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 4 d1 }) J" {* T+ y) @1 o
$FILENAME="image.thumb";
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// 生成图片的宽度 * E% L3 K* P N) m( z# m
$RESIZEWIDTH=400; ! X/ b$ b) Z7 J& T
// 生成图片的高度
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$RESIZEHEIGHT=400;% r) J! C n1 g0 r
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function ResizeImage($im,$maxwidth,$maxheight,$name){ + [' O2 z- h( {
$width = imagesx($im);
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$height = imagesy($im);
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if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
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if($maxwidth && $width > $maxwidth){
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$widthratio = $maxwidth/$width;
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$RESIZEWIDTH=true; 4 r2 b. h4 A$ ?0 ?
} # ^+ q, t. ^* N/ c
if($maxheight && $height > $maxheight){ 4 f+ i- \6 t' w& _1 N% j4 R2 G
$heightratio = $maxheight/$height; & q4 o& F2 X5 K& z9 T) B) n
$RESIZEHEIGHT=true;
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} - {0 g6 ]0 k9 G! n1 {
if($RESIZEWIDTH && $RESIZEHEIGHT){ $ r+ c. N5 v6 B2 g+ x# y
if($widthratio < $heightratio){
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$ratio = $widthratio; & h, M/ x& p0 J+ I' J& L
}else{ + n1 b$ L9 l/ e0 d9 @9 V
$ratio = $heightratio;
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} : D: v o' L- @6 h- R. J2 D
}elseif($RESIZEWIDTH){
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$ratio = $widthratio; : P4 A7 a, D/ b# T) Z1 v
}elseif($RESIZEHEIGHT){
$ratio = $heightratio; ! Q$ y. K) A' U2 P5 A9 G5 R
} ) h: J) L% Z& o: x0 _8 ^( v) `' e
$newwidth = $width * $ratio;
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$newheight = $height * $ratio;
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if(function_exists("imagecopyresampled")){
$newim = imagecreatetruecolor($newwidth, $newheight); P3 o$ \ ]5 I; Q! ? N5 {
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); % f% c8 X, t6 ]( i4 A0 Y* H# S
}else{
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$newim = imagecreate($newwidth, $newheight); ; p4 k6 j6 F1 a7 ?# m1 ?" Z
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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} 1 j) _4 B7 ~( p
ImageJpeg ($newim,$name . ".jpg"); ; Y6 Y9 H) |9 U3 i3 w9 X5 @) I
ImageDestroy ($newim); # p/ p0 P8 _, ~; f! c
}else{ 4 g$ J. _/ V4 `: W; I
ImageJpeg ($im,$name . ".jpg"); " \& N$ c0 K* p, L
}
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}$ a8 n6 Y9 W! b! x5 r3 }+ O7 d3 _ {1 S
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if($_FILES['image']['size']){ 7 P# F. P3 f8 N; R6 r
if($_FILES['image']['type'] == "image/pjpeg"){ $ Z k+ E! y& h* t" j
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
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}elseif($_FILES['image']['type'] == "image/x-png"){
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$im = imagecreatefrompng($_FILES['image']['tmp_name']); 6 v7 _4 n% M: a. R$ ?
}elseif($_FILES['image']['type'] == "image/gif"){ 0 {! Z- R8 {: k' e- Z# [) @
$im = imagecreatefromgif($_FILES['image']['tmp_name']); # u+ o+ Z8 p1 A# c
} 2881064151
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if($im){
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if(file_exists("$FILENAME.jpg")){ 5 {2 A$ ^, s6 v9 U8 x
unlink("$FILENAME.jpg");
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}
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ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME); 8 [' M' h3 D- | F7 z7 v/ [9 C
ImageDestroy ($im);
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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
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include('ResizeImage.php');
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if(!empty($_POST)){
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echo($FILENAME.".jpg?cache=".rand(0,999999));
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}
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?>
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<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > 9 P/ D3 { |! Y2 N+ s9 Y% s# p8 C
<input type="file" name="image" size="50" value="浏览"><p>
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<input type="submit" value="上传图片">
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</form>

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