zmap_GetDataPtr

Retrieve the raw handle to map memory.

void* zmap_GetDataPtr(ZMAP hMap);

A null pointer if:

• The map is not allocated.
• The map is a mosaic (there is no contiguous memory in a mosaic; use zmap_tile_GetDataPtr instead).
• The map is non-contiguous (test with zmap_IsContiguous, and use zmap_GetScanlinePtr to retrieve memory address instead).
• An unspecified error occurred.

A valid (non-null) pointer otherwise.

Pixels are ordered in rows going east-to-west, with rows ordered south to north. To convert from x/y coordinate to memory offset, use the following formula:

long offset = (x + nx * y) * PixelMemSize;

…where ny is the map width (in pixels) and PixelMemSize is the size in memory of one pixel (see zmap_GetPixelSize).

To convert from memory offsets to pixel coordinates, use the following formulae:

long x = (offset/PixelMemSize)%nx;
long y = (offset/PixelMemSize)/nx;

It is recommended that, wherever possible, the zmap_GetPixel / zmap_SetPixel functions are used for accessing map data, instead of direct memory access with zmap_GetDataPtr. Those functions include coordinate checking and memory protection, as well has handling mip-mapping and mosaic tile cache loading/saving and automatically.