我正在尝试更改 C# Windows Forms 应用程序的 ComboBox 下拉列表中突出显示的颜色。 我在整个网络上搜索了一个答案，到目前为止我找到的最佳选择是在绘制所选项目时绘制一个所需颜色的矩形。

Class Search
{
    Public Search()
    {
    }

    private void addFilter()
    {
        ComboBox field = new ComboBox();

        field.Items.AddRange(new string[] { "Item1", "item2" });
        field.Text = "Item1";
        field.DropDownStyle = ComboBoxStyle.DropDownList;
        field.FlatStyle = FlatStyle.Flat;
        field.BackColor = Color.FromArgb(235, 235, 235);
        field.DrawMode = DrawMode.OwnerDrawFixed;
        field.DrawItem += field_DrawItem;
    }

    private void field_DrawItem(object sender, DrawItemEventArgs e)
    {
        if (e.Index >= 0)
        {
            ComboBox combo = sender as ComboBox;

            if (e.Index == combo.SelectedIndex)
                e.Graphics.FillRectangle(new SolidBrush(Color.Gray),
                                         e.Bounds
                                        );
            else
                e.Graphics.FillRectangle(new SolidBrush(combo.BackColor),
                                         e.Bounds
                                        );

            e.Graphics.DrawString(combo.Items[e.Index].ToString(), e.Font,
                                  new SolidBrush(combo.ForeColor),
                                  new Point(e.Bounds.X, e.Bounds.Y)
                                 );
        }
    }
}

此代码的问题在于，一旦选择了下拉列表中的另一个项目，我绘制矩形的另一个项目仍然具有我想要突出显示的颜色。 然后我尝试保存最后绘制的 Item 并重绘它:

Class Search
{
    private DrawItemEventArgs lastDrawn;

    Public Search()
    {
        lastDrawn = null;
    }

    private void addFilter()
    {
        ComboBox field = new ComboBox();

        field.Items.AddRange(new string[] { "Item1", "item2" });
        field.Text = "Item1";
        field.DropDownStyle = ComboBoxStyle.DropDownList;
        field.FlatStyle = FlatStyle.Flat;
        field.BackColor = Color.FromArgb(235, 235, 235);
        field.DrawMode = DrawMode.OwnerDrawFixed;
        field.DrawItem += field_DrawItem;
    }

    private void field_DrawItem(object sender, DrawItemEventArgs e)
    {
        if (e.Index >= 0)
        {
            ComboBox combo = sender as ComboBox;
            if (e.Index == combo.SelectedIndex)
            {
                e.Graphics.FillRectangle(new SolidBrush(Color.Gray), e.Bounds);
                if(lastDrawn != null)
                    lastDrawn.Graphics.FillRectangle(new SolidBrush(combo.BackColor),
                                                 lastDrawn.Bounds
                                                );
                lastDrawn = e;
            }
            else
                e.Graphics.FillRectangle(new SolidBrush(combo.BackColor),
                                         e.Bounds
                                        );

            e.Graphics.DrawString(combo.Items[e.Index].ToString(), e.Font,
                                  new SolidBrush(combo.ForeColor),
                                  new Point(e.Bounds.X, e.Bounds.Y)
                                 );
        }
    }
}

由于 lastDrawn.Bounds(类型不兼容)，此行返回错误

lastDrawn.Graphics.FillRectangle(new SolidBrush(combo.BackColor),
                                                 lastDrawn.Bounds
                                                );

我觉得改变下拉菜单的高亮颜色是不可能的。 提前致谢!

最佳答案

如果您在项目的多个地方使用ComboBox，那么一遍又一遍地为DrawItem 事件重复相同的代码是没有意义的.只需将此类添加到您的项目中，您将拥有一个具有 HightlightColor 属性的新 ComboBox 控件，这将使在整个项目中使用该控件变得更加容易:

class AdvancedComboBox : ComboBox
{
    new public System.Windows.Forms.DrawMode DrawMode { get; set; }
    public Color HighlightColor { get; set; }

    public AdvancedComboBox()
    {
        base.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawFixed;
        this.HighlightColor = Color.Gray;
        this.DrawItem += new DrawItemEventHandler(AdvancedComboBox_DrawItem);
    }

    void AdvancedComboBox_DrawItem(object sender, DrawItemEventArgs e)
    {
        if (e.Index < 0)
            return;

        ComboBox combo = sender as ComboBox;
        if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
            e.Graphics.FillRectangle(new SolidBrush(HighlightColor),
                                     e.Bounds);
        else
            e.Graphics.FillRectangle(new SolidBrush(combo.BackColor),
                                     e.Bounds);

        e.Graphics.DrawString(combo.Items[e.Index].ToString(), e.Font,
                              new SolidBrush(combo.ForeColor),
                              new Point(e.Bounds.X, e.Bounds.Y));

        e.DrawFocusRectangle();
    }
}

关于c# - 更改 ComboBox 突出显示的颜色，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/13212179/