new collapsible text box widget

app/View/CollapsibleTextBoxWidget.php

@@ -0,0 +1,80 @@
+<?php
+
+
+namespace App\View;
+
+/**
+ * Collapsible text box widget
+ */
+class CollapsibleTextBoxWidget
+{
+    private $maxHeight;
+    private $collapsing;
+    private $text;
+    private $srPrefix;
+    private $srEscape;
+
+    /**
+     * Add a prefix inside the text box shown only to screen readers, Lynx etc.
+     *
+     * @param string $content
+     * @param bool $escape - use html escape, default true
+     * @return $this
+     */
+    public function srPrefix($content, $escape=true)
+    {
+        $this->srEscape = $escape;
+        $this->srPrefix = $content;
+        return $this;
+    }
+
+    /**
+     * @param string $text - text to show
+     * @param int $thresholdLength - mb_character length that triggers the collapsible behavior; choose experimentally
+     * @param string $maxHeight - max height CSS value (e.g. 8em)
+     */
+    public function __construct($text, $thresholdLength, $maxHeight)
+    {
+        $this->text = $text;
+        $this->collapsing = mb_strlen($text) > $thresholdLength;
+        $this->maxHeight = $maxHeight;
+    }
+
+    private function processText($t)
+    {
+        $out = e($t);
+        $out = str_replace("\r\n", "\n", $out);
+
+        $out = '<p class="last-p-mb-0"> '.str_replace("\n\n",
+                " </p>". '<p class="last-p-mb-0"> ', $out).' </p>';
+
+        $out = nl2br($out);
+
+        $out = preg_replace('|(https?://[^\s]+)|i', '<a href="\1">\1</a>', $out);
+
+        return $out;
+    }
+
+    public function render()
+    {
+        $content = $this->processText($this->text);
+
+        $prefix = '';
+        if ($this->srPrefix) {
+            $prefix = '<span class="sr-only">'.
+                ($this->srEscape ? e($this->srPrefix) : $this->srPrefix).
+                '&nbsp;</span>';
+        }
+
+        if ($this->collapsing) {
+            return '<div class="block-collapse" style="max-height:'.$this->maxHeight.'">' . $prefix . $content . '</div>';
+        } else {
+            return $prefix.'<div>' . $prefix . $content . '</div>';
+        }
+    }
+
+    public function __toString()
+    {
+        return (string) $this->render();
+    }
+}

app/View/WidgetFactory.php

@@ -31,6 +31,11 @@ class WidgetFactory
             "</div>";
     }
 
+    public function collapsible($text, $thrSize, $maxHeight)
+    {
+        return new CollapsibleTextBoxWidget($text, $thrSize, $maxHeight);
+    }
+
     private function baseWidget($view, $name, $label)
     {
         return (new Widget($view, $name, $label))->layout($this->labelCols, $this->fieldCols);