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.

Note

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

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

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);
        }

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

Other Resources

Images, Bitmaps, and Metafiles

Working with Images, Bitmaps, Icons, and Metafiles

Change History

Date	History	Reason
September 2009	Updated instructions and example code.	Customer feedback.
September 2008	Added instructions on how to run the code example.	Customer feedback.