205 lines
4.8 KiB
Markdown
205 lines
4.8 KiB
Markdown
---
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id: "eventwidget"
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title: "EventWidget"
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sidebar_label: "EventWidget"
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---
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> Abstract class that adds event handling support to all widgets.
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*This class implements an event emitter and merges it with Qt's event and signal system. It allows us to register and unregister event and signal listener at will from javascript**
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`EventWidget` is an abstract class and hence no instances of the same should be created. It exists so that we can add event handling functionalities to all widget's easily. This is an internal class.
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### Example
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```javascript
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const { QWidget, QWidgetSignals, WidgetEventTypes } = require("@nodegui/nodegui");
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const view = new QWidget();
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// You either listen for a widget's signal
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view.addEventListener('windowTitleChanged', () => {
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console.log("window title changed");
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});
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// or you can listen for an event
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view.addEventListener(WidgetEventTypes.MouseMove, () => {
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console.log("mouse moved");
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});
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```
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## Type parameters
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▪ **Signals**: *object*
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## Hierarchy
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* [Component](component.md)
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↳ **EventWidget**
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↳ [NodeObject](nodeobject.md)
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## Index
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### Constructors
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* [constructor](eventwidget.md#constructor)
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### Properties
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* [native](eventwidget.md#abstract-native)
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* [nodeChildren](eventwidget.md#nodechildren)
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* [nodeParent](eventwidget.md#optional-nodeparent)
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### Methods
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* [addEventListener](eventwidget.md#addeventlistener)
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* [removeEventListener](eventwidget.md#removeeventlistener)
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* [setNodeParent](eventwidget.md#setnodeparent)
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## Constructors
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### constructor
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\+ **new EventWidget**(`native`: [NativeElement](../globals.md#nativeelement)): *[EventWidget](eventwidget.md)*
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*Overrides [Component](component.md).[constructor](component.md#constructor)*
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**Parameters:**
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Name | Type |
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------ | ------ |
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`native` | [NativeElement](../globals.md#nativeelement) |
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**Returns:** *[EventWidget](eventwidget.md)*
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## Properties
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### `Abstract` native
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• **native**: *[NativeElement](../globals.md#nativeelement)*
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*Inherited from [Component](component.md).[native](component.md#abstract-native)*
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___
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### nodeChildren
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• **nodeChildren**: *Set‹[Component](component.md)›*
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*Inherited from [Component](component.md).[nodeChildren](component.md#nodechildren)*
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___
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### `Optional` nodeParent
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• **nodeParent**? : *[Component](component.md)*
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*Inherited from [Component](component.md).[nodeParent](component.md#optional-nodeparent)*
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## Methods
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### addEventListener
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▸ **addEventListener**<**SignalType**>(`signalType`: SignalType, `callback`: Signals[SignalType]): *void*
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**Type parameters:**
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▪ **SignalType**: *keyof Signals*
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**Parameters:**
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Name | Type | Description |
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------ | ------ | ------ |
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`signalType` | SignalType | SignalType is a signal from the widgets signals interface. |
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`callback` | Signals[SignalType] | Corresponding callback for the signal as mentioned in the widget's signal interface |
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**Returns:** *void*
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void
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For example in the case of QPushButton:
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```js
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const button = new QPushButton();
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button.addEventListener('clicked',(checked)=>console.log("clicked"));
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// here clicked is a value from QPushButtonSignals interface
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```
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▸ **addEventListener**(`eventType`: [WidgetEventTypes](../enums/widgeteventtypes.md), `callback`: function): *void*
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**Parameters:**
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▪ **eventType**: *[WidgetEventTypes](../enums/widgeteventtypes.md)*
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▪ **callback**: *function*
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For example in the case of QPushButton:
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```js
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const button = new QPushButton();
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button.addEventListener(WidgetEventTypes.HoverEnter,()=>console.log("hovered"));
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```
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▸ (`event?`: [NativeRawPointer](../globals.md#nativerawpointer)‹"QEvent"›): *void*
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**Parameters:**
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Name | Type |
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------ | ------ |
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`event?` | [NativeRawPointer](../globals.md#nativerawpointer)‹"QEvent"› |
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**Returns:** *void*
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___
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### removeEventListener
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▸ **removeEventListener**<**SignalType**>(`signalType`: SignalType, `callback`: Signals[SignalType]): *void*
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**Type parameters:**
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▪ **SignalType**: *keyof Signals*
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**Parameters:**
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Name | Type |
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------ | ------ |
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`signalType` | SignalType |
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`callback` | Signals[SignalType] |
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**Returns:** *void*
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▸ **removeEventListener**(`eventType`: [WidgetEventTypes](../enums/widgeteventtypes.md), `callback`: function): *void*
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**Parameters:**
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▪ **eventType**: *[WidgetEventTypes](../enums/widgeteventtypes.md)*
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▪ **callback**: *function*
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▸ (`event?`: [NativeRawPointer](../globals.md#nativerawpointer)‹"QEvent"›): *void*
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**Parameters:**
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Name | Type |
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------ | ------ |
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`event?` | [NativeRawPointer](../globals.md#nativerawpointer)‹"QEvent"› |
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**Returns:** *void*
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___
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### setNodeParent
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▸ **setNodeParent**(`parent?`: [Component](component.md)): *void*
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*Inherited from [Component](component.md).[setNodeParent](component.md#setnodeparent)*
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**Parameters:**
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Name | Type |
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------ | ------ |
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`parent?` | [Component](component.md) |
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**Returns:** *void*
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