private void Form1_Load(object sender, EventArgs e)
{
myComboBox.Items.Clear();
Array allColors = Enum.GetValues(typeof(KnownColor)); //获得系统颜色集合
foreach (KnownColor var in allColors)
{
myComboBox.Items.Add(var.ToString()); //加载该选项框的子项
}
myComboBox.SelectedIndex = 1;
}
private void myComboBox_DrawItem(object sender, DrawItemEventArgs e)
{
//判断是否需要重绘
if (e.Index >= 0)
{
string colorName = myComboBox.Items[e.Index].ToString(); //子项的颜色名
SolidBrush brush = new SolidBrush(Color.FromName(colorName)); //画笔
Font font = new Font("宋体", 9); //字体样式
Brush brushs = Brushes.Black;
Rectangle rect = e.Bounds; //获得需要重绘的区域
rect.Inflate(-2, -2); //缩放一定大小
Rectangle rectColor = new Rectangle(rect.Location,new Size(20,rect.Height));
e.Graphics.FillRectangle(brush, rectColor); // 填充颜色
e.Graphics.DrawRectangle(Pens.Black, rectColor); // 绘制边框
//绘制文字
e.Graphics.DrawString(colorName, font, brushs, (rect.X+22), rect.Y);
}
}
同时还需要设置该控件的DrawMode和DropDownStyle属性,类似的控件Listbox也可按同样方法实现颜色选择,DrawMode属性为NORMAL时,有选中效果,但自己绘制的选项则不会出现选中效果,若想实现,可在DrawItem中加入一个状态判定,如:
//绘制选中效果
if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
{
SolidBrush brushItem = new SolidBrush(SystemColors.MenuHighlight); //画笔
Rectangle rectItem = e.Bounds;
e.Graphics.FillRectangle(brushItem, rectItem);
}
else
{
SolidBrush brushItem = new SolidBrush(SystemColors.Window); //画笔
Rectangle rectItem = e.Bounds;
e.Graphics.FillRectangle(brushItem, rectItem);
}
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