图像旋转坐标计算

def rotate_wh(angle, width, height):
    new_height = int(width * fabs(sin(radians(angle))) + height * fabs(cos(radians(angle))))
    new_width = int(height * fabs(sin(radians(angle))) + width * fabs(cos(radians(angle))))
    return new_width, new_height

如下图所示根据A点的坐标计算B点的坐标，A和B都是相对对画布的图像坐标。

def calculate_left_top_point(x, y, angle, w, h, new_w, new_h):
    if angle < 0:
        angle = angle + 360
    else:
        angle = angle

    if  0 <= angle < 90:
        x_left_top = x - h * sin(radians(angle))
        y_left_top = y
    elif 90 <= angle < 180:
        x_left_top = x - new_w
        y_left_top = y - h * sin(radians(angle - 90))
    elif 180 <= angle < 270:
        x_left_top = x - w * cos(radians(angle - 180))
        y_left_top = y - new_h
    else:
        x_left_top = x
        y_left_top = y - w * cos(radians(angle - 270))

    return x_left_top, y_left_top

参考资料
图像旋转算法原理-- 旋转矩阵
图像旋转原理python实现