signaturecapture.cs

微软的行业应用解决方案示例

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

namespace SignatureCapture
{
    public partial class SignatureCapture : UserControl
    {
        #region Fields

        private Graphics _signatureSurface;
        private Bitmap _bitmap;
        private bool _stylusCaptured;
        private int _oldX, _oldY;
		private bool _signatureCaptured = false;

        #endregion

        #region Properties

        public bool SignatureCaptured
        {
            get
            {
                return _signatureCaptured;
            }
        }

        #endregion

        #region Constructors

        public SignatureCapture()
        {
            InitializeComponent();

            //Prepare initial state of the signature drawing surface
            InitializeGraphics();
        }

        #endregion

        #region UserControl Methods

        /// <summary>
        /// As the control gets resized by the user, it must repaint itself
        /// </summary>
        /// <param name="e"></param>
        protected override void OnResize(EventArgs e)
        {
            //Prepare initial state of the signature drawing surface
            InitializeGraphics();

            base.OnResize(e);
        }

        /// <summary>
        /// The signature get drawn every time the form repaints itself
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(PaintEventArgs e)
        {
            if (this._bitmap != null)
            {
                //Draw image whenever the form repaints itself
                e.Graphics.DrawImage(this._bitmap, 0, 0);
            }

            base.OnPaint(e);
        }

        /// <summary>
        /// This eliminates flicker
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaintBackground(PaintEventArgs e)
        {
            base.OnPaintBackground(e);
        }

        /// <summary>
        /// This fires when the user taps their stylus on the control
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseDown(MouseEventArgs e)
        {
            // Set stylus capture
            this._stylusCaptured = true;

            //Retrieve the old coordinates
            this._oldX = e.X;
            this._oldY = e.Y;

            base.OnMouseDown(e);
        }

        /// <summary>
        /// This fires when the user lifts their stylus from the control
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseUp(MouseEventArgs e)
        {
            // Release stylus capture
            this._stylusCaptured = false;

            base.OnMouseUp(e);
        }

        /// <summary>
        /// This fires as the user draws their signature on the control
        /// </summary>
        /// <param name="e"></param>
        protected override void OnMouseMove(MouseEventArgs e)
        {
            int _x, _y;

            if (this._stylusCaptured)
            {
				// mark the fact that you have some signature
				_signatureCaptured = true;

                // Retrieve coordinates
                _x = e.X;
                _y = e.Y;

                if (this._signatureSurface != null)
                {
                    //Create a black pen with a thickness of 2
                    Pen _pen = new Pen(Color.Black, 2);
                    // Draw line from the old coordinates to the new coordinates
                    this._signatureSurface.DrawLine(_pen, this._oldX, this._oldY, _x, _y);
                }

                // Update the signature surface
                this.Invalidate(new Rectangle(Math.Min(_x, this._oldX),
                                              Math.Min(_y, this._oldY),
                                              Math.Abs(this._oldX - _x) + 1,
                                              Math.Abs(this._oldY - _y) + 1));

                //Retrieve the old coordinates
                this._oldX = _x;
                this._oldY = _y;
            }

            base.OnMouseMove(e);
        }

        #endregion

        #region Methods

        /// <summary>
        /// Prepares the initial or resized state of 
        /// the signature drawing surface
        /// </summary>
        private void InitializeGraphics()
        {
            this._stylusCaptured = false;

            // Create offscreen drawing surface
            this._bitmap = new Bitmap(this.Size.Width, this.Size.Height);
            if (this._bitmap != null)
            {
                //Create a graphics object from the bitmap
                this._signatureSurface = Graphics.FromImage(this._bitmap);

                if (this._signatureSurface != null)
                {
                    //Blank out the signature surface by making it all white
                    this._signatureSurface.FillRectangle(new SolidBrush(Color.White),
                                                0,
                                                0,
                                                this.Size.Width,
                                                this.Size.Height);
                }
            }
        }

        /// <summary>
        /// Makes the signature surface blank
        /// </summary>
        public void Clear()
        {
			_signatureCaptured = false;

            if (this._signatureSurface != null)
            {							
                //Blank out the signature surface by making it all white
                this._signatureSurface.FillRectangle(new SolidBrush(System.Drawing.Color.White),
                                            0,
                                            0,
                                            this.Size.Width,
                                            this.Size.Height);
                this.Invalidate();
            }
        }

        /// <summary>
        /// Saves signature as a Gif file to the path provided
        /// </summary>
        /// <param name="filePath">filename to save the image</param>
        public void Save(string filePath, ImageFormat imageFormat)
        {
            if (this._bitmap != null && !string.IsNullOrEmpty(filePath))
            {
                //Save the bitmap as a Gif file
                this._bitmap.Save(@filePath, imageFormat);
            }
        }


		

        #endregion
    }
}