Scribbling 3.0 Style

Just a quick update. Got a little farther with the samples the last couple evenings. Fixed up a few bugs causing some issues with a couple of the ones that already build, like native-instantiation.exe. Then I tore into Scribble.cs.

It was originally ported from a gtk example back in the early days. It may have been before we really had much subclassing support in Gtk#. I decided to see if gtk+ was still shipping the sample, and just do a clean port of the current sample instead of trying a minimal update.

The majority of the work needed to port the old sample to 3.0 boiled down to a Gdk.Pixmap to Cairo.Surface port. The ExposeEvent to Drawn event transition was needed as well. This is starting to sound a bit like a broken record, though I would imagine many readers have never heard a broken record.

But I digress.

The finished port of the gtk+ sample is now in master, along with all the fixes to the stack to expose some needed API that wasn't getting generated. The list of non-working samples is getting shorter.

More Progress

Been slogging along with the process of auditing API and fixing samples to compile and not crash instantly. Things got a whole lot more stable in the last couple evenings. I pushed a bunch of updates today that allow the cairo drawing sample in the Gtk# samples to run cleanly.

The configure now requires the gtk+-3.0.0 release since it has hit the streets. There was a bit of API churn between 2.99.0 and 3.0.0, which accounted for one of the more insidious crashes to track down. Geoff Norton helped me figure that one out today, and when I reparsed for the 3.0 API a lot of things fell into place.

The size negotiation and drawing API changes are going to make for a little work when people start switching over. These are the most common trip-ups I'm experiencing in the samples. Any custom widgets which overloaded Widget.OnSizeRequested in 2.x will need to pick one or more of the new negotiation VMs and port to them. For example, in the PolarFixed sample, I made the existing OnSizeRequested method private and delegated to it from new overrides for OnGetPreferredWidth and OnGetPreferredHeight.

In CairoSample, the only substantial change required was converting the old OnExposeEvent override to a new OnDrawn method. The new method utilizes the new AllocatedWidth and AllocatedHeight properties to obtain sizing info to pass into the rendering methods. Of course, the code was already drawing to a Cairo.Context, so the logic was ready to go. A widget using the Gdk drawing API, or Style painting may have substantially more work to make the shift.

I'll try to blog more impressions of the porting effort as I move through the samples, and I encourage anyone who decides to dig in with their own apps to try to capture the knowledge, be it by sending a message to gtk-sharp-list, blogging, or adding them directly to the porting guide I've started on the wiki.

Signs of Life

With gtk+ closing in on their 3.0 release, many folks have been inquiring about Gtk# 3 lately. We've had a number of offers to help as well. I've been tied up with another project at the ol' day job, but I've been dedicating a fair amount of evening and weekend time toward 3.0 bindings since the holidays. It also looks like I'm going to be getting some more cycles to push the effort forward in the near future.

Over the past couple evenings, I've pushed a series of commits to github.com which update master to a 2.99.x API level. Several of the samples are still not being built because of 3.0 API breakage. Most of the samples which currently build also run cleanly, but there are some crashes there to address as well.

I've temporarily created a cairo-sharp.dll from the copy of Mono.Cairo we have been carrying in the tree, with a few updates to expose some of the new 1.10 API. This will likely get merged back into the mcs/class tree, but it's a convenient place for us to move fast with fleshing out the new bits.

The generated APIs are completely unaudited at this point. The improvements in the external Gio and Builder bindings since they spun off remain unmerged. There is plenty of work to go around if people would like to jump in and help. We are going to need migration docs, new API docs, the list goes on...

Since people are likely wondering, the module still starts from a C parse. I have experimented with starting from GIR format but feel at this point, given the current tooling state, that it will be quicker to get to 3.0 using the existing GAPI parser for gtk-sharp. Since this is getting long already, I'll expand on the reasons in another blog, plus talk about the approach I think we can take to begin incorporating GIR as a starting point in new bindings.