Ole wrote: My interpretation of this is: - the FigureCanvas gets the first resize event and repaints itself (*) - during the repaint it gets the second resize event - since it is already in the repaint process, the second request is ignored (or queued) and returns immediately - this leads to the processing of the second resize for the scrollbar - after the first repaint (*) is finished, the first resize of the scrollbar is started
Remember, this is not a multi-threaded system. You can't receive a second repaint event while the drawing code is happening because the event loop is not in a separate thread. You can make calls that will put a repaint event on the X event queue. When the resize code is finished, the event queue will then be processed in the order they were received. I'd guess that something in your repaint/drawing code is changing the size of the widgets which is probably should not be doing. From: Darren Dale [mailto:dsdal...@gmail.com] Sent: Thursday, May 28, 2009 8:57 AM To: Ole Streicher Cc: matplotlib-users@lists.sourceforge.net Subject: Re: [Matplotlib-users] Strange resize behaviour for qt backend On Thu, May 28, 2009 at 7:55 AM, Ole Streicher <ole-usenet-s...@gmx.net<mailto:ole-usenet-s...@gmx.net>> wrote: Hi again, is there no idea on this topic? Does the update work for you as it should? I am really busy with other things, and can't offer suggestions unless you post a short, simple, standalone script that demonstrates the problem. Darren I started to debugging it a bit by adding debug output to the moveEvent()/resizeEvent() functions. I seems that the resizeEvents (resp. moveEvents) come out of order. The following comes when one resizes the window width: figure resize to PyQt4.QtCore.QSize(803, 474) <-- first event figure resize to PyQt4.QtCore.QSize(879, 474) <-- second event scroll resize to PyQt4.QtCore.QSize(879, 15) <-- second event (wrong!!) scroll resize to PyQt4.QtCore.QSize(803, 15) <-- first event My interpretation of this is: - the FigureCanvas gets the first resize event and repaints itself (*) - during the repaint it gets the second resize event - since it is already in the repaint process, the second request is ignored (or queued) and returns immediately - this leads to the processing of the second resize for the scrollbar - after the first repaint (*) is finished, the first resize of the scrollbar is started Who should be blamed for that? Is it - Qt since they dont distribute the events in the order of occurrence to the layout childs? - or FigureCanvas since it returns from the secons call while the first one is not finished yet? How can I workaround this? Best regards, Ole Ole Streicher <ole-usenet-s...@gmx.net<mailto:ole-usenet-s...@gmx.net>> writes: > Hi, > > I am using matplotlib for some data vizualization. To ensure a > consistent user interface among the whole application, I do the > scrolling/zooming stuff myself. So, for a diagram, a horizontal > scrollbar is displayed below the diagram that enabled to shift along the > x axis. This is (part of) the code: > > ------------------------8<----------------------------------------------- > from PyQt4 import QtGui, QtCore > from matplotlib.figure import Figure,SubplotParams > > class DiagramWidget(QtGui.QWidget): > def __init__(self, parent): > QtGui.QWidget.__init__(self, parent) > layout = QtGui.QVBoxLayout(self) > self.diagram = InnerDiagramWidget(self) > self.scrollbar = QtGui.QScrollBar(QtCore.Qt.Horizontal, self) > self.connect(self.scrollbar, QtCore.SIGNAL('valueChanged(int)'), > self.diagram.scroll_event) > layout.addWidget(self.diagram) > layout.addWidget(self.scrollbar) > # ... > > class InnerDiagramWidget(FigureCanvas): > def __init__(self, parent): > fig = Figure(facecolor = 'w', > subplotpars = SubplotParams(left = 0.08, right=0.96, > bottom = 0.1, top=0.98)) > self.axes = fig.add_subplot(111) > FigureCanvas.__init__(self, fig) > FigureCanvas.setParent(self, parent) > FigureCanvas.setSizePolicy(self, > QtGui.QSizePolicy.Expanding, > QtGui.QSizePolicy.Expanding) > FigureCanvas.updateGeometry(self) > > def scroll_event(self, x): > pass # here is real code ofcourse > # ... > ------------------------8<----------------------------------------------- > > However, when I put this DiagramWidget into a window and try to resize > it vertically by mouse (with some data ... about 4000 points), the > scrollbar is not alwas shown correctly. > > One can see that the diagram widget size does not change with every mouse > move, and the scrollbar sometimes goes out of the visible window, where > it is unusable. > > The similar occurres in the horizontal direction: sometimes the > scrollbar gets not updated properly. This is the case when the Figure > canvas takes a long time for update. > > If I put the scrollbar on top of the widget, everything is fine, except > that is the wrong place for a scrollbar :-) > > Is this a bug in FigureCanvas, in Qt or in my code? How can I debug and > solve this? > > Best regards > > Ole > > > ------------------------------------------------------------------------------ > Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT > is a gathering of tech-side developers & brand creativity professionals. Meet > the minds behind Google Creative Lab, Visual Complexity, Processing, & > iPhoneDevCamp as they present alongside digital heavyweights like Barbarian > Group, R/GA, & Big Spaceship. http://p.sf.net/sfu/creativitycat-com ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. 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