function _image_captcha_image_generator_print_string in CAPTCHA 6
Same name and namespace in other branches
- 5.3 image_captcha/image_captcha.user.inc \_image_captcha_image_generator_print_string()
- 6.2 image_captcha/image_captcha.user.inc \_image_captcha_image_generator_print_string()
- 7 image_captcha/image_captcha.user.inc \_image_captcha_image_generator_print_string()
Helper function for drawing text on the image
Parameters
$background_mode if the text is for the background of the double vision mode:
1 call to _image_captcha_image_generator_print_string()
- _image_captcha_generate_image in image_captcha/
image_captcha.user.inc - base function for generating a image CAPTCHA
File
- image_captcha/
image_captcha.user.inc, line 230
Code
function _image_captcha_image_generator_print_string(&$image, $width, $height, $font, $font_size, $text, $background_mode = FALSE) {
// get characters
$characters = _image_captcha_utf8_split($text);
$character_quantity = count($characters);
// get character width for builtin font
if ($font == 'BUILTIN') {
$character_width = imagefontwidth(5);
$character_height = imagefontheight(5);
$bbox = array(
0,
$character_height,
$character_width,
$character_height,
$character_width,
0,
0,
0,
);
}
// get colors
$background_rgb = _image_captcha_hex_to_rgb(variable_get('image_captcha_background_color', '#ffffff'));
$foreground_rgb = _image_captcha_hex_to_rgb(variable_get('image_captcha_foreground_color', '#000000'));
// correct foreground for background mode (double vision)
if ($background_mode) {
for ($i = 0; $i < 3; $i++) {
$foreground_rgb[$i] = 0.75 * $background_rgb[$i] + 0.25 * $foreground_rgb[$i];
}
}
$background_color = imagecolorallocate($image, $background_rgb[0], $background_rgb[1], $background_rgb[2]);
$foreground_color = imagecolorallocate($image, $foreground_rgb[0], $foreground_rgb[1], $foreground_rgb[2]);
// precalculate the value ranges for color randomness
$foreground_randomness = (int) variable_get('image_captcha_foreground_color_randomness', 100);
if ($foreground_randomness) {
if ($background_mode) {
$foreground_randomness *= 0.25;
}
$foreground_color_range = array();
for ($i = 0; $i < 3; $i++) {
$foreground_color_range[$i] = array(
max(0, $foreground_rgb[$i] - $foreground_randomness),
min(255, $foreground_rgb[$i] + $foreground_randomness),
);
}
}
// set default text color
$color = $foreground_color;
// the image is seperated in different character cages, one for each character
// each character will be somewhere inside that cage
$ccage_width = $width / $character_quantity;
$ccage_height = $height;
foreach ($characters as $c => $character) {
// initial position of character: in the center of its cage
$center_x = ($c + 0.5) * $ccage_width;
$center_y = 0.5 * $height;
// get character dimensions for ttf fonts
if ($font != 'BUILTIN') {
$bbox = imagettfbbox($font_size, 0, realpath($font), $character);
}
// determine print position: at what coordinate should the character be
// printed so that the bounding box would be nicely centered in the cage?
$pos_x = $center_x - 0.5 * ($bbox[0] + $bbox[2]);
$pos_y = $center_y - 0.5 * ($bbox[1] + $bbox[7]);
// calculate available room to jitter: how much can the character be moved
// so that it stays inside its cage?
$dev_x = 0.5 * max(0, $ccage_width - ($bbox[2] - $bbox[0]));
$dev_y = 0.5 * max(0, $ccage_height - ($bbox[1] - $bbox[7]));
// add jitter to position
$pos_x = $pos_x + mt_rand(-$dev_x, $dev_x);
$pos_y = $pos_y + mt_rand(-$dev_y, $dev_y);
// calculate text color in case of randomness
if ($foreground_randomness) {
$color = imagecolorallocate($image, mt_rand($foreground_color_range[0][0], $foreground_color_range[0][1]), mt_rand($foreground_color_range[1][0], $foreground_color_range[1][1]), mt_rand($foreground_color_range[2][0], $foreground_color_range[2][1]));
}
// draw character
if ($font == 'BUILTIN') {
imagestring($image, 5, $pos_x, $pos_y, $character, $color);
}
else {
imagettftext($image, $font_size, 0, $pos_x, $pos_y, $color, realpath($font), $character);
}
// for debugging purposes: draw character bounding box
// imagerectangle($image, $pos_x + $bbox[0], $pos_y + $bbox[1], $pos_x + $bbox[2], $pos_y + $bbox[7], $color);
}
// return a sign of success
return TRUE;
}