In Lumiera, "Tracks" are not what you'd expect from
conventional video editing software. They are a mere
grouping devide, and are also used to implement the
"media bins" and tool palettes.
But having "folders" on the timeline would be likewise
confusing, as would be to have a "branch" or "tree".
To get out of that dilemma, we chose an understandable
but deliberately somewhat strange name: "Fork"
It was common understanding on the Mailinglist that we
should handle this renaming in a tuned-down and discrete
way: The UI will continue to show "Tracks" for a familiar
sight and "Bins" in the Asset section. But Lumiera developers
will be nudged to accomodate by renaming the entity in
source code accordingly
Cockoo hashing is a thrilling algorithm.
We investigated it during the time or our first draft
towards a confirugation system in 2008. This usage turned
up some problems -- not sure if based on the implementation
or the algorithm itself; at that time, we just switched
to the probabilistic splay tree. The whole configuration
system effort stalled afterwards; so the cuckoo implementation
remained in tree as a zombie.
This switches the Lumiera UI from GTK-2 to GTK-3
Unfortunately, this move breaks two crucial features, which have been
disabled for now: the display of video and our custom timeline widget.
Since both of these require some reworking, which in fact has already
started, we prefer to do the library and framework switch right away.
over time, a specific Lumiera code writing style has emerged.
The GUI, as it stood, used somewhat different conventions,
which now have been aligned to the common standard.
Basically we use GNU style, with some adjustments for OO-programming,
we prefer CamelCase, and write TypeNames uppercase, variableNames lowercase
it is a widely accepted rule to shape names with the usage site in mind.
Especially this means, that we use the singular form for all kinds
of collections and assortments.
Thus, the namespace should be called "widget" not "widgets",
because at usage site this becomes gui::widget::TimelineWidget
Likewise for "dialogs" and "pannels"
a long standing TODO to document the actual start-up sequence, which
is implemented this way since a long time now. There was an unwritten
section in the "Linking and Application Structure", which seems the
apropriate place for this kind of intricate techincal details.
Last week, Benny Lyons was here on visit in munich and he was pondering
the idea of an experimental secondary build system, as a way to learn
more about the source structure of Lumiera. This reminded me to fill
some missing parts of the documentation. Possibly this is also the
right moment to land the GTK-3 transition?
The actual trick to make it work is to use decltype on the function operator
http://stackoverflow.com/questions/7943525/is-it-possible-to-figure-out-the-parameter-type-and-return-type-of-a-lambda/7943765#7943765
In addition, we now pick up the functor by template type and
store it under that very type. For one, this cuts the size
of the generated class by a factor of two. And it gives the
compiler the ability to inline a closure as much as is possible,
especially when the created Binder / Mutator lives in the same
reference frame the closure taps into.
to carry out that rather obvious step, I was bound to consider
all the implications of choosing a given layout and handling pattern
for our external structure representation.
Finally, I settled upon the following decisions
- the value space represented within the DataCap is flat, not further structured
- the distinction between "attribute" and "nested object" is merely conceptual
and will be enforced solely by the diff detection / representation protocol
- basically, a nested subtree may appear as an attribute; the difference
between attributes and children lies solely in the way of access and referral:
by-name vs. positional
- it is pointless to save space for the representation of the discriminator ID
- but we can omit any further explicit type tag, because
- we do *not* support programming by switch-on-type, and thus
- we do *not* support full introspection, only a passive type-safety check
- this is *not* a limitation, since we acknowledge that GenNode is a *Monad*
- and the partial function needed within any flatMap implementation
maps naturally onto our Variant-Visitor; thus
- the DataCap can basically just *be* a Variant
- and GenNode has just to supply the neccessary shaffolding
to turn that into a full fledged Monad implementation, including
direct construction by wrapping a value and flatMap with tree walk
All relevant uses will rely on the more strict access policy
implemented with the new util::AccessCasted. Along the same line
of thinking, I've removed the "second try" convenience conversion
from the typed get-Function of OpaqueHolder. Such an unbounded
"convert it somehow" approach is almost never a good idea. Either,
one knows by design the precise type to expect, or alternatively
should rely on the base interface solely.
...with the sole exception of the usage in WrapperPointer,
which in itself looks obsolete to me; we should better re-think
the way we handle "wrapped" objects for the BuilderTools, once
we actually start implementing the Builder
Ticket #450
Note: the new Variant implementation is a re-write from scratch
and does not rely on util::AccessCasted any more. Anyway, both
are now thoroughly covered by unit test
NOTE: this was a one-time verification. Unfortunately there is no way
to verify a failing compilation automatically from a unit-test.
Thus we need to comment out these invalid cases, leaving them
here just for later referral. Need to check those manually
for new compilers to be sure!
this overload will be picked only if none of the more specific
overloads is applicable. Instantiating this overload will then
trigger a static assertion failure. This way we sort out
impossible or dangerous combinations at compile time already.
I found no simple way to include the actual type parameters in
the generated error message (string concatenation at compiletime)
The throw-statement is only there to prevent a warning due
to missing return statement.
...since I consider that a comparatively safe convenience feature.
Of course we *do perform* a NULL check and throw an exception.
So now the actual casting or conversion functions are designed
to work always on the same level of references or pointers,
which means we can just use the standard conversions of the
language. This has the nice effect of ruling out dangerous
combinations (like taking a L-ref from a R-ref) automatically
TODO: might break some unit-tests...
Explanation: our wrapper around boost::format has special
built-in support for custom operator string(). Any type,
which is neiter standard, or printable through such a
custom string conversion, is represented as a type-string.
For this fallback case, we now use our recently added
demangling call (which actually relies on a rather obscure
but standard compiler API)
still passes compilation, but not actually tested.
The visitor-style accees needs to be implemented, and the
whole virtual copy support mechanism extracted into a separate
header and covered by unit test
now the solution with the copy policy class is in place,
I prefer to return to the more verbose yet clearer notion
of distinct constructors for each case on the outer and
the inner capsule likewise.
The idea with the separate builder class would be significant
only if this class would also provide the copy support. This
turns out to be difficult, due to the access restrictions
and the necessary passing of type parameters.
turns out to be quite a tough challenge....
since obviously we want to support usage of types with
partially disabled copy/assignment operations within Variant.
As long as the corresponding operations on the container aren't
invoked, we expect those types to be usable just fine.
The problem arises at the interaction with type erasure;
to support corret copy / assignement in such a situation, we need
virtual copy / assignment operators. And, since these are to be installed
into a VTable, the templated functions will be instantiated allways,
which might cause invocation of inhibited copy / assignement functions
and thus compilation failure, in spite of never actually invoking such
an illegal operation.
The drafted solution is to mix in a specifically configured copy support policy,
which at least raises a runtime error, instead of invoking the incriminating operation(s)
finally got all those copy / assgnment flavours straight.
Still unsolved: unable to instantiate the Variant template
for a type with private assignment operator (like e.g. Time )
The problem is our virtual assignement operator, which forces
instantiation of the implementation (for the VTable), even if
the actual assignment is never invoked.
this was an immature first desgin attempt; we need a lightweight
Variant (typesafe union) implementation, so now is the time for
a second attempt. The existing Variant is used only once, and this
usage as such is in a questionable context, likely to be reworked
when we actually start coding up the builder. So I'll just move
it away and mark it @deprecated for the time being.
After some reconsideration, I decide to stick to the approach with the closures,
but to use a metaprotramming technique to build an inheritance chain.
While I can not decide on the real world impact of storing all those closures,
in theory this approach should enable the compiler to remove all of the
storage overhead. Since, when storing the result into an auto variable
right within scope (as demonstrated in the test), the compiler
sees the concrete type and might be able to boil down the actual
generated virtual function implementations, thereby inlining the
given closures.
Whereas, on the other hand, if we'd go the obvious conventional route
and place the closures into a Map allocated on the stack, I wouldn't
expect the compiler to do data flow analysis to prove this allocation
is not necessary and inline it away.
NOTE: there is now guarantee this inlining trick will ever work.
And, moreover, we don't know anything regarding the runtime effect.
The whole picture is way more involved as it might seem at first sight.
Even if we go the completely conventional route and require every
participating object to supply an implementation of some kind of
"Serializable" interface, we'll end up with a (hand written!)
implementation class for each participating setup, which takes
up space in the code segment of the executable. While the closure
based approach chosen here, consumes data segment (or heap) space
per instance for the functors (or function pointers) representing
the closures, plus code segment space for the closures, but the
latter with a way higher potential for inlining, since the closure
code and the generated virtual functions are necessarily emitted
within the same compilation unit and within a local (inline, not
publickly exposed) scope.
so yes, it is complicated, and inevitably involves three layers
of indirection. The alternative seems to bind the GUI direcly to
the Session interface -- is there a middle gound?
For the messages from GUI to Proc, we have our commands, based
on PlacementRef entities. But for feeding model updates to the
GUI, whatever I consider, I end up either with diff messages or
an synchronised access to Session attributes, which ties the
responsiveness of the GUI to the Builder operation.
- we use a GenNode element
- this holds a polymorphic value known as DataCap
- besides simple attribute values, this may hold collections of GenNode sub elements
- a special kind of GenNode collection, the Record, is used to represent objects
The purpose of this setup is to enable an external model representation
which is only loosely coupled to the interndal data representation
through the exchange of (tree)diff messages
previously this operation was named 'attach', which an be confused
with attching an object to this location. Indeed, the session interface
even offers such an attach function. By renaming the focus moving
operation into QueryFocus::shift(Scope), this ambiguity is resolved
This is the first step towards a generic backbone to connect
any GUI elements to the session within Proc-Layer.
It is based on a spefic understanding of Model-View-Controller,
which turns the Model-Controller interactions into messages.
sans the implementation of the index lookup table(s)
The algorithm is KISS, a variant of insertion sort, i.e.
worst time quadratic, but known to perform well on small data sets.
The mere generation of the diff description is O(n log n), since
we do not verify that we can "find" out of order elements. We leave
this to the consumer of the diff, which at this point has to scan
into the rest of the data sequence (leading to quadratic complexity)
finally....
The problem is that the C++ "dependent types" defeat the typical
DSL usage, where you define some helper function in a generic
language setup class and mix this language in as superclass.
This is, C++ requires us to refer explicitly to any dependent type,
since, due to possible template specialisations, the parser
can't know if a given symbol is a inherited type or a field.
As a solution, we place the token constructor functors into a
static struct "token", which allows to write e.g. token.insert(xyz)
As decided in beb57cde
this changeset switches our basic list diff language to work
in the style of an insertion sort. Rather than 'pushing back'
out-of-order elements, we scan and bring forward missing elements.
Later, when passing the original location of the elements
fetched this way, a 'skip' verb will help to clean up
possible leftowers, so implementation is possible
(and indeed acomplished) without shifting any other elements.
and this adds a twist: conceptually, we identify the token
with the abstract handler function it represents. But C++
does not allow us to compare member pointers to virtual functions,
for good reason: even two pointers with the "same offset" into
the VTable might end up referring to different implementations,
when bound to instances of different subclasses. This is what
polymorphism is all about.
At this point it seems reasonably, albeit a bit uggly, to use the
diagnostic ID as placeholder instead, and just compare these IDs
instead. We assume that in practice tokens will be defined through
the provided helper macro, which ensures unique identifiers.
basically just a function to pick up the container and element type automatically.
The actual implementation is delegated to the exisiting lib::iter_stl::IterSnapshot
Heureka! found out that the C++ standard library exposes a
cross vendor C++ ABI, which amongst others allows to show
object code names and type-IDs in the language-level, human
readable unmangeld form.
Of course, actual application code should not rely on such a
internal representation, yet it is of tremendous help when
writing and debugging unit tests.
Signed-off-by: Ichthyostega <prg@ichthyostega.de>
Actually I arried at the conclusion, that the *receiving* of
a diff representation is actually a typical double-dispatch situation.
This leads to the attempt to come up with a specialised visitor
as standard pattern to handle and apply a diff. Obviously,
we do not want the classical GoF-Visitor, but (yes, we had
that discussion allready) -- well in terms of runtime cost,
we have to deal with at least two indirections anyway;
so now I'm exploring the idea to implement one of these
indirections through a functor object, which at the same time
acts as "Tag" in the diff representation language (instead
of using an enum as tag)
Uniform sequence at start of source files
- copyright claim
- license
- file comment
- header guard
- lumiera includes
- library / system includes
Lumiera uses Brittish spelling. Add an according note to the styleguide.
initial considerations; there is a concurrency problem, since
all of session handling within Proc is deliberately not threadsafe.
Thus the decision is to make this the gui::model::SessionFacade's responsibility
The actual problem is not resolved; the pluginloader
should detect the duplicate and not add the handle
to the database initially. Or it should add it
as "duplicate" or "alternate implementation"
Which probably means we need to coder some additional
corner cases. But certainly not now, we have other
more important stuff to do first... we've already
lost the battle against Duke Nukem Forever :-P
Mark parts of the timeline state handling which will certainly
not be retained: any part where the GUI widgets "hold" some kind
of model. GUI widgets shall be *mapped upon* a model representation
and *wired* with callbacks.
Especially I am suspicious when GUI presentation code "reaches into"
any kind of model data structure to find out something. It should
be the other way round (dont call us, we call you)
actually we should make our timeline a real custom widget,
and do it according to the letter. I.e. really implement
all those callbacks which are recommended, but no other
callbacks.
This has the additional benefit of being able to retrieve
the drawing style in the official way, and define our own
CSS classes, which can be styled by the user in a systematic way.
This is not really a solution, but kind of narrowes down the problem.
Our GUI uses an obsolete C-ish approach at releasing resources at
several points. This is probably a left-over from earlier days.
Especially since we started out with libGDL without C++ wrappers.
And at that time, we didn't use smart-pointers, as we should do,
but we tried to do things manually, which is an approach which never
works in an event driven and condition based environment. Goto fail.
Here I just commented out the manual clean-up code from several dtors.
The real solution would be not to allocate these resources through
the raw C calls at first place, but rather use the mm-wrappers
and leave it to them to unwind at the right moment.
TODO:
- scan the GUI code for *every* instance where we still muck around with gobjects
and either replace that by a mm-wrapper, or wrap it in a smart handle.
- make sure that *all* dtors are either empty, or really airtight and EX_FREE
doh...
this happens when you draft some quite intricate logic and then
get sidelined with other tasks for several years. Mind me, I didn't
even recall that I had treated this whole issue and created
a clean-up thread.
A full fledged implementation would have a real lifecycle and
thus detect the re-entrance; but since none of the components
to be managed by the OutputDirector is even remotely planned
or even coded, the functions were just drafted as stubs.
Which caused us happily to create yet another clean-up thread
whenever the subsystem-runner signalled "please shut down".
Our GUI shutdown logic looks rather confused. Why the hell do
some widgets "unregister" themselves in a dtor. This should never
be necessary. Maybe it's a leftover from C-style programming
and obsolete now, after the switch to GDLmm
the problem seems to be the interplay with the installed user
theme; what looks well with one theme is messed up with another
one, quite insidious.
Attempt to settle down on a set of default definitions
for borders and element background colors, which make the
Lumiera Gui "dark" but still respect the user's theme
for geometry and widget style
verified: basically works
todo: better handling of parse errors.
Currently this is treated as an unexpected exception and just
terminates the whole application, without any suitable diagnostics.
This makes working on the stylesheet somewhat brittle. GTK-3 actually
offers a signal to be invoked in case of CSS parsing errors
(see #953)
Comment out the active part of the GdkDisplayer implementation,
but retain the class, to make compilation pass.
With the Switch to GTK-3, only Cairo drawing is supported.
We need a new solution for video display...
Lots off commented out blocks of code
but most issues are related to simple function name changes,
set/get_flags calls, anything that has to do with a Gtk::Style...
Plan of attack from here is to go one-by one of each commented-out or code and update to gtk3 specs.
trying to track down where these messages
GLib-GObject-CRITICAL **: g_object_unref: assertion G_IS_OBJECT (object) failed
are coming from. These appear when iconifying panels.
as always, it turned out that the alledged "compiler bug"
rather was my own sloppyness: I forgot properly to undo a change
I made while fighting with compilation problems: the wrapper in
the factory didn't use std::forward, resulting in a plain flat
slicing copy. This, rightfully, triggered the assertion in the
session query resolver (since a sliced Goal can not be dynamic cast
to a specific Query subclass).
TODO: the toolfactory needs a redesign anyway,
this was just placeholder code added in a very early
state of the Lumiera project. We have way better memory
managing facilities at hand now
the use of a custom finisihing functor, which is applied
to any generated product. This can be used for registration,
memory management or similar framework aspects
Implement the first simple usage scenario for the
unified MultiFact template, using variadic templates.
NOTE:
- the obvious solution based on std::forward
triggers strange behaviour in GCC-4.7
- the inline lambda in the test case traps the
CLang-3.0 parster with a segfault. Horay!
...but the whole design looks still overengineered. See #388
- should get rid of the explicit specialisation
- always use a function signature and thus have arguments?
- why inheriting from the wrapper?
still puzzled why this instantiation of MultiFact fails to compile with GCC 4.8
so I'm bound to understand why the types involved
need indeed to be are structured the way they are right now.
previous versions used to resolve this ambiguity in favour of a ctor call,
but now the compiler treats such constructs as function definition;
this is reasonable, since C++11 introduced the notion of a "generalised
initialisation", which is always written as a (possibly empty) list
in braces.
In these specific cases here, we just omit the empty parens
Since we have now a generic bridge to supply std::hash functions based on
an exisiting boost::hash function, we removed the explicit std::hash
specialisation for "Placement-ID".
This caused the PlacementIndex implementation to fail at compilation
with a quite obscure error, which in fact seems to be caused by the
absence of any specific specialisation. The symptom is that a iterator
range could not be assigned to the predefined iterator type of
std::unordered_multimap, due to a mismatch in the embedded traits type
__umap_traits<__cache_default<_Key, _Hash>::value>>
While I didn't track down that problem entirely, to verify my hypothesis,
the problem can be avoided by using the default -- which is now to
pick up an existing boost::hash function for this type and use this
to generate the std::hash function.
right now we have to defeat an unfortunate static assertion in
the standard library, which is expected to go away in the future.
We use a hack to hijack the problematic definition with the preprocessor,
which requires our header to be first.
NOTE: this header contains a potentially dangerous, temporary workaround
to defeat the static assertion in the default implementation of std::hash,
as shipped with GCC 4.7.x
This assertion turns out to be detrimental all kinds of metaprogramming
based solutions, since it defeats SFINAE. It is expected to be removed
in GCC 4.8
the rules are:
- our own headers go before any library headers
- all headers need to be spelled relative to include root
- ensure that gtk is always included via gui/gtk-base.hpp
c++11 uses another hashtable implementation.
This uncovered some poorly written tests, which relied on
objects being returned in a specific order. As far as poissible,
we're using generic query functions now to get our test objects.
But these tests still rely on a specifically crafted test index content,
which as such is acceptable IMHO. The only remaining problem is
that we check the order of generated output in some tests, and this
order is still implementation dependent.
a real fix would be to rewrite the test to collect the retrieved
values and do a structural verification of the results. This
would mean to write a lot of code for such a marginal topic,
which was implemented just for sake of completenes anyway.
Hopefully my lack of "motivation" doesn't backfire eventually ;-)
Conversion means automatic conversion. In our case,
what we need ist the ability to *construct* a bool from
our (function) object -- while functors aren't automatically
convertible to bool. Thus we use one of the new predicates
from <type_traits>
...uncovered by switching to c++11
When invoking an individual test, we used to erase
the 0-th cmdline argument, which happens to be allways
the name of the test being invoked. Yet none of our
tests actually complied to that contract. Rather,
all tests taking arguments access them by 1-based
argument index. Previously, the argument values just
happened to be still in memory at the original location
after erasing the 0st element.
"Fixed" that by changing the contract. Now, the 0th argument
remains in place, but when there are no additional arguments,
the whole cmdline is cleared.
This is messy, but the test runer needs to be rewritten
entirely, the whole API is clumsy and dangerous. Ticket #289
* use a development snapshot of lib SigC including the recent C++11 adaptations
* never include whole namespaces. Here we got a clash between std::bind and sigc::bind
* use lambdas
* to make the binding code more readable
* to take the nested invocations apart, which resolves the return type ambiguity
In the November developer meeting, Christian and I agreed that
it's best to remove that offending LUID specifications altogether.
Those embedded LUIDs where one of the issues blocking the transition to C++11
This is a partial and preliminary fix; we had an occasional
numeric overflow on 32bit platforms in some tests.
The complete fix will be to introduce a typedef and then
rework the relevant APIs (which are preliminary anyway,
thus no urge right now)
our front-end for boost::format, the class lib::_Fmt
was lacking an reliable specialisation for long and ulong.
This is due to the notorious problem of these types being
of platform dependant size. As a fix, we're speclialising
explicitly for int16_t, int32_t and int64_t and avoid the
common names 'short', 'int' and 'long' alltogether.
And especially for non-64bit-platform (NONPORTABLE)
we add an explicit specialisation for long
The recommendation is to use the link flag --no-undefined
and to fed *all* dependencies to the respective link step.
This changeset enables this strict linking of dependencies.
It turned out that our dependencies were already sane
(with the sole exception of a direct dependency to X-Lib
in the XV viewer widget)
