LEADTOOLS Windows Forms (Leadtools.WinForms assembly)

RedirectPaint Method

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Example 





Leadtools.WinForms Namespace > RasterImageViewer Class : RedirectPaint Method
The Graphics object used to paint.
Rectangle which determines the portion of the image to paint.
Rectangle which determines where the image is placed, and how it is scaled.
Rectangle which clips the image display.
The matrix is used to transform from physical to logical coordinates
Displays the contents of the RasterImageViewer in the given Graphics object.
Syntax
public virtual void RedirectPaint( 
   Graphics graphics,
   Rectangle src,
   Rectangle dest,
   Rectangle destClip,
   Matrix transform
)
'Declaration
 
Public Overridable Sub RedirectPaint( _
   ByVal graphics As Graphics, _
   ByVal src As Rectangle, _
   ByVal dest As Rectangle, _
   ByVal destClip As Rectangle, _
   ByVal transform As Matrix _
) 
'Usage
 
Dim instance As RasterImageViewer
Dim graphics As Graphics
Dim src As Rectangle
Dim dest As Rectangle
Dim destClip As Rectangle
Dim transform As Matrix
 
instance.RedirectPaint(graphics, src, dest, destClip, transform)

            

        

            

            

            

        

            

            
public:
virtual void RedirectPaint( 
   Graphics^ graphics,
   Rectangle src,
   Rectangle dest,
   Rectangle destClip,
   Matrix^ transform
) 

            

        

            

        
            
Parameters
graphics


The Graphics object used to paint.
src


Rectangle which determines the portion of the image to paint.
dest


Rectangle which determines where the image is placed, and how it is scaled.
destClip


Rectangle which clips the image display.
transform


The matrix is used to transform from physical to logical coordinates

            
            

            
            
            
            
Remarks
Use this function to paint the contents of the RasterImageViewer onto any System.Drawing.Graphics object. The contents of the RasterImageViewer includes the Image and anything painted in the PostImagePaint event handler. When using this function, pass either a valid transform or a dest rectangle, but NOT BOTH. It is an error to pass both a transform and a dest rectangle.



If you pass a transformmatrix, it is applied to the graphics object before any painting takes place. If you pass a dest rectangle, internally a transform is constructed from src and dest and it is applied to the graphics object before any painting takes place. Passing Rectangle.Empty for the src rectangle gives the default, which is equivalent to the size of the Image. Passing Rectangle.Empty for the destClip rectangle is equivalent to passing same System.Drawing.Rectangle as dst. Passing null for the transform argument means that src and dest are used to create a transform.

            
            
Example

             
    

            
            

            Copy Code
                
            

            

    

     

            
Imports Leadtools.WinForms
Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.ImageProcessing.Color
Imports Leadtools.Drawing

Private Class MyForm2 : Inherits Form
   Private Class MyPanel : Inherits Panel
      Protected Overrides Sub OnPaintBackground(ByVal pe As PaintEventArgs)
         ' do nothing
      End Sub
   End Class

   Private viewer As RasterImageViewer
   Private panel As MyPanel

   Public Sub New(ByVal title As String)
      Text = title
      Size = New Size(750, 450)

      ' Create the raster viewer
      viewer = New RasterImageViewer()
      viewer.DoubleBuffer = True
      viewer.Dock = DockStyle.Fill

      ' Load an image into the viewer
      Dim codecs As RasterCodecs = New RasterCodecs()
      viewer.Image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Sample1.cmp"))
      codecs.Dispose()

      ' Create the panel
      panel = New MyPanel()
      panel.Parent = Me
      panel.Width = 400
      panel.Height = 400
      panel.Dock = DockStyle.Right
      panel.BackColor = Color.Beige
      panel.BorderStyle = BorderStyle.Fixed3D

      Controls.Add(panel)
      panel.BringToFront()

      Controls.Add(viewer)
      viewer.BringToFront()

      AddHandler panel.Paint, AddressOf panel_Paint
      AddHandler viewer.PostImagePaint, AddressOf viewer_PostImagePaint
      AddHandler viewer.RedirectImagePaint, AddressOf viewer_RedirectImagePaint
   End Sub

   Private Sub viewer_RedirectImagePaint(ByVal sender As Object, ByVal e As EventArgs)
      panel.Invalidate()
   End Sub

   Private Sub panel_Paint(ByVal sender As Object, ByVal e As PaintEventArgs)
      If Not viewer.Image Is Nothing Then
         Dim dx As Integer = viewer.Image.Width \ 2
         Dim dy As Integer = viewer.Image.Height \ 2
         Dim dest As Rectangle = viewer.SourceRectangle

         ' move center of image to origin
         Dim m1 As Matrix = New Matrix(1, 0, 0, 1, -dx, -dy)

         ' mirror the image
         Dim m2 As Matrix = New Matrix(-1, 0, 0, 1, 0, 0)
         m1.Multiply(m2, MatrixOrder.Append)

         ' move back to original location
         Dim m3 As Matrix = New Matrix(1, 0, 0, 1, dx, dy)
         m1.Multiply(m3, MatrixOrder.Append)

         ' scale image to fit on panel
         Dim scaleX As Single = CSng(panel.Width) / CSng(viewer.Image.Width)
         Dim scaleY As Single = CSng(panel.Height) / CSng(viewer.Image.Height)
         Dim m4 As Matrix = New Matrix(scaleX, 0, 0, scaleY, 0, 0)
         m1.Multiply(m4, MatrixOrder.Append)

         ' display contents of RaserImageViewer on panel
         viewer.RedirectPaint(e.Graphics, Rectangle.Empty, Rectangle.Empty, Rectangle.Empty, m1)
      End If
   End Sub

   Private Sub viewer_PostImagePaint(ByVal sender As Object, ByVal e As PaintEventArgs)
      Dim graphics As Graphics = e.Graphics
      Dim graphicsState As GraphicsState = graphics.Save()

      Dim font As Font = New Font("Arial", 16)
      e.Graphics.DrawString("This text stays with the window", font, Brushes.Yellow, New PointF(100, 100))

      graphics.MultiplyTransform(viewer.Transform)
      e.Graphics.DrawString("This text stays with the image.", font, Brushes.White, New PointF(100, 200))

      graphics.Restore(graphicsState)
      graphics.Flush()
   End Sub
End Class

Public Sub RasterImageViewer_RedirectPaint(ByVal title As String)
   Dim form As MyForm2 = New MyForm2(title)
   form.ShowDialog()
End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
End Class

            

   

     

            
using Leadtools.WinForms;
using Leadtools;
using Leadtools.Codecs;
using Leadtools.ImageProcessing.Color;
using Leadtools.Drawing;

class MyForm2 : Form
{
   class MyPanel : Panel
   {
      protected override void  OnPaintBackground(PaintEventArgs pe)
      {
         // do nothing
      }
   }

   RasterImageViewer viewer;
   MyPanel panel;

   public MyForm2(string title)
   {
      Text = title;
      Size = new Size(750, 450);

      // Create the raster viewer
      viewer = new RasterImageViewer();
      viewer.DoubleBuffer = true;
      viewer.Dock = DockStyle.Fill;

      // Load an image into the viewer
      RasterCodecs codecs = new RasterCodecs();
      viewer.Image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Sample1.cmp"));
      codecs.Dispose();

      // Create the panel
      panel = new MyPanel();
      panel.Parent = this;
      panel.Width = 400;
      panel.Height = 400;
      panel.Dock = DockStyle.Right;
      panel.BackColor = Color.Beige;
      panel.BorderStyle = BorderStyle.Fixed3D;

      Controls.Add(panel);
      panel.BringToFront();

      Controls.Add(viewer);
      viewer.BringToFront();

      panel.Paint += new PaintEventHandler(panel_Paint);
      viewer.PostImagePaint += new PaintEventHandler(viewer_PostImagePaint);
      viewer.RedirectImagePaint += new EventHandler(viewer_RedirectImagePaint);
   }

   void viewer_RedirectImagePaint(object sender, EventArgs e)
   {
      panel.Invalidate();
   }

   void panel_Paint(object sender, PaintEventArgs e)
   {
      if(viewer.Image != null)
      {
         int dx = viewer.Image.Width / 2;
         int dy = viewer.Image.Height / 2;
         Rectangle dest = viewer.SourceRectangle;

         // move center of image to origin
         Matrix m1 = new Matrix(1,0,0,1,-dx,-dy);

         // mirror the image
         Matrix m2 = new Matrix(-1, 0, 0, 1, 0, 0);
         m1.Multiply(m2, MatrixOrder.Append);

         // move back to original location
         Matrix m3 = new Matrix(1, 0, 0, 1, dx, dy);
         m1.Multiply(m3, MatrixOrder.Append);

         // scale image to fit on panel
         float scaleX = (float)panel.Width / (float)viewer.Image.Width;
         float scaleY = (float)panel.Height / (float)viewer.Image.Height;
         Matrix m4 = new Matrix(scaleX, 0, 0, scaleY, 0, 0);
         m1.Multiply(m4, MatrixOrder.Append);

         // display contents of RaserImageViewer on panel
         viewer.RedirectPaint(
            e.Graphics,
            Rectangle.Empty, //_viewer.SourceRectangle,
            Rectangle.Empty,
            Rectangle.Empty, //e.ClipRectangle, 
            m1);
      }
   }

   private void viewer_PostImagePaint(object sender, PaintEventArgs e)
   {
      Graphics graphics = e.Graphics;
      GraphicsState graphicsState = graphics.Save();

      Font font = new Font("Arial", 16);
      e.Graphics.DrawString("This text stays with the window", font, Brushes.Yellow, new PointF(100,100));

      graphics.MultiplyTransform(viewer.Transform);
      e.Graphics.DrawString("This text stays with the image.", font, Brushes.White, new PointF(100,200));

      graphics.Restore(graphicsState);
      graphics.Flush();
   }
}

public void RasterImageViewer_RedirectPaint(string title)
{
   MyForm2 form = new MyForm2(title);
   form.ShowDialog();
}

static class LEAD_VARS
{
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
}

            

   

      
	
      
	
    

            
            
Requirements
Target Platforms

            
            
See Also
Reference
RasterImageViewer Class

RasterImageViewer Members




        
    

	
    

        

 
 
          

























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