Working with Layers

Take the following steps to show/hide layers from a vector drawing:

Start with the project you created in Implementing Hit Testing.

1. Add these local variables under the HDC hDC; statement in the WndProc function:

   L_INT nIndex;   
   VECTORLAYER Layer;   
   VECTORLAYERDESC LayerDesc; 

2. Add the following lines in WM_CREATE handler right after L_VecInit ( &Vector ); statement:

   L_VecLoadFile (MAKE_IMAGE_PATH(TEXT("random.dxf")), &Vector, NULL, NULL ); 

3. Add the following lines before the case 'x' statement of the WM_CHAR message:

      case '1':   
      case '2':   
     // get layer from index   
     if( wParam == '1' )   
      nIndex = 0;   
     else   
      nIndex = 1;   
     L_VecGetLayerByIndex ( &Vector, nIndex, &Layer );   
     L_VecGetLayer ( &Vector, &Layer, &LayerDesc );   
     // flip the visible state of the layer   
     LayerDesc.bVisible = !LayerDesc.bVisible;   
     // update   
     L_VecSetLayer ( &Vector, &Layer, &LayerDesc );   
     L_VecFreeLayer ( &LayerDesc );   
     InvalidateRect( hWnd, NULL, FALSE );   
     break; 

4. Compile and run the demo.

5. The sample image (random.dxf) shipped with LEADTOOLS has 2 layers. You should be able to hide/show those layers by pressing 1 and 2 on your keyboard.