[Geany-Devel] splitwindow2

[Thomas Martitz]

Am 11.10.2013 00:55, schrieb Matthew Brush:
> On 13-10-10 03:03 AM, Thomas Martitz wrote:
>> Hello,
>>
>> I just wanted to let you know that I'm working on a new splitwindow
>> implementation and I would like to have early input. But, also as a
>> warning, I'm progressing only slowly because I'm at the final phase of
>> my master thesis which currently needs more attention that Geany 
>> hacking.
>>
>> Anyway, we all know about the limitations of the splitwindow plugin.
>> They include (not a complete list):
>> - the other view can only have one document
>
> You can actually change which document it shows by using the little 
> drop-down button at the top. Still, real notebooks would be nicer.

Yea, right. I worded it badly. I meant the other view can only hold one 
document and you can swap that one only using non-standard methods.

>
>> - you cannot undo/redo: you need to select the tab in the main notebook
>> to do that
>
> You can undo using the builtin Scintilla right-click context menu, but 
> still would be great to have full keybindings+edit menu functionality.

Oh, I wasn't aware of that. Still crap :)

>
>> - state is not saved/restored across Geany restarts
>> - it's completely awkward because the other view shows a doc that's also
>> in the main view, editing in the other view will change the main view at
>> the same time.
>
> I think this is intended and I find it useful personally. I don't 
> think it should be taken out, IMO.

>
>> - you cannot toggle between the views with a keybinding (e.g. ctrl+tab)
>> - weird focus behavior
>> - more...
>
> ...Basically all edit keybindings, the edit/context menu and also 
> auto-indentation and similar features implemented inside Geany.
>
>>
>> My plan is to reimplement splitwindow using a different approach: by
>> having two real, independemt notebooks, one primary and one seconary.
>>
>
> Why limit it to two? Even if it ends up being the default/primary mode 
> of operation, IMO it'd be a shame to make another hard-coded 
> assumption.[1]

Well, first: I'm not going to be hardcode two notebooks (except where 
necessary and trivial extend, e.g. for my current "toggle this between 
notebooks". 99% of the now hardcoded places will work fine, e.g. I'm 
using gtk_widget_get_parent(sci) to get a doc's notebook and implement a 
foreach_notebook() macro. So this should make it really trivial to 
support even more than 2 notebooks.

But still, I personally don't have a need for more than 2 notebooks. 
Plus I see it will be difficult to support, because you need to nest 
GtkPaneds. Since you suggest arbitrary splits you can do this only 
programmatically which sounds like a major headache to me (especially 
w.r.t. saving/restoring state). For now I want to concentrate on lifting 
the hardcoded single notebook without ending up in the same situation 
for two ones and without worrying about the heavy case of arbitrary 
notebook placing. Then we can continue from there on with more 
sophisticated stuff.

However if you have already successfully implemented this in a toy 
editor I welcome you to join the fun.


>
>> New docs will be opened in the primary one by default, but can be moved
>> to the secondary one at will. This means that no document can be shown
>> in both at the same time which makes it a loss less awkward. It also
>
> As mentioned above, this is actually a feature and IMO it should be 
> kept unless there is some serious technical reason that makes it 
> impossible. Scintilla can easily be showing the same document in two 
> views and it keeps them in sync (see SCI_SETDOCPOINTER and friends).


Do you edit on both views or just read on one part of the doc while 
editing the other? If this works automagically via scintilla then fine 
but I can imagine it has more implications/complications apart from 
Scintilla. Thus for me this has low priority so I would like to get the 
non-duplicate docs use case working first.

>
>> lets us lift the other limitations:
>> - undo/redo will work
>> - state can be saved across restarts (config file format will probably
>> need some changes for this)
>> - toggling with keybindings between views can work
>> - you can arbitrarily assign docs to views using different methods
>>
>> The nice things about splitwindow that should be probably be kept:
>> - chose between horizontal and vertical split
>> - automatic sizing of the views
>
> Just to be clear, because Lex's message made it sound like it was 
> slightly magic; it's just the width/height available divided by two 
> right now IIRC (which is fine IMO). With your above item about saving 
> state, hopefully it would include the splitter positions, but I guess 
> it's not a big deal if not.

Automatic sizing also includes what to do if one or both of the 
notebooks becomes empty, a previously empty one becomes non-empty or how 
to deal with the user making non-50/50 splits. Although I'm not even 
sure the current splitwindow handles all cases well?

>
>> - anything else?
>>
>
> Even though I usually rant against hard-coding language specific stuff 
> into the core, I think it would be extremely useful to have an option 
> to open header/implementation file in the other view. For example if 
> I'm editing foo.c, it could look for foo.h (either being open or in 
> same directory), and open it in the other view. It could work the 
> other way around as well. I think it'd probably only be really useful 
> for C, C++ and Obj-C filetypes, although I don't know that many 
> languages, so aybe some others could benefit as well.

This is provided by two plugins already. I think those plugins should be 
able to show the header on the other notebook once they are adapted for 
multiple notebooks. I also think of other use cases, e.g. geanyvc 
opening the file diff/log/blame of the current file in the other notebook.

>
>> Unfortunately Geany's core is pretty hardcoded as to assume one (and
>> only one) notebook for documents. This means that for this various
>> changes to Geany core are necessasry, some of which may be difficult to
>> do without breaking the plugin API/ABI. Some are gonna hate this but I'm
>> not currently planning do this as a plugin because the core needs a lot
>> of changes anyway for breaking the single notebook assumption. But I'm
>> very open for discussion which is why I'm writing this early.
>>
>
> I agree it should be a core feature and a lot of users (myself 
> included) consider it a critical feature. I think it could be done 
> without breaking too much in the plugin API except a few functions 
> like document_compare_by_tab_order() and document_get_notebook_page() 
> and stuff, but maybe I'm missing something.


One problem is that there are some document_* functions which only refer 
to page numbers. These are ambiguous with two (or more) notebooks. So 
plugins that call this might act up. For now I changed these functions 
to use the notebook that's currently focused but I of course added 
corresponding functions with an explicit notebook parameter too.

There are also many direct uses of main_widgets.notebook, changing these 
might (or might not) affect plugins.


>
>> I already have an experimental version up and running that doesn't even
>> require all that much changes[1] and it seems to work nicely. See
>> this[2] screenshot.
>>
>> So, any opinions?
>>
>
> It sounds like you already are planning some of this, but it would be 
> nice to cleanup a lot of the assumptions/hardcoded stuff/weirdness 
> while making these fairly intrusive changes. For example:
>
> - The relationship between documents and notebooks they're in, as you 
> discussed. As Lex mentioned, it would be nice to not make too much new 
> hard-coded assumptions about other documents only being allowed in 
> another notebook, but rather making it extensible to support multiple 
> windows in the future. Also as I mentioned, it would be nice to not 
> make any hard-coded assumptions about only having two split notebooks[1].

The notebook of a doc can be retrieved via 
gtk_widget_get_parent(doc->editor->sci) without hardcoding. I'm using 
this where possible.

> - The relationship between documents (models) and Scintilla (views), 
> they should be almost completely independent. There shouldn't need to 
> have document->editor->scintilla, the document needn't care what view 
> it's in, only the reverse. I have no idea where GeanyEditor fits into 
> this, I've never understood why it exists; it's not a view, it's not a 
> model, and it's not really a controller either, it's like part wrapper 
> over Scintilla, part extension of GeanyDocument or something like this 
> I guess?

Sorry, I think this item is out of scope for this work. FWIW, I don't 
quite understand the deal about GeanyEditor either.

> - The lifetimes of documents. I don't see any reason to recycle a 
> fairly small structure like GeanyDocument, especially since we 
> basically set it up and tear it down each time anyway. I doubt the 
> overhead of freeing an old GeanyDocument structure and allocating a 
> new one later is worth the contortions it causes in code and the 
> weirdness in the plugin API.

Seems completely unrelated to splitwindow.

> - This follows with above, document_get_current() should *never* 
> return NULL. It makes absolutely no sense to me to allow having Geany 
> open without a document open. It'd be like having Firefox open with no 
> tabs/webpages open. Either it should open a blank untitled document 
> when the last one closes (this option exists already IIRC) or Geany 
> itself should just close (probably too annoying :) These last two 
> would get rid of weirdness like doc->is_valid, DOC_VALID(), 
> "documents" macro wrapping documents_array, foreach_document() macro 
> to iterate documents, etc.

Also unrelated.

> - Encapsulating the GeanyDocument so that plugins can't mess with 
> read-only members. For example, it makes no sense to allow plugins to 
> change doc->read_only, or doc->file_name (one of them actually does 
> this). It would be nice to make the API consistent here, like we have 
> document_set_text_changed() to mark the document as ditry/clean, but 
> there's no getter like document_get_text_changed(), which is 
> inconsistent and it allows plugins to seriously break Geany if they 
> aren't careful. This one is of course fairly off-topic and could be 
> attacked separately afterwards, I just thought it was worth mentioning 
> since you talked about needing to break the plugin API, it might be 
> useful to improve it during the breakage.
>

Also unrelated. I agree that big API breakage should be as rare and 
concentrated as possible (i.e. within a single release) but not as part 
of a single change. Let's not blow this splitwindow work up with 
unrelated changes. This would just make review impossible and cost more 
time to get done.


> I actually use the current crippled split view *extensively* so I 
> would also be really interested in helping out with this. If it was 
> useful we could make a branch on the main repository to work from and 
> get more visibility with it probably.
>

Fine with me. You can also make PRs on my github until this is set up 
(but beware that I still amend and rebase) :)


> Cheers,
> Matthew Brush

Thanks for your input.

Best regards.
Thomas Martitz