Kivy应用在使用cv.VideoCapture()时无法检测到触摸事件。

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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:

import numpy as np
import cv2 as cv
from matplotlib import pyplot as plt

cap = cv.VideoCapture('partido/06_centro.mp4')
cv.namedWindow("Video")

def get_roi(frame, x, y):
    roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
    mask = np.zeros(frame.shape[:2], np.uint8)
    cv.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
    return cv.bitwise_and(frame, frame, mask=mask)

def mouse_callback(event, x, y, flags, param):
    if event == cv.EVENT_LBUTTONDOWN:
        roi_frame = get_roi(frame, x, y)
        cv.imshow("ROI Frame", roi_frame)

cv.setMouseCallback("Video", mouse_callback)

while True:
    ret, frame = cap.read()

    cv.imshow("Video", frame)

    key = cv.waitKey(1) & 0xFF

    if key == ord('q'):
        break

cap.release()
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):

import cv2
from kivy.app import App
from kivy.uix.image import Image
from kivy.graphics.texture import Texture
from kivy.clock import Clock
import numpy as np

# 程序的其余部分没有翻译

if __name__ == '__main__':
    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:

import numpy as np
import cv2 as cv
from matplotlib import pyplot as plt

cap = cv.VideoCapture('partido/06_centro.mp4')
cv.namedWindow("Video")

def get_roi(frame, x, y):
    roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
    mask = np.zeros(frame.shape[:2], np.uint8)
    cv.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
    return cv.bitwise_and(frame, frame, mask=mask)

def mouse_callback(event, x, y, flags, param):
    if event == cv.EVENT_LBUTTONDOWN:
        roi_frame = get_roi(frame, x, y)
        cv.imshow("ROI Frame", roi_frame)


cv.setMouseCallback("Video", mouse_callback)

while True:
    ret, frame = cap.read()

    cv.imshow("Video", frame)
    
    key = cv.waitKey(1) & 0xFF

    if key == ord('q'):
        break

cap.release()
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):

import cv2
from kivy.app import App
from kivy.uix.image import Image
from kivy.graphics.texture import Texture
from kivy.clock import Clock
import numpy as np


def get_roi(frame, x, y):
    roi_corners = np.array([[x-50, y-50], [x+50, y-50], [x+50, y+50], [x-50, y+50]])
    mask = np.zeros(frame.shape[:2], np.uint8)
    cv2.drawContours(mask, [roi_corners], 0, (255, 255, 255), -1)
    return cv2.bitwise_and(frame, frame, mask=mask)

class VideoPlayerApp(App):

    def build(self):
        self.image = Image(allow_stretch=True, keep_ratio=False)
        Clock.schedule_interval(self.update, 1.0/30.0)
        self.cap = cv2.VideoCapture("./partido/06_centro.mp4")
        return self.image

    def on_touch_down(self, touch):
        print("Touch down")
        if self.image.collide_point(*touch.pos):
            x, y = touch.pos
            x = int(x / self.image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
            y = int(y / self.image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
            ret, frame = self.cap.read()
            if ret:
                roi_frame = get_roi(frame, x, y)
                cv2.imshow("ROI Frame", roi_frame)

    def update(self, dt):
        ret, frame = self.cap.read()

        if ret:
            buf = cv2.flip(frame, 0).tobytes()
            image_texture = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
            image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
            self.image.texture = image_texture

    def on_stop(self):
        self.cap.release()
        cv2.destroyAllWindows()
        
if __name__ == '__main__':
    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:

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:

def on_touch_down(self, image, touch):
    print("Touch down")
    if image.collide_point(*touch.pos):
        x, y = touch.pos
        x = int(x / image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        y = int(y / image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        ret, frame = self.cap.read()
        if ret:
            roi_frame = get_roi(frame, x, y)
            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:

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

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

def on_touch_down(self, image, touch):
    print("Touch down")
    if image.collide_point(*touch.pos):
        x, y = touch.pos
        x = int(x / image.width * self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        y = int(y / image.height * self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        ret, frame = self.cap.read()
        if ret:
            roi_frame = get_roi(frame, x, y)
            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.

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  • 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
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