Attribute Modifier (AttributeModifier)

declare interface AttributeModifier<T> {

  applyNormalAttribute?(instance: T): void;

  applyPressedAttribute?(instance: T): void;

  applyFocusedAttribute?(instance: T): void;

  applyDisabledAttribute?(instance: T): void;

  applySelectedAttribute?(instance: T): void;

}

ButtonModifier01.ets

declare class CommonMethod<T> {
  attributeModifier(modifier: AttributeModifier<T>): T;
}

ButtonModifier01.ets

export class MyButtonModifier implements AttributeModifier<ButtonAttribute> {
  // A private member variable that can be dynamically modified externally
  public isDark: boolean = false

  // The constructor allows for parameter passing when creating an instance.
  constructor(dark?: boolean) {
    this.isDark = dark ?? false
  }

  applyNormalAttribute(instance: ButtonAttribute): void {
    // instance is the attribute object for the Button, which can be modified here.
    if (this.isDark) {// Service logic can be written here.
      // After attribute changes trigger the apply function, attributes that were set before but not included in the change will revert to their default values.
      instance.backgroundColor('#707070')
    } else {
      // Chaining of attribute methods is supported.
      instance.backgroundColor('#17A98D')
        .borderColor('#707070')
        .borderWidth(2)
    }
  }
}

ButtonModifier01.ets

// pages/Button1.ets
import { MyButtonModifier } from '../Common/ButtonModifier01'

@Entry
@Component
struct Button1 {
  // The modifier is decorated with @State, with behavior consistent with that of a regular object.
  @State modifier: MyButtonModifier = new MyButtonModifier(true);

  build() {
    Row() {
      Column() {
        Button('Button')
          .attributeModifier(this.modifier)
          .onClick(() => {
            // When the level-1 attribute of the modifier is changed, a UI update is triggered, causing applyNormalAttribute to be executed again.
            this.modifier.isDark = !this.modifier.isDark
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

Button1.ets

export class MyButtonModifier implements AttributeModifier<ButtonAttribute> {
  // A private member variable that can be dynamically modified externally
  public isDark: boolean = false

  // The constructor allows for parameter passing when creating an instance.
  constructor(dark?: boolean) {
    this.isDark = dark ?? false
  }

  applyNormalAttribute(instance: ButtonAttribute): void {
    // instance is the attribute object for the Button, which can be modified here.
    if (this.isDark) {// Service logic can be written here.
      // After attribute changes trigger the apply function, attributes that were set before but not included in the change will revert to their default values.
      instance.backgroundColor('#707070')
    } else {
      // Chaining of attribute methods is supported.
      instance.backgroundColor('#17A98D')
        .borderColor('#707070')
        .borderWidth(2)
    }
  }
}

ButtonModifier01.ets

// pages/Button2.ets
import { MyButtonModifier } from '../Common/ButtonModifier01'

@Entry
@Component
struct Button2 {
  @State modifier: MyButtonModifier = new MyButtonModifier(true);

  build() {
    Row() {
      Column() {
        // As the attribute is set before the modifier, the button's color changes in accordance with the value of the modifier.
        Button('Button')
          .backgroundColor('#2787D9')
          .attributeModifier(this.modifier)
          .onClick(() => {
            this.modifier.isDark = !this.modifier.isDark
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

Button2.ets

export class MyButtonModifier2 implements AttributeModifier<ButtonAttribute> {
  public isDark: boolean = false

  constructor(dark?: boolean) {
    this.isDark = dark ?? false
  }

  applyNormalAttribute(instance: ButtonAttribute): void {
    if (this.isDark) {
      instance.backgroundColor(Color.Black)
        .width(200)
    } else {
      instance.backgroundColor(Color.Red)
        .width(100)
    }
  }
}

ButtonModifier02.ets

export class MyButtonModifier3 implements AttributeModifier<ButtonAttribute> {
  public isDark2: boolean = false

  constructor(dark?: boolean) {
    this.isDark2 = dark ? dark : false
  }

  applyNormalAttribute(instance: ButtonAttribute): void {
    if (this.isDark2) {
      instance.backgroundColor('#2787D9')
    } else {
      instance.backgroundColor('#707070')
    }
  }
}

ButtonModifier03.ets

// pages/Button3.ets
import { MyButtonModifier2 } from '../Common/ButtonModifier02';
import { MyButtonModifier3 } from '../Common/ButtonModifier03';

@Entry
@Component
struct Button3 {
  @State modifier: MyButtonModifier2 = new MyButtonModifier2(true);
  @State modifier2: MyButtonModifier3 = new MyButtonModifier3(true);

  build() {
    Row() {
      Column() {
        Button('Button')
          .attributeModifier(this.modifier)
          .attributeModifier(this.modifier2)
          .onClick(() => {
            this.modifier.isDark = !this.modifier.isDark
            this.modifier2.isDark2 = !this.modifier2.isDark2
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}

Button3.ets

export class MyButtonModifier4 implements AttributeModifier<ButtonAttribute> {
  applyNormalAttribute(instance: ButtonAttribute): void {
    // instance is the attribute object for the Button, used to set attributes for the normal state.
    instance.backgroundColor('#17A98D')
      .borderColor('#707070')
      .borderWidth(2)
  }

  applyPressedAttribute(instance: ButtonAttribute): void {
    // instance is the attribute object for the Button, used to set attributes for the pressed state.
    instance.backgroundColor('#2787D9')
      .borderColor('#FFC000')
      .borderWidth(5)
  }
}

ButtonModifier04.ets

// pages/Button4.ets
import { MyButtonModifier4 } from '../Common/ButtonModifier04'

@Entry
@Component
struct Button4 {
  @State modifier: MyButtonModifier4 = new MyButtonModifier4();

  build() {
    Row() {
      Column() {
        Button('Button')
          .attributeModifier(this.modifier)
      }
      .width('100%')
    }
    .height('100%')
  }
}

Button4.ets