Ticket #37690: 37690.patch

src/wp-admin/js/editor-expand.js

@@ -16 +16 @@
                         $textTop = $( '#ed_toolbar' ),
                         $textEditor = $( '#content' ),
                         textEditor = $textEditor[0],
+                        $textEditorClone = $textEditor.clone().attr({ id: 'content-clone', name: null }),
+                        textEditorClone = $textEditorClone[0],
                         oldTextLength = 0,
                         $bottom = $( '#post-status-info' ),
                         $menuBar = $(),
@@ -76 +78 @@
                 }
 
                 function textEditorResize() {
-                        if ( mceEditor && ! mceEditor.isHidden() ) {
+                        if ( ( mceEditor && ! mceEditor.isHidden() ) || ! textEditorClone ) {
                                 return;
                         }
 
@@ -89 +91 @@
                         var top = window.scrollTop;
 
                         if ( length < oldTextLength ) {
-                                // textEditor.scrollHeight is not adjusted until the next line.
-                                textEditor.style.height = 'auto';
+                                if ( oldTextLength - length === 1 ) {
+                                        textEditor.style.height = ( height - 19 ) + 'px';
 
-                                if ( textEditor.scrollHeight > autoresizeMinHeight ) {
-                                        textEditor.style.height = textEditor.scrollHeight + 'px';
+                                        if ( textEditor.scrollHeight > autoresizeMinHeight ) {
+                                                textEditor.style.height = textEditor.scrollHeight + 'px';
+                                        } else {
+                                                textEditor.style.height = autoresizeMinHeight + 'px';
+                                        }
                                 } else {
-                                        textEditor.style.height = autoresizeMinHeight + 'px';
+                                        textEditorClone.value = textEditor.value;
+
+                                        if ( textEditorClone.scrollHeight > autoresizeMinHeight ) {
+                                                textEditor.style.height = textEditorClone.scrollHeight + 'px';
+                                        } else if ( textEditorClone.scrollHeight < height ) {
+                                                textEditor.style.height = autoresizeMinHeight + 'px';
+                                        }
                                 }
 
                                 // Prevent scroll-jumping in Firefox and IE.
@@ -112 +123 @@
                         oldTextLength = length;
                 }
 
+                // Append the cloned textarea after the "real" one and move it off screen.
+                $textEditor.after( $textEditorClone.css({ position: 'absolute', left: '-10000em' }) );
+
                 // We need to wait for TinyMCE to initialize.
                 $document.on( 'tinymce-editor-init.editor-expand', function( event, editor ) {
                         var VK = window.tinymce.util.VK,