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
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$FILENAME="image.thumb";
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// 生成图片的宽度
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$RESIZEWIDTH=400; # M% X G0 k4 q7 I$ q
// 生成图片的高度
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$RESIZEHEIGHT=400;2 `' D) E5 d8 a \9 i% `5 a
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function ResizeImage($im,$maxwidth,$maxheight,$name){ + a/ F8 H/ D9 o
$width = imagesx($im);
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$height = imagesy($im); 5 P' @4 ?2 j3 v K
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ 5 q! c! Z3 S) u+ p3 x" e
if($maxwidth && $width > $maxwidth){ 6 X2 h9 e2 j6 N. w; v
$widthratio = $maxwidth/$width; 5 I$ _4 ^6 _% o# c0 T
$RESIZEWIDTH=true;
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}
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if($maxheight && $height > $maxheight){
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$heightratio = $maxheight/$height; 0 B+ x1 d: O! p2 e
$RESIZEHEIGHT=true;
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}
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if($RESIZEWIDTH && $RESIZEHEIGHT){
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if($widthratio < $heightratio){
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$ratio = $widthratio; 3 W) R. A, @' w" q- ?) q8 Y& s9 J
}else{
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$ratio = $heightratio;
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} - f2 s. j# i- J3 P4 O+ H! S: M; I- r) I
}elseif($RESIZEWIDTH){ # C2 q' B% _& p4 u7 \' v0 B4 Z
$ratio = $widthratio;
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}elseif($RESIZEHEIGHT){ R% w+ C. y0 z- ^( k1 l6 P
$ratio = $heightratio; 8 ]! |) ~* q( T+ ~. f$ u) [
} ) P; a- w9 M( `* w' @8 E
$newwidth = $width * $ratio; ! B% J. T- I, W' H
$newheight = $height * $ratio;
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if(function_exists("imagecopyresampled")){ M6 o+ S, [* p: G% u/ z: j
$newim = imagecreatetruecolor($newwidth, $newheight); ) k) e# |, ]& G9 y
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); ; [/ R; l- o9 z Z
}else{
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$newim = imagecreate($newwidth, $newheight); + ~" R9 R0 I0 _/ H& q; g) i, ]
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); ) N; ?: j7 _# |' y- L( t9 V
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ImageJpeg ($newim,$name . ".jpg"); 9 h& {/ ~8 v. C+ I% C \3 \( Y
ImageDestroy ($newim); 7 P9 q: s W8 a6 z& E: N% B
}else{
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ImageJpeg ($im,$name . ".jpg"); 8 u5 I4 E" }# ?3 i6 | C8 M+ h; d
}
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}
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if($_FILES['image']['size']){
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if($_FILES['image']['type'] == "image/pjpeg"){
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$im = imagecreatefromjpeg($_FILES['image']['tmp_name']); ) C/ N$ `" o. E! p% q/ z
}elseif($_FILES['image']['type'] == "image/x-png"){
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$im = imagecreatefrompng($_FILES['image']['tmp_name']); 1 \1 |1 m( g/ j' y2 q
}elseif($_FILES['image']['type'] == "image/gif"){
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$im = imagecreatefromgif($_FILES['image']['tmp_name']); 3 e0 n x2 R3 t0 w; o) Z
} 2881064151
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if($im){
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if(file_exists("$FILENAME.jpg")){
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unlink("$FILENAME.jpg");
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} 4 a6 A1 U2 O6 o! k* o6 t
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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ImageDestroy ($im);
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} % J! J, ^5 |' k7 t
}
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?>

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以下是测试代码(demo.php)

代码如下:

<?php " Y' r9 {/ c6 Z1 Q! o. w1 s
include('ResizeImage.php');
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if(!empty($_POST)){ 9 o% b/ R+ M" J0 p" c, T
echo($FILENAME.".jpg?cache=".rand(0,999999)); , P( |0 @( @9 M4 ?6 N3 l
} 9 d2 X% ^0 C$ ?: H, [
?> 4 l6 E! N6 `9 ^5 e1 g o
<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" >
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<input type="file" name="image" size="50" value="浏览"><p>
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<input type="submit" value="上传图片"> 9 u. n2 j" c, T
</form>

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