GetPageThumbnail Method (GdViewer)

In This Topic

Creates a custom sized high quality (HQ) thumbnail of the specified page of the document displayed in the GdViewer control. The required page is converted to an image resource with the size and the background color you have specified, which is subsequently stored as an object of the type GdPictureImage. The created image is clearly recognizable by the returned unique image identifier and you can take advantages of the GdPicture14.GdPictureImaging or the GdViewer classes and their methods for further manipulation with the thumbnail.

Syntax

Visual Basic
C#
Delphi
JScript
Managed Extensions for C++
C++/CLI

'Declaration
 
Public Function GetPageThumbnail( _
   ByVal Width As Integer, _
   ByVal Height As Integer, _
   ByVal Page As Integer, _
   ByVal BackColor As Color _
) As Integer

public int GetPageThumbnail( 
   int Width,
   int Height,
   int Page,
   Color BackColor
)

public function GetPageThumbnail( 
    Width: Integer;
    Height: Integer;
    Page: Integer;
    BackColor: Color
): Integer;

public function GetPageThumbnail( 
   Width : int,
   Height : int,
   Page : int,
   BackColor : Color
) : int;

public: int GetPageThumbnail( 
   int Width,
   int Height,
   int Page,
   Color BackColor
)

public:
int GetPageThumbnail( 
   int Width,
   int Height,
   int Page,
   Color BackColor
)

Parameters

Width: The required width of the newly created thumbnail image, in pixels.
Height: The required height of the newly created thumbnail image, in pixels.
Page: The required page of the displayed document for creating the thumbnail.
BackColor: A color object that defines the background color of the thumbnail's margins. The created thumbnail image includes predefined margin on both sides painted with the specified color.

Return Value

A unique image identifier of the GdPictureImage object representing the newly created thumbnail's image resource. The returned value is non-zero if the image is successfully created. Please first of all use the GetStat method to determine if this method has been successful.

Just to remind you that you need to release the image using the ReleaseGdPictureImage method after being used.

Remarks

It is recommend to use the GetStat method to identify the specific reason for the method's failure, if any instead of checking the returned value.

Likewise just to remind you that you need to release the image using the ReleaseGdPictureImage method.

Example

How to save the current page of the displayed document as a thumbnail in the PNG format.

VB.NET
C#

'We assume that the GdViewer1 control has been properly integrated.
If GdViewer1.DisplayFromFile("") = GdPictureStatus.OK Then
    Dim imageID As Integer = GdViewer1.GetPageThumbnail(256, 256, GdViewer1.CurrentPage, Color.FromArgb(255, 180, 180, 180))
    If GdViewer1.GetStat() = GdPictureStatus.OK Then
        Using oGdPictureImaging As GdPictureImaging = New GdPictureImaging()
            If oGdPictureImaging.SaveAsPNG(imageID, "thumbnail.png") = GdPictureStatus.OK Then
                MessageBox.Show("The created thumbnail has been saved successfully.", "GdViewer.GetPageThumbnail")
            Else
                MessageBox.Show("The created thumbnail can't be saved. Status: " + oGdPictureImaging.GetStat().ToString(), "GdViewer.GetPageThumbnail")
            End If
        End Using
        GdViewer1.ReleaseGdPictureImage(imageID)
    Else
        MessageBox.Show("The thumbnail can't be created. Status: " + GdViewer1.GetStat().ToString(), "GdViewer.GetPageThumbnail")
    End If
Else
    MessageBox.Show("The file can't be loaded. Status: " + GdViewer1.GetStat().ToString(), "GdViewer.GetPageThumbnail")
End If

//We assume that the GdViewer1 control has been properly integrated.
if (GdViewer1.DisplayFromFile("") == GdPictureStatus.OK)
{
    int imageID = GdViewer1.GetPageThumbnail(256, 256, GdViewer1.CurrentPage, Color.FromArgb(255, 180, 180, 180));
    if (GdViewer1.GetStat() == GdPictureStatus.OK)
    {
        using (GdPictureImaging oGdPictureImaging = new GdPictureImaging())
        {
            if (oGdPictureImaging.SaveAsPNG(imageID, "thumbnail.png") == GdPictureStatus.OK)
                MessageBox.Show("The created thumbnail has been saved successfully.", "GdViewer.GetPageThumbnail");
            else
                MessageBox.Show("The created thumbnail can't be saved. Status: " + oGdPictureImaging.GetStat().ToString(), "GdViewer.GetPageThumbnail");
        }
        GdViewer1.ReleaseGdPictureImage(imageID);
    }
    else
        MessageBox.Show("The thumbnail can't be created. Status: " + GdViewer1.GetStat().ToString(), "GdViewer.GetPageThumbnail");
}
else
    MessageBox.Show("The file can't be loaded. Status: " + GdViewer1.GetStat().ToString(), "GdViewer.GetPageThumbnail");

Reference

GdViewer Class
GdViewer Members
ReleaseGdPictureImage Method