Op Mon, 27 Feb 2012 17:02:01 -0800 (PST)
JPolk <jpolk5...@yahoo.com> schreef:
>
> okay, this may seem a bit superfluous, but would be a very nice
> animation effect to have in one's toolbox..
>
> For those that don't know what a "write on" animation is,...you
> probably see them on TV everyday,..
> but it's when a whole sentence is displayed a character at time, with
> just a fraction of a second delay
> in-between each character...
>
> Thought this would be trivial at first,...but there's something going
> on in Qt that senses there's about to
> be a bunch of fast updates, so it waits until everything is done and
> updates *once*, which defeats the
> purpose....
>
> Here's how the madness unfolds,..
>
> text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed
> diam nonummy nibh euismod tincidunt ut laoreet"
>
> accum = QString("")
>
> for i in range(0, len(text)):
> accum = accum + text[i]
> self.label.setText(accum)
> self.label.update()
> sleep(.1)
>
> So, I accumulate the string char by char calling update() and sleep()
> at each interval,...a button triggers this function.
> But instead of seeing the effect progress as expected, it just
> display the whole string at once...
> Anybody got any ideas how to achieve this effect ?
the sleep function causes the main thread (GUI thread) to be blocked,
so the widget is not repainted. It only repaints when the for-loop has
terminated, and thus shows the full string at once.
A solution would be to use a timer that regularly updates the label text
(attached).
--
Wilbert Berendsen
(http://www.wilbertberendsen.nl)
#!/usr/bin/env python
import os
import sys
from PyQt4 import QtCore, QtGui, uic
from PyQt4.QtCore import ( QString )
class BasicWindow(QtGui.QMainWindow):
def __init__(self, parent=None):
super(BasicWindow, self).__init__(parent)
#self.setupUi(self)
self.label = QtGui.QLabel(self)
self.label.setGeometry(QtCore.QRect(73, 110, 574, 331))
self.pushButton = QtGui.QPushButton(self)
self.pushButton.setGeometry(QtCore.QRect(66, 30, 75, 27))
self.pushButton.setText("DoIt")
scrX = 2048
scrY = 1150
winX = 720
winY = 530
pX = (scrX - winX) / 2
pY = (scrY - winY) / 2
self.setGeometry(pX, pY, winX, winY)
self.label.setText('')
self.pushButton.clicked.connect(self.DoIt)
self.timer = QtCore.QTimer(interval=50, timeout=self.timeout)
def DoIt(self):
self.textGen = self.generateText()
self.timer.start()
def generateText(self):
text = "Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna"
for i in range(len(text)):
yield text[:i]
def timeout(self):
for accum in self.textGen:
self.label.setText(accum)
return
self.timer.stop()
def main():
app = QtGui.QApplication(sys.argv)
form = BasicWindow()
form.show()
app.exec_()
if __name__ == '__main__':
main()
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