You'll need to rewrite the Mage_Sales_Model_Order_Pdf_Invoice
class from a module. Specifically the insertOrder
method located in the parent Mage_Sales_Model_Order_Pdf_Abstract
class.
It's a pretty big method to overwrite, specially for something cosmetic. Optionally see if you can change the Order #
string in the app/locale/[language]/Mage_Sales.csv
to fit your needs.
But, if you do want to rewrite the new class would look something like this
class MageSE_Rewritepdf_Model_Sales_Order_Pdf_Invoice extends Mage_Sales_Model_Order_Pdf_Invoice
{
/**
* Insert order to pdf page
*
* @param Zend_Pdf_Page $page
* @param Mage_Sales_Model_Order $obj
* @param bool $putOrderId
*/
protected function insertOrder(&$page, $obj, $putOrderId = true)
{
if ($obj instanceof Mage_Sales_Model_Order) {
$shipment = null;
$order = $obj;
} elseif ($obj instanceof Mage_Sales_Model_Order_Shipment) {
$shipment = $obj;
$order = $shipment->getOrder();
}
$this->y = $this->y ? $this->y : 815;
$top = $this->y;
$page->setFillColor(new Zend_Pdf_Color_GrayScale(0.45));
$page->setLineColor(new Zend_Pdf_Color_GrayScale(0.45));
$page->drawRectangle(25, $top, 570, $top - 55);
$page->setFillColor(new Zend_Pdf_Color_GrayScale(1));
$this->setDocHeaderCoordinates(array(25, $top, 570, $top - 55));
$this->_setFontRegular($page, 10);
if ($putOrderId) {
/**
* THIS IS WHAT YOU WANT TO CHANGE
*/
$page->drawText(
Mage::helper('sales')->__('Order # ') . $order->getRealOrderId(), 35, ($top -= 30), 'UTF-8'
);
}
[...]
// and the rest of the method
}
}
and the modules config.xml
like this
<?xml version="1.0"?>
<config>
<modules>
<MageSE_Rewritepdf>
<version>0.1.0</version>
</MageSE_Rewritepdf>
</modules>
<global>
<models>
<sales>
<rewrite>
<order_pdf_invoice>MageSE_Rewritepdf_Model_Sales_Order_Pdf_Invoice</order_pdf_invoice>
</rewrite>
</sales>
</models>
</global>
</config>