# Focus Control

Focus control attributes set whether a component is focusable and how it participates in focus navigation.

>  **NOTE**
>
>  The APIs of this module are supported since API version 8. Updates will be marked with a superscript to indicate their earliest API version.


## Attributes

| Name              | Type| Description                                  |
| -------------------- | -------- | ---------------------------------------- |
| focusable            | boolean  | Whether the current component is focusable.<br>**NOTE**<br>Components that have default interaction logic, such as **\<Button>** and **\<TextInput>**, are focusable by default. Other components, such as **\<Text>** and **\<Image>**, are not focusable by default. Only focusable components can trigger a [focus event](ts-universal-focus-event.md).|
| tabIndex<sup>9+<sup> | number   | Tab order of the component in sequential focus navigation with the **Tab** key. When components with positive **tabIndex** values are present, only these components are reachable through sequential focus navigation, and they are navigated cyclically in ascending order based on the **tabIndex** value. When components with positive **tabIndex** values are not present, those components with a **tabIndex** value of **0** are navigated based on the preset focus navigation rule.<br>- **tabIndex** >= 0: The component is focusable and can be reached through sequential keyboard navigation.<br>- **tabIndex** < 0 (usually **tabIndex** = -1): The component is focusable, but cannot be reached through sequential keyboard navigation.<br>Default value: **0**|
| defaultFocus<sup>9+<sup> | boolean  | Whether to set the component as the default focus of the page. This attribute takes effect only when the page is new and accessed for the first time.<br>Default value: **false**|
| groupDefaultFocus<sup>9+<sup> | boolean  | Whether to set the component as the default focus of the parent container. This parameter takes effect only when the container is new and obtains focus for the first time.<br>Default value: **false**<br>**NOTE**<br><br>This parameter must be used together with **tabIndex**. When **tabIndex** is set for a container and **groupDefaultFocus(true)** is set for a child in the container or for the container itself, then when the container obtains focus for the first time through sequential Tab navigation, the focus automatically moves to the specified component. If **groupDefaultFocus(true)** is set for multiple components in the container (including the container itself), the first component found in the component tree in-depth traversal receives the focus.|
| focusOnTouch<sup>9+<sup> | boolean | Whether the component is focusable on touch.<br>Default value: **false**<br>**NOTE**<br>The component can obtain focus only when it is touchable or clickable.|

## focusControl<sup>9+</sup>

Implements focus control.

### requestFocus<sup>9+</sup>

requestFocus(value: string): boolean

Requests the focus to move to the specified component. This API can be used in global method statements. 

**Parameters**

| Name| Type| Mandatory| Description|
| ----- | ------ | ---- | ---- |
| value | string | Yes  | String bound to the target component using **key(value: string)** or **id(value: string)**.|

**Return value**

| Type| Description|
| ------- | ---- |
| boolean | Returns whether the focus is successfully moved to the target component. Returns **true** if the specified component exists and the focus is successfully moved to the target component; returns **false** otherwise.|

>  **NOTE**
>
>  The following components support focus control: **\<TextInput>**, **\<TextArea>**, **\<Search>**, **\<Button>**, **\<Text>**, **\<Image>**, **\<List>**, and **\<Grid>**. Currently, the running effect of the focus event can be displayed only on a real device.

## Example

### Example 1

This example shows how to use **defaultFocus**, **groupDefaultFocus**, and **focusOnTouch**.

**defaultFocus** sets the bound component as the initial focus of the page after the page is created. **groupDefaultFocus** sets the bound component as the initial focus of the **tabIndex** container after the container is created. **focusOnTouch** sets the bound component to obtain focus upon being clicked.

```ts
// focusTest.ets
@Entry
@Component
struct FocusableExample {
  @State inputValue: string = ''

  build() {
    Scroll() {
      Row({ space: 20 }) {
        Column({ space: 20 }) {
          Column({ space: 5 }) {
            Button('Group1')
              .width(165)
              .height(40)
              .fontColor(Color.White)
              .focusOnTouch(true)           // The button is focusable on touch.
            Row({ space: 5 }) {
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
                .focusOnTouch(true)           // The button is focusable on touch.
            }
            Row({ space: 5 }) {
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
            }
          }.borderWidth(2).borderColor(Color.Red).borderStyle(BorderStyle.Dashed)
          .tabIndex(1)                      // The column is the initial component to have focus in sequential keyboard navigation.
          Column({ space: 5 }) {
            Button('Group2')
              .width(165)
              .height(40)
              .fontColor(Color.White)
            Row({ space: 5 }) {
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
                .groupDefaultFocus(true)      // The button obtains focus when its upper-level column is in focus.
            }
            Row({ space: 5 }) {
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
              Button()
                .width(80)
                .height(40)
                .fontColor(Color.White)
            }
          }.borderWidth(2).borderColor(Color.Green).borderStyle(BorderStyle.Dashed)
          .tabIndex(2)                      // The column is the second component to have focus in sequential keyboard navigation.
        }
        Column({ space: 5 }) {
          TextInput({placeholder: 'input', text: this.inputValue})
            .onChange((value: string) => {
              this.inputValue = value
            })
            .width(156)
            .defaultFocus(true)             // The <TextInput> component is the initial default focus of the page.
          Button('Group3')
            .width(165)
            .height(40)
            .fontColor(Color.White)
          Row({ space: 5 }) {
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
          }
          Button()
            .width(165)
            .height(40)
            .fontColor(Color.White)
          Row({ space: 5 }) {
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
          }
          Button()
            .width(165)
            .height(40)
            .fontColor(Color.White)
          Row({ space: 5 }) {
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
            Button()
              .width(80)
              .height(40)
              .fontColor(Color.White)
          }
        }.borderWidth(2).borderColor(Color.Orange).borderStyle(BorderStyle.Dashed)
        .tabIndex(3)                      // The column is the third component to have focus in sequential keyboard navigation.
      }.alignItems(VerticalAlign.Top)
    }
  }
}
```
Diagrams:

When you press the **Tab** key for the first time, the focus switches to the component bound to **defaultFocus**.

![defaultFocus](figures/defaultFocus.png)

When you press the **Tab** key for the second time, the focus switches to the container that matches **tabIndex(1)** and automatically moves to the component bound to **groupDefaultFocus**.

![groupDefaultFocus1](figures/groupDefaultFocus1.png)

When you press the **Tab** key for the third time, the focus switches to the container that matches **tabIndex(2)** and automatically moves to the component bound to **groupDefaultFocus**.

![groupDefaultFocus2](figures/groupDefaultFocus2.png)

When you press the **Tab** key for the fourth time, the focus switches to the container that matches **tabIndex(3)** and automatically moves to the component bound to **groupDefaultFocus**.

![groupDefaultFocus3](figures/groupDefaultFocus3.png)

Click the component bound to **focusOnTouch**. The component then obtains focus.

![focusOnTouch](figures/focusOnTouch.png)

### Example 2

This example shows how to use **focusControl.requestFocus** to move the focus to the specified component.

```ts
// requestFocus.ets
import promptAction from '@ohos.promptAction';

@Entry
@Component
struct RequestFocusExample {
  @State idList: string[] = ['A', 'B', 'C', 'D', 'E', 'F', 'LastPageId']
  @State selectId: string = 'LastPageId'

  build() {
    Column({ space:20 }){
      Row({space: 5}) {
        Button("id: " + this.idList[0] + " focusable(false)")
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[0])
          .focusable(false)
        Button("id: " + this.idList[1])
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[1])
      }
      Row({space: 5}) {
        Button("id: " + this.idList[2])
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[2])
        Button("id: " + this.idList[3])
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[3])
      }
      Row({space: 5}) {
        Button("id: " + this.idList[4])
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[4])
        Button("id: " + this.idList[5])
          .width(200).height(70).fontColor(Color.White)
          .id(this.idList[5])
      }
      Row({space: 5}) {
        Select([{value: this.idList[0]},
                {value: this.idList[1]},
                {value: this.idList[2]},
                {value: this.idList[3]},
                {value: this.idList[4]},
                {value: this.idList[5]},
                {value: this.idList[6]}])
          .value(this.selectId)
          .onSelect((index: number) => {
            this.selectId = this.idList[index]
          })
        Button("RequestFocus")
          .width(200).height(70).fontColor(Color.White)
          .onClick(() => {
            let res = focusControl.requestFocus(this.selectId)      // Move the focus to the component specified by this.selectId.
            if (res) {
              promptAction.showToast({message: 'Request success'})
            } else {
              promptAction.showToast({message: 'Request failed'})
            }
          })
      }
    }.width('100%').margin({ top:20 })
  }
}
```

Diagrams:

Press the **Tab** key to activate the focus state.

Below shows how the UI behaves when you request focus for a component that does not exist.

![requestFocus1](figures/requestFocus1.png)

Below shows how the UI behaves when you request focus for a component that is not focusable.

![requestFocus2](figures/requestFocus2.png)

Below shows how the UI behaves when you request focus for a focusable component.

![requestFocus3](figures/requestFocus3.png)