> As discussed in another message, I don't think we should mess with
> `org-latex-compile'. Instead, we could factor out the needed part in
> `org-latex-compile' and make it a generic function. Then we can
> introduce a new function to specifically handle previewing related
> compilation.
>
> Note that I'm not asking you to implement the factoring out part in your
> patch, but to tell me if the following would fulfill your needs for
> `org-create-formula-image'. I'm sending its docstring again.
>

I have rebase my patch to new function org-compile-file, the v8 patch is
very different with the earlier version, it is more simpler i think,
please comment again, thanks for your help!