How to "Take a snapshot" as on Acrobat?

private void Form1_Load(object sender, EventArgs e)
{    
    // Create an instance PdfDocumentView
    PdfDocumentView view = new PdfDocumentView();
 
    // Load the document to be exported as image
    documentView.Load("../../Data/PDF_Succinctly.pdf"); 
 
    // ExportAsImage return the bitmap image of any page of the loaded pdf document
    Bitmap image = documentView.ExportAsImage(0);
 
    // Select a region to take snapshot 
    Rectangle newRect = new Rectangle(150, 100, 400, 400);
 
    // Use Bitmap.Clone( ) to  save the image in local drive
    System.Drawing.Imaging.PixelFormat format = image.PixelFormat;
    Bitmap cloneBitmap = image.Clone(newRect, format);
    cloneBitmap.Save("PDF_Succinctly.png");    
}