On Tuesday 18 March 2008 02:30:29 pm Michael Droettboom wrote: > Darren Dale wrote: > > I discovered another blitting bug in backend_qt4agg.py. Qt expects a > > pixmap stringBuffer formatted in ARGB, but mpl formats in RGBA. The qt4 > > backend usually uses the _renderer.tostring_bgra method to return a > > properly formatted buffer: > > > > if QtCore.QSysInfo.ByteOrder == QtCore.QSysInfo.LittleEndian: > > stringBuffer = self.renderer._renderer.tostring_bgra() > > else: > > stringBuffer = self.renderer._renderer.tostring_argb() > > > > The problem I am seeing is when we are blitting, and the tostring_bgra is > > not available. > > The blitting code in backend_qt4agg.py, starting around line 112, > > gets a buffer from a region copied from a bbox: > > > > reg = self.copy_from_bbox(bbox) > > stringBuffer = reg.to_string() > > qImage = QtGui.QImage(stringBuffer, w, h, QtGui.QImage.Format_ARGB32) > > > > reg does not have a method to swap the byte order, and Qt does not have a > > Format_RGBA32. Could anyone suggest how to swap the byte order? > > There might be some numpy "trick" to massage the data. However, it > looks to me like BufferRegion (in _backend_agg.cpp) needs to grow a > byte-swapped version of to_string()... but maybe someone with more > experience with the Qt backend has a better idea whether this used to > work and why it may have stopped working.
Thanks for responding. I don't think it ever worked properly with the Qt backends. I just dropped back to the maintenance branch to check the following script: from matplotlib import rcParams rcParams['backend']='qt4agg' from pylab import * from matplotlib.widgets import Cursor ax=axes() ax.plot([1, 2, 3, 4, 5], 'ro', ms=10) cursor = Cursor(ax, useblit=True) show() and it shows the same behavior. Darren ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
