PDFOffice_Windows_exe/PDF Office/CustomControl/CustomImageControl.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace PDF_Office.CustomControl
{
    internal class CustomImageControl : FrameworkElement
    {
        private DrawingVisual PresentChild { get; set; }
        private DrawingContext DrawDC { get; set; }
        public CustomImageControl()
        {
            PresentChild = new DrawingVisual();
            AddVisualChild(PresentChild);
            AddLogicalChild(PresentChild);
        }
        protected override Visual GetVisualChild(int index)
        {
            if (PresentChild == null)
            {
                throw new ArgumentOutOfRangeException();
            }
            return PresentChild;
        }
        protected override int VisualChildrenCount
        {
            get
            {
                if (PresentChild != null)
                {
                    return 1;
                }
                return 0;
            }
        }

        public DrawingContext OpenDraw()
        {
            if (DrawDC == null)
            {
                DrawDC = PresentChild?.RenderOpen();
            }
            return DrawDC;
        }
        public void CloseDraw()
        {
            DrawDC?.Close();
            DrawDC = null;
        }
    }
}