<?php
/**
 * @package dompdf
 * @link    http://dompdf.github.com/
 * @author  Benj Carson <benjcarson@digitaljunkies.ca>
 * @author  Fabien Ménager <fabien.menager@gmail.com>
 * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
 */
namespace Dompdf\Adapter;

use Dompdf\Canvas;
use Dompdf\Dompdf;
use Dompdf\Image\Cache;
use Dompdf\Helpers;

/**
 * Image rendering interface
 *
 * Renders to an image format supported by GD (jpeg, gif, png, xpm).
 * Not super-useful day-to-day but handy nonetheless
 *
 * @package dompdf
 */
class GD implements Canvas
{
    /**
     * @var Dompdf
     */
    protected $_dompdf;

    /**
     * Resource handle for the image
     *
     * @var resource
     */
    protected $_img;

    /**
     * Resource handle for the image
     *
     * @var resource[]
     */
    protected $_imgs;

    /**
     * Apparent canvas width in pixels
     *
     * @var int
     */
    protected $_width;

    /**
     * Apparent canvas height in pixels
     *
     * @var int
     */
    protected $_height;

    /**
     * Actual image width in pixels
     *
     * @var int
     */
    protected $_actual_width;

    /**
     * Actual image height in pixels
     *
     * @var int
     */
    protected $_actual_height;

    /**
     * Current page number
     *
     * @var int
     */
    protected $_page_number;

    /**
     * Total number of pages
     *
     * @var int
     */
    protected $_page_count;

    /**
     * Image antialias factor
     *
     * @var float
     */
    protected $_aa_factor;

    /**
     * Allocated colors
     *
     * @var array
     */
    protected $_colors;

    /**
     * Background color
     *
     * @var int
     */
    protected $_bg_color;

    /**
     * Background color array
     *
     * @var int
     */
    protected $_bg_color_array;

    /**
     * Actual DPI
     *
     * @var int
     */
    protected $dpi;

    /**
     * Amount to scale font sizes
     *
     * Font sizes are 72 DPI, GD internally uses 96. Scale them proportionally.
     * 72 / 96 = 0.75.
     *
     * @var float
     */
    const FONT_SCALE = 0.75;

    /**
     * Class constructor
     *
     * @param mixed $size The size of image to create: array(x1,y1,x2,y2) or "letter", "legal", etc.
     * @param string $orientation The orientation of the document (either 'landscape' or 'portrait')
     * @param Dompdf $dompdf
     * @param float $aa_factor Anti-aliasing factor, 1 for no AA
     * @param array $bg_color Image background color: array(r,g,b,a), 0 <= r,g,b,a <= 1
     */
    public function __construct($size = 'letter', $orientation = "portrait", Dompdf $dompdf, $aa_factor = 1.0, $bg_color = [1, 1, 1, 0])
    {

        if (!is_array($size)) {
            $size = strtolower($size);

            if (isset(CPDF::$PAPER_SIZES[$size])) {
                $size = CPDF::$PAPER_SIZES[$size];
            } else {
                $size = CPDF::$PAPER_SIZES["letter"];
            }
        }

        if (strtolower($orientation) === "landscape") {
            list($size[2], $size[3]) = [$size[3], $size[2]];
        }

        $this->_dompdf = $dompdf;

        $this->dpi = $this->get_dompdf()->getOptions()->getDpi();

        if ($aa_factor < 1) {
            $aa_factor = 1;
        }

        $this->_aa_factor = $aa_factor;

        $size[2] *= $aa_factor;
        $size[3] *= $aa_factor;

        $this->_width = $size[2] - $size[0];
        $this->_height = $size[3] - $size[1];

        $this->_actual_width = $this->_upscale($this->_width);
        $this->_actual_height = $this->_upscale($this->_height);

        $this->_page_number = $this->_page_count = 1;
        $this->_page_text = [];

        if (is_null($bg_color) || !is_array($bg_color)) {
            // Pure white bg
            $bg_color = [1, 1, 1, 0];
        }

        $this->_bg_color_array = $bg_color;

        $this->new_page();
    }

    /**
     * @return Dompdf
     */
    public function get_dompdf()
    {
        return $this->_dompdf;
    }

    /**
     * Return the GF image resource
     *
     * @return resource
     */
    public function get_image()
    {
        return $this->_img;
    }

    /**
     * Return the image's width in pixels
     *
     * @return float
     */
    public function get_width()
    {
        return $this->_width / $this->_aa_factor;
    }

    /**
     * Return the image's height in pixels
     *
     * @return float
     */
    public function get_height()
    {
        return $this->_height / $this->_aa_factor;
    }

    /**
     * Returns the current page number
     * @return int
     */
    public function get_page_number()
    {
        return $this->_page_number;
    }

    /**
     * Returns the total number of pages in the document
     * @return int
     */
    public function get_page_count()
    {
        return $this->_page_count;
    }

    /**
     * Sets the current page number
     *
     * @param int $num
     */
    public function set_page_number($num)
    {
        $this->_page_number = $num;
    }

    /**
     * Sets the page count
     *
     * @param int $count
     */
    public function set_page_count($count)
    {
        $this->_page_count = $count;
    }

    /**
     * Sets the opacity
     *
     * @param $opacity
     * @param $mode
     */
    public function set_opacity($opacity, $mode = "Normal")
    {
        // FIXME
    }

    /**
     * Allocate a new color.  Allocate with GD as needed and store
     * previously allocated colors in $this->_colors.
     *
     * @param array $color The new current color
     * @return int           The allocated color
     */
    protected function _allocate_color($color)
    {
        $a = isset($color["alpha"]) ? $color["alpha"] : 1;

        if (isset($color["c"])) {
            $color = Helpers::cmyk_to_rgb($color);
        }

        list($r, $g, $b) = $color;

        $r *= 255;
        $g *= 255;
        $b *= 255;
        $a = 127 - ($a * 127);

        // Clip values
        $r = $r > 255 ? 255 : $r;
        $g = $g > 255 ? 255 : $g;
        $b = $b > 255 ? 255 : $b;
        $a = $a > 127 ? 127 : $a;

        $r = $r < 0 ? 0 : $r;
        $g = $g < 0 ? 0 : $g;
        $b = $b < 0 ? 0 : $b;
        $a = $a < 0 ? 0 : $a;

        $key = sprintf("#%02X%02X%02X%02X", $r, $g, $b, $a);

        if (isset($this->_colors[$key])) {
            return $this->_colors[$key];
        }

        if ($a != 0) {
            $this->_colors[$key] = imagecolorallocatealpha($this->get_image(), $r, $g, $b, $a);
        } else {
            $this->_colors[$key] = imagecolorallocate($this->get_image(), $r, $g, $b);
        }

        return $this->_colors[$key];
    }

    /**
     * Scales value up to the current canvas DPI from 72 DPI
     *
     * @param float $length
     * @return float
     */
    protected function _upscale($length)
    {
        return ($length * $this->dpi) / 72 * $this->_aa_factor;
    }

    /**
     * Scales value down from the current canvas DPI to 72 DPI
     *
     * @param float $length
     * @return float
     */
    protected function _downscale($length)
    {
        return ($length / $this->dpi * 72) / $this->_aa_factor;
    }

    /**
     * Draws a line from x1,y1 to x2,y2
     *
     * See {@link Style::munge_color()} for the format of the color array.
     * See {@link Cpdf::setLineStyle()} for a description of the format of the
     * $style parameter (aka dash).
     *
     * @param float $x1
     * @param float $y1
     * @param float $x2
     * @param float $y2
     * @param array $color
     * @param float $width
     * @param array $style
     */
    public function line($x1, $y1, $x2, $y2, $color, $width, $style = null)
    {

        // Scale by the AA factor and DPI
        $x1 = $this->_upscale($x1);
        $y1 = $this->_upscale($y1);
        $x2 = $this->_upscale($x2);
        $y2 = $this->_upscale($y2);
        $width = $this->_upscale($width);

        $c = $this->_allocate_color($color);

        // Convert the style array if required
        if (is_array($style) && count($style) > 0) {
            $gd_style = [];

            if (count($style) == 1) {
                for ($i = 0; $i < $style[0] * $this->_aa_factor; $i++) {
                    $gd_style[] = $c;
                }

                for ($i = 0; $i < $style[0] * $this->_aa_factor; $i++) {
                    $gd_style[] = $this->_bg_color;
                }
            } else {
                $i = 0;
                foreach ($style as $length) {
                    if ($i % 2 == 0) {
                        // 'On' pattern
                        for ($i = 0; $i < $style[0] * $this->_aa_factor; $i++) {
                            $gd_style[] = $c;
                        }

                    } else {
                        // Off pattern
                        for ($i = 0; $i < $style[0] * $this->_aa_factor; $i++) {
                            $gd_style[] = $this->_bg_color;
                        }
                    }
                    $i++;
                }
            }

            if (!empty($gd_style)) {
                imagesetstyle($this->get_image(), $gd_style);
                $c = IMG_COLOR_STYLED;
            }
        }

        imagesetthickness($this->get_image(), $width);

        imageline($this->get_image(), $x1, $y1, $x2, $y2, $c);
    }

    /**
     * @param float $x1
     * @param float $y1
     * @param float $r1
     * @param float $r2
     * @param float $astart
     * @param float $aend
     * @param array $color
     * @param float $width
     * @param array $style
     */
    public function arc($x1, $y1, $r1, $r2, $astart, $aend, $color, $width, $style = [])
    {
        // @todo
    }

    /**
     * Draws a rectangle at x1,y1 with width w and height h
     *
     * See {@link Style::munge_color()} for the format of the color array.
     * See {@link Cpdf::setLineStyle()} for a description of the $style
     * parameter (aka dash)
     *
     * @param float $x1
     * @param float $y1
     * @param float $w
     * @param float $h
     * @param array $color
     * @param float $width
     * @param array $style
     */
    public function rectangle($x1, $y1, $w, $h, $color, $width, $style = null)
    {

        // Scale by the AA factor and DPI
        $x1 = $this->_upscale($x1);
        $y1 = $this->_upscale($y1);
        $w = $this->_upscale($w);
        $h = $this->_upscale($h);
        $width = $this->_upscale($width);

        $c = $this->_allocate_color($color);

        // Convert the style array if required
        if (is_array($style) && count($style) > 0) {
            $gd_style = [];

            foreach ($style as $length) {
                for ($i = 0; $i < $length; $i++) {
                    $gd_style[] = $c;
                }
            }

            if (!empty($gd_style)) {
                imagesetstyle($this->get_image(), $gd_style);
                $c = IMG_COLOR_STYLED;
            }
        }

        imagesetthickness($this->get_image(), $width);

        imagerectangle($this->get_image(), $x1, $y1, $x1 + $w, $y1 + $h, $c);
    }

    /**
     * Draws a filled rectangle at x1,y1 with width w and height h
     *
     * See {@link Style::munge_color()} for the format of the color array.
     *
     * @param float $x1
     * @param float $y1
     * @param float $w
     * @param float $h
     * @param array $color
     */
    public function filled_rectangle($x1, $y1, $w, $h, $color)
    {
        // Scale by the AA factor and DPI
        $x1 = $this->_upscale($x1);
        $y1 = $this->_upscale($y1);
        $w = $this->_upscale($w);
        $h = $this->_upscale($h);

        $c = $this->_allocate_color($color);

        imagefilledrectangle($this->get_image(), $x1, $y1, $x1 + $w, $y1 + $h, $c);
    }

    /**
     * Starts a clipping rectangle at x1,y1 with width w and height h
     *
     * @param float $x1
     * @param float $y1
     * @param float $w
     * @param float $h
     */
    public function clipping_rectangle($x1, $y1, $w, $h)
    {
        // @todo
    }

    public function clipping_roundrectangle($x1, $y1, $w, $h, $rTL, $rTR, $rBR, $rBL)
    {
        // @todo
    }

    /**
     * Ends the last clipping shape
     */
    public function clipping_end()
    {
        // @todo
    }

    /**
     *
     */
    public function save()
    {
        $this->get_dompdf()->getOptions()->setDpi(72);
    }

    /**
     *
     */
    public function restore()
    {
        $this->get_dompdf()->getOptions()->setDpi($this->dpi);
    }

    /**
     * @param $angle
     * @param $x
     * @param $y
     */
    public function rotate($angle, $x, $y)
    {
        // @todo
    }

    /**
     * @param $angle_x
     * @param $angle_y
     * @param $x
     * @param $y
     */
    public function skew($angle_x, $angle_y, $x, $y)
    {
        // @todo
    }

    /**
     * @param $s_x
     * @param $s_y
     * @param $x
     * @param $y
     */
    public function scale($s_x, $s_y, $x, $y)
    {
        // @todo
    }

    /**
     * @param $t_x
     * @param $t_y
     */
    public function translate($t_x, $t_y)
    {
        // @todo
    }

    /**
     * @param $a
     * @param $b
     * @param $c
     * @param $d
     * @param $e
     * @param $f
     */
    public function transform($a, $b, $c, $d, $e, $f)
    {
        // @todo
    }

    /**
     * Draws a polygon
     *
     * The polygon is formed by joining all the points stored in the $points
     * array.  $points has the following structure:
     * <code>
     * array(0 => x1,
     *       1 => y1,
     *       2 => x2,
     *       3 => y2,
     *       ...
     *       );
     * </code>
     *
     * See {@link Style::munge_color()} for the format of the color array.
     * See {@link Cpdf::setLineStyle()} for a description of the $style
     * parameter (aka dash)
     *
     * @param array $points
     * @param array $color
     * @param float $width
     * @param array $style
     * @param bool $fill Fills the polygon if true
     */
    public function polygon($points, $color, $width = null, $style = null, $fill = false)
    {

        // Scale each point by the AA factor and DPI
        foreach (array_keys($points) as $i) {
            $points[$i] = $this->_upscale($points[$i]);
        }

        $c = $this->_allocate_color($color);

        // Convert the style array if required
        if (is_array($style) && count($style) > 0 && !$fill) {
            $gd_style = [];

            foreach ($style as $length) {
                for ($i = 0; $i < $length; $i++) {
                    $gd_style[] = $c;
                }
            }

            if (!empty($gd_style)) {
                imagesetstyle($this->get_image(), $gd_style);
                $c = IMG_COLOR_STYLED;
            }
        }

        imagesetthickness($this->get_image(), $width);

        if ($fill) {
            imagefilledpolygon($this->get_image(), $points, count($points) / 2, $c);
        } else {
            imagepolygon($this->get_image(), $points, count($points) / 2, $c);
        }
    }

    /**
     * Draws a circle at $x,$y with radius $r
     *
     * See {@link Style::munge_color()} for the format of the color array.
     * See {@link Cpdf::setLineStyle()} for a description of the $style
     * parameter (aka dash)
     *
     * @param float $x
     * @param float $y
     * @param float $r
     * @param array $color
     * @param float $width
     * @param array $style
     * @param bool $fill Fills the circle if true
     */
    public function circle($x, $y, $r, $color, $width = null, $style = null, $fill = false)
    {
        // Scale by the AA factor and DPI
        $x = $this->_upscale($x);
        $y = $this->_upscale($y);
        $r = $this->_upscale($r);

        $c = $this->_allocate_color($color);

        // Convert the style array if required
        if (is_array($style) && count($style) > 0 && !$fill) {
            $gd_style = [];

            foreach ($style as $length) {
                for ($i = 0; $i < $length; $i++) {
                    $gd_style[] = $c;
                }
            }

            if (!empty($gd_style)) {
                imagesetstyle($this->get_image(), $gd_style);
                $c = IMG_COLOR_STYLED;
            }
        }

        imagesetthickness($this->get_image(), $width);

        if ($fill) {
            imagefilledellipse($this->get_image(), $x, $y, $r, $r, $c);
        } else {
            imageellipse($this->get_image(), $x, $y, $r, $r, $c);
        }
    }

    /**
     * Add an image to the pdf.
     * The image is placed at the specified x and y coordinates with the
     * given width and height.
     *
     * @param string $img_url the path to the image
     * @param float $x x position
     * @param float $y y position
     * @param int $w width (in pixels)
     * @param int $h height (in pixels)
     * @param string $resolution
     * @return void
     *
     * @throws \Exception
     * @internal param string $img_type the type (e.g. extension) of the image
     */
    public function image($img_url, $x, $y, $w, $h, $resolution = "normal")
    {
        $img_type = Cache::detect_type($img_url, $this->get_dompdf()->getHttpContext());

        if (!$img_type) {
            return;
        }

        $func_name = "imagecreatefrom$img_type";
        if (!function_exists($func_name)) {
            if (!method_exists("Dompdf\Helpers", $func_name)) {
                throw new \Exception("Function $func_name() not found.  Cannot convert $img_type image: $img_url.  Please install the image PHP extension.");
            }
            $func_name = "\\Dompdf\\Helpers::" . $func_name;
        }
        $src = @call_user_func($func_name, $img_url);

        if (!$src) {
            return; // Probably should add to $_dompdf_errors or whatever here
        }

        // Scale by the AA factor and DPI
        $x = $this->_upscale($x);
        $y = $this->_upscale($y);

        $w = $this->_upscale($w);
        $h = $this->_upscale($h);

        $img_w = imagesx($src);
        $img_h = imagesy($src);

        imagecopyresampled($this->get_image(), $src, $x, $y, 0, 0, $w, $h, $img_w, $img_h);
    }

    /**
     * Writes text at the specified x and y coordinates
     * See {@link Style::munge_color()} for the format of the color array.
     *
     * @param float $x
     * @param float $y
     * @param string $text the text to write
     * @param string $font the font file to use
     * @param float $size the font size, in points
     * @param array $color
     * @param float $word_spacing word spacing adjustment
     * @param float $char_spacing
     * @param float $angle Text angle
     *
     * @return void
     */
    public function text($x, $y, $text, $font, $size, $color = [0, 0, 0], $word_spacing = 0.0, $char_spacing = 0.0, $angle = 0.0)
    {
        // Scale by the AA factor and DPI
        $x = $this->_upscale($x);
        $y = $this->_upscale($y);
        $size = $this->_upscale($size) * self::FONT_SCALE;

        $h = $this->get_font_height_actual($font, $size);
        $c = $this->_allocate_color($color);

        // imagettftext() converts numeric entities to their respective
        // character. Preserve any originally double encoded entities to be
        // represented as is.
        // eg: &amp;#160; will render &#160; rather than its character.
        $text = preg_replace('/&(#(?:x[a-fA-F0-9]+|[0-9]+);)/', '&#38;\1', $text);

        $text = mb_encode_numericentity($text, [0x0080, 0xff, 0, 0xff], 'UTF-8');

        $font = $this->get_ttf_file($font);

        // FIXME: word spacing
        imagettftext($this->get_image(), $size, $angle, $x, $y + $h, $c, $font, $text);
    }

    public function javascript($code)
    {
        // Not implemented
    }

    /**
     * Add a named destination (similar to <a name="foo">...</a> in html)
     *
     * @param string $anchorname The name of the named destination
     */
    public function add_named_dest($anchorname)
    {
        // Not implemented
    }

    /**
     * Add a link to the pdf
     *
     * @param string $url The url to link to
     * @param float $x The x position of the link
     * @param float $y The y position of the link
     * @param float $width The width of the link
     * @param float $height The height of the link
     */
    public function add_link($url, $x, $y, $width, $height)
    {
        // Not implemented
    }

    /**
     * Add meta information to the PDF
     *
     * @param string $label label of the value (Creator, Producer, etc.)
     * @param string $value the text to set
     */
    public function add_info($label, $value)
    {
        // N/A
    }

    /**
     * @param string $view
     * @param array $options
     */
    public function set_default_view($view, $options = [])
    {
        // N/A
    }

    /**
     * Calculates text size, in points
     *
     * @param string $text the text to be sized
     * @param string $font the desired font
     * @param float $size the desired font size
     * @param float $word_spacing word spacing, if any
     * @param float $char_spacing char spacing, if any
     *
     * @return float
     */
    public function get_text_width($text, $font, $size, $word_spacing = 0.0, $char_spacing = 0.0)
    {
        $font = $this->get_ttf_file($font);
        $size = $this->_upscale($size) * self::FONT_SCALE;

        // imagettfbbox() converts numeric entities to their respective
        // character. Preserve any originally double encoded entities to be
        // represented as is.
        // eg: &amp;#160; will render &#160; rather than its character.
        $text = preg_replace('/&(#(?:x[a-fA-F0-9]+|[0-9]+);)/', '&#38;\1', $text);

        $text = mb_encode_numericentity($text, [0x0080, 0xffff, 0, 0xffff], 'UTF-8');

        // FIXME: word spacing
        list($x1, , $x2) = imagettfbbox($size, 0, $font, $text);

        // Add additional 1pt to prevent text overflow issues
        return $this->_downscale($x2 - $x1) + 1;
    }

    /**
     * @param $font
     * @return string
     */
    public function get_ttf_file($font)
    {
        if ( stripos($font, ".ttf") === false ) {
            $font .= ".ttf";
        }

        if (!file_exists($font)) {
            $font_metrics = $this->_dompdf->getFontMetrics();
            $font = $font_metrics->getFont($this->_dompdf->getOptions()->getDefaultFont()) . ".ttf";
            if (!file_exists($font)) {
                if (strpos($font, "mono")) {
                    $font = $font_metrics->getFont("DejaVu Mono") . ".ttf";
                } elseif (strpos($font, "sans") !== false) {
                    $font = $font_metrics->getFont("DejaVu Sans") . ".ttf";
                } elseif (strpos($font, "serif")) {
                    $font = $font_metrics->getFont("DejaVu Serif") . ".ttf";
                } else {
                    $font = $font_metrics->getFont("DejaVu Sans") . ".ttf";
                }
            }
        }

        return $font;
    }

    /**
     * Calculates font height, in points
     *
     * @param string $font
     * @param float $size
     * @return float
     */
    public function get_font_height($font, $size)
    {
        $size = $this->_upscale($size) * self::FONT_SCALE;

        $height = $this->get_font_height_actual($font, $size);

        return $this->_downscale($height);
    }

    protected function get_font_height_actual($font, $size)
    {
        $font = $this->get_ttf_file($font);
        $ratio = $this->_dompdf->getOptions()->getFontHeightRatio();

        // FIXME: word spacing
        list(, $y2, , , , $y1) = imagettfbbox($size, 0, $font, "MXjpqytfhl"); // Test string with ascenders, descenders and caps
        return ($y2 - $y1) * $ratio;
    }

    /**
     * @param string $font
     * @param float $size
     * @return float
     */
    public function get_font_baseline($font, $size)
    {
        $ratio = $this->_dompdf->getOptions()->getFontHeightRatio();
        return $this->get_font_height($font, $size) / $ratio;
    }

    /**
     * Starts a new page
     *
     * Subsequent drawing operations will appear on the new page.
     */
    public function new_page()
    {
        $this->_page_number++;
        $this->_page_count++;

        $this->_img = imagecreatetruecolor($this->_actual_width, $this->_actual_height);

        $this->_bg_color = $this->_allocate_color($this->_bg_color_array);
        imagealphablending($this->_img, true);
        imagesavealpha($this->_img, true);
        imagefill($this->_img, 0, 0, $this->_bg_color);

        $this->_imgs[] = $this->_img;
    }

    public function open_object()
    {
        // N/A
    }

    public function close_object()
    {
        // N/A
    }

    public function add_object()
    {
        // N/A
    }

    public function page_text()
    {
        // N/A
    }

    public function page_line()
    {
        // N/A
    }

    /**
     * Streams the image to the client.
     *
     * @param string $filename The filename to present to the client.
     * @param array $options Associative array: 'type' => jpeg|jpg|png; 'quality' => 0 - 100 (JPEG only);
     *     'page' => Number of the page to output (defaults to the first); 'Attachment': 1 or 0 (default 1).
     */
    public function stream($filename, $options = [])
    {
        if (headers_sent()) {
            die("Unable to stream image: headers already sent");
        }

        if (!isset($options["type"])) $options["type"] = "png";
        if (!isset($options["Attachment"])) $options["Attachment"] = true;
        $type = strtolower($options["type"]);

        switch ($type) {
            case "jpg":
            case "jpeg":
                $contentType = "image/jpeg";
                $extension = ".jpg";
                break;
            case "png":
            default:
                $contentType = "image/png";
                $extension = ".png";
                break;
        }

        header("Cache-Control: private");
        header("Content-Type: $contentType");

        $filename = str_replace(["\n", "'"], "", basename($filename, ".$type")) . $extension;
        $attachment = $options["Attachment"] ? "attachment" : "inline";
        header(Helpers::buildContentDispositionHeader($attachment, $filename));

        $this->_output($options);
        flush();
    }

    /**
     * Returns the image as a string.
     *
     * @param array $options Associative array: 'type' => jpeg|jpg|png; 'quality' => 0 - 100 (JPEG only);
     *     'page' => Number of the page to output (defaults to the first).
     * @return string
     */
    public function output($options = [])
    {
        ob_start();

        $this->_output($options);

        return ob_get_clean();
    }

    /**
     * Outputs the image stream directly.
     *
     * @param array $options Associative array: 'type' => jpeg|jpg|png; 'quality' => 0 - 100 (JPEG only);
     *     'page' => Number of the page to output (defaults to the first).
     */
    protected function _output($options = [])
    {
        if (!isset($options["type"])) $options["type"] = "png";
        if (!isset($options["page"])) $options["page"] = 1;
        $type = strtolower($options["type"]);

        if (isset($this->_imgs[$options["page"] - 1])) {
            $img = $this->_imgs[$options["page"] - 1];
        } else {
            $img = $this->_imgs[0];
        }

        // Perform any antialiasing
        if ($this->_aa_factor != 1) {
            $dst_w = $this->_actual_width / $this->_aa_factor;
            $dst_h = $this->_actual_height / $this->_aa_factor;
            $dst = imagecreatetruecolor($dst_w, $dst_h);
            imagecopyresampled($dst, $img, 0, 0, 0, 0,
                $dst_w, $dst_h,
                $this->_actual_width, $this->_actual_height);
        } else {
            $dst = $img;
        }

        switch ($type) {
            case "jpg":
            case "jpeg":
                if (!isset($options["quality"])) {
                    $options["quality"] = 75;
                }

                imagejpeg($dst, null, $options["quality"]);
                break;
            case "png":
            default:
                imagepng($dst);
                break;
        }

        if ($this->_aa_factor != 1) {
            imagedestroy($dst);
        }
    }
}
