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.

Help Version 19.0.2017.10.27

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LEADTOOLS Vector C API Help

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