How does the TextInput component obtain focus?

Scenario 1: Active Focus Acquisition/Loss of TextInput.

Call the focusControl.requestFocus API to actively move the focus to the specified component. The code snippet is as follows:

// xxx.ets
@Entry
@Component
struct TextInputExample {
  build() {
    Row() {
      Column() {
        Button('The second focus acquisition')
          .onClick(() => {
            focusControl.requestFocus('BBB'); // Get focus on the second input box
          })


        TextInput({ placeholder: 'Please enter the content.' })
          .showUnderline(true)
          .width(380)
          .height(60)
          .id('AAA')
        TextInput({ placeholder: 'Please enter the content.' })
          .showUnderline(true)
          .width(380)
          .height(60)
          .id('BBB')
      }
      .width('100%')
    }
    .height('100%')
  }
}

Scenario 2: When the page is initially constructed, the TextInput component configured as the default focus obtains focus.

Set the defaultFocus attribute to configure the bound component as the default focus when the page is created. The code snippet is as follows:

// xxx.ets
@Entry
@Component
struct TextInputExample {
  build() {
    Row() {
      Column() {
        TextInput({ placeholder: 'Please enter the content.' })
          .showUnderline(true)
          .width(380)
          .height(60)


        TextInput({ placeholder: 'Please enter the content.' })
          .showUnderline(true)
          .defaultFocus(true) // When the page is first opened, this TextInput gets focus
          .width(380)
          .height(60)
      }
      .width('100%')
    }
    .height('100%')
  }
}

Scenario 3: When the page is initially constructed, the TextInput component configured as the default focus obtains focus, without bringing up the keyboard.

Set enableKeyboardOnFocus(false), so that the keyboard does not pop up when the TextInput component obtains focus. The code snippet is as follows:

// xxx.ets
@Entry
@Component
struct TextInputExample {
  build() {
    Row() {
      Column() {
        TextInput({ placeholder: 'Please enter the content.' })
          .defaultFocus(true) // When the page is first opened, this TextInput gets focus
          .enableKeyboardOnFocus(false) // Is TextInput bound to an input method when focusing through methods other than clicking.
          .placeholderColor(Color.Grey)
          .placeholderFont({ size: 14, weight: 400 })
          .caretColor(Color.Blue)
          .width('95%')
          .height(40)
          .margin(20)
      }
      .width('100%')
    }
    .height('100%')
  }
}

Scenario 4: When the page is initially constructed, the TextInput component not configured as the default focus does not obtain focus or brings up the keyboard, which is the default behavior of the TextInput component.
The code snippet is as follows:
```
// xxx.ets
@Entry
@Component
struct TextInputExample {
  build() {
    Column() {
      TextInput({ placeholder: 'Please enter the content.' })
    }
    .width('100%')
  }
}
```

目录

How does the TextInput component obtain focus?