php 生成缩略图代码可自动填充空白处

时间：2015-01-23 来源：西部数据作者：西部数据

网站大多数生成缩略图都是按比例操作的,今天我们来看看可以固定图片大小,不够的地方自动填充空白,有需要的朋友可以参考一下.

php 生成缩略图代码可自动填充空白处实例代码如下:

<?php

error_reporting( E_ALL );

// 测试

imagezoom('1.jpg', '2.jpg', 400, 300, '#FFFFFF');

/*

php缩略图函数：

等比例无损压缩，可填充补充色 author: 华仔

主持格式：

bmp 、jpg 、gif、png

param:

@srcimage : 要缩小的图片

@dstimage : 要保存的图片

@dst_width: 缩小宽

@dst_height: 缩小高

@backgroundcolor: 补充色如：#FFFFFF 支持 6位不支持3位

*/

function imagezoom( $srcimage, $dstimage, $dst_width, $dst_height, $backgroundcolor ) {

// 中文件名乱码

if ( PHP_OS == 'WINNT' ) {

$srcimage = iconv('UTF-8', 'GBK', $srcimage);

$dstimage = iconv('UTF-8', 'GBK', $dstimage);

}

$dstimg = imagecreatetruecolor( $dst_width, $dst_height );

$color = imagecolorallocate($dstimg

, hexdec(substr($backgroundcolor, 1, 2))

, hexdec(substr($backgroundcolor, 3, 2))

, hexdec(substr($backgroundcolor, 5, 2))

);

imagefill($dstimg, 0, 0, $color);

if ( !$arr=getimagesize($srcimage) ) {

echo "要生成缩略图的文件不存在";

exit;

}

$src_width = $arr[0];

$src_height = $arr[1];

$srcimg = null;

$method = getcreatemethod( $srcimage );

if ( $method ) {

eval( '$srcimg = ' . $method . ';' );

}

$dst_x = 0;

$dst_y = 0;

$dst_w = $dst_width;

$dst_h = $dst_height;

if ( ($dst_width / $dst_height - $src_width / $src_height) > 0 ) {

$dst_w = $src_width * ( $dst_height / $src_height );

$dst_x = ( $dst_width - $dst_w ) / 2;

} elseif ( ($dst_width / $dst_height - $src_width / $src_height) < 0 ) {

$dst_h = $src_height * ( $dst_width / $src_width );

$dst_y = ( $dst_height - $dst_h ) / 2;

}

imagecopyresampled($dstimg, $srcimg, $dst_x

, $dst_y, 0, 0, $dst_w, $dst_h, $src_width, $src_height);

// 保存格式

$arr = array(

'jpg' => 'imagejpeg'

, 'jpeg' => 'imagejpeg'

, 'png' => 'imagepng'

, 'gif' => 'imagegif'

, 'bmp' => 'imagebmp'

);

$suffix = strtolower( array_pop(explode('.', $dstimage ) ) );

if (!in_array($suffix, array_keys($arr)) ) {

echo "保存的文件名错误";

exit;

} else {

eval( $arr[$suffix] . '($dstimg, "'.$dstimage.'");' );

}

imagejpeg($dstimg, $dstimage);

imagedestroy($dstimg);

imagedestroy($srcimg);

}

function getcreatemethod( $file ) {

$arr = array(

'474946' => "imagecreatefromgif('$file')"

, 'FFD8FF' => "imagecreatefromjpeg('$file')"

, '424D' => "imagecreatefrombmp('$file')"

, '89504E' => "imagecreatefrompng('$file')"

);

$fd = fopen( $file, "rb" );

$data = fread( $fd, 3 );

$data = str2hex( $data );

if ( array_key_exists( $data, $arr ) ) {

return $arr[$data];

} elseif ( array_key_exists( substr($data, 0, 4), $arr ) ) {

return $arr[substr($data, 0, 4)];

} else {

return false;

}

}

function str2hex( $str ) {

$ret = "";

for( $i = 0; $i < strlen( $str ) ; $i++ ) {

$ret .= ord($str[$i]) >= 16 ? strval( dechex( ord($str[$i]) ) )

: '0'. strval( dechex( ord($str[$i]) ) );

}

return strtoupper( $ret );

}

// BMP 创建函数 php本身无

function imagecreatefrombmp($filename)

{

if (! $f1 = fopen($filename,"rb")) return FALSE;

$FILE = unpack("vfile_type/Vfile_size/Vreserved/Vbitmap_offset", fread($f1,14));

if ($FILE['file_type'] != 19778) return FALSE;

$BMP = unpack('Vheader_size/Vwidth/Vheight/vplanes/vbits_per_pixel'.

'/Vcompression/Vsize_bitmap/Vhoriz_resolution'.

'/Vvert_resolution/Vcolors_used/Vcolors_important', fread($f1,40));

$BMP['colors'] = pow(2,$BMP['bits_per_pixel']);

if ($BMP['size_bitmap'] == 0) $BMP['size_bitmap'] = $FILE['file_size'] - $FILE['bitmap_offset'];

$BMP['bytes_per_pixel'] = $BMP['bits_per_pixel']/8;

$BMP['bytes_per_pixel2'] = ceil($BMP['bytes_per_pixel']);

$BMP['decal'] = ($BMP['width']*$BMP['bytes_per_pixel']/4);

$BMP['decal'] -= floor($BMP['width']*$BMP['bytes_per_pixel']/4);

$BMP['decal'] = 4-(4*$BMP['decal']);

if ($BMP['decal'] == 4) $BMP['decal'] = 0;

$PALETTE = array();

if ($BMP['colors'] < 16777216)

{

$PALETTE = unpack('V'.$BMP['colors'], fread($f1,$BMP['colors']*4));

}

$IMG = fread($f1,$BMP['size_bitmap']);

$VIDE = chr(0);

$res = imagecreatetruecolor($BMP['width'],$BMP['height']);

$P = 0;

$Y = $BMP['height']-1;

while ($Y >= 0)

{

$X=0;

while ($X < $BMP['width'])

{

if ($BMP['bits_per_pixel'] == 24)

$COLOR = unpack("V",substr($IMG,$P,3).$VIDE);

elseif ($BMP['bits_per_pixel'] == 16)

{ //开源代码phpfensi.com

$COLOR = unpack("n",substr($IMG,$P,2));

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 8)

{

$COLOR = unpack("n",$VIDE.substr($IMG,$P,1));

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 4)

{

$COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1));

if (($P*2)%2 == 0) $COLOR[1] = ($COLOR[1] >> 4) ; else $COLOR[1] = ($COLOR[1] & 0x0F);

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

elseif ($BMP['bits_per_pixel'] == 1)

{

$COLOR = unpack("n",$VIDE.substr($IMG,floor($P),1));

if (($P*8)%8 == 0) $COLOR[1] = $COLOR[1] >>7;

elseif (($P*8)%8 == 1) $COLOR[1] = ($COLOR[1] & 0x40)>>6;

elseif (($P*8)%8 == 2) $COLOR[1] = ($COLOR[1] & 0x20)>>5;

elseif (($P*8)%8 == 3) $COLOR[1] = ($COLOR[1] & 0x10)>>4;

elseif (($P*8)%8 == 4) $COLOR[1] = ($COLOR[1] & 0x8)>>3;

elseif (($P*8)%8 == 5) $COLOR[1] = ($COLOR[1] & 0x4)>>2;

elseif (($P*8)%8 == 6) $COLOR[1] = ($COLOR[1] & 0x2)>>1;

elseif (($P*8)%8 == 7) $COLOR[1] = ($COLOR[1] & 0x1);

$COLOR[1] = $PALETTE[$COLOR[1]+1];

}

else

return FALSE;

imagesetpixel($res,$X,$Y,$COLOR[1]);

$X++;

$P += $BMP['bytes_per_pixel'];

}

$Y--;

$P+=$BMP['decal'];

}

fclose($f1);

return $res;

}

// BMP 保存函数，php本身无

function imagebmp ($im, $fn = false)

{

if (!$im) return false;

if ($fn === false) $fn = 'php://output';

$f = fopen ($fn, "w");

if (!$f) return false;

$biWidth = imagesx ($im);

$biHeight = imagesy ($im);

$biBPLine = $biWidth * 3;

$biStride = ($biBPLine + 3) & ~3;

$biSizeImage = $biStride * $biHeight;

$bfOffBits = 54;

$bfSize = $bfOffBits + $biSizeImage;

fwrite ($f, 'BM', 2);

fwrite ($f, pack ('VvvV', $bfSize, 0, 0, $bfOffBits));

fwrite ($f, pack ('VVVvvVVVVVV', 40, $biWidth, $biHeight, 1, 24, 0, $biSizeImage, 0, 0, 0, 0));

$numpad = $biStride - $biBPLine;

for ($y = $biHeight - 1; $y >= 0; --$y)

{

for ($x = 0; $x < $biWidth; ++$x)

{

$col = imagecolorat ($im, $x, $y);

fwrite ($f, pack ('V', $col), 3);

}

for ($i = 0; $i < $numpad; ++$i)

fwrite ($f, pack ('C', 0));

}

fclose ($f);

return true;

}

?>