Ownerdrawn TreeView (WinForms)

Question

我有一个带有复选框的 TreeView 控件，该控件完全由所有者绘制 (DrawMode = TreeViewDrawMode.OwnerDrawAll)。

我想要做的是绘制复选框所有者，以便它们可以具有灰色状态。我为此使用VisualStyleRenderer。

当我必须将展开/折叠字形和复选框正确放置在项目边界中时，就会出现问题，因为字形和复选框的“命中测试区域”似乎都是未知且不可更改的。

有没有办法获得这些区域的边界，或者用自定义值替换默认值？

Answer 1

我遇到了同样的问题。您必须将绘图偏移适当的量，这是可以预测的。

这里可能比您需要的更多，但这是我与日历控件一起使用的自定义树的绘图：

private void TreeViewControl_DrawNode(Object sender, DrawTreeNodeEventArgs e)
{
    //What might seem like strange positioning/offset is to ensure that our custom drawing falls in
    //  line with where the base drawing would appear.  Otherwise, click handlers (hit tests) fail 
    //  to register properly if our custom-drawn checkbox doesn't fall within the expected coordinates.

    Int32 boxSize = 16;
    Int32 offset = e.Node.Parent == null ? 3 : 21;
    Rectangle bounds = new Rectangle(new Point(e.Bounds.X + offset, e.Bounds.Y + 1), new Size(boxSize, boxSize));
    ControlPaint.DrawCheckBox(e.Graphics, bounds, e.Node.Checked ? ButtonState.Checked : ButtonState.Normal);
    if (e.Node.Parent != null)
    {
        Color c = Color.Black;
        String typeName = e.Node.Name.Remove(0, 4);
        Object o = Enum.Parse(typeof(CalendarDataProvider.CalendarDataItemType), typeName);
        if (o != null && (o is CalendarDataProvider.CalendarDataItemType))
            c = CalendarDataProvider.GetItemTypeColor((CalendarDataProvider.CalendarDataItemType)o);
        bounds = new Rectangle(new Point(bounds.X + boxSize + 2, e.Bounds.Y + 1), new Size(13, 13));
        using (SolidBrush b = new SolidBrush(c))
            e.Graphics.FillRectangle(b, bounds);
        e.Graphics.DrawRectangle(Pens.Black, bounds);
        e.Graphics.DrawLine(Pens.Black, new Point(bounds.X + 1, bounds.Bottom + 1), new Point(bounds.Right + 1, bounds.Bottom + 1));
        e.Graphics.DrawLine(Pens.Black, new Point(bounds.Right + 1, bounds.Y + 1), new Point(bounds.Right + 1, bounds.Bottom + 1));
    }
    Font font = new Font("Microsoft Sans Serif", 9f, e.Node.Parent == null ? FontStyle.Bold : FontStyle.Regular);
    bounds = new Rectangle(new Point(bounds.X + boxSize + 2, e.Bounds.Y), new Size(e.Bounds.Width - offset - 2, boxSize));
    e.Graphics.DrawString(e.Node.Text, font, Brushes.Black, bounds);
}