php generates image thumbnails (supports: JPEG, GIT, PNG, BMP)

class Thumb
{

 public function create($srcPath, $dstPath, $dstWidth, $dstHeight)
 {
 if (!file_exists($srcPath)) {
 return false;
 }

 @$srcSize = getimagesize($srcPath);
 if (empty($srcSize)) {
 return false;
 }

 $srcWith = intval($srcSize[0]);
 $srcHeight = intval($srcSize [1]);

 //If the size of the original image is larger than the size of the specified thumbnail, generate a thumbnail, otherwise copy the original file
 if ($srcWith <= $dstWidth && $srcHeight <= $dstHeight) {
 return copy($srcPath, $dstPath);
 }

 //Read the original image resource
 @$srcImage = imagecreatefromjpeg($srcPath);
 if (empty($srcImage)) {
 @$srcImage = imagecreatefromgif( $srcPath);
 }
 if (empty($srcImage)) {
 @$srcImage = imagecreatefrompng($srcPath);
 }
 if (empty($srcImage)) {
 @$srcImage = $this->_imageCreateFromBMP ($srcPath);
 }

 if (empty($srcImage)) {
 return false;
 }

 //Get the size of the thumbnail and generate a new image accordingly
 $dstSize = $this-> _getDstSize(
 $srcWith, $srcHeight, $dstWidth, $dstHeight
 );

 @$dstImage = imagecreatetruecolor(
 $dstSize['width'], $dstSize['height']
 );

 @imagecopyresampled(
 $dstImage, $srcImage , 0, 0, 0, 0,
 $dstSize['width'], $dstSize['height'],
 $srcWith, $srcHeight
 );

 return @imagepng($srcPath, $ dstPath);
 }

 private function _imageCreateFromBMP($filePath)
 {
 $fileHandle = fopen($filePath, 'rb');
 if (empty($fileHandle)) {
 return false;
 }

 $file = unpack(
 'vfile_type/Vfile_size/Vreserved/Vbitmap_offset',
 fread($fileHandle, 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($fileHandle, 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' . $bmp['colors '],
 fread($fileHandle, $bmp['colors'] * 4)
 );
 }
 $image = fread($fileHandle, $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) {
 $color = unpack(' V', substr($image, $p, 3) . $vide);
 } else if ($bmp['bits_per_pixel'] == 16) {
 $color = unpack('n', substr($image, $p, 2));
 $color[1] = $palette[$color[1]+1];
 } else if ($bmp['bits_per_pixel'] == 8) {
 $color = unpack(' n', $vide . substr ($image, $p, 1));
 $color[1] = $palette[$color[1]+1];
 } else if ($bmp['bits_per_pixel'] = =4) {
 $color = unpack('n', $vide . substr($image, 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];
 }else if ($bmp['bits_per_pixel'] == 1) {
                    $color = unpack('n', $vide . substr($image, floor($p), 1));
                    switch (($p * 8) % 8) {
                        case  0:
                            $color[1] = ($color[1] >> 7);
                            break;
                        case  1:
                            $color[1] = ($color[1] & 0x40) >> 6;
                            break;
                        case  2:
                            $color[1] = ($color[1] & 0x20) >> 5;
                            break;
                        case  3:
                            $color[1] = ($color[1] & 0x10) >> 4;
                            break;
                        case  4:
                            $color[1] = ($color[1] & 0x8) >> 3;
                            break;
                        case  5:
                            $color[1] = ($color[1] & 0x4) >> 2;
                            break;
                        case  6:
                            $color[1] = ($color[1] & 0x2) >> 1;
                            break;
                        case  7:
                            $color[1] = ($color[1] & 0x1);
                            break;
                     }
                     $color[1] = $palette[$color[1] + 1];
                } else {
                    return false;
                }
                imagesetpixel($res, $x, $y, $color[1]);
                $x++;
                $p += $bmp['bytes_per_pixel'];
            }
            $y--;
            $p += $bmp['decal'];
        }
        fclose($fileHandle);
        return $res;
    }

    private function _getDstSize($srcWith, $srcHeight, $dstWidth, $dstHeight)
    {
        $size = array('width' => $srcWith, 'height' => $srcHeight);
        if ($dstWidth > 0 && $dstHeight > 0) {
            if ($srcWith > 0 && $srcHeight > 0) {
                if ($srcWith / $srcHeight >= $dstWidth / $dstHeight) {
                    if ($srcWith > $dstWidth) {
                        $size['width']  = $dstWidth;
                        $size['height'] = $srcHeight * $dstWidth / $srcWith;
                    }
                } else {
                    if ($srcHeight > $dstHeight) {
                        $size['width']  = $srcWith * $dstHeight / $srcHeight;
                        $size['height'] = $dstHeight;
                    }
                }
            }
        }
        return $size;
    }
}

JPEG, php, GIT