Katsushi Kawamori

<h4>Integrates Canvas into WordPress.</h4>
<ul>
<li>Provide canvas shortcode.</li>
<li>Provides a filter hook when saving the canvas.</li>
<li>It supports both mouse and touch.</li>
<li>It supports both the management screen and the public screen. The appearance of buttons and select boxes on the public screen depends on the CSS of the theme.</li>
</ul>
<h4>How to use the canvas</h4>
<span class="embed-youtube" style="text-align:center; display: block;"><iframe class="youtube-player" width="640" height="360" src="https://www.youtube.com/embed/_9XWJJbY6mQ?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation"></iframe></span>
<h4>Sample of how to use the filter hook</h4>
<ul>
<li>Shortcode for canvas display</li>
</ul>
<pre><code>echo do_shortcode( '[freecanvas height=500]' );
</code></pre>
<ul>
<li>shortcode<br />
Attribute : Default : Description<br />
width : 700 : Canvas width<br />
height : 700 : Canvas height<br />
name : The date and time string when the canvas was loaded : Unique name for this canvas<br />
form_name: null : The name of the form value you want to get<br />
form_name2: null : The name of the form value you want to get<br />
form_name3: null : The name of the form value you want to get</li>
<li>Filter hook & Function</li>
</ul>
<pre><code>/**
 * Filter hook & function for outputs a PNG image file */
 *
 * @param string $image_data  image_data.
 * @param string $name  name.
 * @param string $form_value  form_value.
 * @param string $form_value2  form_value2.
 * @param string $form_value3  form_value3.
 */
function canvas_save( $image_data, $name, $form_value, $form_value2, $form_value3 ) {
    $wp_uploads = wp_upload_dir();
    $relation_path_true = strpos( $wp_uploads['baseurl'], '../' );
    if ( $relation_path_true > 0 ) {
        $upload_dir = wp_normalize_path( realpath( $wp_uploads['basedir'] ) );
    } else {
        $upload_dir = wp_normalize_path( $wp_uploads['basedir'] );
    }
    $filename = $upload_dir . '/' . $name . '.png';
    $image = imagecreatefromstring( $image_data );
    imagepng( $image, $filename );
}
add_filter( 'free_canvas_save', 'canvas_save', 10, 5 );
</code></pre>
<ul>
<li>Filter hook<br />
Variable : Description : From<br />
$image_data : PNG image data by Base64 : Value of Canvas<br />
$name : Unique name for this canvas : Value of Free Canvas<br />
$form_value : Form value obtained from form_name : Value of Form<br />
$form_value2 : Form value obtained from form_name2 : Value of Form<br />
$form_value3 : Form value obtained from form_name3 : Value of Form</li>
</ul>


Free Canvas

Provide a canvas. Various cooperation is possible by shortcode and filter.

luileito

<p>μcaptcha is a math handwriting captcha scheme for touch-capable devices. Instead of entering text with a keyboard, you just retype a mathematical expression shown on a web canvas. μcaptcha belongs to the set of protocols called HIPs (Human Interactive Proofs), which allow a person to authenticate as belonging to a select group; e.g., human as opposed to machine, adult as opposed to a child, etc.</p>
<p>μcaptcha allows you protect your online forms from illegitimate access or abuse. Furthermore, as a byproduct of solving μcaptchas, a valuable labeled dataset of online handwritten math expressions is collected. μcaptcha is thus channeling the users’ effort into creating valuable resources for machine learning. <a href="https://mucaptcha.com/faq.html" rel="nofollow ugc">Learn how μcaptcha works</a></p>
<h3>Requirements</h3>
<ol>
<li>You need the μcaptcha API keys. <a href="https://api.mucaptcha.com" rel="nofollow ugc">Get them here</a>.</li>
<li>Your server must have <a href="http://php.net/manual/book.curl.php" rel="nofollow ugc">the cURL library</a> installed. Most servers do.</li>
</ol>
<h3>Translations</h3>
<ul>
<li>English (default)</li>
<li>Español (es_ES)</li>
<li>Català (ca_ES)</li>
<li>Other languages? – <a href="https://github.com/luileito/mucaptcha-wordpress/pulls" rel="nofollow ugc">Just make a pull request</a></li>
</ul>


μcaptcha

Integrates μcaptcha with WordPress, including comment and login/registration forms.

Free Canvas vs μcaptcha