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. $FILENAME="image.thumb";
   - o0 d+ |, m/ X9 {
3. // 生成图片的宽度
   
4. $RESIZEWIDTH=400;
   2 @, N+ M9 w# W# a( p+ i! V3 O1 a
5. // 生成图片的高度
   
6. $RESIZEHEIGHT=400;
   5 N2 P3 W' J& u1 _
7. 
   ! [# s' T+ z# s
8. function ResizeImage($im,$maxwidth,$maxheight,$name){
   ! T" K0 T$ {: {4 F# q
9. $width = imagesx($im);
   ' u8 M2 l7 X* _; G3 H. X3 D
10. $height = imagesy($im);
    ( J, v4 {3 d& c; ^
11. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
    
12. if($maxwidth && $width > $maxwidth){
    % ^+ |5 s+ k( R+ H: O
13. $widthratio = $maxwidth/$width;
    7 e% v% O  k1 q- g
14. $RESIZEWIDTH=true;
    
15. }
    
16. if($maxheight && $height > $maxheight){
    ! h/ R3 h8 W6 _
17. $heightratio = $maxheight/$height;
    
18. $RESIZEHEIGHT=true;
    6 f. \  |. D0 q) @: `) B7 |% f
19. }
    0 H- D: O, l/ L" s2 D* W
20. if($RESIZEWIDTH && $RESIZEHEIGHT){
    1 }' _* A- j( [
21. if($widthratio < $heightratio){
    
22. $ratio = $widthratio;
    
23. }else{
    1 O) H, ~8 B- e( f( X( g& J
24. $ratio = $heightratio;
    
25. }
    
26. }elseif($RESIZEWIDTH){
    
27. $ratio = $widthratio;
    # ?" Q1 p- q6 d7 U' c
28. }elseif($RESIZEHEIGHT){
    1 }+ G$ B7 U0 Y8 P) H
29. $ratio = $heightratio;
    
30. }
    
31. $newwidth = $width * $ratio;
    7 {' |" P* C9 B1 \. g
32. $newheight = $height * $ratio;
    ( z# @4 k* q* A9 d$ l; `+ l
33. if(function_exists("imagecopyresampled")){
    % V6 l' x% b- v$ f; I
34. $newim = imagecreatetruecolor($newwidth, $newheight);
    
35. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    
36. }else{
    $ V3 |6 L8 w: D
37. $newim = imagecreate($newwidth, $newheight);
    
38. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
    
39. }
    + X7 K1 }7 J" Q8 m* V
40. ImageJpeg ($newim,$name . ".jpg");
    
41. ImageDestroy ($newim);
    
42. }else{
    - N  E9 w, z/ e6 z
43. ImageJpeg ($im,$name . ".jpg");
    8 y8 ~$ e. k8 R6 Y" D2 L
44. }
    5 R$ l+ R/ {) y' E
45. }
    ' N; w* ~) B+ x9 C' Q3 H2 S
46. 
    
47. if($_FILES['image']['size']){
    
48. if($_FILES['image']['type'] == "image/pjpeg"){
    % [, _) f/ f: T# y
49. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
    
50. }elseif($_FILES['image']['type'] == "image/x-png"){
    7 i8 D0 m. U& R
51. $im = imagecreatefrompng($_FILES['image']['tmp_name']);
    ) _4 a2 U2 M6 l  Y$ F# Q
52. }elseif($_FILES['image']['type'] == "image/gif"){
    . I5 x/ ], y- d& p% M
53. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
    5 k1 A. O7 J$ z1 w" o8 [, z+ T
54. } 2881064151
    
55. if($im){
    
56. if(file_exists("$FILENAME.jpg")){
    7 _/ P- j% j9 J0 k$ D) x" C
57. unlink("$FILENAME.jpg");
    8 w; T; r8 R$ f$ {+ ~: K, C- E
58. }
    4 O! }' @6 w0 Z. m8 N% W+ G
59. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
    - @! H3 V$ D4 d5 z! |
60. ImageDestroy ($im);
    
61. }
    8 [- A7 V1 q4 o$ m6 ?( K! w/ X
62. }
    
63. ?>

复制代码

以下是测试代码(demo.php)
" j4 S1 u7 q* E& w# E
: j; T/ K6 ^* V代码如下:

1. <?php
   & K. l' N! R& o9 O, O7 V( R0 l
2. include('ResizeImage.php');
   7 V! b8 ?! \9 M: F, V' t9 D( n
3. if(!empty($_POST)){
   
4. echo($FILENAME.".jpg?cache=".rand(0,999999));
   
5. }
   
6. ?>
   ( O4 m* o2 x& A# U
7. <form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >
   4 k0 F; S- [5 l: v# E$ ]
8. <input type="file" name="image" size="50" value="浏览"><p>
   & ~! U9 q% F/ F( b' j3 _0 E' g2 J
9. <input type="submit" value="上传图片">
   
10. </form>

复制代码