PHP缩略图等比例无损压缩，可填充空白区域补充色

复制代码 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)
{
$COLOR = unpack("n",substr($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;
}
?>