允许在.NET TreeView中进行多选

Question

我陷入了.NET 2.0 Windows Forms.

它看起来不像标准TreeView控件中存在选择多个节点的能力.

我正在尝试为上下文菜单选择执行此操作.因此,复选框不是可接受的UI范例.

提供非常必要的功能的最佳方法是什么？

Answer 1

我们曾在WTL项目中做过一次,但.NET所需的基本工作是相同的.要实现多选树控制,您需要自己绘制树项并覆盖键盘和鼠标处理.您还需要维护自己选择的项目列表.

不要忘记考虑选择规则(例如,允许父母和孩子),并且不要忘记实现键盘快捷键,包括使用Ctrl,Shift和Ctrl + Shift选择,以及用于选择/取消选择的空格键.

Answer 2

TreeView.CheckBoxes

Answer 3

复选框是否可以选择？还是想要像在列表框中一样进行选择？

• 内置复选框
• 选择就像您进入列表框一样，需要自定义树控件

CodeProject上有一个多选树控件：多选树视图

Answer 4

最简单的解决方案是扩展框架附带的现有 TreeView 控件，并使用捕获多个选择的逻辑覆盖 OnBeforeSelect 和 OnAfterSelect 方法。

一个例子可以在这里找到：http : //www.arstdesign.com/articles/treeviewms.html

Answer 5

下面的代码将允许您调整您使用的背景颜色，以确保所有选定的节点都突出显示。

protected override void WndProc(ref Message m)
{
    switch (m.Msg) {
        // WM_REFLECT is added because WM_NOTIFY is normally sent just
        // to the parent window, but Windows.Form will reflect it back
        // to us, MFC-style.
        case Win32.WM_REFLECT + Win32.WM_NOTIFY: {
            Win32.NMHDR nmhdr = (Win32.NMHDR)m.GetLParam(typeof(Win32.NMHDR));
            switch((int)nmhdr.code) {
                case Win32.NM_CUSTOMDRAW:
                    base.WndProc(ref m);
                    Win32.NMTVCUSTOMDRAW nmTvDraw = (Win32.NMTVCUSTOMDRAW)m.GetLParam(typeof(Win32.NMTVCUSTOMDRAW));
                    switch (nmTvDraw.nmcd.dwDrawStage) {
                        case Win32.CDDS_ITEMPREPAINT:
                            // Find the node being painted.
                            TreeNode n = TreeNode.FromHandle(this, nmTvDraw.nmcd.lItemlParam);
                            if (allSelected.Contains(n))
                                // Override its background colour.
                                nmTvDraw.clrTextBk = ColorTranslator.ToWin32(SystemColors.Highlight);
                            m.Result = (IntPtr)Win32.CDRF_DODEFAULT;  // Continue rest of painting as normal
                            break;
                    }
                    Marshal.StructureToPtr(nmTvDraw, m.LParam, false);  // copy changes back
                    return;
            }
            break;
        }
    }
    base.WndProc(ref m);
}

// WM_NOTIFY notification message header.
[System.Runtime.InteropServices.StructLayout(LayoutKind.Sequential)]
public class NMHDR
{
    private IntPtr hwndFrom;
    public IntPtr idFrom;
    public uint code;
}

[StructLayout(LayoutKind.Sequential)]
public struct NMCUSTOMDRAW
{
    public NMHDR hdr;
    public int dwDrawStage;
    public IntPtr hdc;
    public RECT rc;
    public IntPtr dwItemSpec;
    public int uItemState;
    public IntPtr lItemlParam;
}

[StructLayout(LayoutKind.Sequential)]
public struct NMTVCUSTOMDRAW
{
    public NMCUSTOMDRAW nmcd;
    public int clrText;
    public int clrTextBk;
    public int iLevel;
}

public const int CDIS_SELECTED = 0x0001;
public const int CDIS_FOCUS = 0x0010;
public const int CDDS_PREPAINT = 0x00000001;
public const int CDDS_POSTPAINT = 0x00000002;
public const int CDDS_PREERASE = 0x00000003;
public const int CDDS_POSTERASE = 0x00000004;
public const int CDDS_ITEM = 0x00010000;  // item specific 
public const int CDDS_ITEMPREPAINT = (CDDS_ITEM | CDDS_PREPAINT);
public const int CDDS_ITEMPOSTPAINT = (CDDS_ITEM | CDDS_POSTPAINT);
public const int CDDS_ITEMPREERASE = (CDDS_ITEM | CDDS_PREERASE);
public const int CDDS_ITEMPOSTERASE = (CDDS_ITEM | CDDS_POSTERASE);
public const int CDDS_SUBITEM = 0x00020000;
public const int CDRF_DODEFAULT = 0x00000000;
public const int CDRF_NOTIFYITEMDRAW = 0x00000020;
public const int CDRF_NOTIFYSUBITEMDRAW = 0x00000020;  // flags are the same, we can distinguish by context

public const int WM_USER = 0x0400;
public const int WM_NOTIFY = 0x4E;
public const int WM_REFLECT = WM_USER + 0x1C00;