Signal and Slot in PyQT5 - python-2.7

Question

I use PyQt5 in Python2.7. I have three Classes. Thread, PlayStreaming and UIWidget.
class Thread(QtCore.QThread):
changePixmap = QtCore.pyqtSignal(QtGui.QImage)
scaled_size = QtCore.QSize(640, 480)
curScale=1.0
maxHeight=0
maxScale=0
def run(self):
cap = cv2.VideoCapture(1)
cap.set(3,1280);
cap.set(4,1024);
time.sleep(2)
maxHeight=cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
maxScale=maxHeight/480.0
while True:
ret, frame = cap.read()
if ret:
r=1
face_locations=[]
rescaleSize=int(480*curScale)
if(frame.shape[0] > 480 and frame.shape[1] > 640):
r = rescaleSize / float(frame.shape[0])
dim = (int(frame.shape[1] * r), rescaleSize)
face_locations = face_recognition.face_locations(cv2.resize(frame, dim, fx=0.0, fy=0.0))
else:
face_locations = face_recognition.face_locations(frame)
for face_location in face_locations:
top, right, bottom, left = face_location
cv2.rectangle(frame,(int(right/r),int(top/r)),(int(left/r),int(bottom/r)),(0,255,0),2)
rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
convertToQtFormat = QtGui.QImage(rgbImage.data, rgbImage.shape[1], rgbImage.shape[0], QtGui.QImage.Format_RGB888)
p = convertToQtFormat.scaled(self.scaled_size, QtCore.Qt.KeepAspectRatio)
self.changePixmap.emit(p)
def scaled(self, scaled_size):
self.scaled_size = scaled_size
def scaleup(self):
self.curScale = self.curScale + 0.1
if( self.curScale > maxScale):
self.curScale=maxScale
print(self.curScale)
class PlayStreaming(QtWidgets.QLabel):
reSize = QtCore.pyqtSignal(QtCore.QSize)
def __init__(self):
super(PlayStreaming, self).__init__()
self.initUI()
#QtCore.pyqtSlot(QtGui.QImage)
def setImage(self, image):
self.label.setPixmap(QtGui.QPixmap.fromImage(image))
def initUI(self):
self.setWindowTitle("Image")
# create a label
self.label = QtWidgets.QLabel(self)
##############instance of Thread############
th = Thread(self)
############################################
th.changePixmap.connect(self.setImage)
self.reSize.connect(th.scaled)
th.start()
lay = QtWidgets.QVBoxLayout(self)
lay.addWidget(self.label, alignment=QtCore.Qt.AlignCenter)
def resizeEvent(self, event):
self.reSize.emit(self.size())
class UIWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(UIWidget, self).__init__(parent)
# Initialize tab screen
self.tabs = QtWidgets.QTabWidget()
self.tab1 = QtWidgets.QWidget()
self.tab2 = QtWidgets.QWidget()
self.tab3 = QtWidgets.QWidget()
# Add tabs
self.tabs.addTab(self.tab1, "Face")
self.tabs.addTab(self.tab2, "Human")
self.tabs.addTab(self.tab3, "Vehicle")
# Create first tab
self.createGridLayout()
self.tab1.layout = QtWidgets.QVBoxLayout()
##############instance of PlayStreaming############
self.display = PlayStreaming()
###################################################
self.tab1.layout.addWidget(self.display, stretch=1)
self.tab1.layout.addWidget(self.horizontalGroupBox)
self.tab1.setLayout(self.tab1.layout)
# Add tabs to widget
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.tabs)
def createGridLayout(self):
self.horizontalGroupBox = QtWidgets.QGroupBox("")
self.horizontalGroupBox.setStyleSheet("QGroupBox{ background-color: red; border: none;}")
hlay1 = QtWidgets.QHBoxLayout()
self.TestButton=QtWidgets.QPushButton('Test')
hlay1.addWidget(self.TestButton)
self.RunButton=QtWidgets.QPushButton('Run')
hlay1.addWidget(self.RunButton)
self.ScaleUpButton=QtWidgets.QPushButton('ScaleUp')
###################This button clicked signal to Thread class#########
#############How to send??????????????????????########################
self.ScaleUpButton.clicked.connect(scaleup)
hlay1.addWidget(self.ScaleUpButton)
self.ScaleDownButton=QtWidgets.QPushButton('ScaleDown')
hlay1.addWidget(self.ScaleDownButton)
hlay2 = QtWidgets.QHBoxLayout()
hlay2.addWidget(QtWidgets.QPushButton('Set Faces'))
hlay2.addWidget(QtWidgets.QPushButton('FacePose'))
hlay2.addWidget(QtWidgets.QPushButton('Gender'))
hlay2.addWidget(QtWidgets.QPushButton('Age'))
hlay2.addWidget(QtWidgets.QPushButton('Recognize'))
layout = QtWidgets.QVBoxLayout()
layout.addLayout(hlay1)
layout.addLayout(hlay2)
self.horizontalGroupBox.setLayout(layout)
PlayStreaming has instance of Thread and UIWidget has instance of PlayStreaming ( Not sure I am using the right terminology for Python as instance)
I like to send self.ScaleUpButton's click signal from UIWidget to scaleup slot in Thread class.
How can I do that?

Answer 1

You have to use the signals and the slots, the idea is that each widget is like a black box so PlayStreaming must have a signal that must call a slot of the thread:
class Thread(QtCore.QThread):
changePixmap = QtCore.pyqtSignal(QtGui.QImage)
def __init__(self, parent=None):
super(Thread, self).__init__(parent)
self.scaled_size = QtCore.QSize(640, 480)
self.curScale=1.0
self.maxScale = 0
def run(self):
cap = cv2.VideoCapture(1)
cap.set(3, 1280);
cap.set(4, 1024);
QtCore.QThread.sleep(2)
maxHeight = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
self.maxScale = maxHeight/480.0
while True:
ret, frame = cap.read()
if ret:
r=1
face_locations=[]
rescaleSize=int(480*self.curScale)
if(frame.shape[0] > 480 and frame.shape[1] > 640):
r = rescaleSize / float(frame.shape[0])
dim = (int(frame.shape[1] * r), rescaleSize)
face_locations = face_recognition.face_locations(cv2.resize(frame, dim, fx=0.0, fy=0.0))
else:
face_locations = face_recognition.face_locations(frame)
for face_location in face_locations:
top, right, bottom, left = face_location
cv2.rectangle(frame,(int(right/r),int(top/r)),(int(left/r),int(bottom/r)),(0,255,0),2)
rgbImage = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
convertToQtFormat = QtGui.QImage(rgbImage.data, rgbImage.shape[1], rgbImage.shape[0], QtGui.QImage.Format_RGB888)
p = convertToQtFormat.scaled(self.scaled_size, QtCore.Qt.KeepAspectRatio)
self.changePixmap.emit(p)
#QtCore.pyqtSlot(QtCore.QSize)
def scaled(self, scaled_size):
self.scaled_size = scaled_size
#QtCore.pyqtSlot()
def scaleup(self):
self.curScale = self.curScale + 0.1
if self.curScale > self.maxScale:
self.curScale = self.maxScale
print(self.curScale)
class PlayStreaming(QtWidgets.QLabel):
reSize = QtCore.pyqtSignal(QtCore.QSize)
scaleupSignal = QtCore.pyqtSignal()
def __init__(self):
super(PlayStreaming, self).__init__()
self.initUI()
#QtCore.pyqtSlot(QtGui.QImage)
def setImage(self, image):
self.label.setPixmap(QtGui.QPixmap.fromImage(image))
def initUI(self):
self.setWindowTitle("Image")
self.label = QtWidgets.QLabel(self)
th = Thread(self)
th.changePixmap.connect(self.setImage)
self.scaleupSignal.connect(th.scaleup)
self.reSize.connect(th.scaled)
th.start()
lay = QtWidgets.QVBoxLayout(self)
lay.addWidget(self.label, alignment=QtCore.Qt.AlignCenter)
def resizeEvent(self, event):
self.reSize.emit(self.size())
class UIWidget(QtWidgets.QWidget):
def __init__(self, parent=None):
super(UIWidget, self).__init__(parent)
# Initialize tab screen
self.tabs = QtWidgets.QTabWidget()
self.tab1 = QtWidgets.QWidget()
self.tab2 = QtWidgets.QWidget()
self.tab3 = QtWidgets.QWidget()
# Add tabs
self.tabs.addTab(self.tab1, "Face")
self.tabs.addTab(self.tab2, "Human")
self.tabs.addTab(self.tab3, "Vehicle")
self.display = PlayStreaming()
# Create first tab
self.createGridLayout()
self.tab1.layout = QtWidgets.QVBoxLayout()
self.tab1.layout.addWidget(self.display, stretch=1)
self.tab1.layout.addWidget(self.horizontalGroupBox)
self.tab1.setLayout(self.tab1.layout)
# Add tabs to widget
layout = QtWidgets.QVBoxLayout(self)
layout.addWidget(self.tabs)
def createGridLayout(self):
self.horizontalGroupBox = QtWidgets.QGroupBox("")
self.horizontalGroupBox.setStyleSheet("QGroupBox{ background-color: red; border: none;}")
hlay1 = QtWidgets.QHBoxLayout()
self.TestButton=QtWidgets.QPushButton('Test')
hlay1.addWidget(self.TestButton)
self.RunButton=QtWidgets.QPushButton('Run')
hlay1.addWidget(self.RunButton)
self.ScaleUpButton=QtWidgets.QPushButton('ScaleUp')
self.ScaleUpButton.clicked.connect(self.display.scaleupSignal)
hlay1.addWidget(self.ScaleUpButton)
self.ScaleDownButton=QtWidgets.QPushButton('ScaleDown')
hlay1.addWidget(self.ScaleDownButton)
hlay2 = QtWidgets.QHBoxLayout()
hlay2.addWidget(QtWidgets.QPushButton('Set Faces'))
hlay2.addWidget(QtWidgets.QPushButton('FacePose'))
hlay2.addWidget(QtWidgets.QPushButton('Gender'))
hlay2.addWidget(QtWidgets.QPushButton('Age'))
hlay2.addWidget(QtWidgets.QPushButton('Recognize'))
layout = QtWidgets.QVBoxLayout()
layout.addLayout(hlay1)
layout.addLayout(hlay2)
self.horizontalGroupBox.setLayout(layout)