Use transparent gray instead of white or black to modify transparency, fixes #3727

[kohana-image.git] / classes / kohana / image / gd.php

<?php defined('SYSPATH') or die('No direct script access.');
/**
 * Support for image manipulation using [GD](http://php.net/GD).
 *
 * @package    Kohana/Image
 * @category   Drivers
 * @author     Kohana Team
 * @copyright  (c) 2008-2009 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class Kohana_Image_GD extends Image {

        // Is GD bundled or separate?
        protected static $_bundled;

        /**
         * Checks if GD is enabled and bundled. Bundled GD is required for some
         * methods to work. Exceptions will be thrown from those methods when GD is
         * not bundled.
         *
         * @return  boolean
         */
        public static function check()
        {
                if ( ! function_exists('gd_info'))
                {
                        throw new Kohana_Exception('GD is either not installed or not enabled, check your configuration');
                }

                if (defined('GD_BUNDLED'))
                {
                        // Get the version via a constant, available in PHP 5.
                        Image_GD::$_bundled = GD_BUNDLED;
                }
                else
                {
                        // Get the version information
                        $info = gd_info();

                        // Extract the bundled status
                        Image_GD::$_bundled = (bool) preg_match('/\bbundled\b/i', $info['GD Version']);
                }

                if (defined('GD_VERSION'))
                {
                        // Get the version via a constant, available in PHP 5.2.4+
                        $version = GD_VERSION;
                }
                else
                {
                        // Get the version information
                        $info = gd_info();

                        // Extract the version number
                        preg_match('/\d+\.\d+(?:\.\d+)?/', $info['GD Version'], $matches);

                        // Get the major version
                        $version = $matches[0];
                }

                if ( ! version_compare($version, '2.0.1', '>='))
                {
                        throw new Kohana_Exception('Image_GD requires GD version :required or greater, you have :version',
                                array('required' => '2.0.1', ':version' => $version));
                }

                return Image_GD::$_checked = TRUE;
        }

        // Temporary image resource
        protected $_image;

        // Function name to open Image
        protected $_create_function;

        /**
         * Runs [Image_GD::check] and loads the image.
         *
         * @return  void
         * @throws  Kohana_Exception
         */
        public function __construct($file)
        {
                if ( ! Image_GD::$_checked)
                {
                        // Run the install check
                        Image_GD::check();
                }

                parent::__construct($file);

                // Set the image creation function name
                switch ($this->type)
                {
                        case IMAGETYPE_JPEG:
                                $create = 'imagecreatefromjpeg';
                        break;
                        case IMAGETYPE_GIF:
                                $create = 'imagecreatefromgif';
                        break;
                        case IMAGETYPE_PNG:
                                $create = 'imagecreatefrompng';
                        break;
                }

                if ( ! isset($create) OR ! function_exists($create))
                {
                        throw new Kohana_Exception('Installed GD does not support :type images',
                                array(':type' => image_type_to_extension($this->type, FALSE)));
                }

                // Save function for future use
                $this->_create_function = $create;

                // Save filename for lazy loading
                $this->_image = $this->file;
        }

        /**
         * Destroys the loaded image to free up resources.
         *
         * @return  void
         */
        public function __destruct()
        {
                if (is_resource($this->_image))
                {
                        // Free all resources
                        imagedestroy($this->_image);
                }
        }

        /**
         * Loads an image into GD.
         *
         * @return  void
         */
        protected function _load_image()
        {
                if ( ! is_resource($this->_image))
                {
                        // Gets create function
                        $create = $this->_create_function;

                        // Open the temporary image
                        $this->_image = $create($this->file);

                        // Preserve transparency when saving
                        imagesavealpha($this->_image, TRUE);
                }
        }

        protected function _do_resize($width, $height)
        {
                // Presize width and height
                $pre_width = $this->width;
                $pre_height = $this->height;

                // Loads image if not yet loaded
                $this->_load_image();

                // Test if we can do a resize without resampling to speed up the final resize
                if ($width > ($this->width / 2) AND $height > ($this->height / 2))
                {
                        // The maximum reduction is 10% greater than the final size
                        $reduction_width  = round($width  * 1.1);
                        $reduction_height = round($height * 1.1);

                        while ($pre_width / 2 > $reduction_width AND $pre_height / 2 > $reduction_height)
                        {
                                // Reduce the size using an O(2n) algorithm, until it reaches the maximum reduction
                                $pre_width /= 2;
                                $pre_height /= 2;
                        }

                        // Create the temporary image to copy to
                        $image = $this->_create($pre_width, $pre_height);

                        if (imagecopyresized($image, $this->_image, 0, 0, 0, 0, $pre_width, $pre_height, $this->width, $this->height))
                        {
                                // Swap the new image for the old one
                                imagedestroy($this->_image);
                                $this->_image = $image;
                        }
                }

                // Create the temporary image to copy to
                $image = $this->_create($width, $height);

                // Execute the resize
                if (imagecopyresampled($image, $this->_image, 0, 0, 0, 0, $width, $height, $pre_width, $pre_height))
                {
                        // Swap the new image for the old one
                        imagedestroy($this->_image);
                        $this->_image = $image;

                        // Reset the width and height
                        $this->width  = imagesx($image);
                        $this->height = imagesy($image);
                }
        }

        protected function _do_crop($width, $height, $offset_x, $offset_y)
        {
                // Create the temporary image to copy to
                $image = $this->_create($width, $height);

                // Loads image if not yet loaded
                $this->_load_image();

                // Execute the crop
                if (imagecopyresampled($image, $this->_image, 0, 0, $offset_x, $offset_y, $width, $height, $width, $height))
                {
                        // Swap the new image for the old one
                        imagedestroy($this->_image);
                        $this->_image = $image;

                        // Reset the width and height
                        $this->width  = imagesx($image);
                        $this->height = imagesy($image);
                }
        }

        protected function _do_rotate($degrees)
        {
                if ( ! Image_GD::$_bundled)
                {
                        throw new Kohana_Exception('This method requires :function, which is only available in the bundled version of GD',
                                array(':function' => 'imagerotate'));
                }

                // Loads image if not yet loaded
                $this->_load_image();

                // Transparent black will be used as the background for the uncovered region
                $transparent = imagecolorallocatealpha($this->_image, 0, 0, 0, 127);

                // Rotate, setting the transparent color
                $image = imagerotate($this->_image, 360 - $degrees, $transparent, 1);

                // Save the alpha of the rotated image
                imagesavealpha($image, TRUE);

                // Get the width and height of the rotated image
                $width  = imagesx($image);
                $height = imagesy($image);

                if (imagecopymerge($this->_image, $image, 0, 0, 0, 0, $width, $height, 100))
                {
                        // Swap the new image for the old one
                        imagedestroy($this->_image);
                        $this->_image = $image;

                        // Reset the width and height
                        $this->width  = $width;
                        $this->height = $height;
                }
        }

        protected function _do_flip($direction)
        {
                // Create the flipped image
                $flipped = $this->_create($this->width, $this->height);

                // Loads image if not yet loaded
                $this->_load_image();

                if ($direction === Image::HORIZONTAL)
                {
                        for ($x = 0; $x < $this->width; $x++)
                        {
                                // Flip each row from top to bottom
                                imagecopy($flipped, $this->_image, $x, 0, $this->width - $x - 1, 0, 1, $this->height);
                        }
                }
                else
                {
                        for ($y = 0; $y < $this->height; $y++)
                        {
                                // Flip each column from left to right
                                imagecopy($flipped, $this->_image, 0, $y, 0, $this->height - $y - 1, $this->width, 1);
                        }
                }

                // Swap the new image for the old one
                imagedestroy($this->_image);
                $this->_image = $flipped;

                // Reset the width and height
                $this->width  = imagesx($flipped);
                $this->height = imagesy($flipped);
        }

        protected function _do_sharpen($amount)
        {
                if ( ! Image_GD::$_bundled)
                {
                        throw new Kohana_Exception('This method requires :function, which is only available in the bundled version of GD',
                                array(':function' => 'imageconvolution'));
                }

                // Loads image if not yet loaded
                $this->_load_image();

                // Amount should be in the range of 18-10
                $amount = round(abs(-18 + ($amount * 0.08)), 2);

                // Gaussian blur matrix
                $matrix = array
                (
                        array(-1,   -1,    -1),
                        array(-1, $amount, -1),
                        array(-1,   -1,    -1),
                );

                // Perform the sharpen
                if (imageconvolution($this->_image, $matrix, $amount - 8, 0))
                {
                        // Reset the width and height
                        $this->width  = imagesx($this->_image);
                        $this->height = imagesy($this->_image);
                }
        }

        protected function _do_reflection($height, $opacity, $fade_in)
        {
                if ( ! Image_GD::$_bundled)
                {
                        throw new Kohana_Exception('This method requires :function, which is only available in the bundled version of GD',
                                array(':function' => 'imagefilter'));
                }

                // Loads image if not yet loaded
                $this->_load_image();

                // Convert an opacity range of 0-100 to 127-0
                $opacity = round(abs(($opacity * 127 / 100) - 127));

                if ($opacity < 127)
                {
                        // Calculate the opacity stepping
                        $stepping = (127 - $opacity) / $height;
                }
                else
                {
                        // Avoid a "divide by zero" error
                        $stepping = 127 / $height;
                }

                // Create the reflection image
                $reflection = $this->_create($this->width, $this->height + $height);

                // Copy the image to the reflection
                imagecopy($reflection, $this->_image, 0, 0, 0, 0, $this->width, $this->height);

                for ($offset = 0; $height >= $offset; $offset++)
                {
                        // Read the next line down
                        $src_y = $this->height - $offset - 1;

                        // Place the line at the bottom of the reflection
                        $dst_y = $this->height + $offset;

                        if ($fade_in === TRUE)
                        {
                                // Start with the most transparent line first
                                $dst_opacity = round($opacity + ($stepping * ($height - $offset)));
                        }
                        else
                        {
                                // Start with the most opaque line first
                                $dst_opacity = round($opacity + ($stepping * $offset));
                        }

                        // Create a single line of the image
                        $line = $this->_create($this->width, 1);

                        // Copy a single line from the current image into the line
                        imagecopy($line, $this->_image, 0, 0, 0, $src_y, $this->width, 1);

                        // Colorize the line to add the correct alpha level
                        imagefilter($line, IMG_FILTER_COLORIZE, 0, 0, 0, $dst_opacity);

                        // Copy a the line into the reflection
                        imagecopy($reflection, $line, 0, $dst_y, 0, 0, $this->width, 1);
                }

                // Swap the new image for the old one
                imagedestroy($this->_image);
                $this->_image = $reflection;

                // Reset the width and height
                $this->width  = imagesx($reflection);
                $this->height = imagesy($reflection);
        }

        protected function _do_watermark(Image $watermark, $offset_x, $offset_y, $opacity)
        {
                if ( ! Image_GD::$_bundled)
                {
                        throw new Kohana_Exception('This method requires :function, which is only available in the bundled version of GD',
                                array(':function' => 'imagelayereffect'));
                }

                // Loads image if not yet loaded
                $this->_load_image();

                // Create the watermark image resource
                $overlay = imagecreatefromstring($watermark->render());

                imagesavealpha($overlay, TRUE);

                // Get the width and height of the watermark
                $width  = imagesx($overlay);
                $height = imagesy($overlay);

                if ($opacity < 100)
                {
                        // Convert an opacity range of 0-100 to 127-0
                        $opacity = round(abs(($opacity * 127 / 100) - 127));

                        // Allocate transparent gray
                        $color = imagecolorallocatealpha($overlay, 127, 127, 127, $opacity);

                        // The transparent image will overlay the watermark
                        imagelayereffect($overlay, IMG_EFFECT_OVERLAY);

                        // Fill the background with the transparent color
                        imagefilledrectangle($overlay, 0, 0, $width, $height, $color);
                }

                // Alpha blending must be enabled on the background!
                imagealphablending($this->_image, TRUE);

                if (imagecopy($this->_image, $overlay, $offset_x, $offset_y, 0, 0, $width, $height))
                {
                        // Destroy the overlay image
                        imagedestroy($overlay);
                }
        }

        protected function _do_background($r, $g, $b, $opacity)
        {
                // Loads image if not yet loaded
                $this->_load_image();

                // Convert an opacity range of 0-100 to 127-0
                $opacity = round(abs(($opacity * 127 / 100) - 127));

                // Create a new background
                $background = $this->_create($this->width, $this->height);

                // Allocate the color
                $color = imagecolorallocatealpha($background, $r, $g, $b, $opacity);

                // Fill the image with white
                imagefilledrectangle($background, 0, 0, $this->width, $this->height, $color);

                // Alpha blending must be enabled on the background!
                imagealphablending($background, TRUE);

                // Copy the image onto a white background to remove all transparency
                if (imagecopy($background, $this->_image, 0, 0, 0, 0, $this->width, $this->height))
                {
                        // Swap the new image for the old one
                        imagedestroy($this->_image);
                        $this->_image = $background;
                }
        }

        protected function _do_save($file, $quality)
        {
                // Loads image if not yet loaded
                $this->_load_image();

                // Get the extension of the file
                $extension = pathinfo($file, PATHINFO_EXTENSION);

                // Get the save function and IMAGETYPE
                list($save, $type) = $this->_save_function($extension, $quality);

                // Save the image to a file
                $status = isset($quality) ? $save($this->_image, $file, $quality) : $save($this->_image, $file);

                if ($status === TRUE AND $type !== $this->type)
                {
                        // Reset the image type and mime type
                        $this->type = $type;
                        $this->mime = image_type_to_mime_type($type);
                }

                return TRUE;
        }

        protected function _do_render($type, $quality)
        {
                // Loads image if not yet loaded
                $this->_load_image();

                // Get the save function and IMAGETYPE
                list($save, $type) = $this->_save_function($type, $quality);

                // Capture the output
                ob_start();

                // Render the image
                $status = isset($quality) ? $save($this->_image, NULL, $quality) : $save($this->_image, NULL);

                if ($status === TRUE AND $type !== $this->type)
                {
                        // Reset the image type and mime type
                        $this->type = $type;
                        $this->mime = image_type_to_mime_type($type);
                }

                return ob_get_clean();
        }

        /**
         * Get the GD saving function and image type for this extension.
         * Also normalizes the quality setting
         *
         * @param   string   image type: png, jpg, etc
         * @param   integer  image quality
         * @return  array    save function, IMAGETYPE_* constant
         * @throws  Kohana_Exception
         */
        protected function _save_function($extension, & $quality)
        {
                switch (strtolower($extension))
                {
                        case 'jpg':
                        case 'jpeg':
                                // Save a JPG file
                                $save = 'imagejpeg';
                                $type = IMAGETYPE_JPEG;
                        break;
                        case 'gif':
                                // Save a GIF file
                                $save = 'imagegif';
                                $type = IMAGETYPE_GIF;

                                // GIFs do not a quality setting
                                $quality = NULL;
                        break;
                        case 'png':
                                // Save a PNG file
                                $save = 'imagepng';
                                $type = IMAGETYPE_PNG;

                                // Use a compression level of 9 (does not affect quality!)
                                $quality = 9;
                        break;
                        default:
                                throw new Kohana_Exception('Installed GD does not support :type images',
                                        array(':type' => $extension));
                        break;
                }

                return array($save, $type);
        }

        /**
         * Create an empty image with the given width and height.
         *
         * @param   integer   image width
         * @param   integer   image height
         * @return  resource
         */
        protected function _create($width, $height)
        {
                // Create an empty image
                $image = imagecreatetruecolor($width, $height);

                // Do not apply alpha blending
                imagealphablending($image, FALSE);

                // Save alpha levels
                imagesavealpha($image, TRUE);

                return $image;
        }

} // End Image_GD