Adding and Displaying Vector Objects

To add a new layer and objects to the vector handle:

Start with the project you created in Implementing Hit Testing.

Note: This tutorial will only use 3 types of objects (Line, Ellipse and Polygon) to keep things simple. For more information about the vector object types supported by the toolkit, refer to the VECTOROBJECT structure.

1. Comment out these local variables from the WndProc function:

   static OPENFILENAME OpenFileName; 
   static L_TCHAR szFileName[ _MAX_PATH ]; 
   static L_TCHAR szFileTitle[ _MAX_PATH ]; 
   static L_TCHAR *szFilter[] = { TEXT("All Files\0*.*\0") }; 

2. Comment out these lines from WM_CREATE handler:

   // reset the OPENFILENAME structure   
   memset( &OpenFileName, 0, sizeof( OPENFILENAME ) );   
   OpenFileName.lStructSize = sizeof( OPENFILENAME );   
   OpenFileName.hwndOwner = hWnd;   
   OpenFileName.lpstrFilter = szFilter[ 0 ];   
   OpenFileName.lpstrFile = szFileName;   
   OpenFileName.nMaxFile = _MAX_PATH;   
   OpenFileName.lpstrFileTitle = szFileTitle;   
   OpenFileName.nMaxFileTitle = _MAX_PATH; 

3. Comment out these 2 cases from the switch( wParam ) statement in WM_COMMAND handle:

   case IDM_OPEN:   
   case IDM_SAVE: 

4. Add these local variables under the VECTORPEN Pen; statement in the WndProc function:

   VECTORLINE Line;  // line vector object   
   VECTORELLIPSE Ellipse;  // circle vector object   
   VECTORPOLYGON Polygon;  // polygon vector object   
   L_INT i; 

5. Add the following lines in WM_CREATE handler after L_VecAttachToWindow and before ResetView:

   // fill in the layer descriptor structure and add new layer to the vector handle   
   LayerDesc.nSize = sizeof( VECTORLAYERDESC );   
   lstrcpy( LayerDesc.szName, TEXT("Default Layer"));   
   LayerDesc.bVisible = TRUE;   
   LayerDesc.bLocked = FALSE;   
   LayerDesc.dwTag = 0L;   
   L_VecAddLayer ( &Vector, &LayerDesc, &Layer, 0L );   
   // make this the active layer in the vector handle   
   L_VecSetActiveLayer ( &Vector, &Layer ); 

6. Add the following code to the WM_CHAR handler, after the break; statement of case B:

   case 'l': 
   case 'L': 
   // add a new vector line 
   L_VecInitObject ( &Line.Object ); 
   Line.Object.nSize = sizeof( VECTORLINE ); 
   Line.Object.nType = VECTOR_LINE; 
   // set the line pen 
   Line.Pen.nSize = sizeof( VECTORPEN ); 
   Line.Pen.NewPen.LogPen.lopnColor = RGB( rand() % 246 + 10, rand() % 246 + 10, rand() % 246 + 10 ); 
   Line.Pen.NewPen.LogPen.lopnStyle = PS_SOLID; 
   Line.Pen.NewPen.LogPen.lopnWidth.x = 1; 
   Line.Pen.NewPen.LogPen.lopnWidth.y = 1; 
   // set the line start and end points 
   for( i = 0; i < 2; i++ ) 
   { 
      Line.Point[ i ].x = rand() % 100; 
      Line.Point[ i ].y = rand() % 100; 
      Line.Point[ i ].z = rand() % 100; 
   } 
   // add the object to the active layer 
   L_VecAddObject ( &Vector, NULL, VECTOR_LINE, &Line, NULL ); 
   // update view parameters and re-paint window 
   ResetView( hWnd, &Vector ); 
   break; 
   case 'e': 
   case 'E': 
   // add a new ellipse object 
   L_VecInitObject ( &Ellipse.Object ); 
   Ellipse.Object.nSize = sizeof( VECTORELLIPSE ); 
   Ellipse.Object.nType = VECTOR_ELLIPSE; 
   // set the ellipse pen 
   Ellipse.Pen.nSize = sizeof( VECTORPEN ); 
   Ellipse.Pen.NewPen.LogPen.lopnColor = RGB( rand() % 246 + 10, rand() % 246 + 10, rand() % 246 + 10 ); 
   Ellipse.Pen.NewPen.LogPen.lopnStyle = PS_SOLID; 
   Ellipse.Pen.NewPen.LogPen.lopnWidth.x = 1; 
   Ellipse.Pen.NewPen.LogPen.lopnWidth.y = 1; 
   // set the ellipse brush 
   Ellipse.Brush.nSize = sizeof( VECTORBRUSH ); 
   Ellipse.Brush.BrushType.StandardBrush.LogBrush.lbColor = RGB( rand() % 246 + 10, rand() % 246 + 10, rand() % 246 + 10 ); 
   Ellipse.Brush.BrushType.StandardBrush.LogBrush.lbStyle = BS_SOLID; 
   Ellipse.Brush.BrushType.StandardBrush.LogBrush.lbHatch = 0; 
   // set the ellipse center, x radius and y radius 
   Ellipse.Point.x = rand() % 100; 
   Ellipse.Point.y = rand() % 100; 
   Ellipse.Point.z = rand() % 100; 
   Ellipse.xRadius = rand() % 10; 
   Ellipse.yRadius = rand() % 10; 
   // add the object to the active layer 
   L_VecAddObject ( &Vector, NULL, VECTOR_ELLIPSE, &Ellipse, NULL ); 
   // update view parameters and re-paint window 
   ResetView( hWnd, &Vector ); 
   break; 
   case 'g': 
   case 'G': 
   // add a new polygon object 
   L_VecInitObject ( &Polygon.Object ); 
   Polygon.Object.nSize = sizeof( VECTORPOLYGON ); 
   Polygon.Object.nType = VECTOR_POLYGON; 
   // set the polygon pen 
   Polygon.Pen.nSize = sizeof( VECTORPEN ); 
   Polygon.Pen.NewPen.LogPen.lopnColor = RGB( rand() % 246 + 10, rand() % 246 + 10, rand() % 246 + 10 ); 
   Polygon.Pen.NewPen.LogPen.lopnStyle = PS_SOLID; 
   Polygon.Pen.NewPen.LogPen.lopnWidth.x = 1; 
   Polygon.Pen.NewPen.LogPen.lopnWidth.y = 1; 
   // set the polygon brush 
   Polygon.Brush.nSize = sizeof( VECTORBRUSH ); 
   Polygon.Brush.BrushType.StandardBrush.LogBrush.lbColor = RGB( rand() % 246 + 10, rand() % 246 + 10, rand() % 246 + 10 ); 
   Polygon.Brush.BrushType.StandardBrush.LogBrush.lbStyle = BS_SOLID; 
   Polygon.Brush.BrushType.StandardBrush.LogBrush.lbHatch = 0; 
   // set the polygon points 
   Polygon.nPointCount = rand() % 5 + 3; 
   Polygon.Point = (pVECTORPOINT) malloc( Polygon.nPointCount * sizeof( VECTORPOINT ) ); 
   for( i = 0; i < Polygon.nPointCount; i++ ) 
   { 
      Polygon.Point[ i ].x = rand() % 100; 
      Polygon.Point[ i ].y = rand() % 100; 
      Polygon.Point[ i ].z = rand() % 100; 
   } 
   // set polygon fill mode 
   Polygon.nPolyFillMode = VECTOR_POLY_ALTERNATE; 
   // add the object to the active layer 
   L_VecAddObject ( &Vector, NULL, VECTOR_POLYGON, &Polygon, NULL ); 
   free( Polygon.Point ); 
   // update view parameters and re-paint window 
   ResetView( hWnd, &Vector ); 
   break; 

7. Compile and run the project. You will be able to add new line objects by pressing L on your keyboard, new ellipse objects by pressing E and new polygon objects by pressing G. You can still perform hit testing and transform your drawing as shown in the previous tutorials.