Kivy应用在使用cv.VideoCapture()时无法检测到触摸事件。

huangapple
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英文:

Kivy app not detecting touch events when using cv.VideoCapture()

问题

我正在开发一个Kivy应用程序。在某一点上，用户将不得不触摸屏幕以指示网球场的角落在哪里。我想获取此触摸的坐标，并创建一个感兴趣区域（ROI）。我很容易使用OpenCV实现了这一点：

  1. import numpy as np
  2. import cv2 as cv
  3. from matplotlib import pyplot as plt
  5. cap = cv.VideoCapture('partido/06_centro.mp4')
  6. cv.namedWindow("Video")
  8. def get_roi(frame, x, y):
  9.     roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
  10.     mask = np.zeros(frame.shape[:2], np.uint8)
  11.     cv.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
  12.     return cv.bitwise_and(frame, frame, mask=mask)
  14. def mouse_callback(event, x, y, flags, param):
  15.     if event == cv.EVENT_LBUTTONDOWN:
  16.         roi_frame = get_roi(frame, x, y)
  17.         cv.imshow("ROI Frame", roi_frame)
  19. cv.setMouseCallback("Video", mouse_callback)
  21. while True:
  22.     ret, frame = cap.read()
  24.     cv.imshow("Video", frame)
  26.     key = cv.waitKey(1) & 0xFF
  28.     if key == ord('q'):
  29.         break
  31. cap.release()
  32. cv.destroyAllWindows()

这段代码有效，但是当我尝试在Kivy中执行相同操作时，我可以显示视频，但它不识别触摸事件（print语句不执行）：

  1. import cv2
  2. from kivy.app import App
  3. from kivy.uix.image import Image
  4. from kivy.graphics.texture import Texture
  5. from kivy.clock import Clock
  6. import numpy as np
  8. # 程序的其余部分没有翻译
  10. if __name__ == '__main__':
  11.     app = VideoPlayerApp().run()

你仍然在使用OpenCV的VideoCapture()方法，并使用schedule_interval来更新Image组件。由于我无法提供更多Kivy代码，你可能需要检查Kivy部分的代码以确保触摸事件正确处理。你可以阅读Kivy的文档或寻求Kivy社区的支持以解决触摸事件未触发的问题。

英文:

I am working on a Kivy app. At some point, the user will have to touch the screen to indicate where the corners of a tennis court are. I want to take the coordinates of this touch, and create a ROI. I did this using OpenCV easily:

  1. import numpy as np
  2. import cv2 as cv
  3. from matplotlib import pyplot as plt
  5. cap = cv.VideoCapture('partido/06_centro.mp4')
  6. cv.namedWindow("Video")
  8. def get_roi(frame, x, y):
  9.     roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
  10.     mask = np.zeros(frame.shape[:2], np.uint8)
  11.     cv.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
  12.     return cv.bitwise_and(frame, frame, mask=mask)
  14. def mouse_callback(event, x, y, flags, param):
  15.     if event == cv.EVENT_LBUTTONDOWN:
  16.         roi_frame = get_roi(frame, x, y)
  17.         cv.imshow("ROI Frame", roi_frame)
  20. cv.setMouseCallback("Video", mouse_callback)
  22. while True:
  23.     ret, frame = cap.read()
  25.     cv.imshow("Video", frame)
  26.     
  27.     key = cv.waitKey(1) & 0xFF
  29.     if key == ord('q'):
  30.         break
  32. cap.release()
  33. cv.destroyAllWindows()

This code works, but now when I try to do the same with Kivy I can show the video but it doesn't recognize the touch event (the print statement is not executed):

  1. import cv2
  2. from kivy.app import App
  3. from kivy.uix.image import Image
  4. from kivy.graphics.texture import Texture
  5. from kivy.clock import Clock
  6. import numpy as np
  9. def get_roi(frame, x, y):
  10.     roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
  11.     mask = np.zeros(frame.shape[:2], np.uint8)
  12.     cv2.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
  13.     return cv2.bitwise_and(frame, frame, mask=mask)
  15. class VideoPlayerApp(App):
  17.     def build(self):
  18.         self.image = Image(allow_stretch=True, keep_ratio=False)
  19.         Clock.schedule_interval(self.update, 1.0/30.0)
  20.         self.cap = cv2.VideoCapture("./partido/06_centro.mp4")
  21.         return self.image
  23.     def on_touch_down(self, touch):
  24.         print("Touch down")
  25.         if self.image.collide_point(*touch.pos):
  26.             x, y = touch.pos
  27.             x = int(x / self.image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
  28.             y = int(y / self.image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
  29.             ret, frame = self.cap.read()
  30.             if ret:
  31.                 roi_frame = get_roi(frame, x, y)
  32.                 cv2.imshow("ROI Frame", roi_frame)
  34.     def update(self, dt):
  35.         ret, frame = self.cap.read()
  37.         if ret:
  38.             buf = cv2.flip(frame, 0).tobytes()
  39.             image_texture = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
  40.             image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
  41.             self.image.texture = image_texture
  43.     def on_stop(self):
  44.         self.cap.release()
  45.         cv2.destroyAllWindows()
  46.         
  47. if __name__ == '__main__':
  48.     app = VideoPlayerApp().run()

I'm still using the method VideoCapture() from OpenCV, and I'm updating the Image component using schedule_interval. I started using Kivy recently, so I can't find the error. Can you help me?

答案1

得分: 2

App 类不处理 on_touch_down 事件，因此您的 on_touch_down() 方法将永远不会被调用。然而，Image 类处理 on_touch_down 事件（所有的 Widgets 都处理）。因此，您可以在 build() 方法中使用您的 Image 绑定到该事件，像这样：

  1. self.image.bind(on_touch_down=self.on_touch_down)

并修改 on_touch_down() 方法以接受正确的参数：

  1. def on_touch_down(self, image, touch):
  2.     print("Touch down")
  3.     if image.collide_point(*touch.pos):
  4.         x, y = touch.pos
  5.         x = int(x / image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
  6.         y = int(y / image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
  7.         ret, frame = self.cap.read()
  8.         if ret:
  9.             roi_frame = get_roi(frame, x, y)
  10.             cv2.imshow("ROI Frame", roi_frame)

请注意，在这个方法中，您可以用 image 替换 self.image，因为它是传递给方法的参数。

英文:

The App class does not handle on_touch_down events, so your on_touch_down() method will never be called. The Image class, however, does handle on_touch_down events (all Widgets do). So you can bind to that event using your Image in your build() method, like this:

  1.     self.image.bind(on_touch_down=self.on_touch_down)

And modify that on_touch_down() method to accept the correct arguments:

  1. def on_touch_down(self, image, touch):
  2.     print("Touch down")
  3.     if image.collide_point(*touch.pos):
  4.         x, y = touch.pos
  5.         x = int(x / image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
  6.         y = int(y / image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
  7.         ret, frame = self.cap.read()
  8.         if ret:
  9.             roi_frame = get_roi(frame, x, y)
  10.             cv2.imshow("ROI Frame", roi_frame)

Note that in this method you can replace self.image with just image since it is an argument passed to the method.

huangapple
  • 本文由 发表于 2023年3月12日 06:46:05
  • 转载请务必保留本文链接：https://go.coder-hub.com/75710048.html
  • event-handling
  • kivy
  • python
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