关于两个PictureBox重叠后透明的问题

我的系统之前就有这么个问题，当两个图片重叠的时候，上面的图片总是将下面的图片覆盖，之前因为忙一直没有腾出时间处理一下

 

 

今天实在看不下去了，然后本来想自己重新写一个，但是问了技术群的大佬，给重写了一个PictureBoxDE 类，效果如下

 

 

 完美的解决了图片的透明，下面我将把这个重写的类发出来，供大家使用参考，也顺便做一下记录

public class ReiongCtr : PictureBox
    {
        protected override void OnSizeChanged(EventArgs e)
        {
            base.OnSizeChanged(e);
            if (BackgroundImage != null)
            {
                Bitmap bit = (Bitmap)BackgroundImage.GetThumbnailImage(Width, Height, null, IntPtr.Zero);
                Region = ImageToRegion(bit, Color.FromArgb(0, 0, 0, 0));
            }
        }
        protected override void OnBackgroundImageChanged(EventArgs e)
        {
            base.OnBackgroundImageChanged(e);
            if (BackgroundImage != null)
            {
                Bitmap bit = (Bitmap)BackgroundImage.GetThumbnailImage(Width, Height, null, IntPtr.Zero);
                Region = ImageToRegion(bit, Color.FromArgb(0, 0, 0, 0));
            }
        }
         
        /// <summary>
        /// 根据图片计算Region路径(低效率)
        /// </summary>
        /// <param name="img">图像资源</param>
        /// <param name="TranColor">欲透明掉的颜色</param>
        /// <returns>一个离散的路径信息</returns>
        public static Region ImageToRegion(Image imgx, Color TranColor)
        {
            if (imgx == null) return null;
            Region rRegion = new Region();
            rRegion.MakeEmpty();


            int ImWidth = imgx.Width;
            int ImHeight = imgx.Height;
            Color curColor;
            Rectangle curRect = new Rectangle();
            curRect.Height = 1;
            bool isTransRgn;

            for (int y = 0; y < ImHeight; y++)
            {
                isTransRgn = true;
                for (int x = 0; x < ImWidth; x++)
                {
                    curColor = ((Bitmap)imgx).GetPixel(x, y);
                    if (curColor == TranColor || x == ImWidth - 1)//如果遇到透明色或行尾
                    {
                        if (isTransRgn == false)//退出有效区
                        {
                            curRect.Width = x - curRect.X;
                            rRegion.Union(curRect);
                        }
                    }
                    else//非透明色
                    {
                        if (isTransRgn == true)//进入有效区
                        {
                            curRect.X = x;
                            curRect.Y = y;
                        }
                    }//if curColor
                    isTransRgn = curColor == TranColor;
                }
            }
            return rRegion;
        }
    }