Copy images, quickly, between two windows (on- or off- screen).
Content from onscreen windows is copied from the onscreen windows back buffer,
or the onscreen windows draw buffer if the imaging pipeline is enabled, but
never from the onscreen windows front buffer.
srcRect and dstRect are set to the size of windows srcWindowPtr and dstWindowPtr
by default. [copyMode] is accepted as input but currently ignored.
CopyWindow is mostly here for compatibility to PTB-2. If you want to copy images
really quickly, use the ‘MakeTexture’ and ‘DrawTexture’ commands. They also
allow for rotated drawing and advanced blending operations.
The current CopyWindow implementation has a couple of restrictions on old
graphics cards, which may not apply anymore on modern cards:
One can’t copy from an offscreen window into the -same- offscreen window.
One can’t copy from an onscreen window into a -different- onscreen window.
Sizes of sourceRect and targetRect need to match for Onscreen->Offscreen copy.