On 08/31/06 13:43, Christopher Barker wrote: > Ken McIvor wrote: > > a wxBitmap is the same format as the native rendering system. While most > systems use 24b RGB (or 32b RGBA), people can still run displays at > 16bpp or whatever, so it's still needed. I can understand why it's still necessary, although it's nice to sometimes pretend that everyone's running 24-bit color displays. I hope I didn't sound too judgemental! >>I don't think we're going to be able to get performance similar to that >>of the accelerator using straight Python code > > But whether it's Python or C++, you still need to do the Image->Bitmap > conversion -- so if we can get rid of the data copying from Agg buffer > to wxImage in Python, we don't need C++. I think we got some wires crossed at some point in the conversation, although it could be that I'm wearing the Stupid Hat today. I was talking about the image-from-a-buffer business not helping us with WX 2.4/2.6 due to the RGBA to RGB conversion. > And it has. For wxPython 2.7 (and now in CVS) there are methods for > dumping 32 bit RGBA data directly into a wxBitmap with no copying, if > the data source is a Python Buffer object. I think I posted a note about > this here yesterday. Yes, you did mention it. I agree completely with this analysis of the situation. When I replied I wasn't thinking in terms of wxPython 2.7. > To really get it to work, the 24bit RGB Agg buffer needs to be a Python > Buffer object -- is it now? I'm sorry I don't have the time to mess with > this now -- maybe some day. I guess Guido lets John borrow his time machine, because RendererAgg appears to already have a buffer_rgba() method. > You can alpha composite into a non-alpha background. You just lose the > alpha there, so that the background couldn't be alpha-composited onto > anything else -- but does it ever need to be? I thought that the buffer's accumulated alpha played a role in compositing new pixels onto it, but I apparently misunderstood. It must be time to read "Compositing Digital Images. Anyway, if the buffer's alpha channel isn't used, then the whole situation does seem a bit odd. Could the information be retained for PNGs or something? > However, there is something to be said for just using alpha everywhere, > and as we'll soon be able to dump RGBA data straight into a wx.Bitmap, > this should work great. Yes, it will be a great improvement over the current situation. Ken