C#动态生成文字图片

 

大家都知道我们如果想把网页上的文字做出比较炫的效果，便只能用POTOSHOP、FIREWORK等图像处理软件把文字做成图片来实现，因为这样才不会依赖浏览者的字体、浏览器类型等。可是在我们的WEB应用中又往往是动态的文字，我们便不能用图像处理软件来处理了，只能让WEB程序动态生成，幸运地是.Net Framework给我们提供了便利，下面我们就利用System.Drawing命名空间下的Bitmap类与Graphics类来编写一个生成文字图片的类，使用该类生成图片时能满足以下需求：
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。

该类实现代码如下：
1using System.Drawing;
2using System.Drawing.Drawing2D;
3using System.Drawing.Imaging;
4
5namespace Ycweb.Controls.Utility
6{
7    /// <summary>
8    /// WaterMark
9    /// </summary>
10    public class Watermark
11    {
12        private int _width;
13        private int _height;
14        private string _fontFamily;
15        private int _fontSize;
16        private bool _adaptable;
17        private FontStyle _fontStyle;
18        private bool _shadow;
19        private string _backgroundImage;
20        private Color _bgColor;
21        private int _left;
22        private string _resultImage;
23        private string _text;
24        private int _top;
25        private int _alpha;
26        private int _red;
27        private int _green;
28        private int _blue;
29        private long _quality;
30
31
32
33        public Watermark()
34        {
35            //
36            // TODO: Add constructor logic here
37            //
38            _width=460;
39            _height=30;
40            _fontFamily = "华文行楷";
41            _fontSize = 20;
42            _fontStyle=FontStyle.Regular;
43            _adaptable=true;
44            _shadow=false;
45            _left = 0;
46            _top = 0;
47            _alpha = 255;
48            _red = 0;
49            _green = 0;
50            _blue = 0;
51            _backgroundImage="";
52            _quality=100;
53            _bgColor=Color.FromArgb(255,229,229,229);
54           
55        }
56
57        /// <summary>
58        /// 字体
59        /// </summary>
60        public string FontFamily
61        {
62            set { this._fontFamily = value; }
63        }
64
65        /// <summary>
66        /// 文字大小
67        /// </summary>
68        public int FontSize
69        {
70            set { this._fontSize = value; }
71        }
72
73        /// <summary>
74        /// 文字风格
75        /// </summary>
76        public FontStyle FontStyle
77        {
78            get{return _fontStyle;}
79            set{_fontStyle = value;}
80        }
81
82        /// <summary>
83        /// 透明度0-255,255表示不透明
84        /// </summary>
85        public int Alpha
86        {
87            get { return _alpha; }
88            set { _alpha = value; }
89        }
90
91        /// <summary>
92        /// 水印文字是否使用阴影
93        /// </summary>
94        public bool Shadow
95        {
96            get { return _shadow; }
97            set { _shadow = value; }
98        }
99
100        public int Red
101        {
102            get { return _red; }
103            set { _red = value; }
104        }
105
106        public int Green
107        {
108            get { return _green; }
109            set { _green = value; }
110        }
111
112        public int Blue
113        {
114            get { return _blue; }
115            set { _blue = value; }
116        }
117
118        /// <summary>
119        /// 底图
120        /// </summary>
121        public string BackgroundImage
122        {
123            set { this._backgroundImage = value; }
124        }
125
126        /// <summary>
127        /// 水印文字的左边距
128        /// </summary>
129        public int Left
130        {
131            set { this._left = value; }
132        }
133
134       
135        /// <summary>
136        /// 水印文字的顶边距
137        /// </summary>
138        public int Top
139        {
140            set { this._top = value; }
141        }
142
143        /// <summary>
144        /// 生成后的图片
145        /// </summary>
146        public string ResultImage
147        {
148            set { this._resultImage = value; }
149        }
150
151        /// <summary>
152        /// 水印文本
153        /// </summary>
154        public string Text
155        {
156            set { this._text = value; }
157        }
158
159       
160        /// <summary>
161        /// 生成图片的宽度
162        /// </summary>
163        public int Width
164        {
165            get { return _width; }
166            set { _width = value; }
167        }
168
169        /// <summary>
170        /// 生成图片的高度
171        /// </summary>
172        public int Height
173        {<
4000
br />174            get { return _height; }
175            set { _height = value; }
176        }
177
178        /// <summary>
179        /// 若文字太大，是否根据背景图来调整文字大小，默认为适应
180        /// </summary>
181        public bool Adaptable
182        {
183            get { return _adaptable; }
184            set { _adaptable = value; }
185        }
186
187        public Color BgColor
188        {
189            get { return _bgColor; }
190            set { _bgColor = value; }
191        }
192
193        /// <summary>
194        /// 输出图片质量，质量范围0-100,类型为long
195        /// </summary>
196        public long Quality
197        {
198            get { return _quality; }
199            set { _quality = value; }
200        }
201
202        /// <summary>
203        /// 立即生成水印效果图
204        /// </summary>
205        /// <returns>生成成功返回true,否则返回false</returns>
206        public bool Create()
207        {
208            try
209            {
210                Bitmap bitmap;
211                Graphics g;
212
213                //使用纯背景色
214                if(this._backgroundImage.Trim()=="")
215                {
216                    bitmap = new Bitmap(this._width, this._height, PixelFormat.Format64bppArgb);
217                    g = Graphics.FromImage(bitmap);
218                    g.Clear(this._bgColor);
219                }
220                else
221                {
222                    bitmap = new Bitmap(Image.FromFile(this._backgroundImage));
223                    g = Graphics.FromImage(bitmap);
224                }
225                g.SmoothingMode = SmoothingMode.HighQuality;
226                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
227                g.CompositingQuality=CompositingQuality.HighQuality;
228
229                Font f = new Font(_fontFamily, _fontSize,_fontStyle);
230                SizeF size = g.MeasureString(_text, f);
231               
232                // 调整文字大小直到能适应图片尺寸
233                while(_adaptable==true && size.Width > bitmap.Width)
234                {
235                    _fontSize--;
236                    f = new Font(_fontFamily, _fontSize, _fontStyle);
237                    size = g.MeasureString(_text, f);
238                }
239               
240                Brush b = new SolidBrush(Color.FromArgb(_alpha, _red, _green, _blue));
241                StringFormat StrFormat = new StringFormat();
242                StrFormat.Alignment = StringAlignment.Near;
243
244                if(this._shadow)
245                {
246                    Brush b2=new SolidBrush(Color.FromArgb(90, 0, 0, 0));
247                    g.DrawString(_text, f, b2,_left+2, _top+1);
248                }
249                g.DrawString(_text, f, b, new PointF(_left, _top), StrFormat);
250               
251                bitmap.Save(this._resultImage, ImageFormat.Jpeg);
252                bitmap.Dispose();
253                g.Dispose();
254                return true;
255            }
256            catch
257            {
258                return false;
259            }
260        }
261    }