+A component is an instance of TComponent or its child class. The base class TComponent implements the mechanism of component properties and events.
+
+A component property can be viewed as a public variable describing a specific aspect of the component, such as the background color, the font size, etc. A property is defined by the existence of a getter and/or a setter method in the component class. For example, in TControl, we have
+
+class TControl extends TComponent {
+ public function getID() {
+ ...
+ }
+ public function setID($value) {
+ ...
+ }
+}
+
+This defines a property named ID. Reading the property (e.g. echo $component->ID;) is equivalent to invoking the getter method (e.g. echo $component->getID();); and writing the property (e.g. $component->ID='Button';) is equivalent to invoking the setter method (e.g. $component->setID('Button');).
+
++A property is read-only if it has a getter method but no setter method. Since PHP method names are case-insensitive, property names are also case-insensitive. A component class inherits all its ancestor classes' properties. +
+ ++Component events are special properties that take method names as their values. Attaching (setting) a method to an event will hook up the method to the places at which the event is raised. Therefore, the behavior of a component can be modified in a way that may not be foreseen during the development of the component. +
+
+A component event is defined by the existence of an on-method. For example, in TButton, we have
+
+class TButton extends TWebControl {
+ public function onClick($param) {
+ ...
+ }
+}
+
+This defines an event named Click, and a handler can be attached to the event using one of the following ways,
+
+$button->Click=$callback;
+$button->Click->add($callback);
+$button->Click[]=$callback;
+$button->attachEventHandler('Click',$callback);
+
+where $callback refers to a valid PHP callback (e.g. a function name, a class method array($object,'method'), etc.)
+
+
+
+A control is an instance of class TControl or its subclass. A control is a component defined in addition with user interface. The base class TControl defines the parent-child relationship among controls which reflects the containment relationship among user interface elements.
+
+A parent control is in charge of the state transition of its child controls. The rendering result of the child controls are usually used to compose the parent control's presentation. +
++The parent-child relationship is usually established by the framework via templates. In code, you may explicitly specify a control as a child of another using the following method, +
+$parent->Controls->add($child); ++where the property
Controls refers to the child control collection of the parent.
+
+
++Pages are top-most controls that have no parent (you may consider application as their container though). The presentation of pages are directly displayed to end-users. +
+ +