[PyQt] Size for hint label

[Mads Ipsen]

Hi,

4-5 years I needed a widget with the following properties:

 * Display text incl. HTML
 * Text should be wrapped on several lines
 * When the widget is put into a layout, the height of the widget
   should be adjusted in such a way that the text exactly fits the
   widget geometry

This subwidget should be used in a layout to provide some detail on how 
the other GUI elements in the layout work but only consume a minimum 
space to display its content.


I thought this was an easy one - but each time I return to the challenge 
I always end by giving up.


The main problem is that the layout breaks down when heightForWidth() is 
implemented and a QSizePolicy with setHeightForWidth(True) is used. It 
can shrink to infinitely small. Apparently this is Qt bug.


Another approach is to call updateGeometry() when a resizeEvent() occurs 
and call setFixedHeight(h) using a width dependent height. But this also 
gives rise to some weird layout behavior.


If anybody has any good suggestions on how to approach this, please let 
me know.


I attach a small snippet that reproduces the layout resizing behavior.

Best regards,

Mads

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import sys
from PyQt4 import QtCore, QtGui

class Square(QtGui.QLabel):
def __init__(self, parent=None):
QtGui.QLabel.__init__(self, parent)
self.setAutoFillBackground(True)

palette = QtGui.QPalette()
palette.setColor(QtGui.QPalette.Window, QtGui.QColor('red'))
self.setPalette(palette)

policy = self.sizePolicy()
policy.setHeightForWidth(True)
self.setSizePolicy(policy)

def sizeHint(self):
return QtCore.QSize(128, 128)

def heightForWidth(self, width):
return width

class Widget(QtGui.QWidget):
def __init__(self, parent=None):
# Call base class constructor
QtGui.QWidget.__init__(self, parent)

# Add a layout
layout = QtGui.QVBoxLayout()
self.setLayout(layout)

# Add Square
label = Square()
layout.addWidget(label)

spacerItem = QtGui.QSpacerItem(20, 40, QtGui.QSizePolicy.Minimum, QtGui.QSizePolicy.Expanding)
layout.addItem(spacerItem)

# Some dummy button
self._push_button = QtGui.QPushButton('Press me')
layout.addWidget(self._push_button)

if __name__ == __main__:
app = QtGui.QApplication(sys.argv)

widget = Widget()
widget.show()

sys.exit(app.exec_())
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[PyQt] QTerminate and Python libs?

[David Cortesi]

The doc for QThread.terminate() says its use is discouraged.

I have a thread that calls urllib2 to read an http page. I am having a
problem where this thread gets hung somewhere in the urllib2 -- remains to
be determined whether in urllib2.urlopen() or in a read() on the resulting
object.

Anyway, I am thinking of implementing a Kill button so the main thread can
stop and recreate the worker threadin case of such a hang. But am puzzled
on several points:

1. Would .terminate of a QThread that is hung within a python lib, actually
achieve anything, i.e. break out of the python hang?

2. If it did exit the python lib code, would it be likely to leave python
itself (or PyQt or Sip) in some bad indeterminate state that would cause
further problems, e.g. when the thread is recreated and calls back into
urllib2?

3. What about QThread.exit() -- I can't figure out if it is meant for
calling from within the thread's code, or from outside it? Would it be of
use in a kill situation?

Any input would be helpful, thank you for your time.
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Re: [PyQt] HeightForWidth label

[Hans-Peter Jansen]

Dear Mads,

Am Mittwoch, 9. Januar 2013, 15:56:29 schrieb Mads Ipsen:
 Hi,
 
 4-5 years I needed a widget with the following properties:
 
   * Display text incl. HTML
   * Text should be wrapped on several lines
   * When the widget is put into a layout, the height of the widget
 should be adjusted in such a way that the text exactly fits the
 widget geometry
 
 This subwidget should be used in a layout to provide some detail on how
 the other GUI elements in the layout work but only consume a minimum
 space to display its content.
 
 I thought this was an easy one - but each time I return to the challenge
 I always end by giving up.
 
 The main problem is that the layout breaks down when heightForWidth() is
 implemented and a QSizePolicy with setHeightForWidth(True) is used. It
 can shrink to infinitely small. Apparently this is Qt bug.

Yes, been there, done that, and failed in similar ways.

The best thing I could come up on this was:

use a QTextBrowser for the text:


self.aboutText.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
self.aboutText.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
self.aboutText.setLineWrapMode(QtGui.QTextEdit.NoWrap)
self.aboutText.setSizePolicy(QtGui.QSizePolicy.Fixed, 
QtGui.QSizePolicy.Fixed)
self.aboutText.setHtml(...)

w = self.aboutText.document().idealWidth()
self.aboutText.document().setTextWidth(w)
ds = self.aboutText.document().size()
self.aboutText.setMinimumSize(int(ds.width() + 3), int(ds.height() + 3))
self.aboutText.updateGeometry()
self.layout().setSizeConstraint(QtGui.QLayout.SetFixedSize)

with this, you can even provide clickable links (but disable openLinks prop):

@QtCore.pyqtSignature(const QUrl )
def on_aboutText_anchorClicked(self, url):
QtGui.QDesktopServices.openUrl(url)

Maybe it gets you going..

Cheers,
Pete
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