Content Modifier (ContentModifier)

ContentModifier allows you to customize the content area of supported components. For example, you can display a star inside a Checkbox component.

Currently, the following components support ContentModifier: Button, Checkbox, DataPanel, TextTimer, Slider, Select, Rating, Radio, Gauge, Toggle, TextClock.

The following example shows how to use ContentModifier to replace the default check box with a pentagon shape. When the check box is selected, a red triangle appears inside the pentagon and the title updates to selected. When the check box is deselected, the triangle disappears and the title changes to not selected.

import { hilog } from '@kit.PerformanceAnalysisKit';
import { resourceManager } from '@kit.LocalizationKit';

const DOMAIN = 0x0000;
// xxx.ets
class MyCheckboxStyle implements ContentModifier<CheckBoxConfiguration> {
  public selectedColor: Color = Color.White;

  constructor(selectedColor: Color) {
    this.selectedColor = selectedColor;
  }

  applyContent(): WrappedBuilder<[CheckBoxConfiguration]> {
    return wrapBuilder(buildCheckbox);
  }
}

@Builder
function buildCheckbox(config: CheckBoxConfiguration) {
  Column({ space: 10 }) {
    Text() {
      Span(config.name)
      // Replace $r('app.string.checked_context') with the actual resource file. In this example, the value in the resource file is "selected."
      // Replace $r('app.string.unchecked_context') with the actual resource file. In this example, the value in the resource file is "unselected."
      Span(config.selected ? $r('app.string.checked_context') : $r('app.string.unchecked_context'))
    }
    Shape() {
      // Pentagon check box style
      Path()
        .width(200)
        .height(60)
        .commands('M100 0 L0 100 L50 200 L150 200 L200 100 Z')
        .fillOpacity(0)
        .strokeWidth(3)
      // Red triangle pattern style
      Path()
        .width(10)
        .height(10)
        .commands('M50 0 L100 100 L0 100 Z')
        .visibility(config.selected ? Visibility.Visible : Visibility.Hidden)
        .fill(config.selected ? (config.contentModifier as MyCheckboxStyle).selectedColor : Color.Black)
        .stroke((config.contentModifier as MyCheckboxStyle).selectedColor)
        .margin({ left: 11, top: 10 })
    }
    .width(300)
    .height(200)
    .viewPort({
      x: 0,
      y: 0,
      width: 310,
      height: 310
    })
    .strokeLineJoin(LineJoinStyle.Miter)
    .strokeMiterLimit(5)
    .onClick(() => {
      // Trigger the check box state change upon click.
      if (config.selected) {
        config.triggerChange(false);
      } else {
        config.triggerChange(true);
      }
    })
    .margin({ left: 150 })
  }
}

@Entry
@Component
struct Index {
  private resmg: resourceManager.ResourceManager | undefined = this.getUIContext().getHostContext()?.resourceManager
  build() {
    Row() {
      Column() {
        // Check boxes for selection and deselection
        // Replace $r('app.string.checkbox_status') with the actual resource file. In this example, the value in the resource file is "Check box status."
        Checkbox({ name: this.resmg?.getStringSync($r('app.string.checkbox_status').id), group: 'checkboxGroup' })
          .select(true)
          .contentModifier(new MyCheckboxStyle(Color.Red))
          .onChange((value: boolean) => {
            hilog.info(DOMAIN, 'testTag', 'Checkbox change is' + value);
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

MyCheckboxStyle.ets