Re: [Inkscape-devel] Hackfest 2018: Actions and Toolbars

If you want to hear and see Alex, Ryan, Bryce and Martin talk about this (and other Hackfest things), there's one more video on youtube (got posted to twitter, but not here yet, as far as I could see): youtu.be/IqQI2Y1PR38

Maren Am 31.03.2018 um 02:03 schrieb Alex Valavanis: > Hi All, > > Here's a summary of my work at the Boston Hackfest. > > Before I continue, I'd like to thank everyone who donated their money > or > time to support this Hackfest.  This has been a really useful event - > it's so much easier to deal with tricky design challenges and project > management stuff when we can meet face to face.  It has also brought > together people with very diverse expertise across the project (UI, > web, > build, extensions, project management etc).  This week, we've figured > out a path to deliver long desired features (multipage support etc), > roadmapped our final route to deliver Inkscape 1.0, done some great > website design work, and handled some tricky code structure issues > that > I'll discuss in this message. > > If you're able to donate some money to support Inkscape, and future > Hackfests, we really appreciate this.  You can find the donation link > on > our website: https://inkscape.org/en/support-us/hackfests/ > > It would also be great to get some more of the regular contributors > from > our wider community to join us at future events (i.e., designers, > bug-team, experienced users... not just C++ developers!).  The > developers can learn so much more about the project by discussing it > with you. > > So... what have I been doing this week? > > == What are Actions? == > > Basically, an "action" is a thing that Inkscape can do (e.g., flip an > object horizontally), which we can identify using an ID code (e.g., > "SP_VERB_OBJECT_FLIP_HORIZONTAL").  We can then hook up buttons, menu > items etc to activate these actions.  In this example, we would set up > our Flip Horizontal button in the select-tool toolbar so that when the > user clicks it, it activates the required action. > > My work this week has focused on improving the way we implement > actions > in our code, which will > > 1. Allow Inkscape to run on machines with future versions of the Gtk+ > library (Gtk 4+) > 2. Provide much better separation between the behaviour and user > interface (i.e.,, separate pieces of the code will describe what > Inkscape "does", and what it "looks like") > 3. Make it much easier to create new "flavours" of the Inkscape user > interface - for example, an "Inkscape for Kids" or "Inkscape CAD" > 4. Make it easier for "non-programmers" to create and reorganise > custom > toolbars and dialogs > 5. Allow us to remove a lot of older "C" code that is very difficult > for current "C++" developers to maintain > > == Where we are now? == > > In the Inkscape code, we have a mechanism called "verbs" that acts as > a > kind of action mechanism... it provides a way of using an ID code to > look up the required commands to perform an action. > > On top of this, we have another structure called SPAction that > essentially hooks up a couple of signals to the verb. > > Finally(ish), we use objects called GtkActions from the Gtk+ library, > which let us create GUI elements (buttons etc) that we can add to our > menus or toolbars that activate the required action. > > We have also got a few custom sub-classes of GtkAction that let us > create special kinds of tool-item that can activate actions... for > example, one of these creates a spin-button (a box with a number in > it, > and "up/down" arrows) that can also handle units, basic arithmetic, > and > provides a label. > > == What's the problem? == > > First, the GtkAction widget (and hence all our custom sub-classes) is > deprecated and has been removed from Gtk+ 4, so we need to change.  > Since Inkscape 1.0 is intended as a "stable" release, we want to make > it > as future-proof as possible. > > The main reason for this deprecation is that the GtkAction widget is a > slightly weird mix of paradigms: it mixes information about how to > display a tool/menu item with information about behaviour.  This > causes > some problems... what if we wanted to run a "headless" Inkscape on a > system that has no display?  What if we wanted to provide several > different GUI options for different kinds of user to trigger the same > behaviour? > > This is one of the reasons why we have the "verbs" system is in place, > as it separates behaviour from the GUI.  However, there is still quite > a > lot of code "overhead" needed if we want to hook up Inkscape's Verb > behaviour to a GUI element.  Essentially, it's "programmers only" > territory.  What if a designer wanted to add a new toolbar button to > their Inkscape to handle a useful feature that is currently buried > deep > in a menu?  What if a teacher wanted to strip out a lot of "advanced" > behaviour from the interface to make it easier to introduce Inkscape > to > their class?  At the moment, they have to edit the C++ code, and > recompile it... a slow and complicated process! > > == Where are we going? == > > We need to move to using GActions (a feature in the Glib/GIO > library).  > This *only* describes the action's behaviour and provides an > "activated" > signal that we can trigger by simply knowing the action's name.  This > is > completely separated from the GUI.  These actions can be activated > very > easily from a whole range of places, for example: > > 1. By attaching the action's name to a GUI element in the C++ code > (replacing our SPAction/GtkAction code) > 2. By activating the action (using its name) from a command-line > interface (replacing some of our verbs code) > 3. By attaching the action's name to elements in a customised GUI > file > 4. From external applications, using the DBus system > > Number 3 in the list provides some very exciting opportunities for > future releases, as non-programmers will be able to make a customised > user interface by drawing one in the Glade application.  You then just > attach the name of the required Inkscape action to each GUI element.  > Want a new button?  Just edit Inkscape's user-interface file in Glade > and see the changes immediately next time you start... no C++ > knowledge > needed! > > == What have I done so far? == > > I've started working through Inkscape's toolbars, and have replaced > the > deprecated GtkAction-based widgets with standard widgets (buttons > etc).  > Some of these now hook up to GAction descriptions of behaviour, while > others are just based on handling GUI signals (e.g., Button::clicked). > > So far, I have migrated the toolbars for the Select, Dropper and > Connector toolbar, and have killed off a couple of the custom > GtkAction-based widgets that were only used in these. > > In the process, I have also migrated the toolbar code to C++, which > should make it a little easier for the current core developers to > maintain.  Since all the data is now stored as C++ member variables, > rather than as GObject data, we now benefit from better compile-time > and > run-time type-checking that will help to safeguard against errors > being > introduced in the code in future. > > I have placed the updated toolbars in the Inkscape::UI::Toolbar > namespace and made them into proper sub-classes of the Gtk::Toolbar > class. > > == How can you help? == > > This important refactoring project must be done before Gtk+ 4 is > widely > used, and represents a major change to the way that our toolbars are > implemented.  It represents a couple of thousand lines of code changes > and will inevitably cause some regression bugs. I will need your help > in > thoroughly testing that all the toolbars work correcly! > > All of these changes are currently in a git branch > ("gtk-actions-migration") and will not be merged into the master > branch > until preliminary testing has been completed.  In other words, this > will > not "mess up" your stable version of Inkscape and will never be part > of > the current 0.92.x release series! I intend to merge this work well in > advance of the Inkscape 1.0 release, so that we have plenty of time > for > very thorough developer and user testing, and several preliminary > bug-fix "alpha" pre-releases before the final stable release. > > For the very brave: please checkout the "gtk-actions-migration" branch > in git, rebuild and test.  Please note that this is work-in progress.  > Do not use this experimental branch for your regular Inkscape drawing > work!!!  The Node toolbar will not work... the Select, Dropper and > Connector toolbars are highly experimental; all the other toolbars are > "at risk"!    If you don't know how to do this, check out our > developer > guide. > > For the quite brave: I'll merge this experimental branch into our > master > development branch in a few weeks once (a) I've completed the basic > work, (b) I've had a good amount of feedback on the branch and know > that > it "works" to some extent.  I'll message you again at this stage and > ask > everyone to help look for bugs.  Again, this will only be visible to > developers and users of our experimental "trunk" PPA in Ubuntu. > > For the intrepid: If you're interested in helping with the code > migration - message me and I'll help to divide up the tasks. > > == The end == > > I hope this gives an insight into the work I've started doing this > week, > and will continue over the coming weeks.  Thanks once again to > everyone > who has contributed time, money or even just attention and enthusiasm > for the Hackfest. > > Best wishes, > > > > Alex Valavanis (valavanisalex) > > Inkscape developer > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > > > > _______________________________________________ > Inkscape-devel mailing list > Inkscape-devel(a)lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/inkscape-devel > ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Inkscape-devel mailing list Inkscape-devel(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/inkscape-devel