GraphicsPathIterator.HasCurve Method

Definition

Namespace:

System.Drawing.Drawing2D

Assembly:

System.Drawing.Common.dll

Source:

GraphicsPathIterator.cs

Indicates whether the path associated with this GraphicsPathIterator contains a curve.

public:
 bool HasCurve();

public bool HasCurve ();

member this.HasCurve : unit -> bool

Public Function HasCurve () As Boolean

Returns

Boolean

This method returns true if the current subpath contains a curve; otherwise, false.

Examples

The following example is designed for use with Windows Forms, and it requires PaintEventArgs e, an OnPaint event object. The code performs the following actions:

• Creates a GraphicsPath object, myPath.

• Adds three lines, a rectangle, and an ellipse.

• Creates a GraphicsPathIterator object for myPath.

• Tests to see if the current path myPath contains a curve.

• Shows the result of the test in a message box.

private:
   void HasCurveExample( PaintEventArgs^ /*e*/ )
   {
      // Create a path and add three lines,
      // a rectangle and an ellipse.
      GraphicsPath^ myPath = gcnew GraphicsPath;
      array<Point>^ myPoints = {Point(20,20),Point(120,120),Point(20,120),Point(20,20)};
      Rectangle myRect = Rectangle(120,120,100,100);
      myPath->AddLines( myPoints );
      myPath->AddRectangle( myRect );
      myPath->AddEllipse( 220, 220, 100, 100 );

      // Create a GraphicsPathIterator for myPath.
      GraphicsPathIterator^ myPathIterator = gcnew GraphicsPathIterator( myPath );

      // Test for a curve.
      bool myHasCurve = myPathIterator->HasCurve();

      // Show the test result.
      MessageBox::Show( myHasCurve.ToString() );
   }

private void HasCurveExample(PaintEventArgs e)
{
             
    // Create a path and add three lines,
    // a rectangle and an ellipse.
    GraphicsPath myPath = new GraphicsPath();
    
    Point[] myPoints = {new Point(20, 20), new Point(120, 120), 
        new Point(20, 120),new Point(20, 20) }; 

    Rectangle myRect = new Rectangle(120, 120, 100, 100);
    myPath.AddLines(myPoints);
    myPath.AddRectangle(myRect);
    myPath.AddEllipse(220, 220, 100, 100);
             
    // Create a GraphicsPathIterator for myPath.
    GraphicsPathIterator myPathIterator = new
        GraphicsPathIterator(myPath);
             
    // Test for a curve.
    bool myHasCurve = myPathIterator.HasCurve();
             
    // Show the test result.
    MessageBox.Show(myHasCurve.ToString());
}

Public Sub HasCurveExample(ByVal e As PaintEventArgs)
    Dim myPath As New GraphicsPath
    Dim myPoints As Point() = {New Point(20, 20), _
        New Point(120, 120), New Point(20, 120), New Point(20, 20)}
    Dim myRect As New Rectangle(120, 120, 100, 100)
    myPath.AddLines(myPoints)
    myPath.AddRectangle(myRect)
    myPath.AddEllipse(220, 220, 100, 100)

    ' Create a GraphicsPathIterator for myPath.
    Dim myPathIterator As New GraphicsPathIterator(myPath)
    Dim myHasCurve As Boolean = myPathIterator.HasCurve()
    MessageBox.Show(myHasCurve.ToString())
End Sub

Remarks

All curves in a path are stored as sequences of Bézier splines. For example, when you add an ellipse to a path, you specify the upper-left corner, the width, and the height of the ellipse's bounding rectangle. Those numbers (upper-left corner, width, and height) are not stored in the path; instead; the ellipse is converted to a sequence of four Bézier splines. The path stores the endpoints and control points of those Bézier splines.

A path stores an array of data points, each of which belongs to a line or a Bézier spline. If some of the points in the array belong to Bézier splines, then HasCurve returns true. If all points in the array belong to lines, then HasCurve returns false.

Certain methods flatten a path, which means that all the curves in the path are converted to sequences of lines. After a path has been flattened, HasCurve will always return false. Calling the Flatten, Widen, or Warp method of the GraphicsPath class will flatten a path.