Updated codeblock editor to work with fade animation

- Added fadeIn to animation JS service.
- Updated overlay to use anim service and to recieve a callback for
after-anim actions.
- Updated code editor popup to refresh Codemirror instance layout after
animation has completed.

Fixes #1672

resources/js/services/animations.js

@@ -5,6 +5,22 @@
  */
 const animateStylesCleanupMap = new WeakMap();
 
+/**
+ * Fade in the given element.
+ * @param {Element} element
+ * @param {Number} animTime
+ * @param {Function|null} onComplete
+ */
+export function fadeIn(element, animTime = 400, onComplete = null) {
+    cleanupExistingElementAnimation(element);
+    element.style.display = 'block';
+    animateStyles(element, {
+        opacity: ['0', '1']
+    }, animTime, () => {
+        if (onComplete) onComplete();
+    });
+}
+
 /**
  * Fade out the given element.
  * @param {Element} element

resources/js/services/code.js

@@ -258,10 +258,18 @@ function setMode(cmInstance, modeSuggestion, content) {
 function setContent(cmInstance, codeContent) {
     cmInstance.setValue(codeContent);
     setTimeout(() => {
-        cmInstance.refresh();
+        updateLayout(cmInstance);
     }, 10);
 }
 
+/**
+ * Update the layout (codemirror refresh) of a cm instance.
+ * @param cmInstance
+ */
+function updateLayout(cmInstance) {
+    cmInstance.refresh();
+}
+
 /**
  * Get a CodeMirror instance to use for the markdown editor.
  * @param {HTMLElement} elem
@@ -301,6 +309,7 @@ export default {
     popupEditor: popupEditor,
     setMode: setMode,
     setContent: setContent,
+    updateLayout: updateLayout,
     markdownEditor: markdownEditor,
     getMetaKey: getMetaKey,
 };