[wxPython-users] What does PrepareDC do in OGL example?

[Christopher Barker]

Armando Serrano Lombillo wrote:
> canvas.PrepareDC(dc)

>  "Call this function to prepare the device context for drawing a scrolled image", 

exactly. If your image is on a scrolled window, then you have two 
coordinate systems -- the "virtual" one and the actual pixel coords of 
the window in its current position. PrepareDC() sets up the DC to deal 
with that, so you can draw in the virtual coordinate system.

It may be that you've tested in only when the image wasn't scrolled, so 
it didn't make a difference then.

-Chris



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