TreeNode图像覆盖

Question

我有一个大约30个图像的图像列表，当TreeNode处于特定状态时，我希望能够在这30个图像之上叠加3个图像。我知道C++ TreeItem可以使用TVIS_OVERLAYMASK来做到这一点：

SetItemState(hItem,INDEXTOOVERLAYMASK(nOverlayIndex), TVIS_OVERLAYMASK);

是否有任何机制可以在.NET中实现类似的结果？

Answer 1

我不知道有什么方法可以自动做覆盖，但是你可以用一个自己绘制的树节点来做。

Answer 2

我看到这个问题还在讨论中，所以我将发布David建议的实现。

internal class MyTree : TreeView
{
    internal MyTree() :
        base()
    {
        // let the tree know that we're going to be doing some owner drawing
        this.DrawMode = TreeViewDrawMode.OwnerDrawText;
        this.DrawNode += new DrawTreeNodeEventHandler(MyTree_DrawNode);
    }

    void MyTree_DrawNode(object sender, DrawTreeNodeEventArgs e)
    {
        // Do your own logic to determine what overlay image you want to use
        Image overlayImage = GetOverlayImage();

        // you have to move the X value left a bit, 
        // otherwise it will draw over your node text
        // I'm also adjusting to move the overlay down a bit
        e.Graphics.DrawImage(overlayImage,
            e.Node.Bounds.X - 15, e.Node.Bounds.Y + 4);

        // We're done! Draw the rest of the node normally
        e.DefaultDraw = true
    }
}

Answer 3

为什么你不直接生成带有覆盖的镜像呢，这样你就不必像这样浪费宝贵的CPU周期了：http://madprops.org/blog/highlighting-treenodes-with-an-overlay-image/：

private void InitializeLinkedTreeImages() 
{ 
    foreach (string key in treeImages.Images.Keys) 
    { 
        Bitmap bmp = new Bitmap(treeImages.Images[key]); 
        Graphics g = Graphics.FromImage(bmp); 
        g.DrawImageUnscaled(Properties.Resources.Linked16, 0, 0); 
        treeImages.Images.Add(key + "Linked", bmp); 
    } 
}