How to: Create Thumbnail Images

A thumbnail image is a small version of an image. You can create a thumbnail image by calling the GetThumbnailImage method of an Image object.

Example

The following example constructs an Image object from a JPG file. The original image has a width of 640 pixels and a height of 479 pixels. The code creates a thumbnail image that has a width of 100 pixels and a height of 100 pixels.

The following illustration shows the thumbnail image.

Thumbnail Image

Note

In this example, a callback method is declared, but never used. This supports all versions of GDI+.

public bool ThumbnailCallback() {
           return true;
       }
      
       private void GetThumbnail(PaintEventArgs e)
       {

           Image.GetThumbnailImageAbort callback = 
               new Image.GetThumbnailImageAbort(ThumbnailCallback);
           Image image = new Bitmap(@"c:\FakePhoto.jpg");
           Image pThumbnail = image.GetThumbnailImage(100, 100, callback, new
              IntPtr());
           e.Graphics.DrawImage(
              pThumbnail,
              10,
              10,
              pThumbnail.Width,
              pThumbnail.Height);
       }
     
Public Function ThumbnailCallback() As Boolean 
   		Return True 
End Function 

Private Sub GetThumbnail(ByVal e As PaintEventArgs) 
   
   		Dim callback As New Image.GetThumbnailImageAbort(AddressOf ThumbnailCallback) 
   		Dim image As Image = New Bitmap("c:\FakePhoto.jpg") 
   		Dim pThumbnail As Image = image.GetThumbnailImage(100, 100, callback, New IntPtr()) 
   		e.Graphics.DrawImage(pThumbnail, 10, 10, pThumbnail.Width, pThumbnail.Height) 
End Sub 

Compiling the Code

The preceding example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler. To run the example, follow these steps:

  1. Create a new Windows Forms application.

  2. Add the example code to the form.

  3. Create a handler for the form's Paint event

  4. In the Paint handler, call the GetThumbnail method and pass e for PaintEventArgs.

  5. Find an image file that you want to make a thumbnail of.

  6. In the GetThumbnail method, specify the path and file name to your image.

  7. Press F5 to run the example.

    A 100 by 100 thumbnail image appears on the form.

See Also

Images, Bitmaps, and Metafiles
Working with Images, Bitmaps, Icons, and Metafiles