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WPF中实现验证码

1.效果图：

2. 实现思路：

首先建立Bitmap对象，绘图，将生成的Bitmap转换为ImageSource，在wpf的Image控件中将ImageSource赋值给Image.Source。

3. 具体实现：

3.1 首先封装一个生成验证码的类，返回为BitMap类型。需要引用using System.Drawing;命名空间。

VerifyCodeHelper类：

 public class VerifyCodeHelper

    {

        public static Bitmap CreateVerifyCode(out string code)

        {

            //建立Bitmap对象，绘图

            Bitmap bitmap = new Bitmap(200, 60);

            Graphics graph = Graphics.FromImage(bitmap);

            graph.FillRectangle(new SolidBrush(Color.White), 0, 0, 200, 60);

            Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);

            Random r = new Random();

            string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ0123456789";

            StringBuilder sb = new StringBuilder();

            //添加随机的五个字母

            for (int x = 0; x < 5; x++)

            {

                string letter = letters.Substring(r.Next(0, letters.Length - 1), 1);

                sb.Append(letter);

                graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));

            }

            code = sb.ToString();

            //混淆背景

            Pen linePen = new Pen(new SolidBrush(Color.Black), 2);

            for (int x = 0; x < 6; x++)

                graph.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));

            return bitmap;

        }

    }

3.2 封装一个图片转换的类，从Bitmap转换成ImageSource 。

ImageFormatConvertHelper类：

public  class ImageFormatConvertHelper

    {

        [DllImport("gdi32.dll", SetLastError = true)]

        private static extern bool DeleteObject(IntPtr hObject);

        /// <summary>  

        /// 从bitmap转换成ImageSource  

        /// </summary>  

        /// <param name="icon"></param>  

        /// <returns></returns>  

        public static ImageSource ChangeBitmapToImageSource(Bitmap bitmap)

        {

            //Bitmap bitmap = icon.ToBitmap();  

            IntPtr hBitmap = bitmap.GetHbitmap();

            ImageSource wpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(

                hBitmap,

                IntPtr.Zero,

                Int32Rect.Empty,

                BitmapSizeOptions.FromEmptyOptions());

            if (!DeleteObject(hBitmap))

            {

                throw new System.ComponentModel.Win32Exception();

            }

            return wpfBitmap;

        }

    }

3.3 上端使用。

img为WPF控件。

 public string  GetImage()

        {

            string code = "";

            Bitmap bitmap = VerifyCodeHelper.CreateVerifyCode(out code);

            ImageSource imageSource = ImageFormatConvertHelper.ChangeBitmapToImageSource(bitmap);

            img.Source = imageSource;

            return code;

        }