C#中GDI繪圖和GDI繪製隨即驗證碼

using System.Drawing; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { GraphicsImage(); } public void GraphicsImage() { int width = 380; int height = 200; Bitmap image = new Bitmap(width, height); Graphics g = Graphics.FromImage(image);//創建畫布 try { //利用Graphics的FillRectangle方法繪製矩形 g.Clear(Color.YellowGreen);//清空背景色 Font font1 = new Font("宋體", 12); Brush brush = new SolidBrush(Color.Black);//設置話刷顏色 Brush brush1 = new SolidBrush(Color.Red); g.DrawString("繪製帶有陰影效果的矩形", font1, brush, 80, 20); g.FillRectangle(brush, 80, 60, 200, 100); g.FillRectangle(brush1, 60, 50, 200, 100);//繪製矩形 System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.BinaryWrite(ms.ToArray()); } catch(Exception ms) { Response.Write(ms.Message); } }

 

效果所示：

二、繪製驗證碼

<asp:Image ID="Image1"  src="Default2.aspx" runat="server" Height="25px" Width="50px" />

//繪圖 using System.Drawing; public partial class Default2 : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { CreatCheckCodeImage(GenerateCheckCode()); } //把生產的驗證碼 打印在空圖片上 private void CreatCheckCodeImage(string checkCode) { if (checkCode == null || checkCode.Trim() == String.Empty) return; System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22); Graphics g = Graphics.FromImage(image); try { //隨即生成器 Random random = new Random(); //清空圖片背景色 g.Clear(Color.White); //畫圖片背景噪音線 for (int i = 0; i < 2; i++) { int x1 = random.Next(image.Width); int x2 = random.Next(image.Width); int y1 = random.Next(image.Height); int y2 = random.Next(image.Height); g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2); } Font font = new Font("宋體", 12, FontStyle.Bold); System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush( new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true); g.DrawString(checkCode, font, brush, 2, 2); //畫圖片 前景噪音點 for (int i = 0; i < 100; i++) { int x = random.Next(image.Width); int y = random.Next(image.Height); image.SetPixel(x, y, Color.FromArgb(random.Next())); } //畫圖片邊框線 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1); System.IO.MemoryStream ms = new System.IO.MemoryStream(); image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); Response.ClearContent(); Response.ContentType = "image/Gif"; Response.BinaryWrite(ms.ToArray()); } finally { g.Dispose(); image.Dispose(); } } //隨機生成驗證碼 private string GenerateCheckCode() { int number; char code; string checkCode = String.Empty; Random random = new Random(); for (int i = 0; i < 4; i++) { number = random.Next(); if (number % 2 == 0) code = (char)('0' + (char)(number % 10)); else code = (char)('A' + (char)(number % 26)); checkCode += code.ToString(); } Response.Cookies.Add(new HttpCookie("CheckCode", checkCode)); return checkCode; } }

效果預覽：

刷新後：