签名用户控件：智能手机、PocketPCs 和 PDA 上的图形编程

• 下载源代码 - 58.4 KB

引言

在本文中，我们将了解图形在智能手机和 PDA 应用程序中的用法。本应用程序的目标是

1. 让用户对 C# Graphics 类有一个基本的了解。
2. 创建一个智能手机签名控件，该控件使用 C# Graphics 类。
3. 创建一个使用签名用户控件的 Autograph 应用程序。

使用 C# 进行图形编程

在开始代码讲解之前，我们将从 C# Graphics 类及其方法开始。借助 System.Drawing 命名空间中的 Graphics 类，您可以渲染各种形状。这些形状包括矩形、填充矩形、直线、椭圆、填充椭圆、扇形、填充扇形和多边形。此类定义了绘制这些形状的方法。每种方法根据形状的需求而有所不同。

• 直线、简单形状。
• 来自位图和其他图像文件的图像。
• 文本。

与 C# Windows 应用程序类似，智能手机或 PDA 也使用图形类。在需要生成图表或从用户获取签名的智能手机应用程序中，图形得到了广泛应用。

命名空间	Contains
System.Drawing	大多数与绘图基本功能相关的类、结构、枚举和委托。

Graphics 类上的每个方法都必须通过创建 Graphics 类的对象 (g) 来访问。下表显示了该类的一些方法。

矩形	DrawRectangle (System.Drawing.Pen, float x, float y, float width, float height)	g.DrawRectangle (new Pen(Color.Pink,2), 20,20,300,150);
填充矩形	FillRectangle(System.Drawing.Brush, float x, float y, float width, float height)	g.FillRectangle (new SolidBrush(Color.Pink), 15,15,200,60);
Line	DrawLine(System.Drawing.Pen, float x, float y, float width, float height)	g.DrawLine(new Pen(Color.Pink,3), 20,20,300,150);
椭圆	DrawEllipse(System.Drawing.Pen, float x, float y, float width, float height)	g.DrawEllipse(new Pen(Color.Pink,3), 15,15,200,150);
填充椭圆	FillEllipse(System.Drawing.Brush, float x, float y, float width, float height)	g.FillEllipse (new SolidBrush(Color.Pink), 20,20,300,150);
Pie	DrawPie(System.Drawing.Pen, float x, float y, float width, float height)	g.DrawPie(new Pen(Color.Black),120,20,170,160,110,100)
填充扇形	FillPie(System.Drawing.Brush, float x, float y, float width, float height)	g.FillPie(new Brush(Color.Black),120,20,170,160,110,100)
Polygon	DrawPolygon(System.Drawing.Pen, new Point[] { new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y)});	g.DrawPolygon(new Pen(Color.Red,2), new Point[] { new Point(140,170), new Point(155,200), new Point(160,245), new Point(195,230), new Point(30,360), new Point(60,200)});
填充多边形	FillPolygon(System.Drawing.Brush, new Point[] { new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y), new Point(x,y)});	g.FillPolygon(new Brush(Color.Red), new Point[] { new Point(140,170), new Point(155,200), new Point(160,245), new Point(195,230), new Point(30,360), new Point(60,200)});

使用 Pen 类，您可以指定边框的颜色和粗细。从上面的示例可以看出，Pen 类用于绘制形状，而 Brush 类用于填充形状。我希望您从上表对 Graphics 类及其方法有了一些了解。

Using the Code

创建签名控件 (Signature.dll)

创建一个新的智能设备项目，并将其命名为“SignatureControl”。选择类库作为项目模板。

现在，您将拥有一个名为“Signaturecontrol”的 Visual Studio 项目和一个名为“Class1”的类文件。将类文件重命名为“SignatureControl.cs”。

包含这些命名空间

using System.Windows.Forms;     // To inherit control class
using System.Drawing;           // To use graphics ,Pen class
using System.IO;                // to write the signature to a physical location

并添加这些引用

• System.Windows.Forms
• System.Drawing

“SignatureControl”类继承自“Control”类。它定义了具有可视表示形式的控件的基类。

public partial class SignatureControl : Control

现在，我们将尝试重写绘制签名时触发的事件和方法。

/* *************Developed by Lison Jose P
 Software Engineer, Date:23-06-2008 ******************/
#region Namespace
using System;
using System.Collections;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.IO;
#endregion
namespace SignatureManipulation
{
    public partial class SignatureControl : Control
    {
        #region Variable declaration
        //GDI object 
        Bitmap bmp;
        //Graphics object 
        Graphics graphics;
        //Pen object
        Pen pen = new Pen(Color.Black);
        // Array List of line segments
        ArrayList signCoord = new ArrayList();
        //Point object
        Point lastPoint = new Point(0, 0);
        // if drawing signature or not
        bool drawSign = false;
        #endregion
        #region Constructor
        public SignatureControl()
        {
            //Default Constructor
        }
        #endregion
        #region Override Events
        #region OnPaint
        /// <summary>
        /// Create GDI object.Initilize memory bitmap where we draw the
        /// signature.
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(PaintEventArgs e)
        {
            // we draw on the memory bitmap on mousemove so there
            // is nothing else to draw at this time 
            CreateGdiObjects();
            e.Graphics.DrawImage(bmp, 0, 0);
        }
        #endregion
        #region OnPaintBackground
        /// <summary>
        /// Override OnPaintBackground to avoid flashing
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaintBackground(PaintEventArgs e)
        {
            // don't pass to base since we paint everything, avoid flashing
        }
        #endregion
        #region OnMouseDown
        /// <summary>
        /// OnMouseDown, get the new X,Y  coordinates
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseDown(MouseEventArgs e)
        {
            base.OnMouseDown(e);
            // process if currently drawing signature
            if (!drawSign)
            {
                // start collecting points
                drawSign = true;
                // use current mouse click as the first point
                lastPoint.X = e.X;
                lastPoint.Y = e.Y;
            }
        }
        #endregion
        #region OnMouseUp
        /// <summary>
        /// Set bool drawsign to false
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseUp(MouseEventArgs e)
        {
            base.OnMouseUp(e);
            // process if drawing signature
            if (drawSign)
            {
                // stop collecting points
                drawSign = false;
            }
        }
        #endregion

        #region OnMouseMove
        /// <summary>
        /// Draw line and get new X,Y coordinates
      /// Each drawn coordinates are added in to an arrayList (signCoord )
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);

            // process if drawing signature
            if (drawSign)
            {
                if (graphics != null)
                {
                    // draw the new segment on the memory bitmap
                    graphics.DrawLine(pen, lastPoint.X, lastPoint.Y, e.X,e.Y);
                    signCoord .Add(lastPoint.X + " " + lastPoint.Y + " " + e.X + " " + e.Y);
                    // update the current position
                    lastPoint.X = e.X;
                    lastPoint.Y = e.Y; 
                    // Invalidates the entire surface of the control and
                    //causes the control to be redrawn. 
                    Invalidate();
                }
            }
        }
        #endregion
        #endregion


        #region Methods
        #region Clear
        /// <summary>
        /// Clear the signature.
        /// </summary>
        public void Clear()
        {
            signCoord .Clear();
            InitBitMap();
            Invalidate();
        }
        #endregion
        #region CreateGdiObjects
        /// <summary>
        /// Create an bitMap objects, required to draw signature.
        /// </summary>
        private void CreateGdiObjects()
        {
            if (bmp == null || bmp.Width != this.Width || bmp.Height != this.Height)
            {
                // memory bitmap to draw on
                InitBitMap();
            }
        }
        #endregion
        #region InitBitMap
        /// <summary>
        ///Initilize the bitmap that is used to draw the signature.
        /// </summary>
        private void InitBitMap()
        {
            // load the background image            
            bmp = new Bitmap(this.Width, this.Height);
            graphics = Graphics.FromImage(bmp);
            graphics.Clear(Color.SlateGray);
        }
        #endregion
        #region StoreSigData
        /// <summary>
        /// Get each set of coordinates from the arrayList and concatinate  
        /// in to a single string. 
        /// </summary>
        /// <param name="fileName">file name 
        /// (physical position to store the signature coordinates)</param>
        public void StoreSigData(String fileName)
        {
            string sigData = "";
            for (int i = 0; i < signCoord .Count; i++)
            { 
                sigData = sigData + signCoord [i].ToString() + "\n";
            }
            CreateFile(fileName, sigData);
        }
        #endregion
        #region CreateFile
        /// <summary>
        /// To create signature file in a physical location. (System.IO)
        /// File consist of each co-ordinates of the signature
        /// </summary>
        /// <param name="fileName">file name</param>
        /// <param name="fileContent">file contents (signature 
        /// coordinates</param>
        private void CreateFile(String fileName, String fileContent)
        {
            StreamWriter sr = File.CreateText(fileName);
            sr.WriteLine(fileContent);
            sr.Close();
        }
        #endregion
        #region getSignCoord 
        /// <summary>
        /// Get all signature coordinates that are stored in arrayList
        /// Return the signature arraylist to the calling form.
        /// On the calling Form, this coordinates can be stored in to
        /// database.
        /// </summary>
        /// <returns>arraylist of signature co-ordinates</returns>
        public ArrayList getSignCoord ()
        {
            return signCoord ;
        }
        #endregion
        #region GetSignData
        /// <summary>
        /// Calling Form take the signature coordinates from file or database
        /// and send as string array to this method.
        /// This method retrive each coordinates from string array 
        /// and send
        /// </summary>
        /// <param name="result">signature co-ordinates</param>
        public void GetSignData(string[] result)
        {
            Graphics graphics;
            // load the background image            
            bmp = new Bitmap(this.Width, this.Height);
            graphics = Graphics.FromImage(bmp);
            graphics.Clear(Color.SlateGray);
            for (int i = 0; i < result.Length - 2; i++)
            {
                string[] strArr = new string[4];
                strArr = ((result[i].ToString()).Split(' '));
                graphics.DrawLine(pen, Convert.ToInt32(strArr[0].ToString()),
                                  Convert.ToInt32(strArr[1].ToString()),
                                  Convert.ToInt32(strArr[2].ToString()),
                                  Convert.ToInt32(strArr[3].ToString()));
                Invalidate();
                strArr = null;
            }
        }
        #endregion
        #endregion
   }
}

现在，从项目属性中选择输出类型为 ClassLibrary，然后生成项目。SignatureControl.dll 文件将创建在项目的 bin 文件夹中。

使用签名控件创建 Autograph 应用程序 (Signature.dll)

创建一个新的智能设备项目，并选择设备应用程序模板。将项目命名为“Autograph”。首先，我们为此应用程序创建数据库。向项目添加一个新的 SQL Mobile 数据库 (.SDF)。将其命名为 SignatureDB.sdf。添加一个名为 tblSignature 的表。在该表中包含以下字段：signName (nvarchar)、signRegard (nvarchar) 和 signSignature (ntext)。

现在，为我们的 Autograph 应用程序创建一个类文件。在名为“Component”的文件夹中添加一个新类文件，并将类文件名命名为 Signature.cs。

Signature.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlServerCe;
using System.Reflection;
using System.IO;

namespace Autograph.Component
{
    class Signature
    {
        private string _name=string.Empty;
        private string _signature=string.Empty;
        private string _regards = string.Empty;

        public string Name
        {
            set { _name = value; }
            get { return _name; }
        }

        public string Sign
        {
            set { _signature = value; }
            get { return _signature; }
        }

        public string Regards
        {
            set { _regards = value; }
            get { return _regards; }
        }

        #region GetSqlCeConnection
        /// <summary>
        /// Method to connect to sql Server
        /// </summary>
        ///<returns>SqlCeConnection</returns>
        public static SqlCeConnection GetSqlCeConnection()
        {
            SqlCeConnection cnMindNet = null;
            String connString = Assembly.GetExecutingAssembly().GetName().CodeBase;
            connString = connString.Replace("Autograph.exe", "SignatureDB.sdf");
            cnMindNet = new SqlCeConnection(String.Format("Data Source={0}", connString));
            return cnMindNet;
        }
        #endregion

        #region SetSign
        /// <summary>
        /// Set the signature deails to database
        /// </summary>
        public void SetSign()
        {
            using (SqlCeConnection conn = GetSqlCeConnection())
            {
                conn.Open();

                string query = "insert into tblSignature (signName,signRegards," + 
                               "signSignature) values " +
                               " ( @name,@regards,@sign )";
                SqlCeCommand cmd = new SqlCeCommand(query, conn);
                cmd.CommandType = CommandType.Text;
                cmd.Parameters.Add("@name", SqlDbType.NVarChar).Value = _name;
                cmd.Parameters.Add("@regards", SqlDbType.NVarChar).Value = _regards;
                cmd.Parameters.Add("@sign", SqlDbType.NText).Value = _signature;
                cmd.ExecuteNonQuery();
            }
        }
        #endregion
        #region GetSign 
        /// <summary>
        /// Get the Signature details from database
        /// </summary>
        /// <returns>Table of signature details</returns>
        public DataTable GetSign()
        {
            using (SqlCeConnection conn = GetSqlCeConnection())
            {
                conn.Open();
                DataTable dt = new DataTable();
                string query = "select signName,signRegards," + 
                               "signSignature from tblSignature";

                SqlCeCommand cmd = new SqlCeCommand(query, conn);
                cmd.CommandType = CommandType.Text;
                SqlCeDataAdapter da = new SqlCeDataAdapter(cmd);
                da.Fill(dt);
                return dt;
            }
        }
        #endregion

    }
}

数据库类型是 SQL Mobile Database (.SDF)，因此请添加此命名空间

using System.Data.SqlServerCe;

现在，向此项目添加两个窗体：一个用于添加签名，另一个用于查看签名。将它们命名为 frmSignature.cs 和 frmViewAll.cs。按照上面的示例截图设计窗体。窗体的代码如下。

frmSignature.cs

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

namespace Autograph
{
    public partial class frmSignature : Form
    {
        #region Constructor
        public frmSignature()
        {
            InitializeComponent();
            txtName.Focus();
        }
        #endregion

        #region lnklProcess_Click
        private void lnklProcess_Click(object sender, EventArgs e)
        {
            
            Cursor.Current = Cursors.WaitCursor;
            ArrayList arrSign = new ArrayList();
            arrSign = uctrlSignature.getPVector();

            if (txtName.Text.Trim() == string.Empty)
            {
                MessageBox.Show(" Name please ", "Autograph", 
                       MessageBoxButtons.OK, MessageBoxIcon.Asterisk,
                       MessageBoxDefaultButton.Button1);
                Cursor.Current = Cursors.Default;   
                return;
            }

            if (arrSign.Count > 0)
            {
                string singature = "";

                for (int i = 0; i < arrSign.Count; i++)
                {
                    singature = singature + arrSign[i].ToString() + "*";
                }

                Component.Signature objSign = new Autograph.Component.Signature();
                objSign.Name = txtName.Text;
                objSign.Regards = txtNotes.Text;
                objSign.Sign = singature;
                objSign.SetSign();                           
                MessageBox.Show(" Thank You :) ", "Autograph", MessageBoxButtons.OK, 
                                MessageBoxIcon.None, MessageBoxDefaultButton.Button1);
            }
            else
            {
                MessageBox.Show(" Signature please ", "Autograph", MessageBoxButtons.OK,
                                MessageBoxIcon.Asterisk, MessageBoxDefaultButton.Button1);
            }

            Cursor.Current = Cursors.Default;
        }
        #endregion

        #region lnklClear_Click
        private void lnklClear_Click(object sender, EventArgs e)
        {
            uctrlSignature.Clear();
        }
        #endregion

        #region lnklView_Click
        private void lnklView_Click(object sender, EventArgs e)
        {
            Cursor.Current = Cursors.WaitCursor;
            frmViewAll objView = new frmViewAll();
            objView.Show();
        }
        #endregion

        #region miAbout_Click
        private void miAbout_Click(object sender, EventArgs e)
        {
            frmAbout objAbout = new frmAbout();
            objAbout.Show();
        }
        #endregion

        #region miClose_Click
        private void miClose_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
        #endregion

        #region frmSignature_Closing
        private void frmSignature_Closing(object sender, CancelEventArgs e)
        {
            Application.Exit();
        }
         #endregion
    }
}

frmViewAll.cs

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

namespace Autograph
{
    public partial class frmViewAll : Form
    {
        bool flag = false;

        #region Constructor
        public frmViewAll()
        {
            InitializeComponent();
            txtLookUp.Focus();
        }
        #endregion

        #region frmViewAll_Load
        private void frmViewAll_Load(object sender, EventArgs e)      
        {            
            Component.Signature objSign = new Autograph.Component.Signature();
            DataTable dtSign = objSign.GetSign();

            if (dtSign.Rows.Count > 0)
            {
                flag = true;
                for (int i = 0; i < dtSign.Rows.Count; i++)
                {
                    DataRow dr = dtSign.Rows[i];
                    ListViewItem item = new ListViewItem(dr["signName"].ToString());
                    item.SubItems.Add(dr["signRegards"].ToString());
                    item.SubItems.Add(dr["signSignature"].ToString());
                    lsvItem.Items.Add(item);
                }
            }
            Cursor.Current = Cursors.Default;
        }
        #endregion

        #region lsvItem_SelectedIndexChanged
        private void lsvItem_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (flag)
            {
                Cursor.Current = Cursors.WaitCursor;
                if (lsvItem.FocusedItem != null)
                {
                    string[] arrStr = (lsvItem.FocusedItem.SubItems[2].Text).Split('*');
                    uctrlSignature.GetSignData(arrStr);
                }
                Cursor.Current = Cursors.Default;
            }
        }
        #endregion

        #region txtLookUp_TextChanged
        private void txtLookUp_TextChanged(object sender, EventArgs e)
        {
            string strLook = string.Empty;
            string check = string.Empty;
            string strLookUp = txtLookUp.Text;
            int resultRow = 0;
            if (strLookUp != "")
            {
                for (int i = 0; i < lsvItem.Items.Count; i++)
                {
                    strLook = lsvItem.Items[i].SubItems[0].Text.ToLower();

                    if (strLookUp.Length <= strLook.Length)
                    {
                        check = strLook.Substring(0, strLookUp.Length).ToLower();

                        if (check == strLookUp)
                        {
                            resultRow = i;
                            lsvItem.Items[resultRow].Focused = true;
                            lsvItem.Items[resultRow].Selected = true;
                            break;
                        }
                    }
                }
            }
        }
        #endregion

        #region miBack_Click
        private void miBack_Click(object sender, EventArgs e)
        {
            this.Close();
            this.Dispose();
        }
        #endregion

        #region miClose_Click
        private void miClose_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
        #endregion
        #region uctrlSignature_GotFocus
        private void uctrlSignature_GotFocus(object sender, EventArgs e)
        {
            uctrlSignature.Capture = false;
        }
        #endregion
    }
}

在您的移动设备上运行该应用程序。现在，如果有名人或您心爱的人来找您签名，您就不必再去找纸和笔了。只需在您的手机上打开此应用程序即可获得电子签名。它还可以帮助您存储其他详细信息，如电话号码、物品清单等，并且易于检索。