CreateLeadDC Method

C#
Visual Basic
Objective-C
Java
C++

public static IntPtr CreateLeadDC( 
   RasterImage image
)

'Declaration

Public Shared Function CreateLeadDC( _
   ByVal image As RasterImage _
) As IntPtr

'Usage

Dim image As RasterImage
Dim value As IntPtr
 
value = RasterImagePainter.CreateLeadDC(image)

public:
static IntPtr CreateLeadDC( 
   RasterImage^ image
)

Parameters

image: The source image.

Return Value

The Windows HDC object this method creates.

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 Windows GDI functions can be used to draw to the image using the returned HDC. The HDC must be freed with the DeleteLeadDC method.

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

The DIB driver 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.

This example draws an ellipse on a raster image.

C#
Visual Basic
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Drawing
Imports Leadtools.ImageProcessing

<TestMethod()> _
Public Sub CreateLeadDCExample()
   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 device context
   Dim hdc As IntPtr = RasterImagePainter.CreateLeadDC(image)
   Using g As Graphics = Graphics.FromHdc(hdc)
      g.DrawEllipse(New Pen(Color.White), point1.X, point1.Y, point2.X - point1.X, point2.Y - point1.Y)
   End Using
   RasterImagePainter.DeleteLeadDC(hdc)

   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Imahe1_CreateLeadDC.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

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Drawing;
using Leadtools.ImageProcessing;

[TestMethod]
public void CreateLeadDCExample()
{
   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 device context
   IntPtr hdc = RasterImagePainter.CreateLeadDC(image);
   using(Graphics g = Graphics.FromHdc(hdc))
   {
      g.DrawEllipse(new Pen(Color.White), point1.X, point1.Y, point2.X - point1.X, point2.Y - point1.Y);
   }
   RasterImagePainter.DeleteLeadDC(hdc);

   codecs.Save(image, Path.Combine(LEAD_VARS.ImagesDir, "Imahe1_CreateLeadDC.bmp"), RasterImageFormat.Bmp, 0);

   image.Dispose();
   codecs.Dispose();
}

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

Target Platforms

Reference

RasterImagePainter Class
RasterImagePainter Members