108 lines
3.1 KiB
Clojure
108 lines
3.1 KiB
Clojure
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=== Objectif ===
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:** Understand ewol basic [class[ewol::Object]]
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:** Use [class[ewol::Object]] correctly
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== Basis of the ewol::Object ==
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An object in Ewol is a simple class: [class[ewol::Object]] This object is the basis of all element in the ewol system.
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This is designed to manage many common things:
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:** Unique ID
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:** Name
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:** Parameters
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:** Signal generation
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:** Xml configuration
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:** Removing
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[note]
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Please do not compare with the gObject basic class...
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[/note]
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== Create an Object: ==
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Creating an object is really simple:
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[code style=c++]
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ewol::widget::ButtonShared tmpButon = ewol::widget::Button::create();
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APPL_INFO("We just create a button widget with unique ID=" << tmpButon->getId() << " name='" << tmpButon->propertyName.get() << "'");
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[/code]
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Note that all object created are [class[ememory::SharedPtr]] base for the current version on [class[std::shared_ptr]].
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We wrapped it because the current inplementation of [class[std::shared_ptr]] is not thread safe, and we want use a thread-safe vertion of it.
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[note]
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The widget is not stored in a ememory::SharedPtr<ewol::widget::Button> but in a ewol::widget::ButtonShared to simplify the using of the pointer.
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You have also: ememory::WeakPtr<ewol::widget::Button> = ewol::widget::ButtonWeak
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[/note]
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Set the name of the object:
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[code style=c++]
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tmpButon->propertyName.set("my widget name");
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APPL_INFO("We just create an Object with ID=" << tmpButon->getId() << " name='" << tmpButon->propertyName.get() << "'");
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[/code]
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== Remove an Object: ==
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Simply use the function:
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[code style=c++]
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tmpButon->destroy();
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[/code]
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This function request his parrent to remove the [class[ememory::SharedPtr]] it keep on it.
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And when all std::shared_ptr is removed the object will be really removed.
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At his point we can think an object is allive all the time someone keep a reference on it, then when you are not a parrent of the object, do not keep a [class[ememory::SharedPtr]] but a [class[ememory::WeakPtr]].
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[note]
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If some Object is not removed when you close the application, the system inform you with displaying all object alive.
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[/note]
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== Retrieve an Object: ==
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In Ewol this is possible to get a object with his name.
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=== Find a global Object (ouside an Object) ===
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[code style=c++]
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#include <ewol/context/Context.h>
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ewol::ObjectShared tmpObject = ewol::getContext().getEObjectManager().getObjectNamed("obj Name");
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if (tmpObject == nullptr) {
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APPL_ERROR("The Object does not exist");
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}
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[/code]
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=== Find a global Object (inside an Object) ===
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[code style=c++]
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ewol::ObjectShared tmpObject = getObjectNamed("obj Name");
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if (tmpObject == nullptr) {
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APPL_ERROR("The Object does not exist");
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}
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[/code]
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=== Find a sub-object ===
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[code style=c++]
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ewol::ObjectShared tmpObject = getSubObjectNamed("obj Name");
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if (tmpObject == NULL) {
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APPL_ERROR("The Object does not exist");
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}
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[/code]
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=== retriving your object type ===
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It could be really interesting to retrive your own instance:
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[code style=c++]
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ewol::ObjectShared tmpObject ...;
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appl::MyOwnObjectShared myObject = std::dynamic_pointer_cast<appl::MyOwnObject>(tmpObject);
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[/code]
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