PHP imagecreatefrombmp 从BMP文件或URL新建一图像

大家都知道php GD库可方便的从URL新建一图像, GD中有imagecreatefromjpeg()，imagecreatefromPNG()....等之类的FUNCTION 可有时从URL中读取的切BMP图像而 可恨的是 GD2中切偏偏没有imageCreateFromBMP() 虽然有imagecreatefromWBMP() 但还是相差还是很远！
用下面FUNCTION可以方便解决


代码如下:

function imagecreatefrombmp($file)
{
global $CurrentBit, $echoMode;
$f=fopen($file,"r");
$Header=fread($f,2);
if($Header=="BM")
{
$Size=freaddword($f);
$Reserved1=freadword($f);
$Reserved2=freadword($f);
$FirstByteOfImage=freaddword($f);
$SizeBITMAPINFOHEADER=freaddword($f);
$Width=freaddword($f);
$Height=freaddword($f);
$biPlanes=freadword($f);
$biBitCount=freadword($f);
$RLECompression=freaddword($f);
$WidthxHeight=freaddword($f);
$biXPelsPerMeter=freaddword($f);
$biYPelsPerMeter=freaddword($f);
$NumberOfPalettesUsed=freaddword($f);
$NumberOfImportantColors=freaddword($f);
if($biBitCount<24)
{
$img=imagecreate($Width,$Height);
$Colors=pow(2,$biBitCount);
for($p=0;$p<$Colors;$p++)
{
$B=freadbyte($f);
$G=freadbyte($f);
$R=freadbyte($f);
$Reserved=freadbyte($f);
$Palette[]=imagecolorallocate($img,$R,$G,$B);
}
if($RLECompression==0)
{
$Zbytek=(4-ceil(($Width/(8/$biBitCount)))%4)%4;
for($y=$Height-1;$y>=0;$y--)
{
$CurrentBit=0;
for($x=0;$x<$Width;$x++)
{
$C=freadbits($f,$biBitCount);
imagesetpixel($img,$x,$y,$Palette[$C]);
}
if($CurrentBit!=0) {freadbyte($f);}
for($g=0;$g<$Zbytek;$g++)
freadbyte($f);
}
}
}
if($RLECompression==1) //$BI_RLE8
{
$y=$Height;
$pocetb=0;
while(true)
{
$y--;
$prefix=freadbyte($f);
$suffix=freadbyte($f);
$pocetb+=2;
$echoit=false;
if($echoit)echo "Prefix: $prefix Suffix: $suffix<BR>";
if(($prefix==0)and($suffix==1)) break;
if(feof($f)) break;
while(!(($prefix==0)and($suffix==0)))
{
if($prefix==0)
{
$pocet=$suffix;
$Data.=fread($f,$pocet);
$pocetb+=$pocet;
if($pocetb%2==1) {freadbyte($f); $pocetb++;}
}
if($prefix>0)
{
$pocet=$prefix;
for($r=0;$r<$pocet;$r++)
$Data.=chr($suffix);
}
$prefix=freadbyte($f);
$suffix=freadbyte($f);
$pocetb+=2;
if($echoit) echo "Prefix: $prefix Suffix: $suffix<BR>";
}
for($x=0;$x<strlen($Data);$x++)
{
imagesetpixel($img,$x,$y,$Palette[ord($Data[$x])]);
}
$Data="";
}
}
if($RLECompression==2) //$BI_RLE4
{
$y=$Height;
$pocetb=0;
/*while(!feof($f))
echo freadbyte($f)."_".freadbyte($f)."<BR>";*/
while(true)
{
//break;
$y--;
$prefix=freadbyte($f);
$suffix=freadbyte($f);
$pocetb+=2;
$echoit=false;
if($echoit)echo "Prefix: $prefix Suffix: $suffix<BR>";
if(($prefix==0)and($suffix==1)) break;
if(feof($f)) break;
while(!(($prefix==0)and($suffix==0)))
{
if($prefix==0)
{
$pocet=$suffix;
$CurrentBit=0;
for($h=0;$h<$pocet;$h++)
$Data.=chr(freadbits($f,4));
if($CurrentBit!=0) freadbits($f,4);
$pocetb+=ceil(($pocet/2));
if($pocetb%2==1) {freadbyte($f); $pocetb++;}
}
if($prefix>0)
{
$pocet=$prefix;
$i=0;
for($r=0;$r<$pocet;$r++)
{
if($i%2==0)
{
$Data.=chr($suffix%16);
}
else
{
$Data.=chr(floor($suffix/16));
}
$i++;
}
}
$prefix=freadbyte($f);
$suffix=freadbyte($f);
$pocetb+=2;
if($echoit) echo "Prefix: $prefix Suffix: $suffix<BR>";
}
for($x=0;$x<strlen($Data);$x++)
{
imagesetpixel($img,$x,$y,$Palette[ord($Data[$x])]);
}
$Data="";
}
}
if($biBitCount==24)
{
$img=imagecreatetruecolor($Width,$Height);
$Zbytek=$Width%4;
for($y=$Height-1;$y>=0;$y--)
{
for($x=0;$x<$Width;$x++)
{
$B=freadbyte($f);
$G=freadbyte($f);
$R=freadbyte($f);
$color=imagecolorexact($img,$R,$G,$B);
if($color==-1) $color=imagecolorallocate($img,$R,$G,$B);
imagesetpixel($img,$x,$y,$color);
}
for($z=0;$z<$Zbytek;$z++)
freadbyte($f);
}
}
return $img;
}
fclose($f);
}
function freadbyte($f)
{
return ord(fread($f,1));
}
function freadword($f)
{
$b1=freadbyte($f);
$b2=freadbyte($f);
return $b2*256+$b1;
}
function freaddword($f)
{
$b1=freadword($f);
$b2=freadword($f);
return $b2*65536+$b1;
}