====== QueryGraphicsList ======

Returns graphics environment information.

==== Synopsis ====

''%%Err QueryGraphicsList (TagArg *ta) Err QueryGraphicsListVA (uint32 ta,...)%%''

==== Description ====

The call looks up values in the environment passed in the ta_Tag elements of the TagArg array, and deposits those values to which addresses the ta_Arg associated values point.

The currently available tags and their return values follow:

  * QUERYGRAF_TAG_END - No return value. Ends processing of the tag list.
  * 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 nsec.
  * 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 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 ====

''%%QueryGraphics%%''()