作者：pzhang

下面的代码可以让一个图片中的任意位置，角度的矩形，旋转到正确的位置，并且居中显示。

import cv2
import numpy as np
import matplotlib.pyplot as plt
from pynput import keyboard,mouse

def plt_show(image):
    plt.imshow(image)
    plt.axis('off')
    plt.show()

def show(image):
    cv2.imshow("raw", image)
    cv2.waitKey(0)

def move_right():
    print("moving right")

def move_left():
    print("moving left")

def move_up():
    print("moving up")

def move_down():
    print("moving down")

def save_picture(angel,image):
    cv2.imwrite("%s/%s.jpg" % ('image', angel),image.shape[0],image.shape[1])

def handlToGray(image):
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    ret, TRE = cv2.threshold(gray, 50, 255, cv2.THRESH_BINARY)  # 图像二值化
    return TRE
#图像转动一定角度
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))
#图像按照给定的x,y 值进行平移
def moving_bound(image,x,y):
    (h, w) = image.shape[:2]
    M = np.float32([[1,0,-x],[0,1,-y]])
    return cv2.warpAffine(image, M, (w, h))
#找到矩形的旋转角度
def find_rect(image):
    gray = handlToGray(image)
    contours, hierarchy = cv2.findContours(gray, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
    rect = cv2.minAreaRect(contours[0])
    return rect


#获取矩形的偏移坐标
def getoffset(image):
    (h, w) = image.shape[:2]
    cx = int(w / 2)
    cy = int(h / 2)
    x_left = 0;
    x_right = 0;
    y_up = 0;
    y_down = 0;

    x_total = 0;
    y_total = 0;

    # 获取左边边框
    for i in range(cx, 0, -1):
        mx = image[cy][i]  # 先取高度，再取宽度
        if (mx == 0):
            x_left = i
            break
    # 获取右边边框
    for i in range(cx, w, 1):
        mx = image[cy][i]
        if (mx == 0):
            x_right = i
            break
    x_total = x_right - x_left

    # 获取上边框
    for i in range(cy, 0, -1):
        my = image[i][cx]
        if (my == 0):
            y_up = i
            break
    # 获取下边框
    for i in range(cy, h, 1):
        mx = image[i][cx]
        if (mx == 0):
            y_down = i
            break
    y_total = y_down - y_up

    x_offset = (x_left + x_total / 2) - cx
    y_offset = (y_up + y_total / 2) - cy

    return x_offset, y_offset, x_total, y_total



def on_press(key):
    pass

def on_release(key):
    if key == keyboard.Key.esc:  # Stop listener
        return False
    elif key == keyboard.Key.right:
        move_right()
    elif key == keyboard.Key.left:
        move_left()
    elif key == keyboard.Key.up:
        move_up()
    elif key == keyboard.Key.down:
        move_down()



def on_move(x, y):
    pass

def on_click(x, y, button, pressed):
    pass

def on_scroll(x, y, dx, dy):
    pass

def main():

    image = cv2.imread("image/raw2.jpg")
    rect = find_rect(image)
    angle = rect[2] #角度
    im = rotate_bound(image, -angle)
    rect = find_rect(im)
    print(rect)
    x,y = rect[0]
    width, height = rect[1]
    box = cv2.boxPoints(rect)
    (h, w) = im.shape[:2]
    cx = int(w / 2)
    cy = int(h / 2)
    im = moving_bound(im,x-cx,y-cy)
    if width < height:
        im = rotate_bound(im, 90)
    TRE = handlToGray(im)
    plt_show(TRE)

main()

# Collect events until released
keyboard_listener = keyboard.Listener(on_press=on_press, on_release=on_release)
mouse_listener = mouse.Listener(on_click=on_click, on_move=on_move, on_scroll=on_scroll)
lst = [keyboard_listener, mouse_listener]

for t in lst: t.start()
for t in lst: t.join()