Question

我想删除Node.Type为5或6的CheckBoxes。我使用此代码：

private void TvOne_DrawNode(object sender, DrawTreeNodeEventArgs e)
{
    int type = (e.Node as Node).typ;
    if (type == 5 || type == 6)
    {
        Color backColor, foreColor;
        if ((e.State & TreeNodeStates.Selected) == TreeNodeStates.Selected)
        {
            backColor = SystemColors.Highlight;
            foreColor = SystemColors.HighlightText;
        }
        else if ((e.State & TreeNodeStates.Hot) == TreeNodeStates.Hot)
        {
            backColor = SystemColors.HotTrack;
            foreColor = SystemColors.HighlightText;
        }
        else
        {
            backColor = e.Node.BackColor;
            foreColor = e.Node.ForeColor;
        }
        using (SolidBrush brush = new SolidBrush(backColor))
        {
            e.Graphics.FillRectangle(brush, e.Node.Bounds);
        }
        TextRenderer.DrawText(e.Graphics, e.Node.Text, this.TvOne.Font,
            e.Node.Bounds, foreColor, backColor);

        if ((e.State & TreeNodeStates.Focused) == TreeNodeStates.Focused)
        {
            ControlPaint.DrawFocusRectangle(e.Graphics, e.Node.Bounds,
                foreColor, backColor);
        }
        e.DrawDefault = false;
    }
    else
    {
        e.DrawDefault = true;
    }
}

问题是那时图像和到根节点的线不存在。如何删除复选框并将图像和线放在那里？

This is wrong!

Answer 1

在您显示的代码中，您正在为所有类型为5或6的节点自己处理绘图。对于其他类型，您只需允许系统绘制节点中的节点。默认方式。这就是为什么他们都有预期的线条，但你所有者绘制的线条没有：你忘了画线！你看，当你说e.DrawDefault = false;时，你会认为你的确意味着它。没有完成常规绘图，包括标准线。

你需要自己绘制这些线条，或者根本没有所有者绘图来弄明白。

从你现在的代码中，看起来你正试图在你的所有者绘制代码中尽可能地模拟系统的原生绘图风格，所以我不清楚你是通过所有者绘图完成了什么第一名。如果你只是试图保持复选框不显示类型5和6节点（就像线条一样，因为你没有绘制它们而根本没有被绘制！），有一种更简单的方法可以在不涉及所有者的情况下完成图。

那么，你问，隐藏单个节点的复选框的简单方法是什么？好吧，事实证明TreeView控件本身实际上支持这一点，但该功能未在.NET Framework中公开。您需要P / Invoke并调用Windows API才能获得它。将以下代码添加到表单类中（确保为using添加了System.Runtime.InteropServices声明）：

private const int TVIF_STATE = 0x8;
private const int TVIS_STATEIMAGEMASK = 0xF000;
private const int TV_FIRST = 0x1100;
private const int TVM_SETITEM = TV_FIRST + 63;

[StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Auto)]
private struct TVITEM
{
    public int mask;
    public IntPtr hItem;
    public int state;
    public int stateMask;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string lpszText;
    public int cchTextMax;
    public int iImage;
    public int iSelectedImage;
    public int cChildren;
    public IntPtr lParam;
}

[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam,
                                         ref TVITEM lParam);

/// <summary>
/// Hides the checkbox for the specified node on a TreeView control.
/// </summary>
private void HideCheckBox(TreeView tvw, TreeNode node)
{
    TVITEM tvi = new TVITEM();
    tvi.hItem = node.Handle;
    tvi.mask = TVIF_STATE;
    tvi.stateMask = TVIS_STATEIMAGEMASK;
    tvi.state = 0;
    SendMessage(tvw.Handle, TVM_SETITEM, IntPtr.Zero, ref tvi);
}

顶部的所有杂乱的东西都是你的P / Invoke声明。您需要一些常量，TVITEM structure描述树视图项的属性，以及SendMessage function。在底部是您实际调用的函数（HideCheckBox）。您只需传入TreeView控件以及要从中删除复选标记的特定TreeNode项。

因此，您可以从每个子节点中删除复选标记，以获得如下所示的内容：

TreeView with checkmarks hidden for child nodes

Answer 2

使用TreeViewExtensions。

使用示例：

private void MyForm_Load(object sender, EventArgs e)
{
     this.treeview1.DrawMode = TreeViewDrawMode.OwnerDrawText;
     this.treeview1.DrawNode += new DrawTreeNodeEventHandler(arbolDependencias_DrawNode);
}

void treeview1_DrawNode(object sender, DrawTreeNodeEventArgs e)
{
    if (e.Node.Level == 1) e.Node.HideCheckBox();
    e.DrawDefault = true;
}

以下是作为Extension方法的答案代码，使用此方法可以：

public static class TreeViewExtensions
{
    private const int TVIF_STATE = 0x8;
    private const int TVIS_STATEIMAGEMASK = 0xF000;
    private const int TV_FIRST = 0x1100;
    private const int TVM_SETITEM = TV_FIRST + 63;

    [StructLayout(LayoutKind.Sequential, Pack = 8, CharSet = CharSet.Auto)]
    private struct TVITEM
    {
        public int mask;
        public IntPtr hItem;
        public int state;
        public int stateMask;
        [MarshalAs(UnmanagedType.LPTStr)]
        public string lpszText;
        public int cchTextMax;
        public int iImage;
        public int iSelectedImage;
        public int cChildren;
        public IntPtr lParam;
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam,
                                             ref TVITEM lParam);

    /// <summary>
    /// Hides the checkbox for the specified node on a TreeView control.
    /// </summary>
    public static void HideCheckBox(this TreeNode node)
    {
        TVITEM tvi = new TVITEM();
        tvi.hItem = node.Handle;
        tvi.mask = TVIF_STATE;
        tvi.stateMask = TVIS_STATEIMAGEMASK;
        tvi.state = 0;
        SendMessage(node.TreeView.Handle, TVM_SETITEM, IntPtr.Zero, ref tvi);
    }
}

Answer 3

这非常好！我所做的唯一修改是仅将TreeNode而不是TreeView传递给HideCheckBox方法。可以从TreeView本身检索TreeNode：

TreeView tvw = node.TreeView;

TreeView通过某些节点删除CheckBox

3 个答案: