我正在使用PyQT5。我想使用QQuickPaintedItem将帧从Opencv发送到QML。我在这里编写了一个示例实现。我似乎无法找到为什么仅在应用程序加载时才调用一次paint事件的原因。它仅绘制从相机到QML组件的一帧图像，而 self.update（）不调用绘制事件。
from OpenGL import GL
from PyQt5.QtQuick import QQuickPaintedItem, QQuickView
from PyQt5.QtGui import QPainter, QPixmap, QImage
from PyQt5.QtQml import qmlRegisterType
import sys
from PyQt5.QtGui import QColor
from PyQt5.QtCore import QUrl,QObject,pyqtSignal
import cv2.cv2 as cv2
from PyQt5.QtWidgets import QApplication
class ImageWriter(QQuickPaintedItem):
cam_frame = None
def __init__(self, *args, **kwargs):
super(ImageWriter, self).__init__(*args, **kwargs)
self.setRenderTarget(QQuickPaintedItem.FramebufferObject)
def paint(self, painter):
print(ImageWriter.cam_frame)
painter.drawPixmap(0,0,ImageWriter.cam_frame)
def update_frame(self,frame):
frame = cv2.resize(frame, (700, 500), cv2.INTER_AREA)
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
frame = QImage(frame, frame.shape[1], frame.shape[0], 17)
ImageWriter.cam_frame = QPixmap.fromImage(frame)
self.update()
def get_frames(app):
cap = cv2.VideoCapture(0)
num = 0
imgw = ImageWriter()
while True:
while num != 30:
_ , bgframe = cap.read()
num += 1
_ , frame = cap.read()
imgw.update_frame(frame)
print("get frames")
app.processEvents()
if __name__ == '__main__':
app = QApplication(sys.argv)
qmlRegisterType(ImageWriter, "imageWriter", 1, 0, "ImageWriter")
view = QQuickView()
view.setSource(QUrl('test.qml'))
rootObject = view.rootObject()
view.show()
get_frames(app)
sys.exit(app.exec_())
这是我为此编写的QML，
import QtQuick 2.0
import imageWriter 1.0
Item {
width: 800
height: 600
ImageWriter {
id : imageWriter
width : 800
height : 600
}
}
我完全不知道为什么 self.update（）不调用paint事件的原因。我不能使用QWidgets，我必须使用它。我在这里缺少什么吗？
答案 0 :(得分：1)
此问题是由两个ImageWriter对象引起的，一个是在imgw = ImageWriter()中创建的，另一个是在QML中创建的，您可以通过在.qml中的.py中添加打印内容来将其合并：
*。py
def get_frames(app):
cap = cv2.VideoCapture(0)
num = 0
imgw = ImageWriter()
print("Python:", imgw)
...
*。qml
...
Component.onCompleted: console.log("QML:", imageWriter)
...
输出：
qml: >>>> ImageWriter(0x55bf2927e770)
Python: <__main__.ImageWriter object at 0x7fce8e4ff798>
如您所见，有2个对象指向不同的内存地址，因此可能的解决方案是使用this library创建单例：
from OpenGL import GL
import sys
from PyQt5 import QtCore, QtGui, QtQml, QtQuick
import cv2
try: from PyQt5.QtCore import pyqtWrapperType
except ImportError:
from sip import wrappertype as pyqtWrapperType
class Singleton(pyqtWrapperType, type):
def __init__(cls, name, bases, dict):
super().__init__(name, bases, dict)
cls.instance=None
def __call__(cls,*args,**kw):
if cls.instance is None:
cls.instance=super().__call__(*args, **kw)
return cls.instance
class ImageWriter(QtQuick.QQuickPaintedItem, metaclass=Singleton):
def __init__(self, *args, **kwargs):
super(ImageWriter, self).__init__(*args, **kwargs)
self.setRenderTarget(QtQuick.QQuickPaintedItem.FramebufferObject)
self.cam_frame = QtGui.QImage()
def paint(self, painter):
painter.drawImage(0, 0, self.cam_frame)
def update_frame(self,frame):
frame = cv2.resize(frame, (700, 500), cv2.INTER_AREA)
frame = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
frame = QtGui.QImage(frame, frame.shape[1], frame.shape[0], 17)
self.cam_frame = frame.copy()
self.update()
def get_frames(app):
cap = cv2.VideoCapture(0)
num = 0
imgw = ImageWriter()
while True:
while num != 30:
_ , bgframe = cap.read()
num += 1
ret, frame = cap.read()
if ret:
imgw.update_frame(frame)
#print("get frames")
app.processEvents()
if __name__ == '__main__':
app = QtGui.QGuiApplication(sys.argv)
QtQml.qmlRegisterType(ImageWriter, "imageWriter", 1, 0, "ImageWriter")
view = QtQuick.QQuickView()
view.setSource(QtCore.QUrl('test.qml'))
rootObject = view.rootObject()
view.show()
get_frames(app)
sys.exit(app.exec_())
通过以上所述，我认为有更好的方法来获取图像，稍后，我将显示一个更好的选择。
使用my previous answer作为基础，我创建了一个模块，该模块除了使用查看器外，还使用opencv实现了摄像头的处理程序，以及一个允许添加滤镜的通用类，为此，该项目必须具有以下结构
├── main.py
├── main.qml
└── PyCVQML
├── cvcapture.py
├── cvitem.py
└── __init__.py
PyCVQML / cvcapture.py
import numpy as np
import threading
import cv2
from PyQt5 import QtCore, QtGui, QtQml
gray_color_table = [QtGui.qRgb(i, i, i) for i in range(256)]
class CVAbstractFilter(QtCore.QObject):
def process_image(self, src):
dst = src
return dst
class CVCapture(QtCore.QObject):
started = QtCore.pyqtSignal()
imageReady = QtCore.pyqtSignal()
indexChanged = QtCore.pyqtSignal()
def __init__(self, parent=None):
super(CVCapture, self).__init__(parent)
self._image = QtGui.QImage()
self._index = 0
self.m_videoCapture = cv2.VideoCapture()
self.m_timer = QtCore.QBasicTimer()
self.m_filters = []
self.m_busy = False
@QtCore.pyqtSlot()
@QtCore.pyqtSlot(int)
def start(self, *args):
if args:
self.setIndex(args[0])
self.m_videoCapture.release()
self.m_videoCapture = cv2.VideoCapture(self._index)
if self.m_videoCapture.isOpened():
self.m_timer.start(0, self)
self.started.emit()
@QtCore.pyqtSlot()
def stop(self):
self.m_timer.stop()
def timerEvent(self, e):
if e.timerId() != self.m_timer.timerId(): return
ret, frame = self.m_videoCapture.read()
if not ret:
self.m_timer.stop()
return
if not self.m_busy:
threading.Thread(target=self.process_image, args=(np.copy(frame),)).start()
@QtCore.pyqtSlot(np.ndarray)
def process_image(self, frame):
self.m_busy = True
for f in self.m_filters:
frame = f.process_image(frame)
image = CVCapture.ToQImage(frame)
self.m_busy = False
QtCore.QMetaObject.invokeMethod(self,
"setImage",
QtCore.Qt.QueuedConnection,
QtCore.Q_ARG(QtGui.QImage, image))
@staticmethod
def ToQImage(im):
if im is None:
return QtGui.QImage()
if im.dtype == np.uint8:
if len(im.shape) == 2:
qim = QtGui.QImage(im.data, im.shape[1], im.shape[0], im.strides[0], QtGui.QImage.Format_Indexed8)
qim.setColorTable(gray_color_table)
return qim.copy()
elif len(im.shape) == 3:
if im.shape[2] == 3:
w, h, _ = im.shape
rgb_image = cv2.cvtColor(im, cv2.COLOR_BGR2RGB)
flip_image = cv2.flip(rgb_image, 1)
qim = QtGui.QImage(flip_image.data, h, w, QtGui.QImage.Format_RGB888)
return qim.copy()
return QtGui.QImage()
def image(self):
return self._image
@QtCore.pyqtSlot(QtGui.QImage)
def setImage(self, image):
if self._image == image: return
self._image = image
self.imageReady.emit()
def index(self):
return self._index
def setIndex(self, index):
if self._index == index: return
self._index = index
self.indexChanged.emit()
@QtCore.pyqtProperty(QtQml.QQmlListProperty)
def filters(self):
return QtQml.QQmlListProperty(CVAbstractFilter, self, self.m_filters)
image = QtCore.pyqtProperty(QtGui.QImage, fget=image, notify=imageReady)
index = QtCore.pyqtProperty(int, fget=index, fset=setIndex, notify=indexChanged)
PyCVQML / cvitem.py
from PyQt5 import QtCore, QtGui, QtQuick
class CVItem(QtQuick.QQuickPaintedItem):
imageChanged = QtCore.pyqtSignal()
def __init__(self, parent=None):
super(CVItem, self).__init__(parent)
# self.setRenderTarget(QtQuick.QQuickPaintedItem.FramebufferObject)
self.m_image = QtGui.QImage()
def paint(self, painter):
if self.m_image.isNull(): return
image = self.m_image.scaled(self.size().toSize())
painter.drawImage(QtCore.QPoint(), image)
def image(self):
return self.m_image
def setImage(self, image):
if self.m_image == image: return
self.m_image = image
self.imageChanged.emit()
self.update()
image = QtCore.pyqtProperty(QtGui.QImage, fget=image, fset=setImage, notify=imageChanged)
PyCVQML / __ init __。py
from PyQt5 import QtQml
from .cvcapture import CVCapture, CVAbstractFilter
from .cvitem import CVItem
def registerTypes(uri = "PyCVQML"):
QtQml.qmlRegisterType(CVCapture, uri, 1, 0, "CVCapture")
QtQml.qmlRegisterType(CVItem, uri, 1, 0, "CVItem")
然后您在main.py中使用它，我添加了2个示例过滤器，为此CVCapture具有filter属性，将过滤器传递给它，它们将按照它们的执行顺序执行建立。要实现新的过滤器，您必须继承CVAbstractFilter并覆盖process_image()方法，该方法将图像作为np.ndarray接收，并应在过滤器之后返回结果。
main.py
import cv2
import numpy as np
from PyQt5 import QtGui, QtCore, QtQuick, QtQml
import PyCVQML
def max_rgb_filter(image):
# split the image into its BGR components
(B, G, R) = cv2.split(image)
# find the maximum pixel intensity values for each
# (x, y)-coordinate,, then set all pixel values less
# than M to zero
M = np.maximum(np.maximum(R, G), B)
R[R < M] = 0
G[G < M] = 0
B[B < M] = 0
# merge the channels back together and return the image
return cv2.merge([B, G, R])
def rgb_to_gray(image):
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
return gray
class MaxRGBFilter(PyCVQML.CVAbstractFilter):
def process_image(self, src):
return max_rgb_filter(src)
class GrayFilter(PyCVQML.CVAbstractFilter):
def process_image(self, src):
return rgb_to_gray(src)
if __name__ == '__main__':
import os
import sys
app = QtGui.QGuiApplication(sys.argv)
PyCVQML.registerTypes()
QtQml.qmlRegisterType(MaxRGBFilter, "Filters", 1, 0, "MaxRGBFilter")
QtQml.qmlRegisterType(GrayFilter, "Filters", 1, 0, "GrayFilter")
view = QtQuick.QQuickView()
view.setTitle("PyCVQML Example")
dir_path = os.path.dirname(os.path.realpath(__file__)
view.setSource(QtCore.QUrl.fromLocalFile(QtCore.QDir(dir_path).absoluteFilePath("main.qml")))
view.show()
sys.exit(app.exec_())
main.qml
import QtQuick 2.0
import PyCVQML 1.0
import Filters 1.0
Item {
width: 800
height: 600
CVItem {
id: imageWriter
anchors.fill: parent
image: capture.image
}
MaxRGBFilter{
id: max_rgb_filter
}
GrayFilter{
id: gray_filter
}
CVCapture{
id: capture
index: 0
filters: [max_rgb_filter, gray_filter]
Component.onCompleted: capture.start()
}
}