C# Dev GridView表格的CustomUnboundColumnData事件异步加载图片类AsynDownImage

  C# Dev GridView表格的CustomUnboundColumnData事件异步加载图片类AsynDownImage

C# Code:

/// <summary>
/// GridView异步加载url地址的图片,通知CustomColumnDataEventArgs参数
/// </summary>
public class AsynDownImage
{
  private string _URL { get; set; }
  
  private Bitmap _Image { get; set; }
  
  private bool _IsReady = false;
  
  private object _Locker = new object();
  
  private List<DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs> _listens;
  
  private bool _UseLocalImage = true;//使用本地缓存图片
  
  public AsynDownImage(string url)
  {
    _UseLocalImage = true;
    _URL = url;
    _listens = new List<DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs>();
    this.StartDown();
  }
  
  /// <summary>
  /// 开始加载图片
  /// </summary>
   void StartDown()
  {
    Task.Run(() =>
    {
      //判断本地缓存文件
       if (_UseLocalImage && ImageFileCache.Instance.Exists(ImageBuckleName.small_images, this._URL))
      {
        this._Image = ImageFileCache.Instance.GetImage(ImageBuckleName.small_images, this._URL);
        lock (_Locker)
        {
          _IsReady = true;
        }
        RunNotify();
        return;
      }
      
      //判断图片路径是否为网络路径
       if (IsUrl(this._URL))
      {
        try
        {
          //读取文件
           using (WebClient wc = new WebClient())
          {
            Stream tream = wc.OpenRead(this._URL);
            this._Image = new Bitmap(tream);
            this._Image = new Bitmap(this._Image, new Size(60, 60));//缩放图片
            
            //缓存图片
             if (_UseLocalImage)
            ImageFileCache.Instance.AddImage(this._URL, this._Image, ImageBuckleName.small_images);
          }
        }
        catch (Exception ex)
        {
          this._Image = null;
        }
        lock (_Locker)
        {
          _IsReady = true;
        }
        RunNotify();
        return;
      }
      });
    }
    
    
    public void AddListener(DevExpress.XtraGrid.Views.Base.CustomColumnDataEventArgs obj)
    {
      lock (_Locker)
      {
        _listens.Add(obj);
        if (this._IsReady)
        {
          obj.Value = this._Image;
        }
      }
    }
    
    void RunNotify()
    {
      lock (_Locker)
      {
        foreach (var o in _listens)
        {
          o.Value = this._Image;
        }
      }
    }
    
    /// <summary>
    /// 识别urlStr是否是网络路径
    /// </summary>
    /// <param name="url"></param>
    /// <returns></returns>
     public static bool IsUrl(string url)
    {
      if (Regex.IsMatch(url, @"((http|ftp|https)://)(([a-zA-Z0-9\._-]+\.[a-zA-Z]{2,6})|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}))(:[0-9]{1,4})*(/[a-zA-Z0-9\&%_\./-~-]*)?"))
      {
        return true;
      }
      else
      {
        return false;
      }
    }
    
  }
  
  
  //来源:C/S框架网 | www.csframework.com | QQ:23404761

ImageFileCache 类：

C# 本地图片缓存器ImageFileCache (www.csframework.com)

http://www.csframework.com/archive/1/arc-1-20210319-3018.htm

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