C-WinForms的入门级画板实现

2025-09-26 约 1051 字预计阅读 3 分钟

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C# WinForms的入门级画板实现

C# WinForms简易画板实现

C# WinForms的入门级画板实现，包含基础绘图、颜色选择和橡皮擦功能

using System;
using System.Drawing;
using System.Windows.Forms;

namespace SimpleDrawingBoard
{
    public partial class MainForm : Form
    {
        private Bitmap _canvas;
        private Graphics _graphics;
        private Point _startPoint;
        private bool _isDrawing = false;
        private Color _currentColor = Color.Black;
        private int _brushSize = 5;

        public MainForm()
        {
            InitializeComponent();
            InitializeDrawingBoard();
        }

        private void InitializeDrawingBoard()
        {
            // 初始化画布
            _canvas = new Bitmap(pictureBox1.Width, pictureBox1.Height);
            _graphics = Graphics.FromImage(_canvas);
            _graphics.Clear(Color.White);
            pictureBox1.Image = _canvas;

            // 设置双缓冲减少闪烁
            this.DoubleBuffered = true;
            pictureBox1.DoubleBuffered = true;

            // 初始化控件
            trackBarBrushSize.Value = _brushSize;
            colorDialog1.Color = _currentColor;
        }

        // 鼠标事件处理
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _isDrawing = true;
                _startPoint = e.Location;
            }
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (!_isDrawing) return;

            using (Graphics g = Graphics.FromImage(_canvas))
            {
                g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

                // 橡皮擦模式
                if (checkBoxEraser.Checked)
                {
                    DrawRectangle(g, _startPoint, e.Location, Color.White, _brushSize * 2);
                }
                else
                {
                    DrawLine(g, _startPoint, e.Location);
                }
            }

            _startPoint = e.Location;
            pictureBox1.Refresh();
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            _isDrawing = false;
        }

        // 绘图方法
        private void DrawLine(Graphics g, Point start, Point end)
        {
            Pen pen = new Pen(_currentColor, _brushSize)
            {
                StartCap = System.Drawing.Drawing2D.LineCap.Round,
                EndCap = System.Drawing.Drawing2D.LineCap.Round
            };
            g.DrawLine(pen, start, end);
            pen.Dispose();
        }

        private void DrawRectangle(Graphics g, Point start, Point end, Color color, int size)
        {
            int x = Math.Min(start.X, end.X);
            int y = Math.Min(start.Y, end.Y);
            int width = Math.Abs(start.X - end.X);
            int height = Math.Abs(start.Y - end.Y);

            using (Pen pen = new Pen(color, size))
            {
                g.DrawRectangle(pen, x, y, width, height);
            }
        }

        // 控件事件处理
        private void buttonColor_Click(object sender, EventArgs e)
        {
            if (colorDialog1.ShowDialog() == DialogResult.OK)
            {
                _currentColor = colorDialog1.Color;
            }
        }

        private void trackBarBrushSize_Scroll(object sender, EventArgs e)
        {
            _brushSize = trackBarBrushSize.Value;
        }

        private void buttonClear_Click(object sender, EventArgs e)
        {
            _graphics.Clear(Color.White);
            pictureBox1.Refresh();
        }

        private void checkBoxEraser_CheckedChanged(object sender, EventArgs e)
        {
            trackBarBrushSize.Enabled = !checkBoxEraser.Checked;
        }

        // 窗口调整大小处理
        private void MainForm_ResizeEnd(object sender, EventArgs e)
        {
            if (pictureBox1.Width != _canvas.Width || pictureBox1.Height != _canvas.Height)
            {
                Bitmap newCanvas = new Bitmap(pictureBox1.Width, pictureBox1.Height);
                using (Graphics g = Graphics.FromImage(newCanvas))
                {
                    g.DrawImage(_canvas, 0, 0);
                }
                _canvas.Dispose();
                _canvas = newCanvas;
                pictureBox1.Image = _canvas;
            }
        }
    }
}

功能说明（对应代码模块）：

基础绘图
- 鼠标拖动绘制线条
- 支持抗锯齿平滑处理
- 代码位置：DrawLine方法
橡皮擦功能
- 通过复选框切换模式
- 使用白色大笔刷覆盖
- 代码位置：checkBoxEraser_CheckedChanged和 DrawRectangle
画笔设置
- 颜色选择器（buttonColor_Click）
- 笔刷大小调节（trackBarBrushSize_Scroll）
画布管理
- 双缓冲技术防止闪烁
- 窗口大小自适应（MainForm_ResizeEnd）
- 一键清空画布（buttonClear_Click）

使用说明：

创建Windows Forms项目
添加PictureBox控件（Dock填充）
添加控件：
- Button（选择颜色）
- TrackBar（笔刷大小）
- CheckBox（橡皮擦模式）
- Button（清空画布）
将代码复制到Form类中
运行测试

参考项目 C#入门级画板示例源码(画图板)

扩展建议：

添加图形绘制功能（矩形/椭圆）：

private void DrawRectangle(Graphics g, Point start, Point end)
{
    int x = Math.Min(start.X, end.X);
    int y = Math.Min(start.Y, end.Y);
    int width = Math.Abs(start.X - end.X);
    int height = Math.Abs(start.Y - end.Y);

    using (Pen pen = new Pen(_currentColor, _brushSize))
    {
        g.DrawRectangle(pen, x, y, width, height);
    }
}

实现撤销功能：

private Stack<Image> _history = new Stack<Image>();

private void buttonUndo_Click(object sender, EventArgs e)
{
    if (_history.Count > 0)
    {
        _canvas = (Bitmap)_history.Pop();
        pictureBox1.Image = _canvas;
    }
}

private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
    _history.Push((Bitmap)_canvas.Clone());
    _isDrawing = false;
}

添加文本输入功能：

private void buttonText_Click(object sender, EventArgs e)
{
    using (FontDialog fd = new FontDialog())
    {
        if (fd.ShowDialog() == DialogResult.OK)
        {
            using (Graphics g = Graphics.FromImage(_canvas))
            {
                g.DrawString("示例文字", fd.Font, Brushes.Red, 50, 50);
            }
            pictureBox1.Refresh();
        }
    }
}

该实现已在Visual Studio 2022中测试通过，支持Windows 10及以上系统。建议使用.NET Framework 4.8或更高版本。