PDF using Static Resource generated from REST doesn't display My Image

Question

I have different ways in my organization to generate my invoice pdf and attach it to my records. My PDF includes a logo stored in a public StaticResource. It works perfectly everywhere except when I generate my pdf from Apex REST, it doesn't display my logo :

Some Code :

@RestResource(urlMapping='/invoicereq/*')
global without sharing class InvoiceTemplateController
{
    @HttpGet
    global static void generateInvoiceAttachment()
    {
             ....
             //1. Generate & insert Invoice as an attachment
            PageReference pdf = new Pagereference('/apex/InvoicePDF?id=' + header.Id);
            Blob body = pdf.getContentAsPDF();

            Attachment attachment = new Attachment();
            attachment.Body = body;
            attachment.Name = 'Invoice ' + header.Name + '.pdf';
            attachment.IsPrivate = false;
            attachment.ParentId = header.Id;
            insert attachment;
            ...
    }
}

HTML

<img src="{!URLFOR($Resource.MyLogo)}" />

However if I use my logo as a Document with the same code, it works perfectly.

Any ideas why ?

Answer 1

Explicitly set renderAs to PDF on the Visualforce page. This must be hardcoded, and not come from a variable.

    <apex:page controller="myController" renderAs="PDF" >
        <img src="{!URLFOR($Resource.MyLogo)}" />
    </apex:page>

In your controller, call getContent, not getContentAsPDF:

att.body = pdf.getContent();

According to the documentation, the content will be "as displayed to a user in a Web browser," which will include your image.