java 让jComboBox的字体居中显示，

jcomboBox.setRenderer(new MyCellRenderer())

class MyCellRenderer extends JLabel implements ListCellRenderer {

public MyCellRenderer() {

setOpaque(true)

}

public Component getListCellRendererComponent(

JList list,

Object value,

int index,

boolean isSelected,

boolean cellHasFocus)

{

setBackground(isSelected ? Color.BLUE : Color.LIGHT_GRAY)

setHorizontalAlignment(SwingConstants.CENTER)

setText(value.toString())

return this

}

}

可以居中显示。实现方法为

将ComboBox.DrawMode设置为DrawMode.OwnerDrawFixed，

对ComboBox的DrawItem事件编程，各个项目居中显示。

具体步骤如下：

（1）在Visual Studio中创建一个“Windows 窗体应用程序”项目。在Form1上布置一个ComboBox控件

（2）Form1窗体代码Form1.cs

using System.Drawing

using System.Windows.Forms

namespace WindowsFormsApplication1

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent()

            // 允许代码重新绘制，固定大小

            comboBox1.DrawMode = DrawMode.OwnerDrawFixed

            string[] items = {

                                 "项目", 

                                 "项目 1", 

                                 "项目 10", 

                                 "项目 100", 

                                 "项目 1000", 

                                 "项目 10000" 

                             }

            comboBox1.Items.AddRange(items)

        }

        // 将comboBox1中的项目居中显示！

        private void comboBox1_DrawItem(object sender, 

            DrawItemEventArgs e)

        {

            string s = this.comboBox1.Items[e.Index].ToString()

            // 计算字符串尺寸（以像素为单位）

            SizeF ss = e.Graphics.MeasureString(s, e.Font)

            // 水平居中

            float left = (float)(e.Bounds.Width - ss.Width) / 2

            if (left < 0) left = 0f

            float top = (float)(e.Bounds.Height - ss.Height) / 2

            // 垂直居中

            if (top < 0) top = 0f

            top = top + this.comboBox1.ItemHeight * e.Index

            // 输出

            e.DrawBackground()

            e.DrawFocusRectangle()

            e.Graphics.DrawString(

                s, 

                e.Font, 

                new SolidBrush(e.ForeColor), 

                left, top)

        }

    }

}

（3）运行效果

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