## Graphics Adapter Device Driver Reference

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### GRADD Model Components

This chapter describes the individual components of the Graphics ADapter Device (GRADD) driver model used for developing device drivers.

The GRADD model is composed of several components that coordinate the communication among each graphic subsystem and the available graphics hardware. The components include the following:

Video Manager (VMAN) The VMAN component binds the GRADD model components together. VMAN synchronizes the communication between translation layers and a GRADD and also manages the graphics pointer.

When an operating system service requests a graphics operation, the associated translation layer sends one of the defined Video Manager Interface (VMI) commands to VMAN. On receiving a VMI command, VMAN either handles the request or sends it down to the appropriate GRADD. For more information about VMAN, refer to Video Manager (VMAN).

Translation Layers A translation layer exists for each graphics engine in OS/2 Warp. The translation layer converts the function calls made by the graphics engine to the VMI protocol required by VMAN. For more information about transition layers, refer to Translation Layers.

SOFTDRAW SOFTDRAW is the default for any simulated graphics functions for nonaccelerated graphics operations.

Acting as a graphics library, SOFTDRAW exports the base drawing functions ( SDBitBlt and SDLine) used by VMAN to simulate graphics operations. SOFTDRAW provides a generic graphics library. Given a pointer to a linear address (a VRAM bit map or system-memory bit map), SOFTDRAW can draw the bits directly into the bit map.

Graphics Adapter Device Driver The GRADDs represent the available video hardware. They execute the requested operation or returns it for simulation.

When a GRADD receives a GHI function call from VMAN that is not mandatory, the GRADD has the option of performing the requested operation or returning the request to VMAN with a return code of RC_SIMULATE. The RC_SIMULATE return code informs VMAN that the operation needs to be simulated in software. For more information about GRADDs, refer to Graphics Adapter Device Driver (GRADD).

The following figure graphically illustrates the components of the GRADD model. [Artwork not shown]