PHP Long shadow icon generator.

.htaccess

# for neater URLS like /{text}/{size}/{bg}

RewriteEngine on
RewriteRule ^img/([^/]+)/(\d+)/([a-fA-F0-9]{6})$ i/index.php?text=$1&size=$2&bg=$3 [NC,QSA]
RewriteRule ^img/([^/]+)/(\d+)$ i/index.php?text=$1&size=$2 [NC,QSA]
RewriteRule ^img/([^/]+)$ i/index.php?text=$1 [NC,QSA]
RewriteRule ^img/([^/]+)/.+$ i/index.php?text=$1 [NC,QSA]

image.php

<?php
/**
 * Copyright 2014 Zohaib Sibte Hassan
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

// --------------------------------- Configuration variables
// These are configuration variables that you can modify
// Customize them as much as you want
// Here are list of parameters you can pass:
//  - size: Size of image
//  - font: font name to use
//  - text: text value to render
//  - bg: background color
//  - fg: foreground color
//  - sh: shadow color
//  - slope_x: shadow slope along x-axis (1 towards right, -1 towards left)
//  - slope_y: shadow slope along y-axis (1 towards bottom, -1 towards top)

// Cache path
// Make it NULL in case you don't want to cache the results
$ImageCacheDir = realpath(__DIR__.'/../cached');

// Default image size
$DefaultImageSize = 128;

// Maximum size of image in pixels
// Use a decent value to throttle CPU/memory usage
$MaxImageSize = 512;

// Directory containing fonts
$FontDirectory = __DIR__.'/../fonts';

// List of supported fonts
// It's a map of name => font file path that is used to render initials
// Font name is passed as ```font``` query parameter
$FontsList = array(
    // Source sans by adobe, available at https://github.com/adobe-fonts/source-sans-pro/releases
    's' =>                  'SourceSansVariable-Roman.ttf',

    // Gidolinya available at http://gidole.github.io/
    'g' =>                  'Gidolinya-Regular.otf',

    // Opensans
    'o' =>                  'OpenSans-Regulare.ttf',

    // PT Sans Narrow
    'p' =>                  'PTN77F.ttf',

    // Multilingual NotoSans font
    'n' => array (
        'common' =>         'NotoSans-Regular.ttf',
        'latin' =>          'NotoSans-Regular.ttf',
        'arabic' =>         'script/NotoNaskhArabic-Regular.ttf',
        'armenian' =>       'script/NotoSans-Armenian-Regular.ttf',
        'bengali' =>        'script/NotoSans-Bengali-Regular.ttf',
        'han' =>            'script/Noto-CJKJP-Regular.otf',
        'hiragana' =>       'script/Noto-CJKJP-Regular.otf',
        'katakana' =>       'script/Noto-CJKJP-Regular.otf',
        'thai' =>           'script/NotoSans-Thai-Regular.ttf',
        'georgian' =>       'script/NotoSans-Georgian-Regular.ttf',
        'mongolian' =>      'script/NotoSans-Mongolian-Regular.ttf',
        'hebrew' =>         'script/NotoSans-Hebrew-Regular.ttf',
        'tibetan' =>        'script/NotoSans-Tibetan-Regular.ttf',
    ),
);

// Default font name if the parameter is not specified
$DefaultFontName = 'n';

// Font scaled size (it's used as ImageSize * FontScaledSize)
// Each font might have different value due to ligature
$FontScaledSize = 0.35;

// Default background color auto or hex value without # e.g. ffaa11
$DefaultBackgroundColor = 'auto';

// Color pallete for auto selecting colors
$ColorPalette = array(
  '1abc9c', '3498db', '9b59b6',
  '34495e', 'f1c40f', 'e67e22',
  'e74c3c', '8764B8');

// Default text
$DefaultText = 'HI';

// Default shadow slope along x-axis
$DefaultSlopeX = 1;

// Default shadow slope along y-axis
$DefaultSlopeY = 1;

// ---------------------- Only modify beyond this if you know what you are doing :)
// --------------------------------------------------------------------------------
mb_language('uni');
mb_internal_encoding('UTF-8');

// Supported language ligatures
$LanguageFontNamePrefix = array(
    'Arabic',
    'Armenian',
    'Bengali',
    'Bopomofo',
    'Braille',
    'Buhid',
    'Canadian_Aboriginal',
    'Cherokee',
    'Cyrillic',
    'Devanagari',
    'Ethiopic',
    'Georgian',
    'Greek',
    'Gujarati',
    'Gurmukhi',
    'Han',
    'Hangul',
    'Hanunoo',
    'Hebrew',
    'Hiragana',
    'Inherited',
    'Kannada',
    'Katakana',
    'Khmer',
    'Lao',
    'Latin',
    'Limbu',
    'Malayalam',
    'Mongolian',
    'Myanmar',
    'Ogham',
    'Oriya',
    'Runic',
    'Sinhala',
    'Syriac',
    'Tagalog',
    'Tagbanwa',
    'Tai_Le',
    'Tamil',
    'Telugu',
    'Thaana',
    'Thai',
    'Tibetan',
    'Yi',
    'Common'
);

function req_get($name, $default = null) {
  return isset($_GET[$name]) ? $_GET[$name] : $default;
}

function hex2rgb($hex) {
   if (is_array($hex)){
    return $hex;
   }

   $hex = str_replace("#", "", $hex);

   if(strlen($hex) == 3) {
      $r = hexdec(substr($hex,0,1).substr($hex,0,1));
      $g = hexdec(substr($hex,1,1).substr($hex,1,1));
      $b = hexdec(substr($hex,2,1).substr($hex,2,1));
   } else {
      $r = hexdec(substr($hex,0,2));
      $g = hexdec(substr($hex,2,2));
      $b = hexdec(substr($hex,4,2));
   }
   $rgb = array($r, $g, $b);
   return $rgb; // returns an array with the rgb values
}

function brighten($color, $steps) {
    list($r, $g, $b) = $color;

    $r = max(0,min(255,$r + $steps));
    $g = max(0,min(255,$g + $steps));
    $b = max(0,min(255,$b + $steps));

    return array($r, $g, $b);
}

function normalize_slope($p) {
    if($p > 1) {
        return 1;
    }

    if($p < -1) {
        return -1;
    }

    return $p;
}

function get_str_lang($txt) {
    global $LanguageFontNamePrefix;
    foreach ($LanguageFontNamePrefix as $lang) {
        $exp = '/\p{'.$lang.'}/u';
        if (preg_match($exp, $txt)) {
            return $lang;
        }
    }

    return 'Latin';
}

function get_font_file($txt, $name) {
    global $FontsList, $FontDirectory;

    if (!isset($FontsList[$name])) {
        throw new Exception("No font defined for $name");
    }

    $info = $FontsList[$name];
    if (is_string($info)) {
        return $FontDirectory.'/'.$info;
    }

    $lang = strtolower(get_str_lang($txt));
    if (isset($info[$lang])) {
        return $FontDirectory.'/'.$info[$lang];
    }

    if (isset($info['common'])) {
        return $FontDirectory.'/'.$info['common'];
    }

    return $FontDirectory.'/'.$info['latin'];
}

function get_cache_path($ids) {
    global $ImageCacheDir;
    if (is_null($ImageCacheDir)) {
        return null;
    }

    return $ImageCacheDir . '/' . hash('sha256', serialize($ids)) . '.png';
}

function render_image($string, $image_width, $image_height, $font_size, $font_file, $bg_color, $fg_color, $shadow_color, $x_slope, $y_slope) {
    $cache_path = get_cache_path(func_get_args());

    // If already cached return that
    if ($cache_path !== NULL && file_exists($cache_path)) {
        return file_get_contents($cache_path);
    }

    // Create image
    $im = imagecreatetruecolor($image_width, $image_height);
    imageantialias($im, true);

    // Create fill brushes
    $fg_fill = imagecolorallocate($im, $fg_color[0], $fg_color[1], $fg_color[2]);
    $bg_fill = imagecolorallocate($im, $bg_color[0], $bg_color[1], $bg_color[2]);
    $sh_fill = imagecolorallocate($im, $shadow_color[0], $shadow_color[1], $shadow_color[2]);

    // Find the bounding box of text
    $text_bounding_box = imagettfbbox($font_size, 0, $font_file, $string);
    $xLeft  = $text_bounding_box[0]; // (lower|upper) left corner, X position
    $xRight = $text_bounding_box[2]; // (lower|upper) right corner, X position
    $yLower = $text_bounding_box[1]; // lower (left|right) corner, Y position
    $yUpper = $text_bounding_box[5]; // upper (left|right) corner, Y position
    $tail_length = max(abs($xLower), abs($xRight), abs($xLeft), abs($yUpper));

    $text_size = array(
        ($xRight - $xLeft),
        ($yLower - $yUpper)
    );

    if ($xLeft > 2) {
        $text_size[0] = abs($xRight);
    }

    if ($yLower > 2) {
        $text_size[1] = abs($yUpper);
    }

    $text_position = array(
        ($image_width / 2) - ($text_size[0] / 2),
        ($image_height / 2) + ($text_size[1] / 2)
    );

    // Fill background
    imagefill($im, 0, 0, $bg_fill);

    // Really inefficent version of draw shadow
    if ($x_slope != 0 && $y_slope != 0) {
        $max_i = $image_height - $text_position[1] + $tail_length;
        for($i=1; $i <= $max_i; $i++) {
            imagettftext($im,
                $font_size ,
                0 ,
                $text_position[0] + $x_slope * $i,
                $text_position[1] + $y_slope * $i,
                $sh_fill,
                $font_file,
                $string);
        }
    }

    // Draw text
    imagettftext($im, $font_size , 0 , $text_position[0] , $text_position[1], $fg_fill , $font_file, $string);

    // Start buffering if not cached
    if ($cache_path === NULL) {
        ob_start();
    }

    imagepng($im, $cache_path, 9);
    imagedestroy($im);

    // flush path from buffer if no cache path
    if ($cache_path === NULL) {
        $ret = ob_get_contents();
        ob_end_clean();
        return $ret;
    }

    // Save CPU do IO
    return file_get_contents($cache_path);
}

// Read request
$ImageSize = (int)req_get('size', $DefaultImageSize);
if ($ImageSize > $MaxImageSize){
    $ImageSize = $MaxImageSize;
}

// Text
$text = mb_strtoupper(req_get('text', $DefaultText));
if (mb_strlen($text) > 2) {
    $text = mb_substr($text, 0, 2);
}

// Background color
if ($DefaultBackgroundColor == 'auto') {
    $index = (crc32(req_get('text', $DefaultText)) >> 16) % count($ColorPalette);
    $DefaultBackgroundColor = $ColorPalette[$index];
}

$bg_color = hex2rgb(req_get('bg', $DefaultBackgroundColor));

// Render
$imgContent = render_image(
    $text,
    $ImageSize,
    $ImageSize,
    (int)($ImageSize * $FontScaledSize),
    get_font_file($text, req_get('font', $DefaultFontName)),
    $bg_color,
    hex2rgb(req_get('fg', brighten($bg_color, 150))),
    hex2rgb(req_get('sh', brighten($bg_color, -100))),
    normalize_slope((float)req_get('slope_x', $DefaultSlopeX)),
    normalize_slope((float)req_get('slope_y', $DefaultSlopeY))
);

header("Content-type: image/png");
echo $imgContent;