'Re: [Gimp-developer] I am hoping to contribute to GIMP. I have some ideas, but I want input if possi'

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List:       gimp-developer
Subject:    Re: [Gimp-developer] I am hoping to contribute to GIMP. I have some ideas, but I want input if possi
From:       Jehan Pagès <jehan.marmottard () gmail ! com>
Date:       2013-12-09 3:56:19
Message-ID: CAFgjPJ8CZAqkqTY=q416KjF_+NdYid3LWNa3iEzccNGs4LK-7Q () mail ! gmail ! com
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Hi,

On Mon, Dec 9, 2013 at 4:35 PM, DeVonte Applewhite <dapplewh@nd.edu> wrote:
> Hello,

First of all, do not send emails to only me please. You are lucky I
check my emails regularly and in particular answer them. Also I am not
the one who knows the code the best. If you really want answers, you
should send to the whole list. I added it in Cc.

> I am trying to just test out the gimpmath portion of the libgimpmath
> folder. It has the vectors, matrices and other math-related functions in it.
> I want to just take the contents of this folder, put these contents in a
> temporary folder that is inside this folder. I'll name that folder temp.
> then, I want to change the implementation of one of the .c files and test it
> with a driver program to see the individual functions get invoked. However,
> I am having a hard time compiling this setup because at times I am not
> including certain libraries and I do not know the exact location of the
> gdouble and gint variables that these programs use. Here is my makefile so
> far. mygimpvector.c is my implementation of the gimp vector.c program. Right
> now, mygimpvector.c is identical to gimpvector.c except for its name being
> different. Do you have any ideas?
> test: mattest.c mygimpmatrix.c
> gcc `pkg-config --cflags --libs glib-2.0` mattest.c mygimpmatrix.c -Wall
>
> Thanks in advance and hope to hear from you soon.

I don't really understand what you are speaking about. Are you
modifying core GIMP code (which last time we talked was your project)
or just testing out existing libgimp in say a C plugin?

As for all the g* types (gint, gdouble...), they are glib types, so
you have to find the adequate glib header to include, but I'm not sure
either that is what you are asking me about.

As for your mygimp* files, are they simply reimplementation of the
gimp* files similarly named? If so, why do you even bother making a
separate file? Why don't you modify inline the existing file, so that
you don't have to bother for modifying Makefiles? (you can always keep
a copy of the current files if you need side-by-side comparison, but
the new implementation should go in the gimp* files)

Also are you trying to modify directly Makefile-s (instead of
Makefile.am) and using bare gcc command lines there? This is a very
non-portable and broken way. No wonder you have issues. Look the
Makefile.am files and try to understand how these work (you can also
look for automake tutorials) if really you need to edit the
compilation.
But as I said earlier, if the goal is only to provide a new
implementation of an existing API, you should not have anything to do
to modify the build.

Jehan

>
>
> On Sun, Nov 17, 2013 at 7:24 PM, DeVonte Applewhite <dapplewh@nd.edu> wrote:
>>
>> Thanks!!! Ah, now I understand. Our initial understanding was that since
>> some parts were made in C++ there would be reason for doing more C++ coding
>> in place of a few C code files. Thank you for clarifying that this plan has
>> large problems and that it would not be merged to the main program
>> (upstream). I think that the brushes are definitely a good route to look
>> into . Thank you for the reference link. Yes, we do not have a large chunk
>> of time, but we definitely will try to spend it as effectively as we can. I
>> will try the IRC channel. It sounds like something I could definitely use
>> since GIMP is a large project that can be overwhelming to understand at
>> once. Glad people are happy and available to discuss questions, suggestions
>> and such. I think my group can make a plan based on this information for
>> sure. Thanks again.
>>
>>
>> On Sun, Nov 17, 2013 at 6:38 PM, Jehan Pagès <jehan.marmottard@gmail.com>
>> wrote:
>>>
>>> Hi,
>>>
>>> On Mon, Nov 18, 2013 at 12:09 PM, DeVonte Applewhite <dapplewh@nd.edu>
>>> wrote:
>>> > Thank you for your response. We have used your input to clarify our
>>> > direction on this project. What do you think of this.
>>> > 1. We will try to make a c++ implementation of gimpvector where we
>>> > overload
>>> > operators and try to string the executable together so that it
>>> > compiles.
>>>
>>> As Sven also answered on the mailing list, GIMP is written in C, not
>>> C++. And even though it may happen that some components may be written
>>> in C++ if really it helped somehow (for instance when using some third
>>> party library in C++ which is the best at what it does), I'm pretty
>>> sure our maintainer won't accept any base class in C++, especially for
>>> no reason.
>>>
>>> Now if that's just for the fun of the experiment and the sake of your
>>> class project, go ahead. :-) But don't have your expectations too
>>> high, because such code may never make it upstream.
>>>
>>> > 2. We will try to make a c++ implementation of gimpmatrix where we
>>> > overload
>>> > operators and try to string the executable together so that it
>>> > compiles. We
>>> > will also see if we can generalize some of the code that implements
>>> > operators.
>>>
>>> Same as above.
>>>
>>> > 3. We will attempt to fix at least one bug. If we can handle that, we
>>> > will
>>> > try to do more bugs given enough time before the project's due date.
>>>
>>> Cool.
>>>
>>> > 4. We are trying to add a new feature to Gimp. It will be something
>>> > small,
>>> > but we still want to do something that will be interesting. We were
>>> > thinking
>>> > of looking into the filters or brush shapes to see what can come of
>>> > that.
>>>
>>> I understand that bug fixes are not sexy and you want something cooler.
>>> :-)
>>> Well there are so many wanted features that it is hard to give advice.
>>> About brush, I know there are some plans on supporting more brush
>>> engine (in particular by using libmypaint, if not mistaken). Maybe
>>> that's a path to follow if you want to improve brushes?
>>> You may have an idea of the biggest planned features there:
>>> http://wiki.gimp.org/index.php/Roadmap
>>> Though if you have other ideas, we are always happy to consider
>>> interesting new concepts.
>>>
>>> But the best would be to come on GIMP's IRC where most of the devs are
>>> hanging around (respectively in their timezones): #gimp on
>>> irc.gimp.org
>>> There you may ask questions if you have any, if you don't understand
>>> something, or want to propose, etc.
>>>
>>> > We understand that this will not increase the speed of Gimp, but it may
>>> > be
>>> > something else entirely that may be helpful to someone by chance (as we
>>> > said
>>> > in our initial plan).
>>> >
>>> > Thanks for this dialogue. It has been quite helpful to us moving
>>> > forward.
>>>
>>> You are welcome. Don't hesitate to come hang around on IRC. There is
>>> no reason to just stop the dialogue. :-)
>>> In any case, for the sake of the class, I understand that you have to
>>> work fast and just implement "something to show your teacher". In this
>>> respect you may not care too much about discussing too much about the
>>> best approach and waste time. If that is the case, I fully understand.
>>> Just be aware that some things are doomed from the start though (like
>>> rewriting base class in C++ as you propose) if the goal is also to
>>> merge upstream. Since I find it sad to waste good work and would
>>> definitely prefer to see new contributors with upstream patches, well
>>> I want to make sure you got this part.
>>> In any case, have fun GIMPing! And maybe see you on IRC. :-)
>>>
>>> Jehan
>>>
>>> > Have a great day.
>>> >
>>> >
>>> > On Tue, Nov 12, 2013 at 4:39 AM, Jehan Pagès
>>> > <jehan.marmottard@gmail.com>
>>> > wrote:
>>> >>
>>> >> Hi,
>>> >>
>>> >> On Tue, Nov 12, 2013 at 5:30 PM, DeVonte Applewhite <dapplewh@nd.edu>
>>> >> wrote:
>>> >> > Hello all,
>>> >> >
>>> >> > I am in a Data Structures class which has a final project. This
>>> >> > project
>>> >> > requires students to fix bugs, improve preexisting data structures,
>>> >> > or
>>> >> > add
>>> >> > extra features to an open source project that has an active
>>> >> > community.
>>> >> > My
>>> >> > group chose GIMP.
>>> >>
>>> >> Nice choice! :-)
>>> >>
>>> >> > I have some ideas about changing data structures in hopes
>>> >> > of generalizing some implementations, improving execution speed and
>>> >> > reducing the amount of code needed to complete implementation of the
>>> >> > .h
>>> >> > files.
>>> >> >
>>> >> > Here are 3 of our ideas. If you could give input (feasibility,
>>> >> > faults in
>>> >> > our plan of action, predicted improvements upon success of these
>>> >> > ideas,
>>> >> > suggestions) on any or all of our ideas, that would be greatly
>>> >> > appreciated.
>>> >>
>>> >> Well I won't comment all the ideas in detail, and my guess is there
>>> >> are few chances others will either, because that would take quite a
>>> >> time! We don't know the whole code by heart, so to understand what you
>>> >> speak about, we would have to read the code you speak about carefully;
>>> >> and even so, when I see the kind of changes you propose, I'm not sure
>>> >> we will just say that's good ideas out of our head by just reading
>>> >> code. You seem to be proposing mostly API change or code optimization.
>>> >> But as often in optimization, it starts with gut feeling (except when
>>> >> dealing with obvious bad designs), and some algorithm cost
>>> >> computation, but in the end only real testing will really tell.
>>> >> So if you really feel that's the way to go, you can still implement
>>> >> it, test it, and if it appears to be a lot better than previously,
>>> >> then you won. Propose a patch with some benchmark results and someone
>>> >> will have at look at this.
>>> >>
>>> >> Now this said, I really wonder if API changes or algorithm
>>> >> optimizations are the best way to start in OpenSource contribution. A
>>> >> codebase like GIMP is huge and very complicated and you want to start
>>> >> with base classes. First of all, classes which are used in a lot of
>>> >> places may also break many different pieces of code if you change
>>> >> things (API or algorithm) there. So that implies a lot of regression
>>> >> testing, which means a lot of time.
>>> >> Second, even though base classes are indeed used in a lot of places,
>>> >> and optimizations are always good, well it is not that obvious that
>>> >> the optimization will get that tremendous speed improvements compared
>>> >> to all the other things done along the way.
>>> >> Last, API change just for the sake of API change, I'm not sure that's
>>> >> the best idea. We will usually do something because we actually want
>>> >> to use it and see it will make actual code better. I'm not sure if API
>>> >> change which "may" make some future code better is a good way to do
>>> >> it.
>>> >>
>>> >> I would think an easier way to start contributing is to fix bugs. We
>>> >> have quite a lot of bugs in our bug tracker waiting to be fixed. Just
>>> >> pick some of them, and fix them. Then you are sure this will be wanted
>>> >> code, and there is no "maybe" or incertitude. Also that's a lot
>>> >> easier, though very visible.
>>> >>
>>> >> But if you're sure your propositions are worth it, the best is to do
>>> >> the changes and propose patches. :-) As I said, I haven't looked at
>>> >> them in details. Maybe that's great ideas, no idea. I know some
>>> >> contributors start with base consolidations, not fixes. It happens.
>>> >> In any case, have fun with GIMP,
>>> >>
>>> >> Jehan
>>> >>
>>> >> > 1. gimp/libgimpmath/gimpmathtypes.h (file in
>>> >> > question:gimp/libgimpmath/gimpmatrix.h(c))
>>> >> > This file declares math structures that gimp uses like vectors and
>>> >> > matrices. The GimpMatrix structure come in 2X2, 3X3 and even 4X4
>>> >> > versions.
>>> >> > Each matrix is a 2Dimensional gdouble array with the appropriate
>>> >> > amount
>>> >> > of
>>> >> > elements to span the NXN matrix.I believe this data structure is
>>> >> > used
>>> >> > for
>>> >> > computation during image editing. There are functions handling
>>> >> > comparisons, identities, transformations, rotations, translations
>>> >> > and
>>> >> > various other
>>> >> > matrix operations. Possible changes: I believe the declaration of 3
>>> >> > special
>>> >> > kinds of gimp
>>> >> > matrices can be generalized to a struct (or class) that holds and
>>> >> > defines
>>> >> > an NXN matrix. We
>>> >> > could make it as general as possible to save the amount of code
>>> >> > necessary
>>> >> > to complete the tasks. This also eliminates two extra structs in the
>>> >> > .h
>>> >> > file. We could also change the structure that holds the matrix
>>> >> > elements.
>>> >> > One way could be by making a nested linked list to emulate an NXN
>>> >> > matrix.
>>> >> > This way, we keep everything in memory and not on the stack. If
>>> >> > necessary,
>>> >> > we could even overload the [] operator to make the functionality act
>>> >> > like
>>> >> > an array. We could also use the std::vector<T> data structures
>>> >> > included
>>> >> > in
>>> >> > the <vector> library to allow for pushing and popping of matrix data
>>> >> > structures to make them dynamic and or more fail-safe.
>>> >> >
>>> >> > 2. gimp/app/core/gimpcontainer.h
>>> >> > This class contains a data structure that is used to store different
>>> >> > things
>>> >> > about the
>>> >> > various objects in gimp. It works hand and hand with the GimpObject
>>> >> > class.
>>> >> > This
>>> >> > class uses what I believe to be some form of tree or heap structure.
>>> >> > The
>>> >> > class
>>> >> > refers to add, remove, reorder, and getChild functions that are
>>> >> > defined
>>> >> > across the
>>> >> > class. The gimp.h code uses the GimpContainer class pointers for
>>> >> > everything
>>> >> > from fonts, to documents, to displays. As this data structure is
>>> >> > used
>>> >> > with
>>> >> > GimpObject (which controls a large amount of functionality in gimp)
>>> >> > and
>>> >> > is
>>> >> > heavily
>>> >> > referenced in the gimp.h file, optimizing this class could go a long
>>> >> > way
>>> >> > in
>>> >> > optimizing the code. If we decrease the amount of time to "reorder"
>>> >> > the
>>> >> > tree, then
>>> >> > we decrease the amount of time several other objects take to be
>>> >> > initialized
>>> >> > and
>>> >> > added to the tree.
>>> >> >
>>> >> > 3. gimp/libgimpmath/gimpvector.h(c)
>>> >> > The GimpVector data structure keeps track of axis orientations and
>>> >> > lengths.
>>> >> > I believe this is used in the various drawing tools. I also believe
>>> >> > the
>>> >> > automated shapes functions may use it for drawing polygons. The
>>> >> > vector
>>> >> > data
>>> >> > structure is a structure that holds four gdouble variables that are
>>> >> > separately declared (gdouble x, y, z, w for the 4axis vector for
>>> >> > example).
>>> >> > There are three
>>> >> > versions of the gimp vector: 2axis, 3axis, and 4axis. A potential
>>> >> > change
>>> >> > to
>>> >> > GimpVector could be altering the way that it is stored like we plan
>>> >> > to
>>> >> > change the GimpMatrix. This means making a
>>> >> > streamlined generalized vector that can be of dimension N. Storing
>>> >> > the
>>> >> > axes
>>> >> > in an std::vector<T> or a linked list of size N could generalize the
>>> >> > vector
>>> >> > to be declared of any arbitrary number of axes. Another thing we
>>> >> > could
>>> >> > do
>>> >> > is overload the operators between vectors such as addition,
>>> >> > subtraction
>>> >> > and
>>> >> > multiplication. Currently they are of the form, GimpVector
>>> >> > add(GimpVector
>>> >> > &gv1,GimpVector &gv2). We could make it as easy as adding two
>>> >> > vectors
>>> >> > with
>>> >> > the + operator to make the code more readable. We can also overload
>>> >> > various
>>> >> > other operators to make the GimpVector data structure more flexible
>>> >> > and
>>> >> > powerful. This hopefully will increase the functionality and potency
>>> >> > of
>>> >> > the
>>> >> > GimpVector data structures and make them more accessible to new Gimp
>>> >> > developers in the future.
>>> >> > _______________________________________________
>>> >> > gimp-developer-list mailing list
>>> >> > List address:    gimp-developer-list@gnome.org
>>> >> > List membership:
>>> >> > https://mail.gnome.org/mailman/listinfo/gimp-developer-list
>>> >
>>> >
>>
>>
>
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