using System;
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using System.Drawing;
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using System.Drawing.Drawing2D;
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using System.Drawing.Imaging;
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using System.Drawing.Text;
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namespace CaptchaImage
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{
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/// <summary>
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/// Õâ¸öÉú³ÉÑéÖ¤ÂëͼƬµÄ´úÂëÀ´×Ô£ºhttp://www.codeproject.com/KB/aspnet/CaptchaImage.aspx
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/// </summary>
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public class CaptchaImage
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{
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// Public properties (all read-only).
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public string Text
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{
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get { return this.text; }
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}
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public Bitmap Image
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{
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get { return this.image; }
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}
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public int Width
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{
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get { return this.width; }
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}
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public int Height
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{
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get { return this.height; }
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}
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// Internal properties.
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private string text;
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private int width;
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private int height;
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private string familyName;
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private Bitmap image;
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// For generating random numbers.
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private Random random = new Random();
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// ====================================================================
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// Initializes a new instance of the CaptchaImage class using the
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// specified text, width and height.
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// ====================================================================
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public CaptchaImage(string s, int width, int height)
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{
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this.text = s;
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this.SetDimensions(width, height);
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this.GenerateImage();
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}
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// ====================================================================
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// Initializes a new instance of the CaptchaImage class using the
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// specified text, width, height and font family.
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// ====================================================================
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public CaptchaImage(string s, int width, int height, string familyName)
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{
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this.text = s;
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this.SetDimensions(width, height);
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this.SetFamilyName(familyName);
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this.GenerateImage();
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}
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// ====================================================================
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// This member overrides Object.Finalize.
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// ====================================================================
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~CaptchaImage()
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{
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Dispose(false);
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}
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// ====================================================================
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// Releases all resources used by this object.
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// ====================================================================
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public void Dispose()
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{
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GC.SuppressFinalize(this);
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this.Dispose(true);
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}
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// ====================================================================
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// Custom Dispose method to clean up unmanaged resources.
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// ====================================================================
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protected virtual void Dispose(bool disposing)
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{
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if (disposing)
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// Dispose of the bitmap.
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this.image.Dispose();
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}
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// ====================================================================
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// Sets the image width and height.
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// ====================================================================
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private void SetDimensions(int width, int height)
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{
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// Check the width and height.
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if (width <= 0)
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throw new ArgumentOutOfRangeException("width", width, "Argument out of range, must be greater than zero.");
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if (height <= 0)
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throw new ArgumentOutOfRangeException("height", height, "Argument out of range, must be greater than zero.");
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this.width = width;
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this.height = height;
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}
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// ====================================================================
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// Sets the font used for the image text.
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// ====================================================================
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private void SetFamilyName(string familyName)
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{
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// If the named font is not installed, default to a system font.
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try
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{
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Font font = new Font(this.familyName, 13F);
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this.familyName = familyName;
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font.Dispose();
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}
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catch (Exception)
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{
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this.familyName = System.Drawing.FontFamily.GenericSerif.Name;
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}
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}
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// ====================================================================
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// Creates the bitmap image.
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// ====================================================================
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private void GenerateImage()
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{
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// Create a new 32-bit bitmap image.
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Bitmap bitmap = new Bitmap(this.width, this.height, PixelFormat.Format32bppArgb);
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// Create a graphics object for drawing.
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Graphics g = Graphics.FromImage(bitmap);
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g.SmoothingMode = SmoothingMode.AntiAlias;
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Rectangle rect = new Rectangle(0, 0, this.width, this.height);
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// Fill in the background.
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HatchBrush hatchBrush = new HatchBrush(HatchStyle.SmallConfetti, Color.LightGray, Color.White);
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g.FillRectangle(hatchBrush, rect);
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// Set up the text font.
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SizeF size;
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float fontSize = rect.Height + 1;
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Font font;
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// Adjust the font size until the text fits within the image.
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do
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{
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fontSize--;
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font = new Font(this.familyName, fontSize, FontStyle.Bold);
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size = g.MeasureString(this.text, font);
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} while (size.Width > rect.Width);
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// Set up the text format.
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StringFormat format = new StringFormat();
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format.Alignment = StringAlignment.Center;
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format.LineAlignment = StringAlignment.Center;
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// Create a path using the text and warp it randomly.
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GraphicsPath path = new GraphicsPath();
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path.AddString(this.text, font.FontFamily, (int)font.Style, font.Size, rect, format);
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float v = 8F;
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PointF[] points =
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{
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new PointF(this.random.Next(rect.Width) / v, this.random.Next(rect.Height) / v),
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new PointF(rect.Width - this.random.Next(rect.Width) / v, this.random.Next(rect.Height) / v),
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new PointF(this.random.Next(rect.Width) / v, rect.Height - this.random.Next(rect.Height) / v),
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new PointF(rect.Width - this.random.Next(rect.Width) / v, rect.Height - this.random.Next(rect.Height) / v)
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};
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Matrix matrix = new Matrix();
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matrix.Translate(0F, 0F);
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path.Warp(points, rect, matrix, WarpMode.Perspective, 0F);
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// Draw the text.
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hatchBrush = new HatchBrush(HatchStyle.LargeConfetti, Color.Green, Color.DarkGray);
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g.FillPath(hatchBrush, path);
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// Add some random noise.
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int m = Math.Max(rect.Width, rect.Height);
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for (int i = 0; i < (int)(rect.Width * rect.Height / 30F); i++)
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{
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int x = this.random.Next(rect.Width);
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int y = this.random.Next(rect.Height);
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int w = this.random.Next(m / 50);
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int h = this.random.Next(m / 50);
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g.FillEllipse(hatchBrush, x, y, w, h);
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}
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// Clean up.
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font.Dispose();
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hatchBrush.Dispose();
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g.Dispose();
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// Set the image.
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this.image = bitmap;
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}
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}
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}
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