Added support for cell formats when writing Excel files

src/Spout/Writer/Common/Creator/Style/StyleBuilder.php

@@ -147,6 +147,18 @@ class StyleBuilder
 
         return $this;
     }
+    /**
+     *  Sets a format
+     *
+     * @api
+     * @param string $format Format
+     * @return StyleBuilder
+     */
+    public function setFormat($format)
+    {
+        $this->style->setFormat($format);
+        return $this;
+    }
 
     /**
      * Returns the configured style. The style is cached and can be reused.

src/Spout/Writer/Common/Manager/Style/StyleMerger.php

@@ -88,6 +88,9 @@ class StyleMerger
         if (!$style->getBorder() && $baseStyle->shouldApplyBorder()) {
             $styleToUpdate->setBorder($baseStyle->getBorder());
         }
+        if (!$style->getFormat() && $baseStyle->shouldApplyFormat()) {
+            $styleToUpdate->setFormat($baseStyle->getFormat());
+        }
         if (!$style->shouldApplyBackgroundColor() && $baseStyle->shouldApplyBackgroundColor()) {
             $styleToUpdate->setBackgroundColor($baseStyle->getBackgroundColor());
         }