L_VecEnumLayers

Summary

Enumerates all layers inside a vector handle.

Syntax

L_LVKRN_API L_INT L_VecEnumLayers(pVector, pEnumProc, pUserData)

Parameters

pVECTORHANDLE pVector

Pointer to a vector handle. The layers within this vector handle will be enumerated.

pVECTORENUMLAYERSPROC pEnumProc

Pointer to the callback function used to enumerate the layers within the vector handle. The callback function must adhere to the function prototype described in VECTORENUMLAYERSPROC.

L_VOID * 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.

Returns

Comments

The L_VecEnumLayers function calls the callback function as it gets the handle of each vector layer.

Required DLLs and Libraries

• LTVKRN
• For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

See Also

Functions

• VECTORENUMLAYERSPROC

Topics

• Working with Vector Layers

Example

This example will show the names of all layers inside a vector handle.

L_INT EXT_CALLBACK MyEnumLayersProc( 
   pVECTORHANDLE pVector, 
   pVECTORLAYER pLayer, 
   L_VOID* pUserData) 
{ 
   L_INT nRet; 
   VECTORLAYERDESC   LayerDesc; 
 
   UNREFERENCED_PARAMETER( pUserData ); 
 
   /* show layer name */ 
   nRet = L_VecGetLayer( pVector, pLayer, &LayerDesc ); 
   if(nRet != SUCCESS) 
      return nRet; 
 
   MessageBox( NULL, LayerDesc.szName, TEXT("Layer Name"), MB_OK ); 
   nRet = L_VecFreeLayer( &LayerDesc ); 
 
   /* Continue enumerating */ 
   return nRet; 
} 
 
L_LTVKRNTEX_API L_INT VecEnumLayersCBExample(pVECTORHANDLE pVector) 
{ 
   L_INT nRet; 
 
   /* Enumerate all layers */ 
   nRet = L_VecEnumLayers( pVector, (pVECTORENUMLAYERSPROC)MyEnumLayersProc, NULL ); 
 
   return nRet; 
 
}