C#动态生成水印图片的类
1、可以指定文字字体、大小和颜色（注:指定的文字在WEB服务器上需要有该字库）；
2、可以加文字阴影；
3、可以指定文字的透明度；
4、可以指定背景图片或背景颜色；
5、可以指定生成的图片大小（宽度与高度）；
6、可以指定文字的位置（左边距和上边距）；
7、当用户设定的文字字号太大，能自动调整文字大小使之能适应生成图片的大小。
using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace Ycweb.Controls.Utility { /**/ /// <summary> /// WaterMark /// </summary> public class Watermark { private int _width; private int _height; private string _fontFamily; private int _fontSize; private bool _adaptable; private FontStyle _fontStyle; private bool _shadow; private string _backgroundImage; private Color _bgColor; private int _left; private string _resultImage; private string _text; private int _top; private int _alpha; private int _red; private int _green; private int _blue; private long _quality; public Watermark() { // // TODO: Add constructor logic here // _width = 460; _height = 30; _fontFamily = "华文行楷"; _fontSize = 20; _fontStyle = FontStyle.Regular; _adaptable = true; _shadow = false; _left = 0; _top = 0; _alpha = 255; _red = 0; _green = 0; _blue = 0; _backgroundImage = ""; _quality = 100; _bgColor = Color.FromArgb(255, 229, 229, 229); } /**/ /// <summary> /// 字体 /// </summary> public string FontFamily { set { this._fontFamily = value; } } /**/ /// <summary> /// 文字大小 /// </summary> public int FontSize { set { this._fontSize = value; } } /**/ /// <summary> /// 文字风格 /// </summary> public FontStyle FontStyle { get { return _fontStyle; } set { _fontStyle = value; } } /**/ /// <summary> /// 透明度0-255,255表示不透明 /// </summary> public int Alpha { get { return _alpha; } set { _alpha = value; } } /**/ /// <summary> /// 水印文字是否使用阴影 /// </summary> public bool Shadow { get { return _shadow; } set { _shadow = value; } } public int Red { get { return _red; } set { _red = value; } } public int Green { get { return _green; } set { _green = value; } } public int Blue { get { return _blue; } set { _blue = value; } } /**/ /// <summary> /// 底图 /// </summary> public string BackgroundImage { set { this._backgroundImage = value; } } /**/ /// <summary> /// 水印文字的左边距 /// </summary> public int Left { set { this._left = value; } } /**/ /// <summary> /// 水印文字的顶边距 /// </summary> public int Top { set { this._top = value; } } /**/ /// <summary> /// 生成后的图片 /// </summary> public string ResultImage { set { this._resultImage = value; } } /**/ /// <summary> /// 水印文本 /// </summary> public string Text { set { this._text = value; } } /**/ /// <summary> /// 生成图片的宽度 /// </summary> public int Width { get { return _width; } set { _width = value; } } /**/ /// <summary> /// 生成图片的高度 /// </summary> public int Height { get { return _height; } set { _height = value; } } /**/ /// <summary> /// 若文字太大，是否根据背景图来调整文字大小，默认为适应 /// </summary> public bool Adaptable { get { return _adaptable; } set { _adaptable = value; } } public Color BgColor { get { return _bgColor; } set { _bgColor = value; } } /**/ /// <summary> /// 输出图片质量，质量范围0-100,类型为long /// </summary> public long Quality { get { return _quality; } set { _quality = value; } } /**/ /// <summary> /// 立即生成水印效果图 /// </summary> /// <returns>生成成功返回true,否则返回false</returns> public bool Create() { try { Bitmap bitmap; Graphics g; //使用纯背景色 if (this._backgroundImage.Trim() == "") { bitmap = new Bitmap(this._width, this._height, PixelFormat.Format64bppArgb); g = Graphics.FromImage(bitmap); g.Clear(this._bgColor); } else { bitmap = new Bitmap(Image.FromFile(this._backgroundImage)); g = Graphics.FromImage(bitmap); } g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.CompositingQuality = CompositingQuality.HighQuality; Font f = new Font(_fontFamily, _fontSize, _fontStyle); SizeF size = g.MeasureString(_text, f); // 调整文字大小直到能适应图片尺寸 while (_adaptable == true && size.Width > bitmap.Width) { _fontSize--; f = new Font(_fontFamily, _fontSize, _fontStyle); size = g.MeasureString(_text, f); } Brush b = new SolidBrush(Color.FromArgb(_alpha, _red, _green, _blue)); StringFormat StrFormat = new StringFormat(); StrFormat.Alignment = StringAlignment.Near; if (this._shadow) { Brush b2 = new SolidBrush(Color.FromArgb(90, 0, 0, 0)); g.DrawString(_text, f, b2, _left + 2, _top + 1); } g.DrawString(_text, f, b, new PointF(_left, _top), StrFormat); bitmap.Save(this._resultImage, ImageFormat.Jpeg); bitmap.Dispose(); g.Dispose(); return true; } catch { return false; } } } }