Support for cell comments in HTML writer and reader

The behavior is similar to what is done in LibreOffice. That means if there is a
comment it will be shown with a small indicator and the actual comment will be
revealed when mouse hover over the indicator.

Fixes #308
Closes #310

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- Support cell comments in HTML writer and reader- [#308](https://github.com/PHPOffice/PhpSpreadsheet/issues/308)
+
 ### Fixed
 
 - Better auto-detection of CSV separators - [#305](https://github.com/PHPOffice/PhpSpreadsheet/issues/305)

docs/references/features-cross-reference.md

@@ -1231,14 +1231,14 @@
         <td style="text-align: center; color: orange;">●</td>
         <td style="text-align: center; color: orange;">●</td>
         <td style="text-align: center;">N/A</td>
-        <td></td>
+        <td style="text-align: center; color: orange;">● <sup>1</sup></td>
         <td style="text-align: center;">N/A</td>
         <td></td>
         <td></td>
     </tr>
     <tr>
         <td style="padding-left: 1em;">Rich Text</td>
-        <td style="text-align: center; color: red;">✖ <sup>1</sup></td>
+        <td style="text-align: center; color: red;">✖ <sup>2</sup></td>
         <td style="text-align: center; color: green;">✔</td>
         <td style="text-align: center; color: red;">✖</td>
         <td style="text-align: center; color: red;">✖</td>
@@ -1256,7 +1256,7 @@
     </tr>
     <tr>
         <td style="padding-left: 1em;">Alignment</td>
-        <td style="text-align: center; color: red;">✖ <sup>2</sup></td>
+        <td style="text-align: center; color: red;">✖ <sup>3</sup></td>
         <td style="text-align: center; color: red;">✖</td>
         <td style="text-align: center; color: red;">✖</td>
         <td style="text-align: center; color: red;">✖</td>
@@ -1568,5 +1568,6 @@
     </tr>
 </table>
 
-1. Only BIFF8 files support Rich Text. Prior to that, comments could only be plain text
-2. Only BIFF8 files support alignment and rotation. Prior to that, comments could only be unformatted text
+1. Only text contents
+2. Only BIFF8 files support Rich Text. Prior to that, comments could only be plain text
+3. Only BIFF8 files support alignment and rotation. Prior to that, comments could only be unformatted text

src/PhpSpreadsheet/Reader/Html.php

@@ -312,6 +312,14 @@ class Html extends BaseReader
                     case 'em':
                     case 'strong':
                     case 'b':
+                        if (isset($attributeArray['class']) && $attributeArray['class'] === 'comment') {
+                            $sheet->getComment($column . $row)
+                                ->getText()
+                                ->createTextRun($child->textContent);
+
+                            break;
+                        }
+
                         if ($cellContent > '') {
                             $cellContent .= ' ';
                         }
@@ -354,6 +362,10 @@ class Html extends BaseReader
                                     }
 
                                     break;
+                                case 'class':
+                                    if ($attributeValue === 'comment-indicator') {
+                                        break; // Ignore - it's just a red square.
+                                    }
                             }
                         }
                         $cellContent .= ' ';

src/PhpSpreadsheet/Writer/Html.php

@@ -830,6 +830,25 @@ class Html extends BaseWriter
             $css['html']['background-color'] = 'white';
         }
 
+        // CSS for comments as found in LibreOffice
+        $css['a.comment-indicator:hover + div.comment'] = [
+            'background' => '#ffd',
+            'position' => 'absolute',
+            'display' => 'block',
+            'border' => '1px solid black',
+            'padding' => '0.5em',
+        ];
+
+        $css['a.comment-indicator'] = [
+            'background' => 'red',
+            'display' => 'inline-block',
+            'border' => '1px solid black',
+            'width' => '0.5em',
+            'height' => '0.5em',
+        ];
+
+        $css['div.comment']['display'] = 'none';
+
         // table { }
         $css['table']['border-collapse'] = 'collapse';
         if (!$this->isPdf) {
@@ -1385,6 +1404,8 @@ class Html extends BaseWriter
                 }
                 $html .= '>';
 
+                $html .= $this->writeComment($pSheet, $coordinate);
+
                 // Image?
                 $html .= $this->writeImageInCell($pSheet, $coordinate);
 
@@ -1646,4 +1667,26 @@ class Html extends BaseWriter
 
         return "<style>\n" . $htmlPage . $htmlBody . "</style>\n";
     }
+
+    /**
+     * Write a comment in the same format as LibreOffice.
+     *
+     * @see https://github.com/LibreOffice/core/blob/9fc9bf3240f8c62ad7859947ab8a033ac1fe93fa/sc/source/filter/html/htmlexp.cxx#L1073-L1092
+     *
+     * @param Worksheet $pSheet
+     * @param string $coordinate
+     *
+     * @return string
+     */
+    private function writeComment(Worksheet $pSheet, $coordinate)
+    {
+        $result = '';
+        if (!$this->isPdf && isset($pSheet->getComments()[$coordinate])) {
+            $result .= '<a class="comment-indicator"></a>';
+            $result .= '<div class="comment">' . nl2br($pSheet->getComment($coordinate)->getText()->getPlainText()) . '</div>';
+            $result .= PHP_EOL;
+        }
+
+        return $result;
+    }
 }

tests/PhpSpreadsheetTests/Functional/HtmlCommentsTest.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Functional;
+
+use PhpOffice\PhpSpreadsheet\RichText\RichText;
+use PhpOffice\PhpSpreadsheet\Spreadsheet;
+
+class HtmlCommentsTest extends AbstractFunctional
+{
+    private $spreadsheet;
+
+    public function providerCommentRichText()
+    {
+        $valueSingle = 'I am comment.';
+        $valueMulti = 'I am ' . PHP_EOL . 'multi-line' . PHP_EOL . 'comment.';
+
+        $plainSingle = new RichText();
+        $plainSingle->createText($valueSingle);
+
+        $plainMulti = new RichText();
+        $plainMulti->createText($valueMulti);
+
+        $richSingle = new RichText();
+        $richSingle->createTextRun($valueSingle)->getFont()->setBold(true);
+
+        $richMultiSimple = new RichText();
+        $richMultiSimple->createTextRun($valueMulti)->getFont()->setBold(true);
+
+        $richMultiMixed = new RichText();
+        $richMultiMixed->createText('I am' . PHP_EOL);
+        $richMultiMixed->createTextRun('multi-line')->getFont()->setBold(true);
+        $richMultiMixed->createText(PHP_EOL . 'comment!');
+
+        return [
+            'single line plain text' => [$plainSingle],
+            'multi-line plain text' => [$plainMulti],
+            'single line simple rich text' => [$richSingle],
+            'multi-line simple rich text' => [$richMultiSimple],
+            'multi-line mixed rich text' => [$richMultiMixed],
+        ];
+    }
+
+    /**
+     * @dataProvider providerCommentRichText
+     *
+     * @param mixed $richText
+     */
+    public function testComments($richText)
+    {
+        $this->spreadsheet = new Spreadsheet();
+
+        $this->spreadsheet->getActiveSheet()->getCell('A1')->setValue('Comment');
+
+        $this->spreadsheet->getActiveSheet()
+            ->getComment('A1')
+            ->setText($richText);
+
+        $reloadedSpreadsheet = $this->writeAndReload($this->spreadsheet, 'Html');
+
+        $actual = $reloadedSpreadsheet->getActiveSheet()->getComment('A1')->getText()->getPlainText();
+        self::assertSame($richText->getPlainText(), $actual);
+    }
+}