Matrix.Multiply Method

Definition

Namespace:

System.Drawing.Drawing2D

Assembly:

System.Drawing.Common.dll

Multiplies this Matrix by the specified Matrix by prepending the specified Matrix.

Overloads

Multiply(Matrix)	Multiplies this Matrix by the matrix specified in the matrix parameter, by prepending the specified Matrix.
Multiply(Matrix, MatrixOrder)	Multiplies this Matrix by the matrix specified in the matrix parameter, and in the order specified in the order parameter.

Multiply(Matrix)

Source:

Matrix.cs

Multiplies this Matrix by the matrix specified in the matrix parameter, by prepending the specified Matrix.

public:
 void Multiply(System::Drawing::Drawing2D::Matrix ^ matrix);

public void Multiply (System.Drawing.Drawing2D.Matrix matrix);

member this.Multiply : System.Drawing.Drawing2D.Matrix -> unit

Public Sub Multiply (matrix As Matrix)

Parameters

matrix

Matrix

The Matrix by which this Matrix is to be multiplied.

Examples

For an example, see Multiply.

Multiply(Matrix, MatrixOrder)

Source:

Matrix.cs

Multiplies this Matrix by the matrix specified in the matrix parameter, and in the order specified in the order parameter.

public:
 void Multiply(System::Drawing::Drawing2D::Matrix ^ matrix, System::Drawing::Drawing2D::MatrixOrder order);

public void Multiply (System.Drawing.Drawing2D.Matrix matrix, System.Drawing.Drawing2D.MatrixOrder order);

member this.Multiply : System.Drawing.Drawing2D.Matrix * System.Drawing.Drawing2D.MatrixOrder -> unit

Public Sub Multiply (matrix As Matrix, order As MatrixOrder)

Parameters

matrix

Matrix

The Matrix by which this Matrix is to be multiplied.

order

MatrixOrder

The MatrixOrder that represents the order of the multiplication.

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 three matrices.

• Lists the contents of matrix 1 to the screen.

• Multiplies matrix 1 by matrix 2 and stores the result in matrix 1.

• Lists the contents of matrix 1 to the screen.

• Multiplies the result stored in matrix 1 by matrix 3, and again stores the result in matrix 1.

• Lists the contents of matrix 1 to the screen.

• Draws a rectangle to the screen prior to applying the matrix 1 transform (the blue rectangle).

• Applies the transform to the rectangle.

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

Notice that the red rectangle has been scaled by a factor of two in the horizontal direction, then rotated 90 degrees, and then moved (translated) 250 points in the x direction and 50 points in the y direction.

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

      // Set up the matrices.
      Matrix^ myMatrix1 = gcnew Matrix( 2.0f,0.0f,0.0f,1.0f,0.0f,0.0f );
      Matrix^ myMatrix2 = gcnew Matrix( 0.0f,1.0f,-1.0f,0.0f,0.0f,0.0f );
      Matrix^ myMatrix3 = gcnew Matrix( 1.0f,0.0f,0.0f,1.0f,250.0f,50.0f );

      // Display the elements of the starting matrix.
      ListMatrixElements( e, myMatrix1, "Beginning Matrix", 6, 40 );

      // Multiply Matrix1 by Matrix 2.
      myMatrix1->Multiply( myMatrix2, MatrixOrder::Append );

      // Display the result of the multiplication of Matrix1 and
      // Matrix2.
      ListMatrixElements( e, myMatrix1, "Matrix After 1st Multiplication", 6, 60 );

      // Multiply the result from the previous multiplication by
      // Matrix3.
      myMatrix1->Multiply( myMatrix3, MatrixOrder::Append );

      // Display the result of the previous multiplication
      // multiplied by Matrix3.
      ListMatrixElements1( e, myMatrix1, "Matrix After 2nd Multiplication", 6, 80 );

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

      // Make the transformation.
      e->Graphics->Transform = myMatrix1;

      // Draw the rectangle after transformation.
      e->Graphics->DrawRectangle( myPen2, 0, 0, 100, 100 );
   }

   //-------------------------------------------------------
   // The following function is a helper function to
   // list the contents of a matrix.
   //-------------------------------------------------------
   void ListMatrixElements1( 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 MultiplyExample(PaintEventArgs e)
{
    Pen myPen = new Pen(Color.Blue, 1);
    Pen myPen2 = new Pen(Color.Red, 1);
             
    // Set up the matrices.
    Matrix myMatrix1 = new Matrix(
        2.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f);  
    
    Matrix myMatrix2 = new Matrix(
        0.0f, 1.0f, -1.0f, 0.0f, 0.0f, 0.0f); 
  
    Matrix myMatrix3 = new Matrix(
        1.0f, 0.0f, 0.0f, 1.0f, 250.0f, 50.0f);  

    // Display the elements of the starting matrix.
    ListMatrixElements(e, myMatrix1, "Beginning Matrix", 6, 40);
             
    // Multiply Matrix1 by Matrix 2.
    myMatrix1.Multiply(myMatrix2, MatrixOrder.Append);
             
    // Display the result of the multiplication of Matrix1 and
             
    // Matrix2.
    ListMatrixElements(e,
        myMatrix1,
        "Matrix After 1st Multiplication",
        6,
        60);
             
    // Multiply the result from the pervious multiplication by
    // Matrix3.
    myMatrix1.Multiply(myMatrix3, MatrixOrder.Append);
             
    // Display the result of the previous multiplication
    // multiplied by Matrix3.
    ListMatrixElements1(e,
        myMatrix1,
        "Matrix After 2nd Multiplication",
        6,
        80);
             
    // Draw the rectangle prior to transformation.
    e.Graphics.DrawRectangle(myPen, 0, 0, 100, 100);
             
    // Make the transformation.
    e.Graphics.Transform = myMatrix1;
             
    // Draw the rectangle after transformation.
    e.Graphics.DrawRectangle(myPen2, 0, 0, 100, 100);
}
             
//-------------------------------------------------------
// The following function is a helper function to
// list the contents of a matrix.
//-------------------------------------------------------
public void ListMatrixElements1(
    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 MultiplyExample(ByVal e As PaintEventArgs)
    Dim myPen As New Pen(Color.Blue, 1)
    Dim myPen2 As New Pen(Color.Red, 1)

    ' Set up the matrices.
    Dim myMatrix1 As New Matrix(2.0F, 0.0F, 0.0F, 1.0F, 0.0F, 0.0F)

    ' Scale.
    Dim myMatrix2 As New Matrix(0.0F, 1.0F, -1.0F, 0.0F, 0.0F, 0.0F)

    ' Rotate 90.
    Dim myMatrix3 As New Matrix(1.0F, 0.0F, 0.0F, 1.0F, 250.0F, 50.0F)

    ' Display the elements of the starting matrix.
    ListMatrixElementsHelper(e, myMatrix1, "Beginning Matrix", 6, 40)

    ' Multiply Matrix1 by Matrix 2.
    myMatrix1.Multiply(myMatrix2, MatrixOrder.Append)

    ' Display the result of the multiplication of Matrix1 and
    ' Matrix2.
    ListMatrixElementsHelper(e, myMatrix1, _
    "Matrix After 1st Multiplication", 6, 60)

    ' Multiply the result from the pervious multiplication by
    ' Matrix3.
    myMatrix1.Multiply(myMatrix3, MatrixOrder.Append)

    ' Display the result of the previous multiplication
    ' multiplied by Matrix3.
    ListMatrixElementsHelper1(e, myMatrix1, _
    "Matrix After 2nd Multiplication", 6, 80)

    ' Draw the rectangle prior to transformation.
    e.Graphics.DrawRectangle(myPen, 0, 0, 100, 100)
    e.Graphics.Transform = myMatrix1

    ' Draw the rectangle after transformation.
    e.Graphics.DrawRectangle(myPen2, 0, 0, 100, 100)
End Sub

' A helper function to list the contents of a matrix.
Public Sub ListMatrixElementsHelper1(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

If the specified order is Prepend, this Matrix is multiplied by the specified matrix in a prepended order. If the specified order is Append, this Matrix is multiplied by the specified matrix in an appended order.