Bug 23015 – RenderTextControl relies on HTMLFormControlElement, making it hard to reuse for WML

• Component: Forms
• Status: RESOLVED FIXED

[Nikolas Zimmermann]

RenderTextControl relies on HTMLFormControlElement, and is not usable within WML at the moment.

One possibility would be to introduce a FormControlElement abstract class, containing two pure-virtual functions: setValueMatchesRenderer/valueMatchesRenderer, as these methods are in use from within RenderTextControl. As RenderObject stores a Node* pointer only, we'd also need to store a FormControlElement pointer in RenderTextControl, as we aren't allowed to cast node() to HTMLFormControlElement, as we want to abstract away the HTML-dependency.

As Node got enough unused bits left, it's easier to store "bool m_controlValueMatchesRenderer : 1" in Node and add non-virtual getter/setter methods. This way RenderTextControl saves all casts from Node -> HTMLFormControlElement and the HTML dependency is gone.

[Nikolas Zimmermann]

Created attachment 26283 [details]
Initial patch

[Sam Weinig]

Comment on attachment 26283 [details]
Initial patch

It's a little sad to be using bits in Node for something as rare as a RenderTextControl.  Otherwise, the patch seems fine. r=me

[Nikolas Zimmermann]

As discussed with Antti & Sam, adding memory to RenderTextControl is not as bad as adding too specialized data (only needed for form control elements) to Node. I'll upload a revised version, implementing my first idea: a shared ABC.

[Nikolas Zimmermann]

Created attachment 26285 [details]
Updated patch

Found a much nicer way to refactor, without adding any extra memory consumption.

[Nikolas Zimmermann]

Landed in r39495.