問題描述

我正在嘗試在 Kivy 中構(gòu)建基于 OpenCv 的相機(jī) Android 應(yīng)用:

I'm trying to build an camera Android app based on OpenCv in Kivy:

ma??in.py

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

class KivyCamera(Image):
    def __init__(self, capture, fps, **kwargs):
        super(KivyCamera, self).__init__(**kwargs)
        self.capture = capture
        Clock.schedule_interval(self.update, 1.0 / fps)

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

        if ret:
            # convert it to texture
            buf1 = cv2.flip(frame, 0)
            buf = buf1.tostring()
            image_texture = Texture.create(size=(frame.shape[1], frame.shape[0]), colorfmt='bgr')
            image_texture.blit_buffer(buf, colorfmt='bgr', bufferfmt='ubyte')
            # display image from the texture
            self.texture = image_texture

class MainApp(App):
    def build(self):
        self.capture = cv2.VideoCapture(0)
        self.camera = KivyCamera(capture=self.capture, fps=30)
        return self.camera

if __name__== "__main__":
    MainApp().run()

buildozer.spec

[app]
title = Test_app
package.name = myapp
package.domain = org.test
source.dir = .
source.include_exts = py,png,jpg,kv,atlas,xml
version = 0.1
requirements = python3,kivy,numpy,opencv
orientation = portrait

# Android specific
fullscreen = 0
android.permissions = INTERNET, ACCESS_FINE_LOCATION, WRITE_EXTERNAL_STORAGE, CAMERA
android.arch = armeabi-v7a
[buildozer]
log_level = 2
warn_on_root = 1

代碼在 Windows 中成功運行.然后我用 buildozer for android 構(gòu)建了代碼，當(dāng)我打開 Android 應(yīng)用程序時，它顯示一個黑屏，屏幕左角有一個小方塊.我認(rèn)為 cv2.VideoCapture() 工作不正常.所以我將 cv2.VideoCapture(0) 更改為 cv2.VideoCapture(-1) 和 cv2.VideoCapture(1).但兩者都不起作用.

Code works successfully in windows. Then i have build the the code with buildozer for android, when I open the Android App it shows a black screen with a small square in the left corner of the screen. I think the cv2.VideoCapture() is not working properly.So I change cv2.VideoCapture(0) to cv2.VideoCapture(-1) and to cv2.VideoCapture(1). But both doesn't work.

誰能幫我解決這個問題?

Can anyone help me out with this ?

推薦答案

我有 2 個解決方案可以讓它在 Android 上運行.

I have 2 solutions to get it to work on Android.

解決方案 1:

我的靈感來自 GitHub 上的 kivy-for-android-opencv-demo:鏈接！因為 Kivy 不再支持 Python2，所以這里是我針對 Python3 的解決方案.

I was inspired by kivy-for-android-opencv-demo, found on GitHub: link! Because Kivy no longer supports Python2, here is my solution for Python3.

main.py

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.graphics.texture import Texture
from kivy.uix.camera import Camera
from kivy.lang import Builder
import numpy as np
import cv2

Builder.load_file("myapplayout.kv")

class AndroidCamera(Camera):
    camera_resolution = (640, 480)
    counter = 0

    def _camera_loaded(self, *largs):
        self.texture = Texture.create(size=np.flip(self.camera_resolution), colorfmt='rgb')
        self.texture_size = list(self.texture.size)

    def on_tex(self, *l):
        if self._camera._buffer is None:
            return None
        frame = self.frame_from_buf()
        self.frame_to_screen(frame)
        super(AndroidCamera, self).on_tex(*l)

    def frame_from_buf(self):
        w, h = self.resolution
        frame = np.frombuffer(self._camera._buffer.tostring(), 'uint8').reshape((h + h // 2, w))
        frame_bgr = cv2.cvtColor(frame, 93)
        return np.rot90(frame_bgr, 3)

    def frame_to_screen(self, frame):
        frame_rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
        cv2.putText(frame_rgb, str(self.counter), (20, 50), cv2.FONT_HERSHEY_SIMPLEX, 1, (0, 255, 0), 2, cv2.LINE_AA)
        self.counter += 1
        flipped = np.flip(frame_rgb, 0)
        buf = flipped.tostring()
        self.texture.blit_buffer(buf, colorfmt='rgb', bufferfmt='ubyte')

class MyLayout(BoxLayout):
    pass

class MyApp(App):
    def build(self):
        return MyLayout()

if __name__ == '__main__':
    MyApp().run()

myappayout.kv

myapplayout.kv

<MyLayout>
    orientation: 'vertical'
    size: root.width, root.height

    AndroidCamera:
        index: 0
        resolution: self.camera_resolution
        allow_stretch: True
        play: True

在 buildozer.spec 中:

in buildozer.spec:

requirements = python3,kivy==2.0.0,opencv==4.5.2,numpy
android.permissions = CAMERA

解決方案 2:

Solution 2:

我從顯示的相機(jī)圖像的小部件中獲取幀，每秒 4 次.如果您不需要每一個框架，并且不需要在框架頂部繪制文本或框等內(nèi)容，那么這是一個簡單的解決方案.

I get the frame from the widget of the displayed camera image, 4 times a second. If you don't need every single frame, and it's not necessary to draw things like text or boxes on top of the frames, then it's an easy solution.

main.py

from kivy.app import App
from kivy.uix.camera import Camera
from kivy.uix.boxlayout import BoxLayout
from kivy.lang import Builder
from kivy.clock import Clock
import numpy as np
import cv2

Builder.load_file('myapplayout.kv')

class AndroidCamera(Camera):
    camera_resolution = (640, 480)
    cam_ratio = camera_resolution[0] / camera_resolution[1]

class MyLayout(BoxLayout):
    pass


class MyApp(App):
    counter = 0

    def build(self):
        return MyLayout()

    def on_start(self):
        Clock.schedule_once(self.get_frame, 5)

    def get_frame(self, dt):
        cam = self.root.ids.a_cam
        image_object = cam.export_as_image(scale=round((400 / int(cam.height)), 2))
        w, h = image_object._texture.size
        frame = np.frombuffer(image_object._texture.pixels, 'uint8').reshape(h, w, 4)
        gray = cv2.cvtColor(frame, cv2.COLOR_RGBA2GRAY)
        self.root.ids.frame_counter.text = f'frame: {self.counter}'
        self.counter += 1
        Clock.schedule_once(self.get_frame, 0.25)

if __name__ == "__main__":
    MyApp().run()

myappayout.kv

myapplayout.kv

<MyLayout>:
    orientation: 'vertical'
    size: root.width, root.height

    GridLayout:
        rows: 2

        RelativeLayout:
            size_hint: 1, 0.8

            AndroidCamera:
                index: 0
                id: a_cam
                resolution: self.camera_resolution
                allow_stretch: True
                play: True
                canvas.before:
                    PushMatrix
                    Rotate:
                        angle: -90
                        origin: self.center
                    Scale:
                        x: self.cam_ratio
                        y: self.cam_ratio
                        origin: self.center
                canvas.after:
                    PopMatrix

        Label:
            size_hint: 1, 0.2
            id: frame_counter
            font_size: self.height * 0.4
            text: ''

buildozer.spec 與解決方案 1 中的相同.

The buildozer.spec is the same as in solution 1.

最后，安裝后別忘了給相機(jī)添加權(quán)限.(我的代碼中沒有包含權(quán)限請求.)

Finally, don't forget to add permission to camera after installation. (No permission request is included in my code.)

這篇關(guān)于android中帶有opencv的kivy相機(jī)應(yīng)用程序顯示黑屏的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！