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 - [+ @1 _6 |, @& h! q
$FILENAME="image.thumb"; 1 Z! E4 {& X2 \) y) H' e; ^
// 生成图片的宽度
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$RESIZEWIDTH=400;
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// 生成图片的高度
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$RESIZEHEIGHT=400;$ y* c4 M2 b7 [, U2 J0 [
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function ResizeImage($im,$maxwidth,$maxheight,$name){ # r& P& a$ _: Q( ^0 X- {
$width = imagesx($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){ , Q9 a9 J3 X2 Y5 z# S5 Q) Y( Z
$widthratio = $maxwidth/$width;
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$RESIZEWIDTH=true;
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}
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if($maxheight && $height > $maxheight){
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$heightratio = $maxheight/$height; 1 ?& ]4 _+ [$ {+ l( O- y
$RESIZEHEIGHT=true; / K: q* j# g8 Y# e! V4 Q
} : V3 I1 t* ]2 c
if($RESIZEWIDTH && $RESIZEHEIGHT){ & y% P& n" X3 h- E
if($widthratio < $heightratio){ : ]) p5 Y" c- |6 n
$ratio = $widthratio; $ U& V. h. g3 { O0 \0 o
}else{ 2 ?; X2 }/ I2 I" m+ @
$ratio = $heightratio; , W) k4 u+ |+ U2 G6 u
} : }0 k- ]! @* x* E
}elseif($RESIZEWIDTH){ - X$ d: Q4 Q# }/ W) X
$ratio = $widthratio;
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}elseif($RESIZEHEIGHT){ " P+ a- O. o" }: w
$ratio = $heightratio; , ~, V) M0 [9 j; W! b
} % q1 x0 `( X" H" @3 f
$newwidth = $width * $ratio; , ]. ~6 W: ^# ?4 k; B: F
$newheight = $height * $ratio; 6 R, D" h2 Z0 ~7 q
if(function_exists("imagecopyresampled")){ ; v+ e1 u6 y" j$ {
$newim = imagecreatetruecolor($newwidth, $newheight); . v' B& w1 P4 j( [$ N6 G
imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 1 S% @$ Q" ?! f% j* r
}else{
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$newim = imagecreate($newwidth, $newheight);
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imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 5 u1 d" n: t+ z0 ]0 x5 ^
} 4 W+ g! ?& j0 P7 h+ g; a' B+ K) v7 ?
ImageJpeg ($newim,$name . ".jpg"); / _# E; z% r9 p8 N& X
ImageDestroy ($newim);
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}else{
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ImageJpeg ($im,$name . ".jpg");
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} - k; Q: w$ c6 `# H1 q
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if($_FILES['image']['size']){
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if($_FILES['image']['type'] == "image/pjpeg"){ 2 e# s4 C ~+ b, Q* T4 {$ L% v
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
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}elseif($_FILES['image']['type'] == "image/x-png"){ % z6 c' J0 d( q, _
$im = imagecreatefrompng($_FILES['image']['tmp_name']); $ t+ c- }: @& e+ ?. _8 w2 H
}elseif($_FILES['image']['type'] == "image/gif"){ , N# J8 D) U1 L( l% P8 M8 o3 V
$im = imagecreatefromgif($_FILES['image']['tmp_name']);
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} 2881064151/ F& e2 n0 m7 ]3 a0 ]$ |+ H# \
if($im){
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if(file_exists("$FILENAME.jpg")){
# y0 A9 b0 S U. s/ k* n! i! t
unlink("$FILENAME.jpg"); - J o/ w# L! C9 i3 Z# k( q0 z9 Z
} : U: ?% o& m3 S# ]
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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ImageDestroy ($im); + ^0 Q3 P, D! R4 ]5 r$ x
} 8 p, c7 r$ `' [9 Q3 U
}
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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)); 5 M' m! r8 f! ?( P% r: h% {9 p7 v
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?> 8 P% Q! l- o7 i# b: Y5 @
<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > ) u+ R! p9 K) e
<input type="file" name="image" size="50" value="浏览"><p> ' }6 ~- `8 Z5 ~9 ]
<input type="submit" value="上传图片"> % d: B. N w9 X& e' k5 y
</form>

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