PHP一般情况下生成的缩略图都比较不理想

admin

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 P( Z' x9 f% n
2. $FILENAME="image.thumb";
   
3. // 生成图片的宽度
   
4. $RESIZEWIDTH=400;
   
5. // 生成图片的高度
   
6. $RESIZEHEIGHT=400;
     ~4 M( v; G+ o. b( X) s  T  p2 W
7. 
   7 e% |1 u( H, m
8. function ResizeImage($im,$maxwidth,$maxheight,$name){
   $ q' E3 l# A: K# k1 \
9. $width = imagesx($im);
   + v5 O/ ]3 [8 M9 e7 Z6 ~
10. $height = imagesy($im);
    
11. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
    ' T# L/ C. k0 T6 o
12. if($maxwidth && $width > $maxwidth){
    
13. $widthratio = $maxwidth/$width;
    
14. $RESIZEWIDTH=true;
    1 \" a4 [( a. x5 d
15. }
    
16. if($maxheight && $height > $maxheight){
    4 }/ s* T: ?7 E& J  \7 M
17. $heightratio = $maxheight/$height;
    
18. $RESIZEHEIGHT=true;
    
19. }
    1 x' t0 ^- O% \, N+ |+ W
20. if($RESIZEWIDTH && $RESIZEHEIGHT){
    
21. if($widthratio < $heightratio){
    , }- ]/ b; {" a' ]4 ^% y
22. $ratio = $widthratio;
    " k4 e- ]( b! L+ B' J4 |5 v9 A
23. }else{
    
24. $ratio = $heightratio;
    
25. }
    + ~, j: T. D3 X
26. }elseif($RESIZEWIDTH){
    8 G# y7 [, q2 A; Z) a
27. $ratio = $widthratio;
    
28. }elseif($RESIZEHEIGHT){
    
29. $ratio = $heightratio;
    
30. }
    " ?% S0 I% V. l0 a' a
31. $newwidth = $width * $ratio;
    4 m9 r9 I, x. `( Y; _- I
32. $newheight = $height * $ratio;
    # S  T* f% Z6 R
33. if(function_exists("imagecopyresampled")){
    
34. $newim = imagecreatetruecolor($newwidth, $newheight);
    
35. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    $ v* Z7 ^% l/ X$ q3 k2 b
36. }else{
    . P( K; S% M9 j7 H* r0 M$ `
37. $newim = imagecreate($newwidth, $newheight);
    9 @9 P4 M6 A3 J0 [/ [
38. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    6 n3 i5 ]1 A, k; l2 N) x
39. }
    4 S1 ^+ y, z7 `
40. ImageJpeg ($newim,$name . ".jpg");
    ( G4 j& h7 H; h7 S
41. ImageDestroy ($newim);
    
42. }else{
    
43. ImageJpeg ($im,$name . ".jpg");
    2 [( J0 ^- ^" M; Q6 w* T  c
44. }
    1 l# Y$ D6 f3 P
45. }
    ( ~- Y9 F) d+ ?1 E1 P
46. 
    
47. if($_FILES['image']['size']){
    
48. if($_FILES['image']['type'] == "image/pjpeg"){
    
49. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
    3 i; Z7 z( o5 t. D
50. }elseif($_FILES['image']['type'] == "image/x-png"){
    1 o4 V' C5 Y: Y1 _# M8 ~
51. $im = imagecreatefrompng($_FILES['image']['tmp_name']);
    
52. }elseif($_FILES['image']['type'] == "image/gif"){
    
53. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
    $ S6 w7 D$ R" R- h
54. } 2881064151
    
55. if($im){
    " y! J7 D# |# Q7 _: s7 p& N6 l$ ~
56. if(file_exists("$FILENAME.jpg")){
    - y; W$ M/ w9 d' s* }$ q( w
57. unlink("$FILENAME.jpg");
    6 Y5 R8 I, Y  T3 K
58. }
    ! i5 Z" P! J$ J$ g. R/ {( Q
59. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
    
60. ImageDestroy ($im);
    + z) @  w; j; B0 T
61. }
    
62. }
    / A6 J0 `' z+ D# y
63. ?>

复制代码

以下是测试代码(demo.php)
) F4 U5 j( `" N9 H
代码如下:

1. <?php
   
2. include('ResizeImage.php');
   
3. if(!empty($_POST)){
   ' R! z3 `" F4 N9 ^5 `3 @
4. echo($FILENAME.".jpg?cache=".rand(0,999999));
   
5. }
   
6. ?>
   5 ?# t* }6 D. Q& y! z0 p7 h! j1 b# C& M3 G
7. <form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >
   ) Y% w, G( d' p8 f0 V! v0 Y( E
8. <input type="file" name="image" size="50" value="浏览"><p>
   1 y" {' q: ]& y4 o  ]
9. <input type="submit" value="上传图片">
   & S" \6 @/ k) J3 c9 q! y
10. </form>

复制代码

9 ^( s$ @$ d$ f$ H+ D
* T+ }2 s( c. J# i7 L