Graphics::IsVisible Method (RectangleF)

 

Indicates whether the rectangle specified by a RectangleF structure is contained within the visible clip region of this Graphics.

Namespace:   System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

public:
bool IsVisible(
	RectangleF rect
)

Parameters

rect
Type: System.Drawing::RectangleF

RectangleF structure to test for visibility.

Return Value

Type: System::Boolean

true if the rectangle specified by the rect parameter is contained within the visible clip region of this Graphics; otherwise, false.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler. The code performs the following actions:

  • Creates a rectangular clipping region and sets it as the clipping region for the graphics object of the form using Replace.

  • Creates two rectangles, one inside the clipping region and one outside.

  • Tests each of the rectangles for visibility and draws only the visible one.

The result is one small red rectangle, which is within the clip region.

public:
   void IsVisibleRectangleF( PaintEventArgs^ e )
   {
      // Set clip region.
      System::Drawing::Region^ clipRegion = gcnew System::Drawing::Region( Rectangle(50,50,100,100) );
      e->Graphics->SetClip( clipRegion, CombineMode::Replace );

      // Set up coordinates of rectangles.
      RectangleF rect1 = RectangleF(100.0F,100.0F,20.0F,20.0F);
      RectangleF rect2 = RectangleF(200.0F,200.0F,20.0F,20.0F);

      // If rectangle is visible, fill it.
      if ( e->Graphics->IsVisible( rect1 ) )
      {
         e->Graphics->FillRectangle( gcnew SolidBrush( Color::Red ), rect1 );
      }

      if ( e->Graphics->IsVisible( rect2 ) )
      {
         e->Graphics->FillRectangle( gcnew SolidBrush( Color::Blue ), rect2 );
      }
   }

.NET Framework
Available since 1.1
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