刚接触这个类，帮一下忙，如果在form1中选择好要画的图形，和大小尺寸，图像要求在form2中的pictureBox显示，form2中的代码怎么写。。。。我仅在form1中写了Form2 f=new Form2();
f.showdiglog();f.show();但是不运行，帮忙看下

在Form2中写画图的代码，然后从Form1将尺寸等参数传递过去，当然也在以在Form1写一个public的画图方法，在Form2再调用

using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace shap
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void sel_ch(object sender, EventArgs e)
        {
            
            
            switch (comboBox1.Text)
            {
                case "正方形":
                    { label1.Text = "正方形的边长";
                  
                        //a= Convert.ToInt32 (textBox1.Text);
                    label2.Visible = false;
                    textBox2.Visible = false;
                    label3.Visible = false;
                    textBox3.Visible = false;
                  
                        break;
                }
            case "长方形":
                {
                    label1.Text = "长方形的长";
                    //int a = Convert.ToInt32(textBox1.Text);
                    //int b = Convert.ToInt32(textBox2.Text);
                    label2.Text = "长方形的宽";
                    label2.Visible = true;
                    textBox2.Visible = true;

                    label3.Visible = false;
                    textBox3.Visible = false;
                    /*Graphics g = f.pictureBox1.CreateGraphics();
                    Pen pen = new Pen(Color.Red, 2);
                    g.DrawRectangle(pen, 10, 10, a, b);*/
                    break;
                }
                case"圆形":
                    {label1.Text = "圆形的半径";
                       
                    
                    label2.Visible = false;
                    textBox2.Visible = false;
                    label3.Visible = false;
                    textBox3.Visible = false;
                  
                        break;
                    }
               
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Hide();

            Form2 f = new Form2();
            f.ShowDialog();
            f.Show();
            Graphics g = f.pictureBox1.CreateGraphics();
            Pen pen = new Pen(Color.Red, 2);
            int a = Convert.ToInt32(textBox1.Text);
            int b = Convert.ToInt32(textBox2.Text);


            switch (comboBox1.Text)
            {
                case "正方形":
                    {
                       
                        g.DrawRectangle(pen, 10, 10,a, a);
                        break;
                    }
                case "长方形":
                    {

                        g.DrawRectangle(pen, 10, 10, a, b);
                        break;
                    }
                case "圆":
                    {
                        g.DrawEllipse(pen, 10, 10, a, a);
                        break;
                    }

            }
        }
    }
}帮忙看看。。。。

好奇怪，能画出来？

不是阿，这是个错误的，请指教。。。。

2楼说的很对，你按他的思路来，应该不会有问题。
我有个疑问，你的form1和form2是父子关系吗，是不是MDI？
如果是：
1、按2楼的思路，在form1中定义所画图形的所需参数。
2、当你点击画图按钮后把这写参数传给form2

不是吧，我添加的一个窗体~~~~是不是父子，我不清楚。。。。。

不会吧 你自己都不知道？？？

如果你连父子窗体都不知道的话 ，我敢肯定你是重新又创建的一个新的FROM。
父子窗体MDI 。。。 Parent。。。。。

我现在也糊涂了，请说明你的目的。