有没有一种简单的方法可以让选定的 TreeNode 在 TreeView 没有焦点时保留其 SystemColors.Highlight BackColor？因为即使 HideSelection 设置为 false，所选的 BackColor 也几乎是看不到的。
TreeView 具有焦点时选定的 TreeNode：
TreeView 没有焦点时选择的 TreeNode：
提前致谢。
编辑：我知道我可以将 DrawMode 设置为 OwnerDrawAll，然后添加一个自定义 DrawNode 事件。我之前确实尝试过，我遇到的问题是我不知道如何正确绘制 TreeNode 的相应 ImageKey。
如果您只想要保留SystemColors.Highlight背景颜色，则无需将TreeView'DrawMode属性设置为TreeViewDrawMode.OwnerDrawAll. 将其设置为TreeViewDrawMode.OwnerDrawText就足够了，因此您无需担心绘制TreeNode' 对应的ImageKey.
设置TreeView.DrawMode为TreeViewDrawMode.OwnerDrawText：
treeView.DrawMode = TreeViewDrawMode.OwnerDrawText;
将 设置Treview.HideSelection为false，以便节点状态将保持为选中状态：
treeView.HideSelection= false;
添加事件处理程序以使用颜色DrawNode绘制背景：SystemColors.Highlight
private void treeView_DrawNode(object sender, DrawTreeNodeEventArgs e)
{
if (e.Node == null) return;
// if treeview's HideSelection property is "True",
// this will always returns "False" on unfocused treeview
var selected = (e.State & TreeNodeStates.Selected) == TreeNodeStates.Selected;
var unfocused = !e.Node.TreeView.Focused;
// we need to do owner drawing only on a selected node
// and when the treeview is unfocused, else let the OS do it for us
if (selected && unfocused)
{
var font = e.Node.NodeFont ?? e.Node.TreeView.Font;
e.Graphics.FillRectangle(SystemBrushes.Highlight, e.Bounds);
TextRenderer.DrawText(e.Graphics, e.Node.Text, font, e.Bounds, SystemColors.HighlightText, TextFormatFlags.GlyphOverhangPadding);
}
else
{
e.DrawDefault = true;
}
}
解决方案就像一个魅力：
public TreeNode previousSelectedNode = null;
private void treeView1_Validating(object sender, System.ComponentModel.CancelEventArgs e)
{
treeView1.SelectedNode.BackColor = SystemColors.Highlight;
treeView1.SelectedNode.ForeColor = Color.White;
previousSelectedNode = treeView1.SelectedNode;
}
private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
{
if(previousSelectedNode != null)
{
previousSelectedNode.BackColor = treeView1.BackColor;
previousSelectedNode.ForeColor = treeView1.ForeColor;
}
}
我使用这个解决方案，效果更好
private void treeView1_Enter(object sender, EventArgs e)
{
if (treeView1.SelectedNode != null)
{
treeView1.SelectedNode.BackColor = Color.Empty;
treeView1.SelectedNode.ForeColor = Color.Empty;
}
}
private void treeView1_Leave(object sender, EventArgs e)
{
if (treeView1.SelectedNode != null)
{
treeView1.SelectedNode.BackColor = SystemColors.Highlight;
treeView1.SelectedNode.ForeColor = Color.White;
}
}
编辑
基于此文档，
默认值为 Color.Empty
所以，treeView1_Enter最好像这样设置颜色
treeView1.SelectedNode.BackColor = Color.Empty;
treeView1.SelectedNode.ForeColor = Color.Empty;
上一个答案
treeView1.SelectedNode.BackColor = treeView1.BackColor;
treeView1.SelectedNode.ForeColor = treeView1.ForeColor;
如果您只需要在树视图失焦时突出显示选定的节点，那么只需使用 treeView.HideSelection = false;
实际上，默认情况下，选定的节点是突出显示的，但不可见，所以我们只需要将 HideSelection 属性设置为 false。
在这里找到了这个很棒的解决方案（MSDN）
对我来说很好，希望它会帮助别人。
如果您知道自己在做什么，您也可以自定义它
using System;
using System.Drawing;
using System.Windows.Forms;
class MyTreeView : TreeView {
public MyTreeView() {
this.DrawMode = TreeViewDrawMode.OwnerDrawText;
}
protected override void OnDrawNode(DrawTreeNodeEventArgs e) {
TreeNodeStates state = e.State;
Font font = e.Node.NodeFont ?? e.Node.TreeView.Font;
Color fore = e.Node.ForeColor;
if (fore == Color.Empty) fore = e.Node.TreeView.ForeColor;
if (e.Node == e.Node.TreeView.SelectedNode) {
fore = SystemColors.HighlightText;
e.Graphics.FillRectangle(SystemBrushes.Highlight, e.Bounds);
ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, fore, SystemColors.Highlight);
TextRenderer.DrawText(e.Graphics, e.Node.Text, font, e.Bounds, fore, TextFormatFlags.GlyphOverhangPadding);
}
else {
e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
TextRenderer.DrawText(e.Graphics, e.Node.Text, font, e.Bounds, fore, TextFormatFlags.GlyphOverhangPadding);
}
}
}
这是树视图的默认行为。更改它所需要做的就是覆盖drawnode。还有另一个堆栈溢出答案比我在这里解释得更好。
以下代码甚至适用于以编程方式选择的节点。
public TreeNode m_previousSelectedNode = null;
private void m_treeView_AfterSelect(object sender, TreeViewEventArgs e)
{
if (m_previousSelectedNode != null)
{
m_previousSelectedNode.BackColor = m_treeView.BackColor;
m_previousSelectedNode.ForeColor = m_treeView.ForeColor;
}
e.Node.BackColor = SystemColors.Highlight;
e.Node.ForeColor = Color.White;
m_previousSelectedNode = m_treeView.SelectedNode;
}
IronGeeks 答案的这个变体对我有用，并且适用于Bold Nodes：
Private Sub TreeView1_DrawNode(sender As Object, e As DrawTreeNodeEventArgs) Handles trvIdent.DrawNode
Dim treeView = e.Node.TreeView
Dim selected = (e.Node Is treeView.SelectedNode)
Dim unfocused = Not treeView.Focused
Dim font = If(e.Node.NodeFont IsNot Nothing, e.Node.NodeFont, treeView.Font)
Dim textSize = e.Graphics.MeasureString(e.Node.Text, font)
Dim bounds = New Rectangle(e.Bounds.X, e.Bounds.Y,
Convert.ToInt32(textSize.Width),
Math.Max(Convert.ToInt32(textSize.Height), e.Bounds.Height))
e.DrawDefault = False
If selected Then
e.Graphics.FillRectangle(SystemBrushes.Highlight, bounds)
e.Graphics.DrawString(e.Node.Text, font, SystemBrushes.HighlightText, bounds.Location)
Else
e.Graphics.FillRectangle(SystemBrushes.Window, bounds)
e.Graphics.DrawString(e.Node.Text, font, SystemBrushes.WindowText, bounds.Location)
End If
'e.Graphics.DrawRectangle(Pens.Magenta, bounds)
End Sub
主要区别在于即使TreeView焦点集中，自定义绘图也会完成。并DrawString()用于代替DrawText().