Working with layers

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 ( TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS EVAL 15\\Images\\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.