PHP一般情况下生成的缩略图都比较不理想

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PHP用GD库生成高质量的缩略图片,PHP一般情况下生成的缩略图都比较不理想。今天试用PHP，GD库来生成缩略图。虽然并不100%完美。可是也应该可以满足缩略图的要求了。

1. <?php
   
2. $FILENAME="image.thumb";
   
3. // 生成图片的宽度
   
4. $RESIZEWIDTH=400;
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5. // 生成图片的高度
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6. $RESIZEHEIGHT=400;
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7. 
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8. function ResizeImage($im,$maxwidth,$maxheight,$name){
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9. $width = imagesx($im);
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10. $height = imagesy($im);
    
11. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
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12. if($maxwidth && $width > $maxwidth){
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13. $widthratio = $maxwidth/$width;
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14. $RESIZEWIDTH=true;
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15. }
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16. if($maxheight && $height > $maxheight){
    
17. $heightratio = $maxheight/$height;
    
18. $RESIZEHEIGHT=true;
    
19. }
    
20. if($RESIZEWIDTH && $RESIZEHEIGHT){
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21. if($widthratio < $heightratio){
    
22. $ratio = $widthratio;
    
23. }else{
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24. $ratio = $heightratio;
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25. }
    
26. }elseif($RESIZEWIDTH){
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27. $ratio = $widthratio;
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28. }elseif($RESIZEHEIGHT){
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29. $ratio = $heightratio;
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30. }
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31. $newwidth = $width * $ratio;
    
32. $newheight = $height * $ratio;
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33. if(function_exists("imagecopyresampled")){
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34. $newim = imagecreatetruecolor($newwidth, $newheight);
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35. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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36. }else{
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37. $newim = imagecreate($newwidth, $newheight);
    
38. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    
39. }
    
40. ImageJpeg ($newim,$name . ".jpg");
    
41. ImageDestroy ($newim);
    
42. }else{
    
43. ImageJpeg ($im,$name . ".jpg");
    
44. }
    
45. }
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46. 
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47. if($_FILES['image']['size']){
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48. if($_FILES['image']['type'] == "image/pjpeg"){
    
49. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
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50. }elseif($_FILES['image']['type'] == "image/x-png"){
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51. $im = imagecreatefrompng($_FILES['image']['tmp_name']);
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52. }elseif($_FILES['image']['type'] == "image/gif"){
    
53. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
    
54. } 2881064151
    
55. if($im){
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56. if(file_exists("$FILENAME.jpg")){
    
57. unlink("$FILENAME.jpg");
    
58. }
    
59. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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60. ImageDestroy ($im);
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61. }
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62. }
    
63. ?>

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以下是测试代码(demo.php)
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1. <?php
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2. include('ResizeImage.php');
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3. if(!empty($_POST)){
   
4. echo($FILENAME.".jpg?cache=".rand(0,999999));
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5. }
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6. ?>
   
7. <form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >
   
8. <input type="file" name="image" size="50" value="浏览"><p>
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9. <input type="submit" value="上传图片">
   
10. </form>

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