combox和panel的使用

Question

这功能很简单嘛，主要是肯定只会在panel出现一个图形，不会出现两个。只不过有点麻烦，需要先画好三角形，正方形，做成控件，以控件形式添加到panel里显示，然后只要处理键盘事件就可以达到效果了。

Answer 1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;namespace WindowsApplication162
{
    public partial class Form1 : Form
    {
        Panel Shape = new Panel();
        Panel P = new Panel();        public Form1()
        {
            InitializeComponent();            ComboBox CB = new ComboBox();
            CB.Parent = this;
            CB.Items.AddRange(new Object[] { "三角形", "正方形" });
            CB.SelectedIndexChanged += new EventHandler(CB_SelectedIndexChanged);
            CB.DropDownStyle = ComboBoxStyle.DropDownList;            P.Parent = this;
            P.Location = new Point(0, 20);
            this.KeyDown += new KeyEventHandler(Form1_KeyDown);
            this.KeyPreview = true;
            CB.KeyDown += new KeyEventHandler(CB_KeyDown);
        }        void CB_KeyDown(object sender, KeyEventArgs e)
        {
            e.SuppressKeyPress = true; // 防止联动，只允许鼠标选择ComboBox
        }        void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            switch (e.KeyCode)
            {
                case Keys.Up: Shape.Top--; break;
                case Keys.Down: Shape.Top++; break;
                case Keys.Left: Shape.Left--; break;
                case Keys.Right: Shape.Left++; break;
            }
        }        void CB_SelectedIndexChanged(object sender, EventArgs e)
        {
            ComboBox CB = (ComboBox)sender;
            GraphicsPath GP = new GraphicsPath();            switch (CB.SelectedIndex)
            {
                case 0:
                    GP.AddLine(0, 60, 30, 0);
                    GP.AddLine(30, 0, 60, 60);
                    GP.AddLine(60, 60, 0, 60);
                    break;
                case 1:
                    GP.AddRectangle(new Rectangle(0, 0, 60, 60));
                    break;
            }            Shape.Parent = P;
            Shape.BackColor = Color.Red;
            Shape.Region = new Region(GP);
        }
    }
}

Answer 2

画三角形等几何图形比较麻烦，用图片代替。再判断键盘事件，改变图片在panel中的位置就可以。