Working with Layers

Start with the project you created in Implementing Hit Testing.

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

1. Click the "Class View" tab of the project workspace.

2. Click to open the MyVectorWindow branch.

3. Double-click the MsgProcCallBack () member function.

4. Declare the following variables local to the MsgProcCallBack() function.

   L_INT  nIndex; 
   LVectorLayer  Layer; 
   VECTORLAYERDESC  LayerDesc; 

5. Add the following code immediately before case 'b':

   case '1': 
   case '2': 
   { 
      // get layer from index 
      if( wParam == '1' ) 
         nIndex = 0; 
      else 
         nIndex = 1; 
       
      GetLayerByIndex (nIndex, &Layer ); 
      // flip the visible state of the layer 
      Layer.GetLayerDesc (&LayerDesc); 
      LayerDesc.bVisible =!LayerDesc.bVisible; 
      Layer.SetLayerDesc (&LayerDesc); 
      InvalidateRect( hWnd, NULL, FALSE ); 
   } 
   break; 

6. Compile and run the demo.

7. 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.