Implementing Hit Testing

To add support for hit testing different vector objects:

POINT pt;
VECTOROBJECT Object;
L_TCHAR szBuffer[ 80 ];
VECTORPEN Pen;

case WM_MOUSEMOVE:
   // hit test object under mouse cursor
   pt.x = LOWORD( lParam );
   pt.y = HIWORD( lParam );
   nRet = L_VecHitTest( &Vector, &pt, &Object );
   if( nRet == SUCCESS )
   {
      // theres an object, show its type in main window caption
      switch( Object.nType )
      {
         case VECTOR_VERTEX: lstrcpy( szBuffer, TEXT("Vertex ")); break;
         case VECTOR_LINE: lstrcpy( szBuffer, TEXT("Line ")); break;
         case VECTOR_RECTANGLE: lstrcpy( szBuffer, TEXT("Rectangle ")); break;
         case VECTOR_POLYLINE: lstrcpy( szBuffer, TEXT("Polyline")); break;
         case VECTOR_POLYBEZIER: lstrcpy( szBuffer, TEXT("Polybezier")); break;
         case VECTOR_POLYGON: lstrcpy( szBuffer, TEXT("Polygon")); break;
         case VECTOR_ELLIPSE: lstrcpy( szBuffer, TEXT("Ellipse")); break;
         case VECTOR_CIRCLE: lstrcpy( szBuffer, TEXT("Circle")); break;
         case VECTOR_ARC: lstrcpy( szBuffer, TEXT("Arc")); break;
         case VECTOR_TEXT: lstrcpy( szBuffer, TEXT("Text")); break;
         case VECTOR_PIE: lstrcpy( szBuffer, TEXT("Pie")); break;
         case VECTOR_CHORD: lstrcpy( szBuffer, TEXT("Chord")); break;
         case VECTOR_RASTER: lstrcpy( szBuffer, TEXT("Raster ")); break;
      }
   }
   else
      lstrcpy( szBuffer, TEXT("No object under mouse cursor"));

   SetWindowText( hWnd, szBuffer );
    break;

case WM_LBUTTONDOWN:
   // hit test object under mouse cursor
   pt.x = LOWORD( lParam );
   pt.y = HIWORD( lParam );
   nRet = L_VecHitTest ( &Vector, &pt, &Object );
   if( nRet == SUCCESS )
   {
      // theres an object, flip its pen width between 1 and 4
      L_VecGetObjectAttributes ( &Vector, &Object, NULL, &Pen, NULL, NULL );
      Pen.NewPen.LogPen.lopnWidth.x = ( Pen.NewPen.LogPen.lopnWidth.x == 1 ) ? 4 : 1;
      L_VecSetObjectAttributes ( &Vector, &Object, NULL, &Pen, NULL, NULL, 0L );

      // reflect our changes
      InvalidateRect( hWnd, NULL, FALSE );
   }
   break;

case WM_RBUTTONDOWN:
   // hit test object under mouse cursor
   pt.x = LOWORD( lParam );
   pt.y = HIWORD( lParam );
   nRet = L_VecHitTest ( &Vector, &pt, &Object );
   if( nRet == SUCCESS )
   {
      // theres an object, delete it
      L_VecDeleteObject ( &Vector, &Object, 0L );

      // reflect our changes
      InvalidateRect( hWnd, NULL, FALSE );
   }
    break;