QueryGraphics
Gets graphics environment information.
Synopsis
Err QueryGraphics (int32 tag,void *ret)
Description
QueryGraphics() looks up a value in the environment based on the passed-in tag and deposits that value in the address pointed to by ret.
Tag Arguments
- The currently available tag arguments and their return values follow:
- QUERYGRAF_TAG_END - No return value.
- QUERYGRAF_TAG_FIELDFREQ - int32 - Returns the display field frequency (in Hz) of the current environment. The return value is 60 for NTSC and 50 for PAL.
- QUERYGRAF_TAG_FIELDTIME - int32 - Returns the length of time for a single video display in usec.
- QUERYGRAF_TAG_FIELDCOUNT - uint32 - Returns a number that is incremented every vblank period.
- QUERYGRAF_TAG_DEFAULTWIDTH - int32 - Returns the default display width for the current hardware. The return value is 320 on every machine that is capable of generating a 320-pixel-wide display. This may not be the preferred width for the environment (PAL for example).
- QUERYGRAF_TAG_DEFAULTHEIGHT - int32 - Returns the default display height for the current hardware. The return value is 240 on every machine that is capable of generating a 240-line-tall display. This may not be the preferred height for the environment (PAL for example).
- QUERYGRAF_TAG_DEFAULTDISPLAYTYPE - int32 - Returns the default display type in the environment. DI_TYPE_NTSC is returned on current NTSC machines. DI_TYPE_PAL1 is returned on current PAL machines.
Arguments
- tag
- Tag number indicating information requested.
- ret
- Pointer to the location in memory where the requested value is deposited.
Return Value
The call returns 0 if successful or an error code (a negative value) if an error occurred.
- GRAFERR_BADTAG is returned if an unknown tag is passed in.
Implementation
Folio call implemented in Graphics folio V21.
Associated Files
graphics.h, graphics.lib
See Also
QueryGraphicsList()