHeight = 200;
// calculate the scale - in this case = 0.4f
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
matrix.postRotate(x);
Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,width, height, matrix, true);
iv.setScaleType(ScaleType.CENTER);
iv.setImageBitmap(resizedBitmap);
}
回答by Singhak
Check this
检查这个
public static Bitmap rotateImage(Bitmap src, float degree)
{
// create new matrix
Matrix matrix = new Matrix();
// setup rotation degree
matrix.postRotate(degree);
Bitmap bmp = Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), matrix, true);
return bmp;
}
回答by Renard
You can use the Canvas API to do that. Note that you need to switch width and height.
您可以使用 Canvas API 来做到这一点。请注意，您需要切换宽度和高度。
final int width = landscapeBitmap.getWidth();
final int height = landscapeBitmap.getHeight();
Bitmap portraitBitmap = Bitmap.createBitmap(height, width, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(portraitBitmap);
c.rotate(90, height/2, width/2);
c.drawBitmap(landscapeBitmap, 0,0,null);
portraitBitmap.compress(CompressFormat.JPEG, 100, stream);
回答by Bondax
Use a Matrix.rotate(degrees) and draw the Bitmap to it's own Canvas using that rotating matrix. I don't know though if you might have to make a copy of the bitmap before drawing.
使用 Matrix.rotate(degrees) 并使用该旋转矩阵将位图绘制到它自己的画布上。我不知道你是否可能需要在绘制之前制作位图的副本。
Use Bitmap.compress(...) to compress your bitmap to an outputstream.
使用 Bitmap.compress(...) 将您的位图压缩为输出流。
回答by Jens van de M?tter
The solution of Singhak works fine. In case you need fit the size of result bitmap (perhaps for ImageView) you can expand the method as follows:
Singhak 的解决方案工作正常。如果您需要适合结果位图的大小（可能适用于 ImageView），您可以按如下方式扩展该方法：
public static Bitmap rotateBitmapZoom(Bitmap bmOrg, float degree, float zoom){
Matrix matrix = new Matrix();
matrix.postRotate(degree);
float newHeight = bmOrg.getHeight() * zoom;
float newWidth = bmOrg.getWidth() / 100 * (100.0f / bmOrg.getHeight() * newHeight);
return Bitmap.createBitmap(bmOrg, 0, 0, (int)newWidth, (int)newHeight, matrix, true);
}
