C#Winform实现手写录入签名与保存为透明png图片

骑猪看日落 2022-12-31 16:18 872阅读 0赞

### C\#Winform实现手写录入签名与保存为透明png图片 ###

*  原理
 *  效果图
 *  实现代码

# 原理 #

在Winform窗体程序中实现鼠标手写输入其实就是画线，基本实现原理是放置一个PictureBox控件，订阅此控件的MouseMove和MouseDown事件，然后通过System.Drawing.Drawing2D.GraphicsPath在MouseMove事件中不断的画线。

# 效果图 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3psYmRtbQ_size_16_color_FFFFFF_t_70]

# 实现代码 #

using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Data;
    using System.Drawing;
    using System.Drawing.Imaging;
    using System.Linq;
    using System.Runtime.InteropServices;
    using System.Text;
    using System.Windows.Forms;
    
    namespace WindowsFormsApplication2
    { 
        public partial class Form1 : Form
        { 
            #region 定义变量
    
            private System.Drawing.Drawing2D.GraphicsPath mousePath = new System.Drawing.Drawing2D.GraphicsPath();
            //画笔透明度
            private int myAlpha = 100;
            //画笔颜色对象
            private Color myUserColor = new Color();
            //画笔宽度
            private int myPenWidth = 3;
            //签名的图片对象
            public Bitmap SavedBitmap;
    
            #endregion
    
            public Form1()
            { 
                InitializeComponent();
            }
    
            private void button1_Click(object sender, EventArgs e)
            { 
                string url = Cachet.CreatPublicSeal.CreatSeal("青岛弯弓信息技术有限公司", "数据服务部", "e:\\seal");
                this.pictureBox1.Image = Image.FromFile(url);
                Console.WriteLine(url);
            }
    
            private void Form1_Load(object sender, EventArgs e)
            { 
    			this.pictureBox1.BackColor = Color.White;       //设置图片初始背景色为白色
            }
    
            #region 鼠标移动事件处理
    
            private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
            { 
                if (e.Button == System.Windows.Forms.MouseButtons.Left)
                { 
                    try
                    { 
                        mousePath.AddLine(e.X, e.Y, e.X, e.Y);
                    }
                    catch (Exception ex)
                    { 
                        MessageBox.Show(ex.Message);
                    }
                }
                pictureBox1.Invalidate();
            }
    
            #endregion
    
            #region 鼠标按下事件处理
    
            private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
            { 
                if (e.Button == System.Windows.Forms.MouseButtons.Left)
                { 
                    mousePath.StartFigure();
                }
            }
    
            #endregion
    
            #region 图片空间画图事件处理
    
            private void pictureBox1_Paint(object sender, PaintEventArgs e)
            { 
                try
                { 
                    myUserColor = System.Drawing.Color.Blue;
                    myAlpha = 255;
                    Pen CurrentPen = new Pen(Color.FromArgb(myAlpha, myUserColor), myPenWidth);
                    e.Graphics.DrawPath(CurrentPen, mousePath);
                }
                catch {  }
            }
    
            #endregion
    
            #region 把图片中的内容保存为透明png图片
    
            private void btnSave_Click(object sender, EventArgs e)
            { 
                SavedBitmap = new Bitmap(pictureBox1.Width, pictureBox1.Height);
                pictureBox1.DrawToBitmap(SavedBitmap, new Rectangle(0, 0, pictureBox1.Width, pictureBox1.Height));
    
                #region 保存为透明的png图片
    
                Bitmap bmp = SavedBitmap;
                BitmapData data = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat);
                int length = data.Stride * data.Height;
                IntPtr ptr = data.Scan0;
                byte[] buff = new byte[length];
                Marshal.Copy(ptr, buff, 0, length);
                for (int i = 3; i < length; i += 4)
                { 
                    if (buff[i - 1] >= 230 && buff[i - 2] >= 230 && buff[i - 3] >= 230)
                    { 
                        buff[i] = 0;
                    }
                }
                Marshal.Copy(buff, 0, ptr, length);
                bmp.UnlockBits(data);
                bmp.Save("e:\\zhenglibing.png", ImageFormat.Png);
    
                #endregion
            }
    
            #endregion
    
            #region 清空图片的内容
    
            private void btnClear_Click(object sender, EventArgs e)
            { 
                pictureBox1.CreateGraphics().Clear(Color.White);
                mousePath.Reset();
            }
    
            #endregion
        }
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3psYmRtbQ_size_16_color_FFFFFF_t_70]: /images/20221120/efd5229e79a343ffa0eca11ecefdf726.png