On 08/28/06 12:19, Christopher Barker wrote: > > wx is really due for an update to support alpha properly. But I guess > you'll always have problems with different data formats.
I think they added preliminary support for alpha channels in 2.5, in the form of wx.Image.HasAlpha(). My beef is that you have to convert everything to a wx.Bitmap before you can do anything useful with it. > Anyway, this thread started because people were having binary > compatibility issues. Even if this doesn't speed up the accelerator, it > may be possible to get the same performance without using > wx-version-specific compiled code -- i.e. pure python. As near as I can tell, the primary slowdown at this point is the way wxWidgets distinguishes from RGB image data (wx.Image) as opposed to displayed image data (wx.Bitmap). Right now you cannot draw a wx.Image without first converting it into a wx.Bitmap, nor can you use a MemoryDC to blit or otherwise munge a wx.Image directly. My impression is that this made sense when wxWindows was getting started (Win16 and Motif), but is more of an artificial distinction at this point. I don't think we're going to be able to get performance similar to that of the accelerator using straight Python code unless something changes in the wxWidgets' Image/Bitmap/MemoryDC department. That being said, I'd love to be proven wrong! If you're interested in the gory details, you should check out the pure-Python implementation of the image conversion functions, at the end of `backend_wxagg.py'. > I do have one question -- does the agg back-end really need to use an > alpha channel for it's buffer? Isn't it the whole image anyway? What is > is it going to get blended with? I don't know enough about Agg to venture an educated guess. My un-educated guess is that there's an RGBA buffer to support alpha in the drawing operations... how can Agg alpha-composite new pixels into the buffer when you draw something, unless you know the alpha values of the existing pixels? Ken ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
