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 # B7 r. [+ {# D6 U9 s
$FILENAME="image.thumb"; : ~# P+ T9 U. ]
// 生成图片的宽度 " Z: G* U/ j+ ^ t
$RESIZEWIDTH=400; ) F( u4 N5 a" y% A
// 生成图片的高度
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$RESIZEHEIGHT=400; Q) N; k7 Q" u" f
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function ResizeImage($im,$maxwidth,$maxheight,$name){
# A! x. T) L* D% f
$width = imagesx($im); * {9 F2 F1 j1 m' A
$height = imagesy($im);
# h3 y& w9 K3 H, X
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ ) [6 K' B: t: d: A+ u- Z
if($maxwidth && $width > $maxwidth){ 7 y: t* u0 [6 q3 g3 |+ w8 e
$widthratio = $maxwidth/$width; $ q: c# H- p/ F5 M
$RESIZEWIDTH=true;
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} ' v! K: f5 v8 h& n7 Z
if($maxheight && $height > $maxheight){
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$heightratio = $maxheight/$height; % B; S! Z7 y8 B6 m
$RESIZEHEIGHT=true;
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} 7 w$ V6 d. K( \; w
if($RESIZEWIDTH && $RESIZEHEIGHT){
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if($widthratio < $heightratio){
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$ratio = $widthratio; & w9 z1 \& `* d% o5 w4 m4 Y, }
}else{ ]7 K2 V- H) \) \' ?& Z
$ratio = $heightratio; 6 v2 e. d; F9 t: G
}
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}elseif($RESIZEWIDTH){
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$ratio = $widthratio;
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}elseif($RESIZEHEIGHT){ 6 q9 X' L! R6 j. \
$ratio = $heightratio;
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} ) I$ M( v( x' d s' | d$ k3 u
$newwidth = $width * $ratio;
# [" l. b6 x2 m) l) S) w3 @$ I$ ^
$newheight = $height * $ratio; 3 t* o* N" |- I9 r2 N8 x
if(function_exists("imagecopyresampled")){
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$newim = imagecreatetruecolor($newwidth, $newheight); . h7 q1 g* q$ m6 [, I/ w% E, g8 z4 a
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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}else{
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$newim = imagecreate($newwidth, $newheight); 2 g$ z& q% }, {: D% u4 k
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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}
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ImageJpeg ($newim,$name . ".jpg"); / E" N' o5 k( [- W4 ~8 h: D
ImageDestroy ($newim); P" ^: }5 a, @2 A% c2 o, _
}else{
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ImageJpeg ($im,$name . ".jpg"); 2 N0 ^" r% k% }9 d
} 4 P/ H0 ^8 L" X" ~+ f3 m0 ?* o9 s
} E; ~4 o$ Z6 R6 i# a( r
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if($_FILES['image']['size']){
# Z. b Y0 ^4 G
if($_FILES['image']['type'] == "image/pjpeg"){
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$im = imagecreatefromjpeg($_FILES['image']['tmp_name']); 2 H9 m. v, }* \. `+ w' R5 y
}elseif($_FILES['image']['type'] == "image/x-png"){
% I5 d6 ?# u' j/ Z* t' ^
$im = imagecreatefrompng($_FILES['image']['tmp_name']);
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}elseif($_FILES['image']['type'] == "image/gif"){
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$im = imagecreatefromgif($_FILES['image']['tmp_name']);
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} 2881064151
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if($im){
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if(file_exists("$FILENAME.jpg")){ 1 G/ y- q' O+ g& v1 y& W b
unlink("$FILENAME.jpg"); # V/ ]2 x% m2 E; x7 }3 I+ ^
}
# K0 a! R3 Y0 ^' Y ~
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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ImageDestroy ($im); r$ c7 ~3 w' g
}
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}
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?>

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以下是测试代码(demo.php)

代码如下:

<?php + o8 P7 m0 I# `* i% M- e
include('ResizeImage.php');
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if(!empty($_POST)){ $ C: x) g) n3 ^! l6 v
echo($FILENAME.".jpg?cache=".rand(0,999999)); 9 M, \" {2 s5 ^3 A! c4 Y: R
} ; p& p0 P5 {9 W* {
?>
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<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > ( Y0 e; y* s- T( x3 I! }5 E
<input type="file" name="image" size="50" value="浏览"><p> 7 A; w+ \% w p" a# S7 P# W5 B
<input type="submit" value="上传图片">
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</form>

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