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处理大量重复图标的资源

winforms .net c#

1

Dennis · 技术社区 · 17 年前

我正在使用带有图像列表的树状视图。由于树视图中充满了项目,因此每个项目都有一个与其关联的图标。其中许多图标可能是相同的,但目前,我没有添加任何代码来跟踪重复项,我只是将每个图标添加到ImageList中,然后跟踪与每个树节点关联的图标。

我的问题是关于.Net如何处理这些资源。例如,运行时是否意识到某些图标完全相同,因此对所有重复的图标只加载一次相同的图标?如果不是,如果这样做了数万次,我是否会遇到资源问题(这不是典型情况,但可能会发生)?

1 回复 | 直到 17 年前

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2

Scott Dorman 17 年前

该框架没有任何机制来处理这样的资源,以确保不会加载重复项。在树视图的情况下尤其如此,因为它使用的ImageList将这些图像作为包含树视图的表单的本地资源进行维护。

public sealed class ImageListManager
{
    private static volatile ImageListManager instance;
    private static object syncRoot = new object();
    private ImageList imageList;

    private ImageListManager()
    {
        this.imageList = new ImageList();
        this.imageList.ColorDepth = ColorDepth.Depth32Bit;
        this.imageList.TransparentColor = Color.Magenta;
    }

    /// <summary>
    /// Gets the <see cref="System.Windows.Forms.ImageList"/>.
    /// </summary>
    public ImageList ImageList
    {
        get
        {
            return this.imageList;
        }
    }

     /// <summary>
     /// Adds an image with the specified key to the end of the collection if it 
     /// doesn't already exist.
     /// </summary>
     public void AddImage(string imageKey, Image image)
     {
        if (!this.imageList.ContainsKey(imageKey))
        {
           this.imageList.Add(imageKey, image);
        }
     }

    /// <summary>
    /// Gets the current instance of the 
    /// <see cref="ImageListManager"/>.
    /// </summary>
    public static ImageListManager Instance
    {
        get
        {
            if (instance == null)
            {
                lock (syncRoot)
                {
                    if (instance == null)
                    {
                        instance = new ImageListManager();
                    }
                }
            }
            return instance;
        }
    }
}

然后给树视图一个对该ImageList的引用,通常在调用 InitializeComponent() .

public partial class Form1 : Form
{
   public Form1()
   {
      InitializeComponent();
      this.treeView1.ImageList = ImageListManager.Instance.ImageList;
   }

   // Making some guesses about how you are adding nodes
   // and getting the associated image.
   public void AddNewTreeNode(string text, string imageKey, Image image)
   {
      TreeNode node = new TreeNode("display text");
      node.Name = "uniqueName";

      // This tells the new node to use the image in the TreeView.ImageList
      // that has imageKey as its key.
      node.ImageKey = imageKey;
      node.SelectedImageKey = imageKey;

      this.treeView1.Nodes.Add(node);

      // If the image doesn't already exist, this will add it.
      ImageListManager.Instance.AddImage(imageKey, image);
   }

}