PdCreateOffscreenContext()

Create an offscreen context in video RAM

Synopsis:

PdOffscreenContext_t *PdCreateOffscreenContext(
                         unsigned long ImageType,
                         unsigned short width,
                         unsigned short height, 
                         unsigned long flags );

Arguments:

ImageType

The type of image. This must currently be 0; the image type is defined by the current video mode.

width, height

The dimensions of the context, in pixels.

flags

Additional parameters to be used in the creation of the context:

Pg_OSC_CRTC_SAFE -- tell the driver that you want to be able to point the CRT at this context at a later date (using PgSwapDisplay()).
The driver may change the dimensions and/or image type of the context in order to comply with this flag.
Pg_OSC_MAIN_DISPLAY -- create an offscreen context from the currently displayed screen. It doesn't make a new offscreen context in video ram, but just wraps the displayed screen with a PdOffscreenContext_t structure.
Pg_OSC_MEM_PAGE_ALIGN -- Ensure that the offscreen context that's created is aligned to __PAGESIZE (4K on an x86). You need to specify this flag in order to use PdGetOffscreenContextPtr() with this context.

Library:

ph

Description:

This function creates an offscreen context in video RAM.

You must target this function at a specific card by calling PdSetTargetDevice(). PdCreateOffscreenContext() blocks until the operation is complete.

If there isn't enough space in video RAM to create the offscreen context, the behavior of this function depends on the driver; most drivers allocate space in system memory instead.

Returns:

A pointer to a PdOffscreenContext_t, or NULL if an error occurred.

Classification:

Photon

Safety:
Interrupt handler	No
Signal handler	No
Thread	No