python opencv对图像进行旋转且不裁剪图片的实现方法

def rotate_bound(image, angle):  # grab the dimensions of the image and then determine the  # center  (h, w) = image.shape[:2]  (cX, cY) = (w // 2, h // 2)   # grab the rotation matrix (applying the negative of the  # angle to rotate clockwise), then grab the sine and cosine  # (i.e., the rotation components of the matrix)  M = cv2.getRotationMatrix2D((cX, cY), -angle, 1.0)  cos = np.abs(M[0, 0])  sin = np.abs(M[0, 1])   # compute the new bounding dimensions of the image  nW = int((h * sin) + (w * cos))  nH = int((h * cos) + (w * sin))   # adjust the rotation matrix to take into account translation  M[0, 2] += (nW / 2) - cX  M[1, 2] += (nH / 2) - cY   # perform the actual rotation and return the image  return cv2.warpAffine(image, M, (nW, nH))