PHP一般情况下生成的缩略图都比较不理想

admin · 发表于 2018-7-7 23:52:53

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。

<?php
: j f9 ]0 C: b
$FILENAME="image.thumb"; 9 m' W0 J9 c1 m/ l
// 生成图片的宽度
- [; E7 u$ e0 ]8 g
$RESIZEWIDTH=400; ( g7 k9 Y. |; \% N/ w s' }2 x
// 生成图片的高度 % B: B3 Q m: c' n* Z9 C [
$RESIZEHEIGHT=400;, }6 d% X* H8 i/ b8 E
W5 U' V3 w# ]. a# y6 v! K; i
function ResizeImage($im,$maxwidth,$maxheight,$name){ 0 k; `1 W! m& l
$width = imagesx($im);
# h7 [% N# |0 m C1 b9 ~
$height = imagesy($im);
' y3 Z. \9 a! Z! C& H q
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ & l1 ]5 q# x) `$ m: M
if($maxwidth && $width > $maxwidth){
% {3 [+ f) z' m. U- y. A/ ]0 `
$widthratio = $maxwidth/$width;
% l! W0 c4 W( `( g0 l/ B' E4 L7 k
$RESIZEWIDTH=true;
! F5 k2 V/ z/ T
} _ n3 K" T' Q$ u$ d0 ~ M
if($maxheight && $height > $maxheight){
. |$ }( U' d8 C( M/ A
$heightratio = $maxheight/$height; / T: t7 y$ Q) T1 S) O! R' x% E* \/ w
$RESIZEHEIGHT=true;
' A0 T' Z% V* D# f* S- C; v
} 1 K% s. Y& k' H+ s
if($RESIZEWIDTH && $RESIZEHEIGHT){
% E% u" Z4 E# b: O0 H2 P- X
if($widthratio < $heightratio){
, [ G! _* b: P9 X |, _( J
$ratio = $widthratio; * Z0 E8 | c; y3 \, G& x+ k3 _
}else{ / R! j1 p, ]# T; B+ z
$ratio = $heightratio; 2 O! e' e1 `" [0 J6 B
}
# T% Z! V5 c; D" ]
}elseif($RESIZEWIDTH){ 1 z5 \, R# l F% F, s8 j
$ratio = $widthratio; ' r* }) o# M' q: Z5 w9 Q- B
}elseif($RESIZEHEIGHT){
& ^. _! c( _" a$ J- _* @
$ratio = $heightratio; & x7 d7 \. v$ h8 N6 C
} * g1 k' { K4 E- W. M6 D
$newwidth = $width * $ratio; ( M2 I1 m3 x8 |- y4 [2 h" |% C
$newheight = $height * $ratio;
# M7 E% S0 ]( q5 O: J D, g
if(function_exists("imagecopyresampled")){
1 K) \3 n- Y, {$ d b
$newim = imagecreatetruecolor($newwidth, $newheight); ; U/ Y$ M" Q8 {6 y
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); ) f6 b% V) E; U' c7 K
}else{ % L/ j) D# M7 L0 W' U
$newim = imagecreate($newwidth, $newheight); - p: V8 E. T" L
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
( f7 }4 z- Y) k8 t- v8 i" D/ M
}
& H# U' r4 G7 C! |0 n( M
ImageJpeg ($newim,$name . ".jpg"); 0 q. c; X7 F* p
ImageDestroy ($newim); $ D( {, _" g- g, b: U C2 v
}else{
3 f9 C% \* M1 U0 B) e& \
ImageJpeg ($im,$name . ".jpg");
* h% b: v T: s1 ?) F
}
! e7 J/ t' s1 g9 R
}; t+ x- P4 s: e
+ C' Z$ z/ l4 A% i, A
if($_FILES['image']['size']){ ! E# B) y/ u- y: x
if($_FILES['image']['type'] == "image/pjpeg"){ , t! T- t6 Z2 I
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
% F$ W; j, C" o8 \% s
}elseif($_FILES['image']['type'] == "image/x-png"){ . ~* e+ j6 A$ p( |9 s7 G; G
$im = imagecreatefrompng($_FILES['image']['tmp_name']); & l; ~/ O$ p# l s/ R6 u9 R
}elseif($_FILES['image']['type'] == "image/gif"){ ! k3 U+ d2 d- I+ t( K- b
$im = imagecreatefromgif($_FILES['image']['tmp_name']);
: l9 s/ U3 W# F# E9 p( C {
} 2881064151
& G6 p! ^# M' t3 [7 d$ I" ?
if($im){
. m0 ^2 I' d) ^! p5 L& a0 ^0 @3 [
if(file_exists("$FILENAME.jpg")){ ! j3 k: S3 i0 c
unlink("$FILENAME.jpg");
. X# F: g$ G& ~( ~/ G
}
- w% {' g2 ~: L5 v0 Y d
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
* z" j7 E, O4 s' q7 ^
ImageDestroy ($im); & J4 T2 o* D q9 c
} 8 _0 W; Y2 Q7 M& `5 I( K' T
} 3 Q+ c5 M+ l7 B" ?3 i! t
?>

复制代码

以下是测试代码(demo.php)

代码如下:

<?php 2 k' [8 X$ C" m2 J; n: y' u' D
include('ResizeImage.php'); : D0 k% y# ?, Z$ @) j% K1 ^4 h& r+ B
if(!empty($_POST)){ 0 w; @- |" z# B+ \, c# S
echo($FILENAME.".jpg?cache=".rand(0,999999)); , q( d7 n1 I5 |6 {/ R) S" |
} 2 g) u+ R* _& {+ K s# \1 z$ t* t
?> ( [- E$ M& g- q
<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > $ ]1 j9 [ q6 g! `& H8 J& U5 E
<input type="file" name="image" size="50" value="浏览"><p> . t7 w* s6 K- t. T! J
<input type="submit" value="上传图片">
5 {% U* h9 a: g+ q
</form>

复制代码

帐号		自动登录	找回密码
密码			立即注册

[php学习资料] PHP一般情况下生成的缩略图都比较不理想