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标题: PHP一般情况下生成的缩略图都比较不理想 [打印本页]
作者: admin    时间: 2018-7-7 23:52
标题: PHP一般情况下生成的缩略图都比较不理想
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
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  2. $FILENAME="image.thumb"; 9 ^5 b) l. l0 c5 J$ w5 r
  3. // 生成图片的宽度
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  4. $RESIZEWIDTH=400; 4 U7 L; s  T% C$ g6 w
  5. // 生成图片的高度
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  6. $RESIZEHEIGHT=400;' R3 W( j! s$ r& L9 G. [5 H

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  8. function ResizeImage($im,$maxwidth,$maxheight,$name){ * z1 c2 k- K  ^% h- u; [/ D
  9. $width = imagesx($im);
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  10. $height = imagesy($im);
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  11. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ . @" s; @, y" u7 v
  12. if($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){ / K, p! K* E" f
  17. $heightratio = $maxheight/$height;
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  18. $RESIZEHEIGHT=true;
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  19. }
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  20. if($RESIZEWIDTH && $RESIZEHEIGHT){
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  21. if($widthratio < $heightratio){
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  22. $ratio = $widthratio; / Q' [: a$ N/ }. j) F& @0 v, }
  23. }else{
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  24. $ratio = $heightratio;
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  25. } 9 b/ o+ q2 S. o
  26. }elseif($RESIZEWIDTH){ , u& C/ B: R* F/ ]% l( S
  27. $ratio = $widthratio;
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  28. }elseif($RESIZEHEIGHT){ ' q- D1 z9 y, R$ ?" W1 }; {( u
  29. $ratio = $heightratio;
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  30. } 8 N# ?+ ~; }, j; ?3 j, a) Z! o- V
  31. $newwidth = $width * $ratio; ) y; d0 w! b6 e% B1 l& J; }0 B* T
  32. $newheight = $height * $ratio;
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  33. if(function_exists("imagecopyresampled")){
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  34. $newim = imagecreatetruecolor($newwidth, $newheight); ; V. W; U8 }" n/ F2 R$ t
  35. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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  36. }else{ + y: G. |, ?# `7 i+ u, z
  37. $newim = imagecreate($newwidth, $newheight);
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  38. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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  40. ImageJpeg ($newim,$name . ".jpg");
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  41. ImageDestroy ($newim); 5 N7 w. X; ^; T+ T' {& P1 q+ }
  42. }else{
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  43. ImageJpeg ($im,$name . ".jpg"); " M! i; L& f- z* Z( ~
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  45. }% i6 P* M% G4 w! i5 ^

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  47. if($_FILES['image']['size']){ 6 ~. g* R/ f3 b
  48. if($_FILES['image']['type'] == "image/pjpeg"){
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  49. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']); 2 m7 N' N. T4 d4 G3 l9 r) k1 i! j$ V
  50. }elseif($_FILES['image']['type'] == "image/x-png"){
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  51. $im = imagecreatefrompng($_FILES['image']['tmp_name']); 1 U+ S% n- ^; w% }' c% N
  52. }elseif($_FILES['image']['type'] == "image/gif"){ . Z6 a) z9 f6 L
  53. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
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  54. } 28810641514 A! i" f5 B7 J# S0 L
  55. if($im){
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  56. if(file_exists("$FILENAME.jpg")){
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  57. unlink("$FILENAME.jpg"); ' L* n! h! Z8 ^% S5 j
  58. }
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  59. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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  60. ImageDestroy ($im); . d/ T( f+ p0 |1 S8 q. i: x" o' d
  61. } & M6 K% M. ]2 I# t
  62. }
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  63. ?>
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以下是测试代码(demo.php) - ^6 }$ K# T: ], i1 E
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代码如下:
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  1. <?php 5 [( o; w( f% t) A
  2. include('ResizeImage.php'); 8 R- G6 R3 N3 T/ C1 E/ v
  3. if(!empty($_POST)){ - d& Y5 }; s, }
  4. echo($FILENAME.".jpg?cache=".rand(0,999999));
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  5. }
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  6. ?>
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  7. <form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > . _9 T, f2 S7 H1 J
  8. <input type="file" name="image" size="50" value="浏览"><p> ' Q0 G6 |! ^' D9 Q" `
  9. <input type="submit" value="上传图片">
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  10. </form>
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