/// <summary>
/// A form that allows to load PDF document into image viewer and
/// highlight focused XObject in PDF document.
/// </summary>
public partial class PdfContentXObjectToolExamples : System.Windows.Forms.Form
{
            
    //...
    Vintasoft.Imaging.UI.ImageViewer _imageViewer;
    Vintasoft.Imaging.Pdf.UI.PdfContentXObjectTool _contentXObjectTool;
    
            
    
    public PdfContentXObjectToolExamples()
    {
        //...
        
        // create an instance of the PdfContentXObjectTool
        _contentXObjectTool = new Vintasoft.Imaging.Pdf.UI.PdfContentXObjectTool();
            
        // set a pen and brush for image selection
        _contentXObjectTool.SelectionImagesBrush = 
            new System.Drawing.SolidBrush(
                System.Drawing.Color.FromArgb(32, System.Drawing.Color.Blue));
        _contentXObjectTool.SelectionImagesPen = System.Drawing.Pens.Red;
        // set a pen and brush for form selection
        _contentXObjectTool.SelectionFormsBrush = 
            new System.Drawing.SolidBrush(
                System.Drawing.Color.FromArgb(32, System.Drawing.Color.Lime));
        _contentXObjectTool.SelectionFormsPen = System.Drawing.Pens.Blue;
            
        // subscribe to content XObject tool events
        _contentXObjectTool.ContentXObjectMouseEnter +=
            new System.EventHandler<Vintasoft.Imaging.Pdf.UI.PdfContentXObjectEventArgs>(ContentXObjectTool_ContentXObjectMouseEnter);
        _contentXObjectTool.ContentXObjectMouseLeave +=
            new System.EventHandler<Vintasoft.Imaging.Pdf.UI.PdfContentXObjectEventArgs>(ContentXObjectTool_ContentXObjectMouseLeave);
            
        // set the content XObject tool as current tool
        _imageViewer.VisualTool = _contentXObjectTool;
    }
            
            
            
    /// <summary>
    /// Occurs when the mouse pointer enters the XObject on PDF page.
    /// </summary>
    private void ContentXObjectTool_ContentXObjectMouseEnter(
        object sender,
        Vintasoft.Imaging.Pdf.UI.PdfContentXObjectEventArgs e)
    {
        // add the focused XObject to a list of selected XObjects
        _contentXObjectTool.SelectedXObjects.Add(e.ContentXObject);
    }
            
    /// <summary>
    /// Occurs when the mouse pointer leaves the the XObject on PDF page.  
    /// </summary>
    private void ContentXObjectTool_ContentXObjectMouseLeave(
        object sender,
        Vintasoft.Imaging.Pdf.UI.PdfContentXObjectEventArgs e)
    {
        // remove the focused XObject from a list of selected XObjects
        _contentXObjectTool.SelectedXObjects.Remove(e.ContentXObject);
    }
            
}