Implement beforeRender and afterRender events

Author: mikehaertl

README.md

@@ -74,6 +74,13 @@ Property | Description
 `startColumn` (optional) | The start column name or its 0-based index. When this is set, the 0-based offset is added to all numeric keys used anywhere in this class. Columns referenced by name will stay unchanged.  Default is 'A'.
 `startRow` (optional) | The start row. Default is 1.
 
+
+Event | Description
+---------|-------------
+`beforeRender` | Triggered before the sheet is rendered. The sheet is available via `$event->source->getSheet()`.
+`afterRender` | Triggered after the sheet was rendered. The sheet is available via `$event->source->getSheet()`.
+
+
 ### ActiveExcelSheet
 
 The class extends from `ExcelSheet` but differs in the following properties:
@@ -290,3 +297,24 @@ $file = \Yii::createObject([
 ]);
 ```
 
+### Events
+
+Since version 2.3.5 there are new events which make it easier to further modify each sheet.
+
+```php
+<?php
+$file = \Yii::createObject([
+    'class' => 'codemix\excelexport\ExcelFile',
+    'sheets' => [
+        'Users' => [
+            'class' => 'codemix\excelexport\ActiveExcelSheet',
+            'query' => User::find(),
+            'startRow' => 3,
+            'on beforeRender' => function ($event) {
+                $sheet = $event->source->getSheet();
+                $sheet->setCellValue('A1', 'List of current users');
+            }
+        ],
+    ],
+]);
+```

src/ExcelSheet.php

@@ -1,13 +1,16 @@
 <?php
 namespace codemix\excelexport;
 
-use yii\base\Object;
+use yii\base\Component;
 
 /**
  * An excel worksheet
  */
-class ExcelSheet extends Object
+class ExcelSheet extends Component
 {
+    const EVENT_BEFORE_RENDER = 'beforeRender';
+    const EVENT_AFTER_RENDER = 'afterRender';
+
     /**
      * @var int|string the start column name or its 0-based index. When this is
      * set, the 0-based offset is added to all numeric keys used anywhere in
@@ -184,10 +187,28 @@ public function setCallbacks($value)
      */
     public function render()
     {
+        $this->beforeRender();
         $this->_row = $this->startRow;
         $this->renderStyles();
         $this->renderTitle();
         $this->renderRows();
+        $this->trigger(self::EVENT_AFTER_RENDER);
+    }
+
+    /**
+     * Trigger the [[EVENT_BEFORE_RENDER]] event
+     */
+    public function beforeRender()
+    {
+        $this->trigger(self::EVENT_BEFORE_RENDER);
+    }
+
+    /**
+     * Trigger the [[EVENT_AFTER_RENDER]] event
+     */
+    public function afterRender()
+    {
+        $this->trigger(self::EVENT_AFTER_RENDER);
     }
 
     /**