一个PHP智能把图片生成缩略图类,可自动根据你图片的大小生成等比例的图片,PHP智能把图片生成缩略图类代码如下:

1. <?php 
2.  /***************************************  *作者：落梦天蝎（beluckly）  
3.  *开源代码phpfensi.com 
4.  *类名：CreatMiniature  
5.  *功能：生成多种类型的缩略图  
6.  *基本参数：$srcFile,$echoType  
7.  *方法用到的参数：  
8.                  $toFile,生成的文件  
9.                  $toW,生成的宽  
10.                  $toH,生成的高  
11.                  $bk1,背景颜色参数 以255为最高  
12.                  $bk2,背景颜色参数  
13.                  $bk3,背景颜色参数  
14.     
15.  *例子：  
16.     
17.      include("thumb.php");  
18.      $cm=new CreatMiniature();  
19.      $cm->SetVar("1.jpg","file");  
20.      $cm->Distortion("dis_bei.jpg",150,200);  
21.      $cm->Prorate("pro_bei.jpg",150,200);  
22.      $cm->Cut("cut_bei.jpg",150,200);  
23.       $cm->BackFill("fill_bei.jpg",150,200);  
24.     
25.  ***************************************/  
26.     
27.  class CreatMiniature  
28.  {  
29.      //公共变量  
30.      var $srcFile="";        //原图  
31.      var $echoType;            //输出图片类型，link--不保存为文件；file--保存为文件  
32.      var $im="";                //临时变量  
33.      var $srcW="";            //原图宽  
34.      var $srcH="";            //原图高  
35.     
36.      //设置变量及初始化  
37.      function SetVar($srcFile,$echoType)  
38.      {  
39.          $this->srcFile=$srcFile;  
40.          $this->echoType=$echoType;  
41.     
42.          $info = "";  
43.          $data = GetImageSize($this->srcFile,$info);  
44.          switch ($data[2])          {  
45.           case 1:  
46.             if(!function_exists("imagecreatefromgif")){  
47.              echo "你的GD库不能使用GIF格式的图片，请使用Jpeg或PNG格式！<a href='javascript：go(-1);'>返回</a>";  
48.              exit();  
49.             }  
50.             $this->im = ImageCreateFromGIF($this->srcFile);  
51.             break;  
52.          case 2:  
53.            if(!function_exists("imagecreatefromjpeg")){  
54.             echo "你的GD库不能使用jpeg格式的图片，请使用其它格式的图片！<a href='javascript：go(-1);'>返回</a>";  
55.             exit();  
56.            }  
57.            $this->im = ImageCreateFromJpeg($this->srcFile);      
58.            break;  
59.          case 3:  
60.            $this->im = ImageCreateFromPNG($this->srcFile);      
61.            break;  
62.        }  
63.        $this->srcW=ImageSX($this->im);  
64.        $this->srcH=ImageSY($this->im);   
65.      }  
66.        
67.      //生成扭曲型缩图  
68.      function Distortion($toFile,$toW,$toH)  
69.      {  
70.          $cImg=$this->CreatImage($this->im,$toW,$toH,0,0,0,0,$this->srcW,$this->srcH);  
71.          return $this->EchoImage($cImg,$toFile);  
72.          ImageDestroy($cImg);  
73.      }  
74.        
75.      //生成按比例缩放的缩图  
76.      function Prorate($toFile,$toW,$toH)  
77.      {  
78.          $toWH=$toW/$toH;  
79.          $srcWH=$this->srcW/$this->srcH;  
80.          if($toWH< =$srcWH)  
81.          {  
82.              $ftoW=$toW;  
83.              $ftoH=$ftoW*($this->srcH/$this->srcW);  
84.          }  
85.       else          {  
86.                $ftoH=$toH;  
87.                $ftoW=$ftoH*($this->srcW/$this->srcH);  
88.          }  
89.          if($this->srcW>$toW||$this->srcH>$toH)  
90.          {  
91.              $cImg=$this->CreatImage($this->im,$ftoW,$ftoH,0,0,0,0,$this->srcW,$this->srcH);  
92.              return $this->EchoImage($cImg,$toFile);  
93.              ImageDestroy($cImg);  
94.          }  
95.          else  
96.          {  
97.              $cImg=$this->CreatImage($this->im,$this->srcW,$this->srcH,0,0,0,0,$this->srcW,$this->srcH);  
98.              return $this->EchoImage($cImg,$toFile);  
99.              ImageDestroy($cImg);  
100.          }  
101.      }  
102.        
103.      //生成最小裁剪后的缩图  
104.      function Cut($toFile,$toW,$toH)  
105.      {  
106.            $toWH=$toW/$toH;  
107.            $srcWH=$this->srcW/$this->srcH;  
108.            if($toWH< =$srcWH)  
109.            {  
110.                 $ctoH=$toH;  
111.                 $ctoW=$ctoH*($this->srcW/$this->srcH);  
112.            }  
113.            else  
114.            {  
115.                $ctoW=$toW;  
116.                $ctoH=$ctoW*($this->srcH/$this->srcW);  
117.            }   
118.          $allImg=$this->CreatImage($this->im,$ctoW,$ctoH,0,0,0,0,$this->srcW,$this->srcH);  
119.          $cImg=$this->CreatImage($allImg,$toW,$toH,0,0,($ctoW-$toW)/2,($ctoH-$toH)/2,$toW,$toH);  
120.          return $this->EchoImage($cImg,$toFile);  
121.          ImageDestroy($cImg);  
122.          ImageDestroy($allImg);  
123.      }  
124.     
125.      //生成背景填充的缩图  
126.      function BackFill($toFile,$toW,$toH,$bk1=255,$bk2=255,$bk3=255)  
127.      {  
128.          $toWH=$toW/$toH;  
129.          $srcWH=$this->srcW/$this->srcH;  
130.          if($toWH< =$srcWH)  
131.          {  
132.              $ftoW=$toW;  
133.              $ftoH=$ftoW*($this->srcH/$this->srcW);  
134.          }  
135.          else  
136.          {  
137.                $ftoH=$toH;  
138.                $ftoW=$ftoH*($this->srcW/$this->srcH);  
139.          }  
140.          if(function_exists("imagecreatetruecolor"))  
141.          {  
142.              @$cImg=ImageCreateTrueColor($toW,$toH);  
143.              if(!$cImg)  
144.              {  
145.                  $cImg=ImageCreate($toW,$toH);  
146.              }  
147.          }  
148.          else  
149.          {  
150.              $cImg=ImageCreate($toW,$toH);  
151.          }  
152.          $backcolor = imagecolorallocate($cImg, $bk1, $bk2, $bk3);        //填充的背景颜色  
153.          ImageFilledRectangle($cImg,0,0,$toW,$toH,$backcolor);  
154.          if($this->srcW>$toW||$this->srcH>$toH)  
155.          {       
156.              $proImg=$this->CreatImage($this->im,$ftoW,$ftoH,0,0,0,0,$this->srcW,$this->srcH);  
157.              /*  
158.               if($ftoW< $toW)  
159.               {  
160.                   ImageCopyMerge($cImg,$proImg,($toW-$ftoW)/2,0,0,0,$ftoW,$ftoH,100);  
161.               }  
162.               else if($ftoH<$toH)  
163.               {  
164.                   ImageCopyMerge($cImg,$proImg,0,($toH-$ftoH)/2,0,0,$ftoW,$ftoH,100);  
165.               }  
166.               */  
167.              if($ftoW<$toW)  
168.              {  
169.                   ImageCopy($cImg,$proImg,($toW-$ftoW)/2,0,0,0,$ftoW,$ftoH);  
170.              }  
171.              else if($ftoH<$toH)  
172.              {  
173.                   ImageCopy($cImg,$proImg,0,($toH-$ftoH)/2,0,0,$ftoW,$ftoH);  
174.              }  
175.              else  
176.              {  
177.                   ImageCopy($cImg,$proImg,0,0,0,0,$ftoW,$ftoH);  
178.              }   
179.          }  
180.          else  
181.          {  
182.               ImageCopyMerge($cImg,$this->im,($toW-$ftoW)/2,($toH-$ftoH)/2,0,0,$ftoW,$ftoH,100);  
183.          }  
184.          return $this->EchoImage($cImg,$toFile);  
185.          ImageDestroy($cImg);  
186.      }  
187.        
188.     
189.      function CreatImage($img,$creatW,$creatH,$dstX,$dstY,$srcX,$srcY,$srcImgW,$srcImgH)  
190.      {  
191.          if(function_exists("imagecreatetruecolor"))  
192.          {  
193.              @$creatImg = ImageCreateTrueColor($creatW,$creatH);              if($creatImg)   
194.                  ImageCopyResampled($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);  
195.              else  
196.              {  
197.                  $creatImg=ImageCreate($creatW,$creatH);  
198.                  ImageCopyResized($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);  
199.              }  
200.           }  
201.           else  
202.           {  
203.              $creatImg=ImageCreate($creatW,$creatH);  
204.              ImageCopyResized($creatImg,$img,$dstX,$dstY,$srcX,$srcY,$creatW,$creatH,$srcImgW,$srcImgH);  
205.           }  
206.           return $creatImg;  
207.      }  
208.        
209.      //输出图片，link---只输出，不保存文件。file--保存为文件  
210.      function EchoImage($img,$to_File)  
211.      {  
212.          switch($this->echoType)          {  
213.              case "link":  
214.                  if(function_exists('imagejpeg')) return ImageJpeg($img);  
215.                  else return ImagePNG($img);  
216.                  break;  
217.              case "file":  
218.                  if(function_exists('imagejpeg')) return ImageJpeg($img,$to_File);  
219.                  else return ImagePNG($img,$to_File);  
220.                  break;  
221.          }  
222.      }  
223.     
224.  }  
225.  ?> 
226.  

出处：http://www.phpfensi.com/php/20140818/4418.html