DD_SURFACE_GLOBAL

The DD_SURFACE_GLOBAL structure contains global surface-related data that can be shared between multiple surfaces.

typedef struct _DD_SURFACE_GLOBAL {
  DWORD  dwBlockSizeY;
  union {
  LPVIDEOMEMORY  lpVidMemHeap;
  DWORD  dwBlockSizeX;
  DWORD  dwUserMemSize;
  };
  FLATPTR  fpVidMem;
  union {
  LONG  lPitch;
  DWORD  dwLinearSize;
  };
  LONG  yHint;
  LONG  xHint;
  DWORD  wHeight;
  DWORD  wWidth;
  ULONG_PTR  dwReserved1;
  DDPIXELFORMAT  ddpfSurface;
  FLATPTR  fpHeapOffset;
  HANDLE  hCreatorProcess;
} DD_SURFACE_GLOBAL;

Members

dwBlockSizeY

Specifies the location in which the driver returns the height, in scanlines, of the offscreen memory block that DirectDraw should allocate. The driver should set this value when it returns DDHAL_PLEASEALLOC_BLOCKSIZE in the fpVidMem member.

lpVidMemHeap

Points to a VIDEOMEMORY structure from which the heap display memory was allocated.

dwBlockSizeX

Specifies the location in which the driver returns the size in bytes of the width of the offscreen memory block that DirectDraw should allocate. The driver should set this value when it returns DDHAL_PLEASEALLOC_BLOCKSIZE in the fpVidMem member.

dwUserMemSize

Specifies the location in which the driver returns the size in bytes of the memory block that DirectDraw should allocate in user-mode system memory. The driver should set this value when it returns DDHAL_PLEASEALLOC_USERMEM in the fpVidMem member.

fpVidMem

If the driver allocates the memory block, it should return the offset into display memory in this member. If the driver requests DirectDraw to do the memory allocation, it can instead return one of the following values in this member from its DdCreateSurface routine:

Value	Meaning
DDHAL_PLEASEALLOC_BLOCKSIZE	DirectDraw should allocate a memory block of size dwBlockSizeX and dwBlockSizeY in offscreen memory.
DDHAL_PLEASEALLOC_USERMEM	DirectDraw should allocate a memory block of size dwUserMemSize in user-mode memory.

dwLinearSize

Specifies the linear size of a non-rectangular surface.

lPitch

Specifies the pitch of the surface; that is, the distance in bytes to the start of the next line. This is also known as the stride of the surface.

yHint

Specifies the y-coordinate of the surface. This member is a 2D Cartesian coordinate specified in device space.

xHint

Specifies the x-coordinate of the surface. This member is a 2D Cartesian coordinate specified in device space.

wHeight

Specifies the height of the surface.

wWidth

Specifies the width of the surface.

dwReserved1

Reserved for use by the display driver.

ddpfSurface

Points to the DDPIXELFORMAT structure that describes the pixel format of the surface.

fpHeapOffset

Points to the raw offset in the source heap.

hCreatorProcess

Reserved for system use and should be ignored by the driver.

Headers

Defined in ddrawint.h. Include winddi.h.

Comments

A vertex buffer, which is created by CreateD3DBuffer, holds a list of vertices used by the D3dDrawPrimitives2 callback for rendering primitives. Windows represents vertex buffers as DirectDraw surfaces, thereby establishing a connection between vertex buffers and the DD_SURFACE_GLOBAL structure.

When a DirectX driver is working with a vertex buffer, it is important for it to be able to correctly determine the size of this buffer. DirectDraw passes the linear buffer size to the driver in the lPitch member of this structure. On Windows 2000 and later versions, but not on Windows 98/Me, the wWidth member of this structure is set to the same value. Note that both structure members should be considered to be read-only. The value that DirectDraw places in these members represents the minimum vertex buffer size. Should the need for a larger buffer arise (such as for optimization), a driver writer is free to create a buffer larger than that size. Under no circumstances, however, should the driver report the larger buffer size to DirectDraw.

DD_SURFACE_GLOBAL

Members

Headers

Comments

See Also