Python OpenCV鼠标事件全解析

Plain Text# 安装OpenCV（核心库，支持鼠标事件与图像处理）pip install opencv-python# 安装NumPy（可选，用于图像数组处理）pip install numpy

Plain Textdef mouse_callback(event, x, y, flags, param):"""OpenCV鼠标事件回调函数:param event: 鼠标事件类型（如左键点击、双击等）:param x: 鼠标在图像中的x坐标（水平方向，以图像左上角为原点）:param y: 鼠标在图像中的y坐标（垂直方向，以图像左上角为原点）:param flags: 鼠标按键状态辅助标识（如按键按下时是否同时移动鼠标）:param param: 传入的额外参数（通过cv2.setMouseCallback()的param参数传递）"""# 函数体：根据event和flags实现具体逻辑pass

Plain Textcv2.setMouseCallback(windowName, onMouse, param=None)""":param windowName: 窗口名称（需与cv2.imshow()创建的窗口名称一致）:param onMouse: 自定义回调函数名称（无需加括号）:param param: 传递给回调函数的额外参数（可选，默认None）"""

事件标识

事件含义

cv2.EVENT_LBUTTONDOWN

鼠标左键按下

cv2.EVENT_LBUTTONUP

鼠标左键抬起

cv2.EVENT_LBUTTONDBLCLK

鼠标左键双击

cv2.EVENT_RBUTTONDOWN

鼠标右键按下

cv2.EVENT_RBUTTONUP

鼠标右键抬起

cv2.EVENT_RBUTTONDBLCLK

鼠标右键双击

cv2.EVENT_MBUTTONDOWN

鼠标中键按下

cv2.EVENT_MBUTTONUP

鼠标中键抬起

cv2.EVENT_MOUSEMOVE

鼠标移动（只要鼠标在窗口内移动就会触发）

cv2.EVENT_MOUSEWHEEL

鼠标滚轮滚动（正数表示向前滚动，负数表示向后滚动）

Plain Textimport cv2import numpy as npdef get_pixel_info(event, x, y, flags, param):"""回调函数：获取像素坐标与颜色"""# 接收传入的图像参数（通过param传递）img = param# 鼠标左键按下事件if event == cv2.EVENT_LBUTTONDOWN:# 获取像素颜色值（BGR格式）b, g, r = img[y, x] # 注意：OpenCV图像数组索引为[行,列]，对应(y,x)# 打印信息print(f"像素坐标：(x={x}, y={y})")print(f"像素颜色（BGR）：B={b}, G={g}, R={r}")# 可选：在点击位置绘制一个红色小圆点标记cv2.circle(img, (x, y), 2, (0, 0, 255), -1) # 半径2px，红色填充cv2.imshow("Pixel Info Window", img)# 鼠标右键按下事件（退出程序）elif event == cv2.EVENT_RBUTTONDOWN:cv2.destroyAllWindows()exit()if __name__ == "__main__":# 读取图像（替换为自己的图像路径）img_path = "test_image.jpg"img = cv2.imread(img_path)if img is None:raise FileNotFoundError(f"未找到图像文件：{img_path}")# 创建窗口并绑定回调函数（将图像作为param参数传递）cv2.namedWindow("Pixel Info Window", cv2.WINDOW_NORMAL) # WINDOW_NORMAL支持窗口缩放cv2.setMouseCallback("Pixel Info Window", get_pixel_info, param=img)# 显示图像并监听事件（0表示无限等待按键）cv2.imshow("Pixel Info Window", img)cv2.waitKey(0)# 释放资源cv2.destroyAllWindows()

Plain Textimport cv2import numpy as npclass DrawRectangle:"""封装矩形绘制逻辑，避免全局变量"""def __init__(self, img):self.img = img.copy() # 原始图像（用于重置）self.temp_img = img.copy() # 临时图像（用于绘制过程中的预览）self.is_drawing = False # 绘制状态：是否正在拖动鼠标self.start_x, self.start_y = -1, -1 # 矩形左上角坐标def mouse_callback(self, event, x, y, flags, param):# 鼠标左键按下：确定矩形左上角顶点if event == cv2.EVENT_LBUTTONDOWN:self.is_drawing = Trueself.start_x, self.start_y = x, y# 鼠标移动：绘制矩形预览（实时更新）elif event == cv2.EVENT_MOUSEMOVE and self.is_drawing:# 每次移动都重置临时图像为原始图像，避免残留多个矩形self.temp_img = self.img.copy()# 判断是否按下Shift键（绘制正方形）if flags & cv2.EVENT_FLAG_SHIFTKEY:# 正方形：宽高相等，取x、y方向偏移量的最小值side_len = max(abs(x - self.start_x), abs(y - self.start_y))end_x = self.start_x + side_len if x > self.start_x else self.start_x - side_lenend_y = self.start_y + side_len if y > self.start_y else self.start_y - side_lencv2.rectangle(self.temp_img, (self.start_x, self.start_y), (end_x, end_y), (0, 255, 0), 2)else:# 普通矩形：直接用当前坐标作为右下角顶点cv2.rectangle(self.temp_img, (self.start_x, self.start_y), (x, y), (0, 255, 0), 2)cv2.imshow("Draw Rectangle Window", self.temp_img)# 鼠标左键抬起：确定矩形右下角顶点，完成绘制elif event == cv2.EVENT_LBUTTONUP:self.is_drawing = False# 绘制最终矩形（绘制在原始图像上，永久保留）cv2.rectangle(self.img, (self.start_x, self.start_y), (x, y), (0, 255, 0), 2)self.temp_img = self.img.copy()cv2.imshow("Draw Rectangle Window", self.temp_img)if __name__ == "__main__":# 读取图像或创建空白图像img_path = "test_image.jpg"if cv2.os.path.exists(img_path):img = cv2.imread(img_path)else:# 无图像时创建800x600的白色空白图像img = np.ones((600, 800, 3), dtype=np.uint8) * 255# 初始化绘制类drawer = DrawRectangle(img)# 创建窗口并绑定回调函数cv2.namedWindow("Draw Rectangle Window", cv2.WINDOW_NORMAL)cv2.setMouseCallback("Draw Rectangle Window", drawer.mouse_callback)# 显示图像并监听按键（ESC键清除矩形）cv2.imshow("Draw Rectangle Window", img)while True:key = cv2.waitKey(1) & 0xFFif key == 27: # ESC键ASCII码为27# 重置图像（清除所有矩形）drawer.img = np.ones((600, 800, 3), dtype=np.uint8) * 255 if not cv2.os.path.exists(img_path) else cv2.imread(img_path)drawer.temp_img = drawer.img.copy()cv2.imshow("Draw Rectangle Window", drawer.img)elif key == ord('q'): # 按Q键退出break# 保存最终图像（可选）cv2.imwrite("drawn_rectangle.jpg", drawer.img)cv2.destroyAllWindows()

Plain Textimport cv2import numpy as npdef draw_free_curve(event, x, y, flags, param):"""回调函数：绘制自由曲线"""# 接收传入的状态参数（字典形式，包含图像、绘制状态、颜色）state = paramimg = state["img"]is_drawing = state["is_drawing"]color = state["color"]last_x, last_y = state["last_x"], state["last_y"]# 鼠标左键按下：开始绘制if event == cv2.EVENT_LBUTTONDOWN:state["is_drawing"] = Truestate["last_x"], state["last_y"] = x, y# 鼠标移动且左键按下：绘制曲线（连接上一个点和当前点）elif event == cv2.EVENT_MOUSEMOVE and is_drawing:cv2.line(img, (last_x, last_y), (x, y), color, 3) # 线宽3pxstate["last_x"], state["last_y"] = x, ycv2.imshow("Free Curve Window", img)# 鼠标左键抬起：结束绘制elif event == cv2.EVENT_LBUTTONUP:state["is_drawing"] = False# 鼠标右键按下：切换曲线颜色（红→绿→蓝）elif event == cv2.EVENT_RBUTTONDOWN:# 颜色切换逻辑if color == (0, 0, 255): # 当前红色，切换为绿色state["color"] = (0, 255, 0)elif color == (0, 255, 0): # 当前绿色，切换为蓝色state["color"] = (255, 0, 0)else: # 当前蓝色，切换为红色state["color"] = (0, 0, 255)print(f"曲线颜色已切换为：{state['color']}（BGR）")if __name__ == "__main__":# 创建800x600的白色空白画布img = np.ones((600, 800, 3), dtype=np.uint8) * 255# 定义状态参数（用字典传递，实现多变量共享）state = {"img": img,"is_drawing": False,"color": (0, 0, 255), # 初始颜色：红色（BGR）"last_x": -1,"last_y": -1}# 创建窗口并绑定回调函数cv2.namedWindow("Free Curve Window", cv2.WINDOW_NORMAL)cv2.setMouseCallback("Free Curve Window", draw_free_curve, param=state)# 显示画布并监听按键cv2.imshow("Free Curve Window", img)while True:key = cv2.waitKey(1) & 0xFFif key == 27: # ESC键清空画布state["img"] = np.ones((600, 800, 3), dtype=np.uint8) * 255cv2.imshow("Free Curve Window", state["img"])elif key == ord('s'): # 按S键保存画布cv2.imwrite("free_curve_drawing.jpg", state["img"])print("画布已保存为：free_curve_drawing.jpg")elif key == ord('q'): # 按Q键退出breakcv2.destroyAllWindows()

Plain Textimport cv2import numpy as npclass ImageZoom:"""封装图像缩放逻辑"""def __init__(self, img):self.img = img.copy() # 原始图像self.zoom_scale = 1.0 # 初始缩放比例（1.0为原尺寸）self.zoom_step = 0.1 # 每次滚轮滚动的缩放步长self.max_scale = 3.0 # 最大缩放比例self.min_scale = 0.5 # 最小缩放比例def mouse_callback(self, event, x, y, flags, param):# 鼠标滚轮滚动事件if event == cv2.EVENT_MOUSEWHEEL:# 获取滚轮滚动方向（delta>0向前滚动，放大；delta<0向后滚动，缩小）delta = cv2.getMouseWheelDelta(flags)if delta > 0:# 放大图像self.zoom_scale = min(self.zoom_scale + self.zoom_step, self.max_scale)else:# 缩小图像self.zoom_scale = max(self.zoom_scale - self.zoom_step, self.min_scale)# 计算缩放后的图像尺寸h, w = self.img.shape[:2]new_h = int(h * self.zoom_scale)new_w = int(w * self.zoom_scale)# 缩放图像（使用cv2.INTER_LINEAR插值，兼顾速度与质量）zoomed_img = cv2.resize(self.img, (new_w, new_h), interpolation=cv2.INTER_LINEAR)# 显示缩放后的图像cv2.imshow("Image Zoom Window", zoomed_img)print(f"当前缩放比例：{self.zoom_scale:.1f}x")if __name__ == "__main__":# 读取图像img_path = "test_image.jpg"img = cv2.imread(img_path)if img is None:raise FileNotFoundError(f"未找到图像文件：{img_path}")# 初始化缩放类zoomer = ImageZoom(img)# 创建窗口并绑定回调函数cv2.namedWindow("Image Zoom Window", cv2.WINDOW_NORMAL)cv2.setMouseCallback("Image Zoom Window", zoomer.mouse_callback)# 显示原始图像cv2.imshow("Image Zoom Window", img)print("提示：鼠标滚轮向前/向后滚动可放大/缩小图像，按Q键退出")# 监听按键（按Q键退出）while True:if cv2.waitKey(1) & 0xFF == ord('q'):breakcv2.destroyAllWindows()

Plain Textimport cv2import numpy as npdef select_and_convert(event, x, y, flags, param):state = paramimg = state["img"]temp_img = state["temp_img"]is_selecting = state["is_selecting"]start_x, start_y = state["start_x"], state["start_y"]if event == cv2.EVENT_LBUTTONDOWN:state["is_selecting"] = Truestate["start_x"], state["start_y"] = x, yelif event == cv2.EVENT_MOUSEMOVE and is_selecting:state["temp_img"] = img.copy()cv2.rectangle(temp_img, (start_x, start_y), (x, y), (0, 255, 0), 2)cv2.imshow("Select and Convert Window", temp_img)elif event == cv2.EVENT_LBUTTONUP:state["is_selecting"] = False# 确保坐标顺序正确（左上角<右下角）x1 = min(start_x, x)y1 = min(start_y, y)x2 = max(start_x, x)y2 = max(start_y, y)# 提取选区内的图像并转为灰度图roi = img[y1:y2, x1:x2] # 选区内的BGR图像roi_gray = cv2.cvtColor(roi, cv2.COLOR_BGR2GRAY)# 将灰度图转为3通道（与原始图像通道数一致），再替换回原始图像roi_gray_3ch = cv2.cvtColor(roi_gray, cv2.COLOR_GRAY2BGR)img[y1:y2, x1:x2] = roi_gray_3chstate["temp_img"] = img.copy()cv2.imshow("Select and Convert Window", temp_img)if __name__ == "__main__":img = cv2.imread("test_image.jpg")if img is None:raise FileNotFoundError("未找到图像文件")state = {"img": img.copy(),"temp_img": img.copy(),"is_selecting": False,"start_x": -1,"start_y": -1}cv2.namedWindow("Select and Convert Window", cv2.WINDOW_NORMAL)cv2.setMouseCallback("Select and Convert Window", select_and_convert, param=state)cv2.imshow("Select and Convert Window", img)cv2.waitKey(0)cv2.imwrite("selected_converted.jpg", state["img"])cv2.destroyAllWindows()

Plain Textimport cv2import numpy as npdef mark_target(event, x, y, flags, param):state = paramimg = state["img"]targets = state["targets"]if event == cv2.EVENT_LBUTTONDOWN:# 绘制红色标记点（圆形）cv2.circle(img, (x, y), 3, (0, 0, 255), -1)# 绘制目标编号cv2.putText(img, f"Target {len(targets)+1}", (x+5, y-5), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 0, 255), 1)# 记录坐标targets.append((x, y))print(f"标注目标{len(targets)}：(x={x}, y={y})")cv2.imshow("Mark Target Window", img)elif event == cv2.EVENT_RBUTTONDOWN:# 右键点击保存标注坐标with open("target_coordinates.txt", "w") as f:for i, (tx, ty) in enumerate(targets, 1):f.write(f"Target {i}: x={tx}, y={ty}\n")print("标注坐标已保存到：target_coordinates.txt")if __name__ == "__main__":img = cv2.imread("test_image.jpg")if img is None:raise FileNotFoundError("未找到图像文件")state = {"img": img.copy(),"targets": [] # 存储目标坐标的列表}cv2.namedWindow("Mark Target Window", cv2.WINDOW_NORMAL)cv2.setMouseCallback("Mark Target Window", mark_target, param=state)print("提示：左键点击标注目标，右键点击保存坐标，按Q键退出")cv2.imshow("Mark Target Window", img)while True:if cv2.waitKey(1) & 0xFF == ord('q'):breakcv2.destroyAllWindows()