136 lines
3.2 KiB
Clojure
136 lines
3.2 KiB
Clojure
=?= Tutorial 2: Object Model =?=
|
|
__________________________________________________
|
|
[left][tutorial[001_HelloWord | Previous: Hello Word]][/left] [right][tutorial[011_ObjectConfig | Next: Object config]][/right]
|
|
|
|
=== Objectif ===
|
|
:** Understand ewol basic object
|
|
:** Use ewol::Object correctly
|
|
|
|
== Basis of the Object ==
|
|
|
|
An object in Ewol is a simple class : [class[ewol::Object]] This object is the basis of all element in the ewol system.
|
|
This is designed to manage basis element of complexe structure:
|
|
|
|
:** Unique ID
|
|
:** Name
|
|
:** Config
|
|
:** Event generation and receving
|
|
:** Xml configuration
|
|
:** Delayed removing
|
|
|
|
[note]
|
|
Please do not compare with the gObject basic class...
|
|
[/note]
|
|
|
|
|
|
== Create an Object: ==
|
|
|
|
This is a really simple way to create an Object, simply generate a new on it :
|
|
[code style=c++]
|
|
widget::Label* tmpObject = new widget::Label();
|
|
if (tmpObject == NULL) {
|
|
APPL_ERROR("An error occured");
|
|
return;
|
|
}
|
|
[/code]
|
|
|
|
The object register itself on the object manager, now it will have a specific Id and no name
|
|
|
|
Force the set of the name :
|
|
|
|
[code style=c++]
|
|
tmpObject->setName("my widget name");
|
|
APPL_INFO("We just create an Object with ID=" << tmpObject->getId() << " name='" << tmpObject->getName() << "'");
|
|
[/code]
|
|
|
|
|
|
== Remove an Object: ==
|
|
|
|
This is important to note that many element can have a reference on the Object.
|
|
|
|
And we did not use "ref-counting" for philosophic reasons ...
|
|
|
|
Then we need to use the fuction:
|
|
[b]removeObject()[/b] to remove the Object, This will notify avery object in the system that this
|
|
specific object has been removed.
|
|
|
|
|
|
Then to remove an object call:
|
|
[code style=c++]
|
|
tmpObject->removeObject();
|
|
[/code]
|
|
|
|
On every object we can have an herited function: [b]virtual void onObjectRemove(ewol::Object * _removeObject);[/b]
|
|
|
|
|
|
We need to implement this fuction to be notify an object is removed:
|
|
[code style=c++]
|
|
void namespeceName::ClassName::onObjectRemove(ewol::Object * _removeObject) {
|
|
if (_removeObject == m_object) {
|
|
m_object = NULL;
|
|
markToRedraw(); // set only for graphical object ...
|
|
}
|
|
}
|
|
[/code]
|
|
|
|
[note]
|
|
If you have well follow the idea, you will never declare an object in local, just use pointer on them.
|
|
[/note]
|
|
|
|
=== Particularity ===
|
|
|
|
An object can remove itself, just use the function:
|
|
[code style=c++]
|
|
autoDestroy();
|
|
[/code]
|
|
|
|
|
|
== Retrieve an Object: ==
|
|
|
|
In Ewol this is possible to get a widget with his name.
|
|
This is really simple.
|
|
|
|
=== In an Object ===
|
|
|
|
Call a simple function define in the Object:
|
|
|
|
[code style=c++]
|
|
#include <ewol/object/Manager.h>
|
|
|
|
...
|
|
|
|
ewol::Object* tmpObject = getObjectManager().get("name of the object");
|
|
if (tmpObject == NULL) {
|
|
APPL_ERROR("The Object does not exist");
|
|
}
|
|
[/code]
|
|
|
|
=== Not in an Object ===
|
|
|
|
In this case, we need to get the context manager and after the object manager:
|
|
|
|
[code style=c++]
|
|
#include <ewol/object/Manager.h>
|
|
#include <ewol/context/Context.h>
|
|
|
|
...
|
|
|
|
ewol::Object* tmpObject = ewol::getContext().getObjectManager().get("name of the object");
|
|
if (tmpObject == NULL) {
|
|
APPL_ERROR("The Object does not exist");
|
|
}
|
|
[/code]
|
|
|
|
|
|
|
|
== conclusion ==
|
|
|
|
If you follow these rules, you will not have memory leek and no segmentation fault on the ewol system.
|
|
|
|
[note]
|
|
To be sure that the name is unique, just add the current creator object Id in the name.
|
|
[/note]
|
|
|
|
|
|
|