Image.GetThumbnailImage Method (Int32, Int32, Image.GetThumbnailImageAbort, IntPtr)

 

Returns a thumbnail for this Image.

Namespace:   System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

Public Function GetThumbnailImage (
	thumbWidth As Integer,
	thumbHeight As Integer,
	callback As Image.GetThumbnailImageAbort,
	callbackData As IntPtr
) As Image

Parameters

thumbWidth
Type: System.Int32

The width, in pixels, of the requested thumbnail image.

thumbHeight
Type: System.Int32

The height, in pixels, of the requested thumbnail image.

callback
Type: System.Drawing.Image.GetThumbnailImageAbort

A Image.GetThumbnailImageAbort delegate.

Note   You must create a delegate and pass a reference to the delegate as the callback parameter, but the delegate is not used.

callbackData
Type: System.IntPtr

Must be Zero.

Return Value

Type: System.Drawing.Image

An Image that represents the thumbnail.

If the Image contains an embedded thumbnail image, this method retrieves the embedded thumbnail and scales it to the requested size. If the Image does not contain an embedded thumbnail image, this method creates a thumbnail image by scaling the main image.

The GetThumbnailImage method works well when the requested thumbnail image has a size of about 120 x 120 pixels. If you request a large thumbnail image (for example, 300 x 300) from an Image that has an embedded thumbnail, there could be a noticeable loss of quality in the thumbnail image. It might be better to scale the main image (instead of scaling the embedded thumbnail) by calling the DrawImage method.

The following code example creates and displays a thumbnail image. This delegate is never called.


Public Function ThumbnailCallback() As Boolean 
  Return False 
End Function 

Public Sub Example_GetThumb(ByVal e As PaintEventArgs) 
    Dim myCallback As New Image.GetThumbnailImageAbort(AddressOf ThumbnailCallback) 
    Dim myBitmap As New Bitmap("Climber.jpg") 
    Dim myThumbnail As Image = myBitmap.GetThumbnailImage(40, 40, myCallback, IntPtr.Zero) 
    e.Graphics.DrawImage(myThumbnail, 150, 75) 
End Sub 

.NET Framework
Available since 1.1
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