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.