使用PyQt创建一个简单的聊天界面

Question

Am currently creating a simple chat application that looks like a usual messaging service. the problem am facing is that Ive failed to add more QLabels on a QVBoxLayout by just pressing the send button. All it does is send the message to the layout as expected but when i send another message, instead of appending, it replaces the first message. The following code is run when the send button is clicked.

self.message = QtGui.QLabel()
# self.messageField is the QTextEdit where the user writes the message
text = self.messageField.toPlainText()
self.message.setText(text)
self.messageField.clear()
# self.messageLayout is our QVBoxLayout
self.messageLayout.addWidget(self.message)
self.messageLayout.setAlignment(self.message, QtCore.Qt.AlignTop)
# self.widget is on top od the QScrollArea and it holds the QVBoxLayout
self.widget.setLayoutDirection(QtCore.Qt.RightToLeft)
self.widget.setLayout(self.messageLayout)

I don't know where the problem lays

Answer 1

self.message = QtGui.QLabel() replaces the first QLabel reference stored as an instance attribute.

Try to implement a list instead, to store all messages from the beginning.

You need to add this before, in the __init__ method :

self.messages = []

And in the method triggered by the button :

message = QtGui.QLabel()

text = self.messageField.toPlainText()
message.setText(text)
self.messageField.clear()
self.messageLayout.addWidget(message)
self.widget.setLayoutDirection(QtCore.Qt.RightToLeft)
self.widget.setLayout(self.messageLayout)
# and to keep a direct reference :
self.messages.append(message)

EDIT :

You may need to define alignment only once at beginning, just after you define your layout, that might fix the centered message issue :

self.messageLayout = QVBoxLayout() # (i assume...)
self.messageLayout.setAlignment(QtCore.Qt.AlignTop)

and i think you should do the same for these 2 lines, no need to repeat this each time you append a message to the list :

self.widget.setLayoutDirection(QtCore.Qt.RightToLeft)
self.widget.setLayout(self.messageLayout)`