phpthumb_functions::GD2ICOstring PHP Method

    public static function GD2ICOstring(&$gd_image_array)
    {
        foreach ($gd_image_array as $key => $gd_image) {
            $ImageWidths[$key] = ImageSX($gd_image);
            $ImageHeights[$key] = ImageSY($gd_image);
            $bpp[$key] = ImageIsTrueColor($gd_image) ? 32 : 24;
            $totalcolors[$key] = ImageColorsTotal($gd_image);
            $icXOR[$key] = '';
            for ($y = $ImageHeights[$key] - 1; $y >= 0; $y--) {
                for ($x = 0; $x < $ImageWidths[$key]; $x++) {
                    $argb = phpthumb_functions::GetPixelColor($gd_image, $x, $y);
                    $a = round(255 * ((127 - $argb['alpha']) / 127));
                    $r = $argb['red'];
                    $g = $argb['green'];
                    $b = $argb['blue'];
                    if ($bpp[$key] == 32) {
                        $icXOR[$key] .= chr($b) . chr($g) . chr($r) . chr($a);
                    } elseif ($bpp[$key] == 24) {
                        $icXOR[$key] .= chr($b) . chr($g) . chr($r);
                    }
                    if ($a < 128) {
                        @($icANDmask[$key][$y] .= '1');
                    } else {
                        @($icANDmask[$key][$y] .= '0');
                    }
                }
                // mask bits are 32-bit aligned per scanline
                while (strlen($icANDmask[$key][$y]) % 32) {
                    $icANDmask[$key][$y] .= '0';
                }
            }
            $icAND[$key] = '';
            foreach ($icANDmask[$key] as $y => $scanlinemaskbits) {
                for ($i = 0; $i < strlen($scanlinemaskbits); $i += 8) {
                    $icAND[$key] .= chr(bindec(str_pad(substr($scanlinemaskbits, $i, 8), 8, '0', STR_PAD_LEFT)));
                }
            }
        }
        foreach ($gd_image_array as $key => $gd_image) {
            $biSizeImage = $ImageWidths[$key] * $ImageHeights[$key] * ($bpp[$key] / 8);
            // BITMAPINFOHEADER - 40 bytes
            $BitmapInfoHeader[$key] = '';
            $BitmapInfoHeader[$key] .= "(";
            // DWORD  biSize;
            $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($ImageWidths[$key], 4);
            // LONG   biWidth;
            // The biHeight member specifies the combined
            // height of the XOR and AND masks.
            $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($ImageHeights[$key] * 2, 4);
            // LONG   biHeight;
            $BitmapInfoHeader[$key] .= "
";
            // WORD   biPlanes;
            $BitmapInfoHeader[$key] .= chr($bpp[$key]) . "";
            // wBitCount;
            $BitmapInfoHeader[$key] .= "";
            // DWORD  biCompression;
            $BitmapInfoHeader[$key] .= phpthumb_functions::LittleEndian2String($biSizeImage, 4);
            // DWORD  biSizeImage;
            $BitmapInfoHeader[$key] .= "";
            // LONG   biXPelsPerMeter;
            $BitmapInfoHeader[$key] .= "";
            // LONG   biYPelsPerMeter;
            $BitmapInfoHeader[$key] .= "";
            // DWORD  biClrUsed;
            $BitmapInfoHeader[$key] .= "";
            // DWORD  biClrImportant;
        }
        $icondata = "";
        // idReserved;   // Reserved (must be 0)
        $icondata .= "
";
        // idType;	   // Resource Type (1 for icons)
        $icondata .= phpthumb_functions::LittleEndian2String(count($gd_image_array), 2);
        // idCount;	  // How many images?
        $dwImageOffset = 6 + count($gd_image_array) * 16;
        foreach ($gd_image_array as $key => $gd_image) {
            // ICONDIRENTRY   idEntries[1]; // An entry for each image (idCount of 'em)
            $icondata .= chr($ImageWidths[$key]);
            // bWidth;		  // Width, in pixels, of the image
            $icondata .= chr($ImageHeights[$key]);
            // bHeight;		 // Height, in pixels, of the image
            $icondata .= chr($totalcolors[$key]);
            // bColorCount;	 // Number of colors in image (0 if >=8bpp)
            $icondata .= "";
            // bReserved;	   // Reserved ( must be 0)
            $icondata .= "
";
            // wPlanes;		 // Color Planes
            $icondata .= chr($bpp[$key]) . "";
            // wBitCount;	   // Bits per pixel
            $dwBytesInRes = 40 + strlen($icXOR[$key]) + strlen($icAND[$key]);
            $icondata .= phpthumb_functions::LittleEndian2String($dwBytesInRes, 4);
            // dwBytesInRes;	// How many bytes in this resource?
            $icondata .= phpthumb_functions::LittleEndian2String($dwImageOffset, 4);
            // dwImageOffset;   // Where in the file is this image?
            $dwImageOffset += strlen($BitmapInfoHeader[$key]);
            $dwImageOffset += strlen($icXOR[$key]);
            $dwImageOffset += strlen($icAND[$key]);
        }
        foreach ($gd_image_array as $key => $gd_image) {
            $icondata .= $BitmapInfoHeader[$key];
            $icondata .= $icXOR[$key];
            $icondata .= $icAND[$key];
        }
        return $icondata;
    }

/**
 * Crée un fichier-image au format ICO
 *
 * Utilise les fonctions de la classe phpthumb_functions.
 *
 * @uses phpthumb_functions::GD2ICOstring()
 *
 * @param ressource $img
 *     Une ressource de type Image GD.
 * @param string $fichier
 *     Le path vers l'image (ex : local/cache-vignettes/L180xH51/image.jpg).
 * @return bool
 *     true si le fichier a bien été créé ; false sinon.
 */
function _image_imageico($img, $fichier)
{
    $gd_image_array = array($img);
    return ecrire_fichier($fichier, phpthumb_functions::GD2ICOstring($gd_image_array));
}