Matrix.Reset Method

Definition

Namespace:

System.Drawing.Drawing2D

Assembly:

System.Drawing.Common.dll

Source:

Matrix.cs

Resets this Matrix to have the elements of the identity matrix.

public:
 void Reset();

public void Reset ();

member this.Reset : unit -> unit

Public Sub Reset ()

Examples

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

• Creates a scaling matrix.

• Lists the matrix elements to the screen.

• Resets the matrix to identity.

• Lists the elements to the screen.

• Translates the matrix by 50 points in the x-axis and 40 points in the y-axis.

• Lists the elements of the translated matrix to the screen.

• Draws a rectangle is drawn to the screen prior to applying the matrix transform (the blue rectangle).

• Applies the transform to the rectangle.

• Draws the transformed rectangle is drawn to the screen (the red rectangle), using the same coordinates as the previous rectangle.

Notice that the red rectangle was not scaled (because of the reset) but was translated in the x-axis and y-axis.

public:
   void ResetExample( PaintEventArgs^ e )
   {
      Pen^ myPen = gcnew Pen( Color::Blue,1.0f );
      Pen^ myPen2 = gcnew Pen( Color::Red,1.0f );

      // Create a matrix that scales by 5 in the x direction and
      // by 3 in the y direction.
      Matrix^ myMatrix = gcnew Matrix( 5.0f,0.0f,0.0f,3.0f,0.0f,0.0f );

      // List the matrix elements to the screen.
      ListMatrixElements( e, myMatrix, "Beginning Matrix", 6, 20 );

      // Reset the matrix to identity.
      myMatrix->Reset();

      // Again list the matrix elements to the screen.
      ListMatrixElements2( e, myMatrix, "Matrix After Reset", 6, 40 );

      // Translate the matrix by 50 points in the x-axis and 40 points
      // in the y-axis.
      myMatrix->Translate( 50.0f, 40.0f );

      // List the matrix elements to the screen.
      ListMatrixElements1( e, myMatrix, "Matrix After Translation", 6, 60 );

      // Draw a rectangle to the screen.
      e->Graphics->DrawRectangle( myPen, 0, 0, 100, 100 );

      // Apply the matrix transform to the Graphics.
      e->Graphics->Transform = myMatrix;

      // Draw another rectangle to the screen that has the transform
      // applied.
      e->Graphics->DrawRectangle( myPen2, 0, 0, 100, 100 );
   }

   //-------------------------------------------------------
   // This function is a helper function to
   // list the contents of a matrix.
   //-------------------------------------------------------
   void ListMatrixElements2( PaintEventArgs^ e, Matrix^ matrix, String^ matrixName, int numElements, int y )
   {
      // Set up variables for drawing the array
      // of points to the screen.
      int i;
      float x = 20,X = 200;
      System::Drawing::Font^ myFont = gcnew System::Drawing::Font( "Arial",8 );
      SolidBrush^ myBrush = gcnew SolidBrush( Color::Black );

      // Draw the matrix name to the screen.
      e->Graphics->DrawString( String::Concat( matrixName, ":  " ), myFont, myBrush, (float)x, (float)y );

      // Draw the set of path points and types to the screen.
      for ( i = 0; i < numElements; i++ )
      {
         e->Graphics->DrawString( String::Concat( matrix->Elements[ i ], ", " ), myFont, myBrush, (float)X, (float)y );
         X += 30;
      }
   }

public void ResetExample(PaintEventArgs e)
{
    Pen myPen = new Pen(Color.Blue, 1);
    Pen myPen2 = new Pen(Color.Red, 1);
             
    // Create a matrix that scales by 5 in the x direction and
    // by 3 in the y direction.
    Matrix myMatrix = new Matrix(
        5.0f, 0.0f, 0.0f, 3.0f, 0.0f, 0.0f); 
             
    // List the matrix elements to the screen.
    ListMatrixElements(e, myMatrix, "Beginning Matrix", 6, 20);
             
    // Reset the matrix to identity.
    myMatrix.Reset();
             
    // Again list the matrix elements to the screen.
    ListMatrixElements2(e, myMatrix, "Matrix After Reset", 6, 40);
             
    // Translate the matrix by 50 points in the x-axis and 40 points
    // in the y-axis.
    myMatrix.Translate(50.0f, 40.0f); 
  
    // List the matrix elements to the screen.
    ListMatrixElements1(e, myMatrix, "Matrix After Translation", 6, 60);
             
    // Draw a rectangle to the screen.
    e.Graphics.DrawRectangle(myPen, 0, 0, 100, 100);
             
    // Apply the matrix transform to the Graphics.
    e.Graphics.Transform = myMatrix;
             
    // Draw another rectangle to the screen that has the transform
    // applied.
    e.Graphics.DrawRectangle(myPen2, 0, 0, 100, 100);
}
             
//-------------------------------------------------------
// This function is a helper function to
// list the contents of a matrix.
//-------------------------------------------------------
public void ListMatrixElements2(
    PaintEventArgs e,
    Matrix matrix,
    string matrixName,
    int numElements,
    int y)
{
             
    // Set up variables for drawing the array
    // of points to the screen.
    int i;
    float x = 20, X = 200;
    Font myFont = new Font("Arial", 8);
    SolidBrush myBrush = new SolidBrush(Color.Black);
             
    // Draw the matrix name to the screen.
    e.Graphics.DrawString(
        matrixName + ":  ",
        myFont,
        myBrush,
        x,
        y);
             
    // Draw the set of path points and types to the screen.
    for(i=0; i < numElements; i++)
    {
        e.Graphics.DrawString(
            matrix.Elements[i].ToString() + ", ",
            myFont,
            myBrush,
            X,
            y);
        X += 30;
    }
}

Public Sub ResetExample(ByVal e As PaintEventArgs)
    Dim myPen As New Pen(Color.Blue, 1)
    Dim myPen2 As New Pen(Color.Red, 1)
    Dim myMatrix As New Matrix(5.0F, 0.0F, 0.0F, 3.0F, 0.0F, 0.0F)

    ListMatrixElementsHelper2(e, myMatrix, "Beginning Matrix", 6, 20)
    myMatrix.Reset()
    ListMatrixElementsHelper(e, myMatrix, "Matrix After Reset", 6, 40)

    ' Translate.
    myMatrix.Translate(50.0F, 40.0F)

    ListMatrixElementsHelper(e, myMatrix, "Matrix After Translation", _
        6, 60)
    e.Graphics.DrawRectangle(myPen, 0, 0, 100, 100)
    e.Graphics.Transform = myMatrix
    e.Graphics.DrawRectangle(myPen2, 0, 0, 100, 100)
End Sub

' A helper function to list the contents of a matrix.
Public Sub ListMatrixElementsHelper2(ByVal e As PaintEventArgs, _
ByVal matrix As Matrix, ByVal matrixName As String, ByVal numElements As Integer, _
ByVal y As Integer)

    ' Set up variables for drawing the array
    ' of points to the screen.
    Dim i As Integer
    Dim x As Single = 20
    Dim j As Single = 200
    Dim myFont As New Font("Arial", 8)
    Dim myBrush As New SolidBrush(Color.Black)

    ' Draw the matrix name to the screen.
    e.Graphics.DrawString(matrixName + ":  ", myFont, myBrush, x, y)

    ' Draw the set of path points and types to the screen.
    For i = 0 To numElements - 1
        e.Graphics.DrawString(matrix.Elements(i).ToString() + ", ", _
        myFont, myBrush, j, y)
        j += 30
    Next i
End Sub

Remarks

The elements on the main diagonal of the identity matrix are 1. All other elements of the identity matrix are 0.