Re: [Gimp-developer] Metadata-Browser and Widgets

2010-04-21 Thread Roman Joost 
Hi Sven,

On Tue, Apr 20, 2010 at 08:23:44PM +0200, Sven Neumann wrote:
 You could use an interface and have your classes implement that
 interface. GObject allows interfaces to have a default implementation.
 You can for example implement common properties in an interface. There
 are few examples of this in GIMP. The GimpSerializable interface is one,
 GimpRectangleTool is also an interface.
Aw cheers for that. That should get me going. I remember that I've used
the GtkTreeStore interface for the XMPModel.

Cheers,
-- 
Roman Joost
www: http://www.romanofski.de
email: romanof...@gimp.org


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Re: [Gimp-developer] Metadata-Browser and Widgets

2010-04-20 Thread Sven Neumann 
Hi,

On Mon, 2010-04-19 at 18:15 +1000, Roman Joost wrote:

 thanks for your quick reply!
 
 On Sun, Apr 18, 2010 at 10:35:33AM +0200, Sven Neumann wrote:
  On Sat, 2010-04-17 at 17:25 +1000, Roman Joost wrote:
  How much code does the TextView class actually borrow from the Entry
  class?
 It would borrow the
 
 * get_text* (which returns a string if the XMPModel
   changed) and
 * set_text method (which sets the value in the XMPModel in case the
   user entered something in the widget).
 
 I actually thought I would also be able to use some of the setup data
 structures or object construction methods. This is almost the same for
 the GtkEntry and the TextView and probably for any other widget. For
 example:
 
 static void   gimp_xmp_model_entry_set_property  (GObject  *object,
   guint property_id,
   const GValue *value,
   GParamSpec   *pspec);
 static void   gimp_xmp_model_entry_get_property  (GObject  *object,
   guint property_id,
   GValue   *value,
   GParamSpec   *pspec);
 
 the class_init, the constructor method need to be always re-declared?

You could use an interface and have your classes implement that
interface. GObject allows interfaces to have a default implementation.
You can for example implement common properties in an interface. There
are few examples of this in GIMP. The GimpSerializable interface is one,
GimpRectangleTool is also an interface.


Sven


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Re: [Gimp-developer] Metadata-Browser and Widgets

2010-04-19 Thread Roman Joost 
Hi Sven,

thanks for your quick reply!

On Sun, Apr 18, 2010 at 10:35:33AM +0200, Sven Neumann wrote:
 On Sat, 2010-04-17 at 17:25 +1000, Roman Joost wrote:
 How much code does the TextView class actually borrow from the Entry
 class?
It would borrow the

* get_text* (which returns a string if the XMPModel
  changed) and
* set_text method (which sets the value in the XMPModel in case the
  user entered something in the widget).

I actually thought I would also be able to use some of the setup data
structures or object construction methods. This is almost the same for
the GtkEntry and the TextView and probably for any other widget. For
example:

static void   gimp_xmp_model_entry_set_property  (GObject  *object,
  guint property_id,
  const GValue *value,
  GParamSpec   *pspec);
static void   gimp_xmp_model_entry_get_property  (GObject  *object,
  guint property_id,
  GValue   *value,
  GParamSpec   *pspec);

the class_init, the constructor method need to be always re-declared?

 There are certainly ways to share most of
 this code, but probably not by inheritance. Some utility functions
 called from both classes might be sufficient, or you use composition and
 embed a common object in your TextView and Entry objects.
In the case of composition - correct me if I'm wrong - I could use some kind of
a general object in e.g. the private of my entry widget:

typedef struct
{
GIMPXMPBinding *binding;
} GimpXmpModelEntryPrivate;

and would be able to use all my methods through that binding object?

typedef struct
{
const gchar *schema_uri;
const gchar *property_name;
XMPModel*xmp_model;
} GIMPXMPBinding;

Although I have to admit - currently there is not much to share (if it really
comes down to three functions). It would almost look like refactoring this code
into utility functions as the better solution.

Cheers,
-- 
Roman Joost
www: http://www.romanofski.de
email: romanof...@gimp.org


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Re: [Gimp-developer] Metadata-Browser and Widgets

2010-04-18 Thread Sven Neumann 
Hi,

On Sat, 2010-04-17 at 17:25 +1000, Roman Joost wrote:

 My understanding so far, if I would inherit from my GtkEntry widget, I
 wouldn't be able to overwrite my implementation so I can display a
 GtkTextView. I also thought about inheriting from a more basic widget
 and somehow use a GtkEntry or GtkTextView as a property. That didn't
 really worked well either.
 
 Now I have a similar implementation working with a GtkTextView as a base
 class including borrowed code from my GtkEntry. I would like to
 merge both to something more flexible, but I can't really think of a
 better architecture.

How much code does the TextView class actually borrow from the Entry
class? What does this code do? There are certainly ways to share most of
this code, but probably not by inheritance. Some utility functions
called from both classes might be sufficient, or you use composition and
embed a common object in your TextView and Entry objects.

 Maybe the clue is to overwrite the constructor which returns either a
 GtkEntry, a GtkTextView or ...?

No, that wouldn't work. The constructor can't change the type of object
it returns.


Sven


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