ImageGear for C and C++ on Linux v20.0 - Updated
API Reference Guide > ART Component API Reference > ART Component Functions Reference > Global Named Block Management Functions > ART_global_block_query

This function queries a global named block for its data returning it in lpBlockData.


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AT_ERRCOUNT ART_global_block_query(
        HIGEAR hIGear, 
        const LPART_BLOCK_NAME lpBlockName, 
        LPVOID lpBlockData, 
        LPDWORD lpBlockSize


Name Type Description
hIGear HIGEAR HIGEAR handle to the image.
lpBlockName const LPART_BLOCK_NAME A far pointer to an 8 byte array of memory that specifies the type of block to query. The block type is either an ART-defined constant beginning with ART_BLOCK or a user-defined block. See ARTAPI.H file for the full list of ART-defined constants.
lpBlockData LPVOID A far VOID pointer which returns block data.
lpBlockSize LPDWORD The size of lpBlockData (in bytes).

Return Value:

Returns the number of ImageGear errors that occurred during the function call.

Supported Raster Image Formats:

All pixel formats supported by ImageGear for C and C++.


Copy Code
HIGEAR hIGear; /* HIGEAR handle of image */
LPVOID blockData; /* data in global block  */
DWORD blockSize; /* size of block, in bytes */
AT_ERRCOUNT nErrCount; /* number of errors on the */
/* error stack  */
/* get the block size */
nErrCount = ART_global_block_query(hIGear, 
blockData = (LPVOID)alloca(blockSize);
/* but the data into blockData */
nErrCount = ART_global_block_query(hIGear, 
ART_BLOCK_GROUP, blockData, &blockSize);


The buffer pointed to by lpBlockData must be large enough to fit the named block data. The size of the block is returned by lpBlockSize.

To find the size of a buffer necessary to hold the block data, call ART_global_block_query() with lpBlockData set to NULL. lpBlockSize returns the size of the block.

An error is set if any of the following conditions are met:

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