SURFOBJ

The SURFOBJ structure is the user object for a surface. A device driver usually calls methods on a surface object only when the surface object represents a GDI bitmap or a device-managed surface.

typedef struct _SURFOBJ {
  DHSURF  dhsurf;
  HSURF  hsurf;
  DHPDEV  dhpdev;
  HDEV  hdev;
  SIZEL  sizlBitmap;
  ULONG  cjBits;
  PVOID  pvBits;
  PVOID  pvScan0;
  LONG  lDelta;
  ULONG  iUniq;
  ULONG  iBitmapFormat;
  USHORT  iType;
  USHORT  fjBitmap;
} SURFOBJ;

Members

dhsurf

Handle to a surface, provided that the surface is device-managed. Otherwise, this member is zero.

hsurf

Handle to the surface.

dhpdev

Identifies the device's PDEV that is associated with the specified surface.

hdev

GDI's logical handle to the PDEV associated with this device.

sizlBitmap

Specifies a SIZEL structure that contains the width and height, in pixels, of the surface. The SIZEL structure is identical to the SIZE structure.

cjBits

Specifies the size of the buffer pointed to by pvBits.

pvBits

If the surface is a standard format bitmap, this is a pointer to the surface's pixels. For BMF_JPEG or BMF_PNG images, this is a pointer to a buffer containing the image data in a JPEG or PNG format. Otherwise, this member is NULL.

pvScan0

Pointer to the first scan line of the bitmap. If iBitmapFormat is BMF_JPEG or BMF_PNG, this member is NULL.

lDelta

Specifies the count of bytes required to move down one scan line in the bitmap. If iBitmapFormat is BMF_JPEG or BMF_PNG, this member is NULL.

iUniq

Specifies the current state of the specified surface. Every time the surface changes, this value is incremented. This enables drivers to cache source surfaces.

For a surface that should not be cached, iUniq is set to zero. This value is used in conjunction with the BMF_DONTCACHE flag of fjBitmap.

iBitmapFormat

Specifies the standard format most closely matching this surface. If the iType member specifies a bitmap (STYPE_BITMAP), this member specifies its format. NT-based operating systems support a set of predefined formats, although applications can also send device-specific formats by using SetDIBitsToDevice. Supported predefined formats include the following:

Value	Meaning
BMF_1BPP	1 bit per pixel.
BMF_4BPP	4 bits per pixel.
BMF_8BPP	8 bits per pixel.
BMF_16BPP	16 bits per pixel.
BMF_24BPP	24 bits per pixel.
BMF_32BPP	32 bits per pixel.
BMF_4RLE	4 bits per pixel, run length encoded.
BMF_8RLE	8 bits per pixel, run length encoded.
BMF_JPEG	JPEG compressed image.
BMF_PNG	PNG compressed image.

iType

Surface type, which is one of the following:

Type	Definition
STYPE_BITMAP	The surface is a bitmap.
STYPE_DEVBITMAP	The surface is a device format bitmap.
STYPE_DEVICE	The surface is managed by the device.

fjBitmap

If the surface is of type STYPE_BITMAP and is a standard uncompressed format bitmap, the following flags can be set. Otherwise, this member should be ignored.

Value	Meaning
BMF_DONTCACHE	The bitmap should not be cached by the driver because it is a transient bitmap, created by GDI, that the driver will never see again. If this flag is set, the iUniq member of this structure will be set to 0.
BMF_KMSECTION	Is used by GDI only and should be ignored by the driver.
BMF_NOTSYSMEM	The bitmap is not in system memory. EngModifySurface sets this flag when it moves a bitmap into video memory.
BMF_NOZEROINIT	The bitmap was not zero-initialized.
BMF_TOPDOWN	The first scan line represents the top of the bitmap.
BMF_WINDOW_BLT	GDI sets this flag to notify the driver of a window move from one screen location to another.

Headers

Declared in winddi.h. Include winddi.h.

Comments

When information about a particular surface is required by a driver, the driver must access the SURFOBJ. This structure allows quick access to the properties of the surface.

When a SURFOBJ structure represents a GDI bitmap, the driver must be able to determine the format of the bitmap and locate the bitmap bits.

When a SURFOBJ structure represents a device surface, the driver must be able to locate the device handle for the surface.

For more information about supporting JPEG and PNG compressed images, see DEVINFO.