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; 

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

    case '1': 
    case '2': 
       // get layer from index 
       if( wParam == '1' ) 
          nIndex = 0; 
          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 ); 

  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.

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LEADTOOLS Vector C++ Class Library Help