RES: gtktreeview problem.

[Ubirajara Marques da Cruz <biracruz cemig com br>]

John,

I did my app studing example found with wikbook did for Vikram Ambrose follow link:  
http://en.wikibooks.org/wiki/GTK%2B_By_Example/Tree_View/DnD

I did test with this examples  change it into many configuretions like liststores, treestores and combination 
of boths.  I am programming into C pure not in Python.  But I can understand the similarity between languages.

My problem is a little bit difficult.

When I was studing these examples I saw vikram plan this app with initial conditions that he knew and into 
this example gtktreemodel won´t change(can not be exchanged or column change). But in my app the program will 
read a data base file get a query, work with this query to fulfill a treestore and a list store too. The 
treestore will store a structure (like building material) and liststore will store each material individual. 
When I wanna build some house (for example) I need to pick each material in a liststore with dnd and copy to 
a place into another gtktreeview with treestore I will start my construction place first the basement, put 
walls, put ceiling and others. Into gtk program I will give me a list of material inside a liststore and a 
treestore that will receive a copy of this materials but showing the parent  relationship. After a built a 
new structure I will save it into data base file again. Many other things will be done with this structure 
like time to build, price and others.

When I start my searchs into internet I found I few material about this conditions. Most part of material 
explains basic dnd app with inicial conditions and gtktreeview/gtktreemodel and stores aren´t change in run 
time execution.

After long time with gtk docs I understood one thing. Gtk drag and drop isn´t a simple copy/move method! It´s 
to professionals. Into my case I am a beginner! But to become a professional I need to start like a beginner 
than let´s go.

To explain my doubt detailed I need you see into link above example of dnd with to gtktreeview to understand 
it.

There, Vikram plains source and dest into main function like I read in your link. Creates a public var with 
targets that dnd will can change between source and destiny widget. Creates a struct that will receive data 
copied from gtktreemodel.  He connects two signals into this example drag_get and drag_receive.

In drag_get it collects selected line , read data of each column and stores this data into a temp var struct 
that he creates at begin of this app. And finaly it inform to gtk_selection_data_set this temporary var 
struct to fulfill selection of source widget.

In drag_receive it copy data from selectiondata struct to a temporary var struct and populates other 
tree/liststore with this datas. This sequence of procedures is easy to understand.

I followed this procedure but to become this function general to my case I need to work with a generic var 
which can receive any kind of data and that can be created in run time execution. Gtk, Gdk and Glib offer 
many type of generic variables and structures that hold data. I chose gvalue and gvaluearray to hold this 
data. Function gtk_tree_model_get_value holds a GValues that is stored into treestore or listore. Another 
benefit to work gvalue is low level definition of var type It is near of glib runtime and you can become 
interprocess very easy to exchange data to another apps out of gtk.

The problem is into drag-get signal  after I fulfill gvaluearray with data. After this I need to attach (copy 
pointer) to selectiondata structure and I did like I sent into first email. But when I take it into 
drag-received signal. Struct is copied but data not. I have a gvaluearray that show the quantity of data but 
when I try to access data they are not there.

I don´t know what is wrong. All times I used memcpy function it works fine but in this case it´s not working. 
I don´t know if this problem is in drag-get  or in drag-received handler. I search in internet about
Problems to copy structures with variable array like members of a structure in runtime. And there are few 
doc´s too and this could be one solution. But I never did some code with this functionality. Another solution 
is a more experience programmer analise my code and discover what I´m doing wrong.

I will appreciate a lot your help.

Thank you.

Ubirajara.





-----Mensagem original-----
De: gtk-app-devel-list [mailto:gtk-app-devel-list-bounces gnome org] Em nome de John Coppens
Enviada em: segunda-feira, 23 de março de 2015 15:06
Para: gtk-app-devel-list gnome org
Assunto: Re: gtktreeview problem.

On Mon, 23 Mar 2015 12:50:28 +0000
Ubirajara Marques da Cruz <biracruz cemig com br> wrote:

> Into ON_DRAG_RECEIVED signal when I copy selection data with memcpy I have a surprise. Gtk selection has 
> the same structure but data is empty. And only one data is copied and it is wrong. It is a genum.

Maybe this tutorial I wrote a few years ago might be of help. It copies one cell of a TreeView to a list, but 
the mechanism is the same. There are quite a few steps involved, however...

http://jcoppens.com/soft/howto/pygtk_dnd/index.en.php

(The code is in Python, but all the steps are also needed in C or C++)

John
_______________________________________________
gtk-app-devel-list mailing list
gtk-app-devel-list gnome org
https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list

As informações contidas nesta mensagem e nos arquivos anexados sao para uso exclusivo do destinatario aqui 
indicado e podem conter assuntos comerciais, de propriedade intelectual ou outras informações confidenciais, 
protegidas pelas leis aplicaveis.
Caso não seja o destinatario correto, por favor, notifique o remetente.