[FIXED] How to add type-writer effect when adding text to QTextEdit in PyQt?

Issue

I have a string and a QTextEdit. Basically, when the user clicks the mouse button, I want to add the string to the QTextEdit, but I want it to print with a "slow/type-writer" effect, so every second the next letter in the string is appended to the text edit until the end of the string.

I think I could maybe use QThread for this, but I am not quite sure how to go about it. I've only just started learning about threads and processes in school. I tried using QThread as shown below, but the program became unresponsive/crashed.

text_edit = QtWidgets.QTextEdit()
string = "This is the sentence I want to display."

thread = QtCore.QThread()
thread.start()

for c in string:
  text_edit.moveCursor(QtGui.QTextCursor.End)
  text_edit.append(c)
  thread.sleep(1)

thread.quit()

Edit:

text_edit = QtWidgets.QTextEdit()
string = "This is the sentence I want to display."

timer = QtCore.QTimer()

for c in string:
  text_edit.moveCursor(QtGui.QTextCursor.End)
  text_edit.append(c)
  timer.start(1000)
  while timer.isActive():
      # something?
  timer.stop()

Solution

I think you are better off using QTimer, than QThread. You can use the class methods to set a singleShot timer for some number of milliseconds in between appending each character onto the existing message. You can fire the timer inside of a method that continues to call itself until it has completely entered the message text.

For Example:

...
...

TEXT = "Some long message that will be typed out one character at a time."

class Window(QWidget):
    def __init__(self, parent=None) -> None:
        super().__init__(parent=parent)
        self.textEdit = QTextEdit(self)
        self.button = QPushButton("Click Me", self)
        self.button.clicked.connect(self.insert_phrase_char)
        self.text_phrase = list(TEXT)
        layout = QVBoxLayout(self)
        layout.addWidget(self.textEdit)
        layout.addWidget(self.button)

    def insert_phrase_char(self):
        if len(self.text_phrase) > 0:
            cursor = self.textEdit.textCursor()
            next_char = self.text_phrase.pop(0)
            cursor.insertText(next_char)
            QTimer.singleShot(300, self.insert_phrase_char)


app = QApplication([])
window = Window()
window.show()
app.exec()

Answered By - Alexander