====== tile_GetDataPtr ======

===== Description =====

Retrieve the raw data pointer for a mosaic tile.

===== Function prototype =====

<code>void* CExtAPI::tile_GetDataPtr(void* hTile);</code>

===== Arguments =====

^ Name ^ Type ^ Comment ^
| hTile | void* | A handle to a mosaic tile. |

===== Return value =====

A null pointer if:
  * The tile handle is invalid.
  * The tile has not been locked for use via [[zeolite:functions:tile_SetLock]] (this is automatic when loading/saving tiles).
A valid non-null pointer otherwise.

===== Comments =====

==== Pixel ordering ====

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:

<code>
long offset = (x + TileSize * y) * PixelMemSize;
</code>

...where //PixelMemSize// is the size in memory of one pixel (see [[zeolite:functions:map_GetPixelSize]]).

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

<code>
long x = (offset/PixelMemSize)%TileSize;
long y = (offset/PixelMemSize)/TileSize;
</code>

==== Use map_GetPixel/map_SetPixel where possible ====

It is recommended that, wherever possible, the [[zeolite:functions:tile_GetPixel]]/[[zeolite:functions:tile_SetPixel]] functions are used for accessing tile data, instead of direct memory access with tile_GetDataPtr. Those functions include coordinate checking and memory protection, as well has handling mip-mapping and mosaic tile cache loading/saving and automatically.