Problem in rotating image in android

I am facing problme in rotating image

Following code works fine

Matrix matrix = new Matrix();
matrix.postRotate(DEGREE,mBitmap.getWidth() / 2, mBitmap.getHeight() / 2);
Bitmap m = Bitmap.createBitmap(mBitmap, 0, 0, mBitmap.getWidth(),mBitmap.getHeight(), matrix, true);
canvas.drawBitmap(m, mX, mY, null);

But I dont want to create a new bitmap again and again so I am using the following code

Matrix matrix = 开发者_开发问答new Matrix();
matrix.postTranslate(mX, mY);
matrix.postRotate(DEGREE,mBitmap.getWidth() / 2, mBitmap.getHeight() / 2);
canvas.drawBitmap(mBitmap, matrix, null);

In that case image goes out of the view. It is not visible.

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Matrix matrix = new Matrix();
canvas.translate(mX, mY);
canvas.drawBitmap(...);
canvas.translate(-mX, -mY);

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Try first rotating it then translating it, because when you translate it first the center is not in the middle any more so you are rotating it with wrong pivot coordinates.

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The pivot point by default when rotating is the top left corner of the image, which is why the view goes out of view. You need to add logic to make the pivot point the center of the image. Unfortunately, geometry is not my strong suit so maybe someone who somewhat enjoys geometry can give you the calculations to make this happen.