Image.php

<?php namespace Mreschke\Helpers;

/**
 * Image and graphic helpers.
 * @copyright 2014 Matthew Reschke
 * @license http://mreschke.com/license/mit
 * @author Matthew Reschke <mail@mreschke.com>
 */
class Image
{

    /**
     * Resize Image, preserves transparency.
     * @author http://mediumexposure.com/smart-image-resizing-while-preserving-transparency-php-and-gd-library/
     * @param string $file full path to image
     * @param string $width
     * @depends imagemagick
     * @return void
     */
    public static function resizeImage($file, $width = 0, $height = 0, $proportional = false, $output = 'file', $delete_original = true, $use_linux_commands = false)
    {
        if ($height <= 0 && $width <= 0) {
            return false;
        }

        $info = getimagesize($file);
        $image = '';

        $final_width = 0;
        $final_height = 0;
        list($width_old, $height_old) = $info;

        if ($proportional) {
            if ($width == 0) {
                $factor = $height/$height_old;
            } elseif ($height == 0) {
                $factor = $width/$width_old;
            } else {
                $factor = min($width / $width_old, $height / $height_old);
            }

            $final_width = round($width_old * $factor);
            $final_height = round($height_old * $factor);
        } else {
            $final_width = ($width <= 0) ? $width_old : $width;
            $final_height = ($height <= 0) ? $height_old : $height;
        }

        switch ($info[2]) {
            case IMAGETYPE_GIF:
                $image = imagecreatefromgif($file);
                break;
            case IMAGETYPE_JPEG:
                $image = imagecreatefromjpeg($file);
                break;
            case IMAGETYPE_PNG:
                $image = imagecreatefrompng($file);
                break;
            default:
                return false;
        }

        $image_resized = imagecreatetruecolor($final_width, $final_height);

        if (($info[2] == IMAGETYPE_GIF) || ($info[2] == IMAGETYPE_PNG)) {
            $trnprt_indx = imagecolortransparent($image);

            // If we have a specific transparent color
            if ($trnprt_indx >= 0) {

                // Get the original image's transparent color's RGB values
                $trnprt_color    = imagecolorsforindex($image, $trnprt_indx);

                // Allocate the same color in the new image resource
                $trnprt_indx    = imagecolorallocate($image_resized, $trnprt_color['red'], $trnprt_color['green'], $trnprt_color['blue']);

                // Completely fill the background of the new image with allocated color.
                imagefill($image_resized, 0, 0, $trnprt_indx);

                // Set the background color for new image to transparent
                imagecolortransparent($image_resized, $trnprt_indx);
            } elseif ($info[2] == IMAGETYPE_PNG) {
                // Always make a transparent background color for PNGs that don't have one allocated already
                // Turn off transparency blending (temporarily)
                imagealphablending($image_resized, false);

                // Create a new transparent color for image
                $color = imagecolorallocatealpha($image_resized, 0, 0, 0, 127);

                // Completely fill the background of the new image with allocated color.
                imagefill($image_resized, 0, 0, $color);

                // Restore transparency blending
                imagesavealpha($image_resized, true);
            }
        }

        imagecopyresampled($image_resized, $image, 0, 0, 0, 0, $final_width, $final_height, $width_old, $height_old);

        if ($delete_original) {
            if ($use_linux_commands) {
                exec('rm '.$file);
            } else {
                @unlink($file);
            }
        }

        switch (strtolower($output)) {
            case 'browser':
                $mime = image_type_to_mime_type($info[2]);
                header("Content-type: $mime");
                $output = null;
                break;
            case 'file':
                $output = $file;
                break;
            case 'return':
                return $image_resized;
                break;
            default:
                break;
        }

        switch ($info[2]) {
            case IMAGETYPE_GIF:
                imagegif($image_resized, $output);
                break;
            case IMAGETYPE_JPEG:
                imagejpeg($image_resized, $output);
                break;
            case IMAGETYPE_PNG:
                imagepng($image_resized, $output);
                break;
            default:
                return false;
        }
        return true;
    }
}