PHP缩略图等比例无损压缩，可填充空白区域补充色

<?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)
{
$COLOR = unpack("n",substr($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;
}
?>