Psychtoolbox>Screen.{mex*} subfunction

proxyPtr = Screen(‘OpenProxy’, windowPtr [, imagingmode]);

Create a proxy object. A proxy is a windowRecord (like a texture, offscreen
window or onscreen window), but without associated image content. Its useful as
a container for all the typical settings associated with a window or texture.
Its main purpose is to store additional hook function chains for use with the
imaging pipeline. The users script can create special proxy objects for
different image processing subtasks, attach proper user defined hook chains to
it, and then switch between different hook chains by simply passing different
proxy objects to the image processing functions. This way we are not limited to
a fixed number of imaging hooks but can create new ones dynamically. Read ‘help
PsychGLImageProcessing’ for more infos about proxies and the pipeline.

‘windowPtr’ is a handle to an associated parent onscreen window. Just pass the
handle of the onscreen window for which image processing is supposed to take
place. The routine returns a handle ‘proxyPtr’ to the new proxy object. You can
delete proxy objects via the regular Screen(‘Close’, proxyPtr) or
Screen(‘CloseAll’); command as you would do with textures or windows. You can
add or modify hook functions by passing the ‘proxyPtr’ to the
Screen(‘Hookfunction’, …) subfunction. You can apply a proxy via the
Screen(‘TransformTexture’) function. ‘imagingmode’ flags to define the boundary
conditions for image processing.

###See also: Hookfunction, TransformTexture