STARTDECOMPRESSDATA

typedef struct _STARTDECOMPRESSDATA 
{ 
   L_UINT uStructSize; 
   pBITMAPHANDLE pBitmap; 
   L_UINT uBitmapStructSize; 
   L_UINT uStripsOrTiles; 
   L_UINT uFormat; 
   L_INT nWidth; 
   L_INT nHeight; 
   L_INT nBitsPerPixel; 
   L_INT nViewPerspective; 
   L_INT nRawOrder; 
   L_INT nLoadOrder; 
   L_INT nXResolution; 
   L_INT nYResolution; 
   FILEREADCALLBACK pfnReadCallback; 
   L_RGBQUAD Palette[256]; 
   L_UINT uFlags; 
   L_VOID* pUserData; 
   L_UINT rgbColorMask[3]; 
   L_INT nPhotoInt; 
   L_INT nPlanarConfig; 
   L_UINT uReserved1; 
} STARTDECOMPRESSDATA, *pSTARTDECOMPRESSDATA; 

The STARTDECOMPRESSDATA structure provides decompression to the L_StartDecompressBuffer function.

Members

uStructSize

Size of this structure in bytes, for versioning. Use the sizeof() operator to calculate this value.

pBitmap

Pointer to the bitmap handle in which to load the image.

uBitmapStructSize

Size of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).

uStripsOrTiles

Flag that indicates whether strips or tiles are being decompressed. Strips have a width equal to the bitmap width, but tiles can have a width that is less than the bitmap width. Possible values are:

uFormat

Format of the image to decompress. Possible values are:

nWidth

Bitmap width.

nHeight

Bitmap height.

nBitsPerPixel

Bits per pixel of the compressed data.

nViewPerspective

View perspective of the compressed data. Possible values are:

nRawOrder

Color order of 24-bit raw data. This is ignored if the image is palettized. Possible values are:

nLoadOrder

Desired color order after a 24-bit image is loaded. This is ignored if the image is palettized. Possible values are:

nXResolution

Horizontal resolution, in dots per inch.

nYResolution

Vertical resolution, in dots per inch.

pfnReadCallback

Optional callback function for additional processing.

If you do not provide a callback function, use NULL as the value of this parameter.

If you do provide a callback function, use the function pointer as the value of this parameter.

The callback function must adhere to the function prototype described in FILEREADCALLBACK Function.

Palette

Palette for uncompressed data that is 8 bits per pixel or less. Fill in the first 2BitsPerPixel entries in this palette and include DECOMPRESS_PALETTE in the uFlags field.

uFlags

Flags that affect the decompression process. Possible values are:

pUserData

Void pointer that you can use to pass one or more additional parameters that the callback function needs.

To use this feature, assign a value to a variable or create a structure that contains as many fields as you need. Then, in this parameter, pass the address of the variable or structure, casting it to L_VOID *. The callback function, which receives the address in its own pUserData parameter, can cast it to a pointer of the appropriate data type to access your variable or structure.

If the additional parameters are not needed, you can pass NULL in this parameter.

rgbColorMask

An array of L_UINT32 values that represent RGB color masks. rgbColorMask[0] is the red mask; rgbColorMask[1] is the green mask; rgbColorMask[2] is the blue mask. This field is valid only if uFormat is FILE_RAW_BITFIELDS.

nPhotoInt

Value that represents color information. Possible values are:

For FILE_RAW_CCITT, FILE_RAW_G3_1D, FILE_RAW_G3_2D and FILE_FAX_G4

For FILE_RAW_PACKBITS

nPlanarConfig

Planar configuration. This value is used only if uFormat is FILE_RAW_PACKBITS. Otherwise, it is ignored. Possible values are:

uReserved1

Reserved for future use. Pass 0.

Comments

As an example, with 16-bit data arranged as RRR RRGG GGGB BBBB, the masks would be:

rgbColorMask[0] = 0x7C00
rgbColorMask[1] = 0x0E30
rgbColorMask[2] = 0x001F

For 32-bit data, the only valid data is RRRR RRRR GGGG GGGG BBBB BBBB. The masks would be:

rgbColorMask[0] = 0xFF0000
rgbColorMask[1] = 0x00FF00
rgbColorMask[2] = 0x0000FF

Some functions which take this structure as a parameter require that the structure be initialized prior to the function call. You must set the uStructSize member to the total size, in bytes, of the structure. Use the sizeof() operator to calculate this value. Functions that do not require the structure be initialized will take the total size of the structure, in bytes, as an additional function parameter.