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 8 R; E& Z/ M- l, G+ H3 |" F4 _$ }. D
$FILENAME="image.thumb"; $ A9 }5 J4 \. H- ?0 e' Q$ y. P. |
// 生成图片的宽度
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$RESIZEWIDTH=400;
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// 生成图片的高度 4 a% t/ F7 ~0 n2 L2 P
$RESIZEHEIGHT=400;
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function ResizeImage($im,$maxwidth,$maxheight,$name){
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$width = imagesx($im); 6 X0 q* D% `$ k6 C% Z/ t
$height = imagesy($im); 4 n/ k; U6 r K
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ " d, W# v6 a1 _# x
if($maxwidth && $width > $maxwidth){ 5 o% J! y* a! J8 v7 Q
$widthratio = $maxwidth/$width; 4 _1 ^: {9 H9 Q! a# o
$RESIZEWIDTH=true; * E' L: I$ F! o1 b5 r$ [' f
}
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if($maxheight && $height > $maxheight){ 7 n! B% y) R+ E2 V
$heightratio = $maxheight/$height; ) z1 q; D6 u1 u8 F2 R. h
$RESIZEHEIGHT=true;
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} % \( {% a, c0 m5 u8 ?* y
if($RESIZEWIDTH && $RESIZEHEIGHT){
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if($widthratio < $heightratio){ : B* U4 c1 K9 l e+ `
$ratio = $widthratio;
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}else{
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$ratio = $heightratio; * G( b7 d5 h+ V/ D
}
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}elseif($RESIZEWIDTH){ / @, ]& y3 U# _
$ratio = $widthratio; % O0 e- D: p9 W% K
}elseif($RESIZEHEIGHT){ 6 X! [. h* s& o
$ratio = $heightratio; b4 q* G9 P: A) x, U' p+ Q
}
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$newwidth = $width * $ratio;
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$newheight = $height * $ratio; 5 c: s0 M4 |0 c* |
if(function_exists("imagecopyresampled")){
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$newim = imagecreatetruecolor($newwidth, $newheight);
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imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
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}else{
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$newim = imagecreate($newwidth, $newheight);
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imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); & p( `8 |9 J: ~* a* m7 B8 m2 I
}
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ImageJpeg ($newim,$name . ".jpg");
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ImageDestroy ($newim); " z }: x$ i7 g" R
}else{
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ImageJpeg ($im,$name . ".jpg"); % u6 Q. {1 ?. y% m
}
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}
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if($_FILES['image']['size']){ $ U! x% d; j+ Y# }
if($_FILES['image']['type'] == "image/pjpeg"){
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$im = imagecreatefromjpeg($_FILES['image']['tmp_name']); ' L9 h" e8 W8 D3 h
}elseif($_FILES['image']['type'] == "image/x-png"){ 7 v ~' a7 f$ k K# \1 f4 F
$im = imagecreatefrompng($_FILES['image']['tmp_name']); 3 {* r* l- W! d& I* k5 }
}elseif($_FILES['image']['type'] == "image/gif"){ $ j' w% V7 E- ]; r5 _9 v
$im = imagecreatefromgif($_FILES['image']['tmp_name']);
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} 2881064151
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if($im){ % T5 P+ I$ i0 v$ L5 A. s# H
if(file_exists("$FILENAME.jpg")){
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unlink("$FILENAME.jpg");
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}
# L4 u# e2 S# H4 M
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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ImageDestroy ($im);
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} - I. W7 r/ G% y" D; ~0 I0 Z
} * U, z4 p% z0 `' p0 u
?>

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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'); % U4 v* n$ |3 s( `
if(!empty($_POST)){
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echo($FILENAME.".jpg?cache=".rand(0,999999)); : Y. ~9 V& I& x; T, \
}
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?>
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<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > 4 |: v: {3 S3 U* S
<input type="file" name="image" size="50" value="浏览"><p> 7 C/ i' W+ a9 Z% s( A/ `4 Z
<input type="submit" value="上传图片"> 9 J$ R* M' m( w4 {/ D+ w
</form>

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