TGA parser

<?php

/****************************************************************************
 * based on:                                                                *
 * http://tfcduke.developpez.com/tutoriel/format/tga/fichiers/tga_specs.pdf *
 ****************************************************************************/

define( "TGA_COLOR_MAP_TYPE_NO_COLOR_MAP", 0 );
define( "TGA_COLOR_MAP_TYPE_COLOR_MAP", 1 );

define( "TGA_IMAGE_TYPE_NONE_DATA", 0 );
define( "TGA_IMAGE_TYPE_COLOR_MAPPED", 1 );
define( "TGA_IMAGE_TYPE_TRUE_COLOR", 2 );
define( "TGA_IMAGE_TYPE_BLACK_AND_WHITE", 3 );
define( "TGA_IMAGE_TYPE_ENCODED_COLOR_MAPPED", 9 );
define( "TGA_IMAGE_TYPE_ENCODED_TRUE_COLOR", 10 );
define( "TGA_IMAGE_TYPE_ENCODED_BLACK_AND_WHITE", 11 );

define( "TGA_IMAGE_ORIGIN_BOTTOM_LEFT", 0x0 );
define( "TGA_IMAGE_ORIGIN_BOTTOM_RIGHT", 0x10 );
define( "TGA_IMAGE_ORIGIN_TOP_LEFT", 0x20 );
define( "TGA_IMAGE_ORIGIN_TOP_RIGHT", 0x30 );

class TGA {
    private $imageHandle;
    private $width;
    private $height;
    private $imageHeader;
    private $imageId;
    private $colorMap;
    private $imageData;
    private $imageFooter;

    public function __construct( $imageHandle, $width = -1, $height = -1 ) {
        $this->imageHandle = $imageHandle;
        $this->width = $width;
        $this->height = $height;
    }

    public function parse() {
        fseek( $this->imageHandle, 0 );

        $this->imageHeader["IdentSize"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );
        $this->imageHeader["ColorMapType"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );
        $this->imageHeader["ImageType"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );

        $this->imageHeader["ColorMapStart"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["ColorMapLength"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["ColorMapBits"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );

        $this->imageHeader["XStart"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["YStart"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["Width"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["Height"] = implode( unpack( "S", fread( $this->imageHandle, 2 ) ) );
        $this->imageHeader["Bits"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );
        $this->imageHeader["Descriptor"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );

        $this->imageHeader["ImageOrigin"] = $this->imageHeader["Descriptor"] & 0x30;
        $this->imageHeader["AttributeBits"] = $this->imageHeader["Descriptor"] & 0x0f;

        if ( $this->imageHeader["IdentSize"] > 0 ) {
            $this->imageId = implode( unpack( "a{$this->imageHeader["IdentSize"]}", fread( $this->imageHandle, $this->imageHeader["IdentSize"] ) ) );
        }

        if ( $this->imageHeader["ColorMapType"] != 0 ) {
            throw new Exception( "tga_not_implemented_colormap", $this->imageHeader["ColorMapType"] );
        }

        fseek( $this->imageHandle, -26, SEEK_END );

        $this->parseFooter();

        fseek( $this->imageHandle, 18 + $this->imageHeader["IdentSize"] );

        switch ( $this->imageHeader["ImageType"] ) {
            case TGA_IMAGE_TYPE_TRUE_COLOR : {
                $this->createImageTrueColor();

                break;
            }
            default : {
                throw new Exception( "tga_not_implemented_image_type", $this->imageHeader["ImageType"] );
            }
        }
    }

    public function close() {
        fclose( $this->imageHandle );
    }

    public function getHeader() {
        return $this->imageHeader;
    }

    public function getFooter() {
        return $this->imageFooter;
    }

    private function parseFooter() {
        $this->imageFooter = array();
        $this->imageFooter["extensionOffset"] = implode( unpack( "L", fread( $this->imageHandle, 4 ) ) );
        $this->imageFooter["developerOffset"] = implode( unpack( "L", fread( $this->imageHandle, 4 ) ) );
        $this->imageFooter["signature"] = implode( unpack( "a16", fread( $this->imageHandle, 16 ) ) );
        $this->imageFooter["dot"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );
        $this->imageFooter["null"] = implode( unpack( "C", fread( $this->imageHandle, 1 ) ) );
    }

    private function createImageTrueColor() {
        if ( $this->width != -1 ) {
            $width = $this->width;
        } else {
            $width = $this->imageHeader["Width"];
        }

        if ( $this->height != -1 ) {
            $height = $this->height;
        } else {
            $height = $this->imageHeader["Height"];
        }

        $this->imageData = imagecreatetruecolor( $width, $height );

        switch ( $this->imageHeader["Bits"] ) {
            case 24 : {
                $pixelDataBytes = $this->imageHeader["Width"] * $this->imageHeader["Height"] * 3;
                $pixelData = unpack( "C{$pixelDataBytes}", fread( $this->imageHandle, $pixelDataBytes ) );

                break;
            }
            default : {
                throw new Exception( "tga_not_implemented_color_depth", $this->imageHeader["Bits"] );
            }
        }

        $horizontalBorder = floor( ( $this->imageHeader["Width"] - $width ) / 2 );
        $verticalBorder = floor( ( $this->imageHeader["Height"] - $height ) / 2 );

        for ( $y = $verticalBorder; $y < $this->imageHeader["Height"] - $verticalBorder; $y++ ) {
            for ( $x = $horizontalBorder; $x < $this->imageHeader["Width"] - $horizontalBorder; $x++ ) {
                $pixelRed = $pixelData[( $y * $this->imageHeader["Width"] + $x ) * 3 + 3];
                $pixelGreen = $pixelData[( $y * $this->imageHeader["Width"] + $x ) * 3 + 2];
                $pixelBlue = $pixelData[( $y * $this->imageHeader["Width"] + $x ) * 3 + 1];

                if ( ( $pixelRed != 0 ) && ( $pixelGreen != 0 ) && ( $pixelBlue != 0 ) ) {
                    $color = imagecolorallocate ( $this->imageData, $pixelRed, $pixelGreen, $pixelBlue );

                    switch ( $this->imageHeader["ImageOrigin"] ) {
                        case TGA_IMAGE_ORIGIN_BOTTOM_LEFT : {
                            imagesetpixel( $this->imageData, $x - $horizontalBorder, $this->imageHeader["Height"] - $y - $verticalBorder, $color );
                            break;
                        }
                        case TGA_IMAGE_ORIGIN_BOTTOM_RIGHT : {
                            imagesetpixel( $this->imageData, $this->imageHeader["Width"] - $x - $horizontalBorder, $this->imageHeader["Height"] - $y - $verticalBorder, $color );
                            break;
                        }
                        case TGA_IMAGE_ORIGIN_TOP_LEFT : {
                            imagesetpixel( $this->imageData, $x - $horizontalBorder, $y - $verticalBorder, $color );
                            break;
                        }
                        case TGA_IMAGE_ORIGIN_TOP_RIGHT : {
                            imagesetpixel( $this->imageData, $this->imageHeader["Width"] - $x - $horizontalBorder, $y - $verticalBorder, $color );
                            break;
                        }
                    }
                }
            }
        }
    }

    public function getImage() {
        return $this->imageData;
    }
}

?>