Question

我遇到标准Windows窗体TreeView的问题;特别是当树视图没有焦点时，默认控件用于渲染所选节点的颜色。这是浅灰色，在某些屏幕上几乎看不见。随后，我已经将TreeView子类化并覆盖了TreeView OnDrawNode事件，以便按照我的意愿为我的节点着色。这很好用，但现在'HotTracking'（当鼠标在给定树节点上时激活突出显示）被我的自定义OnDrawNode事件覆盖。我对Graphics类不太熟悉，并想知道如何修改我当前的子类以包含热跟踪？我知道我可以使用e.Graphics.DrawLine(Pen pen, Point p1, Point p2);但这会变得混乱，有更简单的方法吗？

以下是现有代码：

class CustomTreeView : TreeView 
{
    public CustomTreeView() 
    {
        this.DrawMode = TreeViewDrawMode.OwnerDrawText;
    }

    // Override the drawMode of TreeView.
    protected override void OnDrawNode(DrawTreeNodeEventArgs e) 
    {
        TreeNodeStates treeState = e.State;
        Font treeFont = e.Node.NodeFont ?? e.Node.TreeView.Font;

        // Colors.
        Color foreColor = e.Node.ForeColor;
        string strDeselectedColor = @"#6B6E77", strSelectedColor = @"#94C7FC"; //@"#1ABEE8"; //@"#2FC0EE"; //@"#3A8FEA";
        Color selectedColor = System.Drawing.ColorTranslator.FromHtml(strSelectedColor);
        Color deselectedColor = System.Drawing.ColorTranslator.FromHtml(strDeselectedColor);

        // New brush.
        SolidBrush selectedTreeBrush = new SolidBrush(selectedColor);
        SolidBrush deselectedTreeBrush = new SolidBrush(deselectedColor);

        // Set default font color.
        if (foreColor == Color.Empty)
            foreColor = e.Node.TreeView.ForeColor;

        // Draw bounding box and fill.
        if (e.Node == e.Node.TreeView.SelectedNode) 
        {
            // Use appropriate brush depending on if the tree has focus.
            if (this.Focused)
            {
                foreColor = SystemColors.HighlightText;
                e.Graphics.FillRectangle(selectedTreeBrush /*SystemBrushes.Highlight*/, e.Bounds);
                ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, foreColor, SystemColors.Highlight);
                TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds, foreColor, TextFormatFlags.GlyphOverhangPadding);
            }
            else
            {
                foreColor = SystemColors.HighlightText;
                e.Graphics.FillRectangle(deselectedTreeBrush /*SystemBrushes.Highlight*/, e.Bounds);
                ControlPaint.DrawFocusRectangle(e.Graphics, e.Bounds, foreColor, SystemColors.Highlight);
                TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds, foreColor, TextFormatFlags.GlyphOverhangPadding);
            }
        }
        else 
        {
            // This is firing but is being over written, perhaps by the above?
            if ((e.State & TreeNodeStates.Hot) == TreeNodeStates.Hot)
            {
                e.DrawDefault = true;
                e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
                TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds, System.Drawing.Color.Blue, TextFormatFlags.GlyphOverhangPadding);
            }
            else
            {
                e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
                TextRenderer.DrawText(e.Graphics, e.Node.Text, treeFont, e.Bounds, foreColor, TextFormatFlags.GlyphOverhangPadding);
           }   
        }
    }

像往常一样，非常感谢您的时间。

Answer 1

您需要注意代码中的e.State。 DrawTreeNodeEventArgs.State属性告诉您节点的运行情况，相应地选择颜色。另请查看TreeNode.DrawNode文档中显示的MSDN库示例以获取指导。

Answer 2

只需将TreeView的HotTracking设置为true即可，因为在TreeView中，它包含的节点没有自身标识作为控件，每个节点都由TreeView本身绘制，而节点只包含数据，这就是为什么他们没有事件并且TreeView完成整个工作，所以要设置这些热状态

objTreeView.HotTracking = true;

TreeView将开始为您提供状态，您的代码将正常运行。

正确渲染重写的TreeView

2 个答案: