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
* X8 \0 k, Y; C1 S. T
$FILENAME="image.thumb"; 7 h) O" C. C' y+ z: c1 U5 _+ |" `
// 生成图片的宽度 4 F5 N8 U% N- M" a& O
$RESIZEWIDTH=400; # S: Q* I, P0 J5 g6 e7 ]
// 生成图片的高度 + x- B) h% l* g) t2 Q
$RESIZEHEIGHT=400;
% h& ~9 C5 e* [
" X7 |5 r2 T- c! i4 y
function ResizeImage($im,$maxwidth,$maxheight,$name){ & B, c, T- l4 t. `' F
$width = imagesx($im);
9 x6 n+ {0 N+ p
$height = imagesy($im); , z" a+ N' X& U8 O
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ ! d0 z# v6 p' V3 |" n8 i* M# z: @
if($maxwidth && $width > $maxwidth){
) P3 e. ?0 n5 y! d. |
$widthratio = $maxwidth/$width; + {& N* V, H e8 a2 ]9 [9 j
$RESIZEWIDTH=true; : Z3 k0 C' t- C. p+ {
} - E' X9 |7 h: D
if($maxheight && $height > $maxheight){ 6 }9 g' ~* {, l6 v
$heightratio = $maxheight/$height; . i& d! K9 T7 ]
$RESIZEHEIGHT=true; 3 n" z+ z( u/ C
} 4 |2 ~ L" C: p- h5 d3 q% ]
if($RESIZEWIDTH && $RESIZEHEIGHT){ 6 M$ J5 p5 V) k- Q- f) |, [
if($widthratio < $heightratio){ $ y+ f1 y4 g# f
$ratio = $widthratio;
- j# @. G& ?3 b+ p2 C
}else{ 4 Q# x9 s, i/ p
$ratio = $heightratio;
! u1 e4 J h/ E/ n* a2 ]2 V
}
1 t* H3 a6 D# {0 [* S
}elseif($RESIZEWIDTH){
# o5 I* j& e' o8 T7 q- g: r7 E; M
$ratio = $widthratio;
; i0 U6 j4 |; P1 B6 q$ A/ b0 J
}elseif($RESIZEHEIGHT){ + s! q' E B6 m& d
$ratio = $heightratio; 1 q8 W6 e' F" K$ q0 O- v
}
0 d0 h* @; m- R$ [; X
$newwidth = $width * $ratio;
3 d5 Q/ O- I4 I
$newheight = $height * $ratio; 0 q3 K/ ]$ U3 x
if(function_exists("imagecopyresampled")){
4 K, N, U2 G7 B
$newim = imagecreatetruecolor($newwidth, $newheight); 5 d" I' K: [ x3 L$ a! U' Q" \
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
! B/ A4 I: h3 W q2 h# {& f7 Q+ Y% B
}else{ 0 Y+ Y7 s, z; o' T/ _9 F$ C2 h
$newim = imagecreate($newwidth, $newheight); 2 S; E4 k1 T% d) v) z
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 4 H4 ~7 E8 ?$ ?. {5 x
}
# N8 w5 g, Q2 f% [6 d0 [$ H. Q* l
ImageJpeg ($newim,$name . ".jpg");
; X% m8 u! }7 y; c+ S- s
ImageDestroy ($newim); ' U! n! U4 F; S& ~. |
}else{
* U, l0 E6 e( C0 V% y
ImageJpeg ($im,$name . ".jpg");
1 A7 p7 ^5 T5 d" N1 e
}
. a) A* S4 t! V9 x% S" H
}
" N: P1 i4 I% R- \
4 w% O2 j( Z3 d# K' z
if($_FILES['image']['size']){
; E* B5 `* ~# }8 F4 O5 b5 \' t# Z
if($_FILES['image']['type'] == "image/pjpeg"){ , W' \' }6 r" S9 W" ^
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
* b; v* a* h* v% n# Y7 y
}elseif($_FILES['image']['type'] == "image/x-png"){ ' J# R8 X3 @' A
$im = imagecreatefrompng($_FILES['image']['tmp_name']);
. y) p! v/ ~$ Q! v
}elseif($_FILES['image']['type'] == "image/gif"){
. X+ F% w! Z1 K0 b% ?
$im = imagecreatefromgif($_FILES['image']['tmp_name']); 7 i2 z1 @, n- r6 y9 t7 l) p6 R' B
} 2881064151
& E" B$ z) A: L( q1 V4 Z
if($im){ : H2 j |# W/ |; [ o4 j3 q# Y
if(file_exists("$FILENAME.jpg")){ 3 v2 O. f( ~: h5 W
unlink("$FILENAME.jpg"); % Y* i5 [# X7 i3 Z
} ' T, J& `5 ]$ `0 H# T9 K
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME); 3 T/ i; j$ \! L' r0 ?6 r# c
ImageDestroy ($im);
. L( h# K1 q7 A& s% e; ~$ x. b
} * t- P. ~4 _$ y- q: r; F7 |8 |3 u2 n
} " E; Z/ o0 l1 d: X& Z* L% p; t6 {
?>

复制代码

以下是测试代码(demo.php)

代码如下:

<?php
. ~; k4 D$ Q1 [: p0 E L
include('ResizeImage.php');
: e3 r2 p) J/ b; B# I' D
if(!empty($_POST)){
8 a0 J0 ^; ~1 s6 {
echo($FILENAME.".jpg?cache=".rand(0,999999)); - Y' [/ S* B8 S6 T( c8 i6 T$ B
}
" Y# N% k. M) m U
?>
& _/ `$ l5 c$ b8 ]! N1 u8 }" `
<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >
! h* y- `+ j/ R H( H" G1 x
<input type="file" name="image" size="50" value="浏览"><p> 6 t# a1 b" T) Q2 U& N
<input type="submit" value="上传图片">
" Z/ a/ \, s* l" x: [
</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