PHP支持BMP图像函数

在php里的库对bmp格式的图像是不支持的。PHP对于gif、jpg、png等图像文件都有ImageCreateFromGIF、imagecreatefromjpeg和ImageCreateFromPNG这些函数支持,下面这个函数就是用于实现类似这些函数的功能的。

function ImageCreateFromBMP( $filename ) { 
    // Ouverture du fichier en mode binaire 
    if ( ! $f1 = @fopen ($filename, "rb")) return FALSE ; 
    // 1 : Chargement des ent?tes FICHIER 
    $FILE = unpack ( "vfile_type/Vfile_size/Vreserved/Vbitmap_offset" , fread($f1 ,14)); 
    if ( $FILE ['file_type'] != 19778 ) return FALSE ; 
    // 2 : Chargement des ent?tes BMP 
    $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 ; 
    // 3 : Chargement des couleurs de la palette 
    $PALETTE = array (); 
    if ( $BMP ['colors'] < 16777216 ){ 
        $PALETTE = unpack ( 'V' . $BMP ['colors'] , fread ( $f1 , $BMP ['colors'] * 4 )); 
    } 
    // 4 : Cr?ation de l'image 
    $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']; 
    } 
    // Fermeture du fichier 
    fclose ( $f1 ); 
    return $res ; 
} 

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