Hi peeps,
I'm playing around with QPlainTextEdit and having the weirdest bug.
In my application, I've got keyboard shortcuts to scroll the TextEdit up and
down by way of the QScrollBar.triggerAction() method, with arguments of
SliderPageStepSub and SliderPageStepAdd respectively.
I also need to do some stuff when the scrollbar moves, so I bind the
scrollbar's valueChanged() signal to the appropriate method.
It works all fine when the TextEdit is a QTextEdit.
It no longer works when the TextEdit is a QPlainTextEdit.
This is really bizarre, because the signal is emitted just fine when:
- I move the slider around with the mouse;
- I scroll with the mouse wheel;
- I trigger the SliderSingleStepAdd/Sub actions instead (with Single instead
of Page).
And before you bring up QScrollBar.setTracking, I used it and it doesn't
change anything.
You will find a test case attached herein. Click the buttons to scroll up and
down. Then do the same with the mouse. Compare.
This is with Qt 4.5.2 and SIP 4.9.1-snapshot-20091015 (the default Ubuntu
version).
Anybody has any idea what's going on there? A Qt bug maybe?
Thanks.
-- S.
#!/usr/bin/python
## -*- coding: utf-8 -*-
import sys
import sip
from PyQt4 import QtCore, QtGui
class ExampleWidget( QtGui.QWidget ):
def __init__( s ):
QtGui.QWidget.__init__( s )
layout = QtGui.QHBoxLayout( s )
## Create widgets for left column:
l1 = QtGui.QVBoxLayout()
layout.addLayout( l1 )
s.text1 = QtGui.QTextEdit( s )
s.text1.setPlainText( u"Some text here.\n" * 100 )
b1up = QtGui.QPushButton( "Scroll up!", s )
b1down = QtGui.QPushButton( "Scroll down!", s )
l1.addWidget( s.text1 )
l1.addWidget( b1up )
l1.addWidget( b1down )
s.connect( b1up, QtCore.SIGNAL( "clicked()" ), s.text1Up )
s.connect( b1down, QtCore.SIGNAL( "clicked()" ), s.text1Down )
## Create widgets for right column:
l2 = QtGui.QVBoxLayout()
layout.addLayout( l2 )
s.text2 = QtGui.QPlainTextEdit( s )
s.text2.setPlainText( u"Some other text here.\n" * 100 )
b2up = QtGui.QPushButton( "Scroll up!", s )
b2down = QtGui.QPushButton( "Scroll down!", s )
l2.addWidget( s.text2 )
l2.addWidget( b2up )
l2.addWidget( b2down )
s.connect( b2up, QtCore.SIGNAL( "clicked()" ), s.text2Up )
s.connect( b2down, QtCore.SIGNAL( "clicked()" ), s.text2Down )
## And set up the connections that demonstrate the bug:
s.connect( s.text1.verticalScrollBar(), \
QtCore.SIGNAL( "valueChanged( int )" ), s.hasValueChanged1 )
s.connect( s.text2.verticalScrollBar(), \
QtCore.SIGNAL( "valueChanged( int )" ), s.hasValueChanged2 )
def hasValueChanged1( s, val ):
print "QTextEdit has scrolled to position %d." % val
def hasValueChanged2( s, val ):
print "QPlainTextEdit has scrolled to position %d." % val
def text1Up( s ):
sb = s.text1.verticalScrollBar()
sb.triggerAction( QtGui.QAbstractSlider.SliderPageStepSub )
def text1Down( s ):
sb = s.text1.verticalScrollBar()
sb.triggerAction( QtGui.QAbstractSlider.SliderPageStepAdd )
def text2Up( s ):
sb = s.text2.verticalScrollBar()
sb.triggerAction( QtGui.QAbstractSlider.SliderPageStepSub )
def text2Down( s ):
sb = s.text2.verticalScrollBar()
sb.triggerAction( QtGui.QAbstractSlider.SliderPageStepAdd )
app = QtGui.QApplication( sys.argv )
widget = ExampleWidget()
widget.show()
app.exec_()
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