C#内部并没有提供橡皮擦功能所以，只能使用画笔和颜色填充来实现橡皮擦和清空画板功能。

此次小编写了一个简易的画板功能其中包含橡皮擦，清空面板，在窗体运行中修改画笔颜色和像素等功能。

代码如下:

using Sunny.UI;
using Sunny.UI.Win32;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using static System.Windows.Forms.LinkLabel;

namespace 画板完整版
{
    public partial class Form1 : UIForm
    {
        // 定义绘制对象
        Graphics g;
        Bitmap bmp;

        // 起点坐标
        Point start; bool flag = false;

        // 画笔颜色
        Color c1 = Color.Black;

        //画笔粗细
        int size = 1;
        

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            pictureBox1.Image = Image.FromFile("./1.png");
            bmp = (Bitmap)pictureBox1.Image.Clone();
            g = Graphics.FromImage(bmp);


            // 默认主题
            this.uiComboBox1.SelectedIndex = 0;
            this.uiStyleManager1.Style = (UIStyle)Enum.Parse(typeof(UIStyle), this.uiComboBox1.SelectedItem.ToString());

            // 默认画笔像素
            this.uiComboBox2.SelectedIndex = 0;

            // 设置XY轴默认像素
            this.uiLabel1.Text = "像素: { X:" + "0" + ",Y:" + "0 }";

            // 时间
            timer1.Interval = 1000;
            timer1.Enabled = true;
            this.time.Text = "北京时间: " + (DateTime.Now).Year + "年" + (DateTime.Now).Month + "月" + (DateTime.Now).Day + "日" + (DateTime.Now).Hour + "时" + (DateTime.Now).Minute + "分" + (DateTime.Now).Second + "秒";

        }

        // 时间
        private void timer1_Tick(object sender, EventArgs e)
        {
            this.time.Text = "北京时间: " + (DateTime.Now).Year + "年" + (DateTime.Now).Month + "月" + (DateTime.Now).Day + "日" + (DateTime.Now).Hour + "时" + (DateTime.Now).Minute + "分" + (DateTime.Now).Second + "秒";
        }

        // 修改主题
        private void uiComboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            this.uiStyleManager1.Style = (UIStyle)Enum.Parse(typeof(UIStyle), this.uiComboBox1.SelectedItem.ToString());
        }

        // 清空画板
        private void uiSymbolButton2_Click(object sender, EventArgs e)
        {
            Point[] p =
            {
                new Point(-2,-2),
                new Point(810,-2),
                new Point(810,515),
                new Point(-2,515),
                new Point(-2,-2)
            };
            g.FillPolygon(Brushes.White, p);
            pictureBox1.Image = bmp;
        }

        // 设置画笔
        private void uiSymbolButton3_Click(object sender, EventArgs e)
        {
            if(s==0&&co==null)return;
            size = s; c1 = co;
            this.uiComboBox2.Text = size.ToString();
        }
        // 画笔颜色
        private void uiButton1_Click(object sender, EventArgs e)
        {
            DialogResult r = colorDialog1.ShowDialog();
            if (r == DialogResult.OK)
            {
                c1 = colorDialog1.Color;
            }
        }
        // 画笔粗细
        private void uiComboBox2_SelectedIndexChanged(object sender, EventArgs e)
        {
            size = int.Parse(uiComboBox2.SelectedItem.ToString());
        }

        // 鼠标按下的方法，主要是获取按下时候的坐标也就是起点坐标
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)// 点击了鼠标左键
            {
                start = e.Location; // 当前点击的坐标
                flag = true;
            }
        }
        // 鼠标移动的时候获取点，获取会追的结束点，并且划线
        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            this.uiLabel1.Text = "像素: {X:" + e.X + ",Y:" +e.Y+"}";
            if (flag == false) return;
            g.DrawLine(new Pen(c1, size), start, e.Location);
            start = e.Location;// 重置起始点
            pictureBox1.Image = bmp;
        }
        // 结束绘制
        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            flag = false;
            pictureBox1.Image = bmp;
        }
        // 橡皮
        int s = 0;
        Color co;
        private void uiSymbolButton1_Click(object sender, EventArgs e)
        {
            s = size; co = c1;
            size = 20;
            c1 = Color.White;
            this.uiComboBox2.Text = size.ToString();
        }

        // 保存
        private void uiSymbolButton4_Click(object sender, EventArgs e)
        {
            if(bmp == null) return;
            SaveFileDialog sf = new SaveFileDialog(); // 保存对话框
            sf.Filter = "图像文件|*.png|jpg图片|*.jpg";
            if (sf.ShowDialog() == DialogResult.OK)
            {
                bmp.Save(sf.FileName, ImageFormat.Png); //
                MessageBox.Show("保存至" + sf.FileName, "温馨提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }
    }
}