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CreateGraphics Method

Summary

Creates a GDI+ System.Drawing.Graphics object using this Leadtools.RasterImage as the display surface.

Syntax
C#
VB
C++
public static RasterGraphics CreateGraphics( 
   RasterImage image 
) 
Public Shared Function CreateGraphics( _ 
   ByVal image As RasterImage _ 
) As RasterGraphics 
public: 
static RasterGraphics^ CreateGraphics(  
   RasterImage^ image 
)  

Parameters

image
The source image.

Return Value

The GDI+ System.Drawing.Graphics object this method creates.

Remarks

This method allows you to create an infinite number of drawing capabilities such as paint, erase, color erase and brush, pen, spray gun, flood fill, color tube, text overlay, curve, line, rectangle, polygon, ellipse, freehand shapes, cut and paste, and more.

All GDI+ methods can be used to draw to the image using the returned System.Drawing.Graphics object. The graphics object must be disposed after using it.

If a region is defined for the image, GDI functions act only on the region, not on the entire image.

The GDI+ graphics supports only 1, 4, 8, 16 and 24 bit images. If you are using an image that has some other number of bits per pixel, you must use Leadtools.ImageProcessing.ColorResolutionCommand to change the image to a bits per pixel value supported by the DIB driver.

For more information refer to RasterImage and GDI/GDI+.

For more information, refer to Introduction to Image Processing With LEADTOOLS.

Example

This example draws an ellipse on a raster image.

C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
 
public void CreateGraphicsExample() 
{ 
   RasterCodecs codecs = new RasterCodecs(); 
   RasterImage image = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")); 
 
   LeadPoint point1 = new LeadPoint(image.Width / 8, image.Height / 8); 
   LeadPoint point2 = new LeadPoint(image.Width / 2, image.Height / 2); 
 
   // Convert the coordinates if necessary. 
   if (image.ViewPerspective != RasterViewPerspective.TopLeft) 
   { 
      point1 = image.PointToImage(RasterViewPerspective.TopLeft, point1); 
      point2 = image.PointToImage(RasterViewPerspective.TopLeft, point2); 
   } 
 
   // Create the Graphics object 
   using (RasterGraphics rg = RasterImagePainter.CreateGraphics(image)) 
   { 
      rg.Graphics.DrawEllipse(new Pen(Color.White), point1.X, point1.Y, point2.X - point1.X, point2.Y - point1.Y); 
   } 
 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Image1_CreateGraphics.bmp"), RasterImageFormat.Bmp, 0); 
 
   image.Dispose(); 
   codecs.Dispose(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Drawing 
Imports Leadtools.ImageProcessing 
 
Public Sub CreateGraphicsExample() 
   Dim codecs As New RasterCodecs() 
   Dim image As RasterImage = codecs.Load(Path.Combine(LEAD_VARS.ImagesDir, "Image1.cmp")) 
 
   Dim point1 As New LeadPoint(image.Width \ 8, image.Height \ 8) 
   Dim point2 As New LeadPoint(image.Width \ 2, image.Height \ 2) 
 
   ' Convert the coordinates if necessary. 
   If image.ViewPerspective <> RasterViewPerspective.TopLeft Then 
      point1 = image.PointToImage(RasterViewPerspective.TopLeft, point1) 
      point2 = image.PointToImage(RasterViewPerspective.TopLeft, point2) 
   End If 
 
   ' Create the Graphics object 
   Using rg As RasterGraphics = RasterImagePainter.CreateGraphics(image) 
      rg.Graphics.DrawEllipse(New Pen(Color.White), point1.X, point1.Y, point2.X - point1.X, point2.Y - point1.Y) 
   End Using 
 
   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Image1_CreateGraphics.bmp"), RasterImageFormat.Bmp, 0) 
 
   image.Dispose() 
   codecs.Dispose() 
End Sub 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 

Requirements

Target Platforms

Help Version 20.0.2019.9.19
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Leadtools.Drawing Assembly