Kivy 相机作为 KV 语言小部件

Question

我正在使用带网络摄像头的 Kivy。我跟随@Arnav this example 使用 opencv 来形成和显示相机作为一个小部件。我有"extended"里面的布局python，添加两个按钮作为测试，为更复杂的布局做准备。

class CamApp(App):
    def build(self):
        self.capture = cv2.VideoCapture(0)
        self.my_camera = KivyCamera(capture=self.capture, fps=30,resolution=(1920,1080))
        root = BoxLayout(orientation = 'vertical')
        root.add_widget(self.my_camera,1)
        box2 = BoxLayout(orientation = 'vertical')
        btn1 = Button(text='Hello world 1')
        btn2 = Button(text='Hello world 2')
        box2.add_widget(btn1)
        box2.add_widget(btn2)
        root.add_widget(box2, 0)
        return root
        #return Builder.load_string(kv)

虽然这可行，但我更愿意将 UI 组件移出 python 并移入 kv language 文件。问题是知道如何 "describe" kv 文件中的 self.my_camera？

我不确定是否将 KivyCamera class 作为 kv 文件中的 widget 继承，即

kv = '''
<Cam1@KivyCamera>:
    texture: self.my_camera
    resolution: (1920, 1080)
    pos: self.pos
    size: self.size

或者是否使用 canvas 小部件

<MyWidget>:
    canvas:
        Rectangle:
            source: self.my_camera
            pos: self.pos
            size: self.size

我尝试了其他 "hacked" 实现，但在所有情况下，问题都是通过 self.my_camera 链接到 kv 文件。

有什么建议吗？

Answer 1

也许这个例子可以帮到你。

# Import 'kivy.core.text' must be called in entry point script
# before import of cv2 to initialize Kivy's text provider.
# This fixes crash on app exit.

import kivy.core.text
import cv2
from kivy.app import App
from kivy.base import EventLoop
from kivy.uix.image import Image
from kivy.clock import Clock
from kivy.graphics.texture import Texture
from kivy.uix.boxlayout import BoxLayout
from kivy.core.window import Window


class KivyCamera(Image):

    def __init__(self, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.capture = None

    def start(self, capture, fps=30):
        self.capture = capture
        Clock.schedule_interval(self.update, 1.0 / fps)

    def stop(self):
        Clock.unschedule_interval(self.update)
        self.capture = None

    def update(self, dt):
        return_value, frame = self.capture.read()
        if return_value:
            texture = self.texture
            w, h = frame.shape[1], frame.shape[0]
            if not texture or texture.width != w or texture.height != h:
                self.texture = texture = Texture.create(size=(w, h))
                texture.flip_vertical()
            texture.blit_buffer(frame.tobytes(), colorfmt='bgr')
            self.canvas.ask_update()


capture = None


class QrtestHome(BoxLayout):

    def init_qrtest(self):
        pass

    def dostart(self, *largs):
        global capture
        capture = cv2.VideoCapture(0)
        self.ids.qrcam.start(capture)

    def doexit(self):
        global capture
        if capture != None:
            capture.release()
            capture = None
        EventLoop.close()


class qrtestApp(App):

    def build(self):
        Window.clearcolor = (.4,.4,.4,1)
        Window.size = (400, 300)
        homeWin = QrtestHome()
        homeWin.init_qrtest()
        return homeWin

    def on_stop(self):
        global capture
        if capture:
            capture.release()
            capture = None

qrtestApp().run()

和 kv 文件：

<QrtestHome>:

    BoxLayout:
        orientation: "vertical"

        Label:
            height: 20
            size_hint_y: None
            text: 'Testing the camera'

        KivyCamera:
            id: qrcam

        BoxLayout:
            orientation: "horizontal"
            height: 20
            size_hint_y: None

            Button:
                id: butt_start
                size_hint: 0.5,1
                text: "start"
                on_press: root.dostart()

            Button:
                id: butt_exit
                text: "quit"
                size_hint: 0.5,1
                on_press: root.doexit()

Kivy 相机作为 KV 语言小部件

Kivy Camera as KV language widget

python

opencv

kivy

kivy-language