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 X" L9 r) W6 c8 e2 q% g* A
$FILENAME="image.thumb";
; _( V f- V1 C& E% y5 H) {% } _
// 生成图片的宽度 5 \8 N2 `5 M; X5 O" r8 p
$RESIZEWIDTH=400;
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// 生成图片的高度
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$RESIZEHEIGHT=400;
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function ResizeImage($im,$maxwidth,$maxheight,$name){
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$width = imagesx($im); 7 @6 Y2 b% Q/ z I
$height = imagesy($im); ; {( g2 n/ z G! |
if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){ ; q2 C5 v: c9 j
if($maxwidth && $width > $maxwidth){ 8 ]% q& | [; O9 F8 K
$widthratio = $maxwidth/$width;
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$RESIZEWIDTH=true;
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} $ w6 y, x3 J5 L- X' x+ I
if($maxheight && $height > $maxheight){ 0 i4 O: {, z$ a+ F3 _
$heightratio = $maxheight/$height;
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$RESIZEHEIGHT=true; + s5 o: V- a. d8 _/ p2 h) K
}
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if($RESIZEWIDTH && $RESIZEHEIGHT){
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if($widthratio < $heightratio){ % _* [! c% H2 d/ c. [/ D( x7 F
$ratio = $widthratio; * m9 C* w0 O5 z) ^) n2 T, u6 I9 t# n9 t
}else{
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$ratio = $heightratio;
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}
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}elseif($RESIZEWIDTH){ 3 g: l" b4 b+ Z. U+ [
$ratio = $widthratio;
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}elseif($RESIZEHEIGHT){ * e; f! U. Y) ~8 V7 U! w. z
$ratio = $heightratio; + S a3 F6 Y5 b r9 V
}
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$newwidth = $width * $ratio;
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$newheight = $height * $ratio; ' f" Z8 |( l9 K7 z1 H5 \; D* d* p
if(function_exists("imagecopyresampled")){
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$newim = imagecreatetruecolor($newwidth, $newheight);
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imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); / \0 S: W3 x [) y
}else{ / O( l4 U( {( h: r
$newim = imagecreate($newwidth, $newheight); 0 p0 i' S4 A! h3 f" U+ E. d# ?; b
imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height); 0 k7 P7 a+ _) O3 v& Z
}
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ImageJpeg ($newim,$name . ".jpg"); , B! |' b$ M& r& B* l6 j& r* c
ImageDestroy ($newim); 7 j* u9 }+ J; M, J! k
}else{ * L' g' F( A) Y2 `2 J! E" x
ImageJpeg ($im,$name . ".jpg"); 2 E' N9 r* K4 }# K! T# G- n
} 8 V M- j2 A$ E# X
}
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if($_FILES['image']['size']){
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if($_FILES['image']['type'] == "image/pjpeg"){ . _& u( h1 z6 }+ W9 e5 m4 o$ V9 r `
$im = imagecreatefromjpeg($_FILES['image']['tmp_name']); . h' D p# w2 a5 v: J
}elseif($_FILES['image']['type'] == "image/x-png"){
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$im = imagecreatefrompng($_FILES['image']['tmp_name']); / `- J1 _ N: [: r) }5 B* _9 P
}elseif($_FILES['image']['type'] == "image/gif"){ 0 W* Q2 h% s ?; O4 T4 w
$im = imagecreatefromgif($_FILES['image']['tmp_name']);
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} 2881064151
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if($im){
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if(file_exists("$FILENAME.jpg")){
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unlink("$FILENAME.jpg");
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} 9 t0 N1 h5 G' R6 e' A
ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
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ImageDestroy ($im); ! k4 C, Z0 |% a( i( t
}
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} 5 H' g W" }$ n& p/ u4 t
?>

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以下是测试代码(demo.php)

代码如下:

<?php 0 L) b6 A1 K4 @
include('ResizeImage.php');
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if(!empty($_POST)){ % }. V; j3 I9 {* l+ M: d9 m7 S
echo($FILENAME.".jpg?cache=".rand(0,999999)); 7 M2 M( |1 |8 G( o2 s
} 9 v n1 y$ }) e" B3 U, {" \
?>
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<form name="test" action="?submit=true" enctype="multipart/form-data" method="post" > 5 l$ ]1 e7 u( H& r
<input type="file" name="image" size="50" value="浏览"><p> ; m+ l* Y8 y1 a x& g1 I
<input type="submit" value="上传图片">
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</form>

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