[SalesForce] Apex & VF Code of Send Quote as E-Mail

I would parse the blob into a string and strip certain kinds of html tags for the following reasons :

1. PDF rendering doesn’t support images encoded in the data: URI scheme format
2. Don't use components that rely on JavaScript
3. Don't use components that depend on Salesforce stylesheets
4. tags that rely on JS or an external URI are going to confuse the PDF generator
5. a tag that refers to an external stylesheet that's not a static resource are also going to be problematic.

I suggest you look at Best Practices for Rendering PDF's in the APEX documentation and much of my reasoning will become readily apparent. Creating PDF's from known input data can be tricky enough as it is. Rendering them from other sources which you have no control over would be totally hit or miss without first stripping extraneous tags or links to embedded external content.

Do you have a custom controller for your Quote PDF generator? If not, you can easily create one by creating an extension of the existing one that has a boolean object linked to a checkbox. If the checkbox is true, then the PDF is created, if it's false, then the PDF is aborted. Before any work is done, the controller checks the status of the custom boolean object.

I'm sure you could similarly add that kind of logic into the VF page by adding a validation rule to the checkbox, but I've never done it that way myself. Or, as you've suggested, this could also be done via JavaScript by checking the state of the checkbox.