# Component Animation


In addition to universal attribute animation and transition animation APIs, ArkUI provides default animation effects for certain components, for example, the swipe effect for the [\<List>](../reference/arkui-ts/ts-container-list.md) component and the click effect of the [\<Button>](../reference/arkui-ts/ts-basic-components-button.md#button) component. Based on these default animation effects, you can apply custom animations to the child components through the attribute animation and transition animation APIs.


## Using Default Component Animation

The default animation of a component exhibits the following features:

- Indicate the current state of the component. For example, after the user clicks a **\<Button>** component, the component turns gray, indicating that it is selected.

- Make UI interactions more intuitive and pleasurable.

- Reduce development workload, as the APIs are readily available.

For more effects, see [Component Overview](../reference/arkui-ts/ts-components-summary.md).

Below is the sample code and effect:


```ts
@Entry
@Component
struct ComponentDemo {
  build() {
    Row() {
      Checkbox({ name: 'checkbox1', group: 'checkboxGroup' })
        .select(true)
        .shape(CheckBoxShape.CIRCLE)
        .size({ width: 50, height: 50 })
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
  }
}
```

![en-us_image_0000001649338585](figures/en-us_image_0000001649338585.gif)



## Customizing Component Animation

Some components allow for animation customization for their child components through the [attribute animation](arkts-attribute-animation-overview.md) and [transition animation](arkts-transition-overview.md) APIs. For example, you can customize the swipe animation for child components of [\<Scroll>](../reference/arkui-ts/ts-container-scroll.md).

- For a scroll or click gesture, you can implement various effects by changing affine attributes of the child component.

- To customize the animation for a scroll , you can add a listener to listen for scroll distance in the **onScroll** callback and calculate the affine attribute of each component. You can also define gestures, monitor positions through the gestures, and manually call **ScrollTo** to change the scrolled-to position.

- Fine-tune the final scrolled-to position in the **onScrollStop** callback or gesture end callback.

The following is an example of customizing the swipe animation for the **\<Scroll>** component:


```ts
import curves from '@ohos.curves';
import window from '@ohos.window';
import display from '@ohos.display';
import mediaquery from '@ohos.mediaquery';
import UIAbility from '@ohos.app.ability.UIAbility';

export default class GlobalContext extends AppStorage{
  static mainWin: window.Window|undefined = undefined;
  static mainWindowSize:window.Size|undefined = undefined;
}
/**
 * Encapsulates the WindowManager class.
 */
export class WindowManager {
  private static instance: WindowManager|null = null;
  private displayInfo: display.Display|null = null;
  private orientationListener = mediaquery.matchMediaSync('(orientation: landscape)');

  constructor() {
    this.orientationListener.on('change', (mediaQueryResult: mediaquery.MediaQueryResult) => { this.onPortrait(mediaQueryResult) })
    this.loadDisplayInfo()
  }

  /**
   * Sets the main window.
   * @param win Indicates the current application window.
   */
  setMainWin(win: window.Window) {
    if (win == null) {
      return
    }
    GlobalContext.mainWin = win;
    win.on("windowSizeChange", (data: window.Size) => {
      if (GlobalContext.mainWindowSize == undefined || GlobalContext.mainWindowSize == null) {
        GlobalContext.mainWindowSize = data;
      } else {
        if (GlobalContext.mainWindowSize.width == data.width && GlobalContext.mainWindowSize.height == data.height) {
          return
        }
        GlobalContext.mainWindowSize = data;
      }

      let winWidth = this.getMainWindowWidth();
      AppStorage.setOrCreate<number>('mainWinWidth', winWidth)
      let winHeight = this.getMainWindowHeight();
      AppStorage.setOrCreate<number>('mainWinHeight', winHeight)
      let context:UIAbility = new UIAbility()
      context.context.eventHub.emit("windowSizeChange", winWidth, winHeight)
    })
  }

  static getInstance(): WindowManager {
    if (WindowManager.instance == null) {
      WindowManager.instance = new WindowManager();
    }
    return WindowManager.instance
  }

  private onPortrait(mediaQueryResult: mediaquery.MediaQueryResult) {
    if (mediaQueryResult.matches == AppStorage.get<boolean>('isLandscape')) {
      return
    }
    AppStorage.setOrCreate<boolean>('isLandscape', mediaQueryResult.matches)
    this.loadDisplayInfo()
  }

  /**
   * Changes the screen orientation.
   * @param ori Indicates the orientation.
   */
  changeOrientation(ori: window.Orientation) {
    if (GlobalContext.mainWin != null) {
      GlobalContext.mainWin.setPreferredOrientation(ori)
    }
  }

  private loadDisplayInfo() {
    this.displayInfo = display.getDefaultDisplaySync()
    AppStorage.setOrCreate<number>('displayWidth', this.getDisplayWidth())
    AppStorage.setOrCreate<number>('displayHeight', this.getDisplayHeight())
  }

  /**
   * Obtains the width of the main window, in vp.
   */
  getMainWindowWidth(): number {
    return GlobalContext.mainWindowSize != null ? px2vp(GlobalContext.mainWindowSize.width) : 0
  }

  /**
   * Obtains the height of the main window, in vp.
   */
  getMainWindowHeight(): number {
    return GlobalContext.mainWindowSize != null ? px2vp(GlobalContext.mainWindowSize.height) : 0
  }

  /**
   * Obtains the screen width, in vp.
   */
  getDisplayWidth(): number {
    return this.displayInfo != null ? px2vp(this.displayInfo.width) : 0
  }

  /**
   * Obtains the screen height, in vp.
   */
  getDisplayHeight(): number {
    return this.displayInfo != null ? px2vp(this.displayInfo.height) : 0
  }

  /**
   * Releases resources.
   */
  release() {
    if (this.orientationListener) {
      this.orientationListener.off('change', (mediaQueryResult: mediaquery.MediaQueryResult) => { this.onPortrait(mediaQueryResult)})
    }
    if (GlobalContext.mainWin != null) {
      GlobalContext.mainWin.off('windowSizeChange')
    }
    WindowManager.instance = null;
  }
}

/**
 * Encapsulates the TaskData class.
 */
export class TaskData {
  bgColor: Color | string | Resource = Color.White;
  index: number = 0;
  taskInfo: string = 'music';

  constructor(bgColor: Color | string | Resource, index: number, taskInfo: string) {
    this.bgColor = bgColor;
    this.index = index;
    this.taskInfo = taskInfo;
  }
}

export const taskDataArr: Array<TaskData> =
  [
    new TaskData('#317AF7', 0, 'music'),
    new TaskData('#D94838', 1, 'mall'),
    new TaskData('#DB6B42 ', 2, 'photos'),
    new TaskData('#5BA854', 3, 'setting'),
    new TaskData('#317AF7', 4, 'call'),
    new TaskData('#D94838', 5, 'music'),
    new TaskData('#DB6B42', 6, 'mall'),
    new TaskData('#5BA854', 7, 'photos'),
    new TaskData('#D94838', 8, 'setting'),
    new TaskData('#DB6B42', 9, 'call'),
    new TaskData('#5BA854', 10, 'music')

  ];

@Entry
@Component
export struct TaskSwitchMainPage {
  displayWidth: number = WindowManager.getInstance().getDisplayWidth();
  scroller: Scroller = new Scroller();
  cardSpace: number = 0; // Widget spacing
  cardWidth: number = this.displayWidth / 2 - this.cardSpace / 2; // Widget width
  cardHeight: number = 400; // Widget height
  cardPosition: Array<number> = []; // Initial position of the widget
  clickIndex: boolean = false;
  @State taskViewOffsetX: number = 0;
  @State cardOffset: number = this.displayWidth / 4;
  lastCardOffset: number = this.cardOffset;
  startTime: number|undefined=undefined

  // Initial position of each widget
  aboutToAppear() {
    for (let i = 0; i < taskDataArr.length; i++) {
      this.cardPosition[i] = i * (this.cardWidth + this.cardSpace);
    }
  }

  // Position of each widget
  getProgress(index: number): number {
    let progress = (this.cardOffset + this.cardPosition[index] - this.taskViewOffsetX + this.cardWidth / 2) / this.displayWidth;
    return progress
  }

  build() {
    Stack({ alignContent: Alignment.Bottom }) {
      // Background
      Column()
        .width('100%')
        .height('100%')
        .backgroundColor(0xF0F0F0)

      // <Scroll> component
      Scroll(this.scroller) {
        Row({ space: this.cardSpace }) {
          ForEach(taskDataArr, (item:TaskData, index) => {
            Column()
              .width(this.cardWidth)
              .height(this.cardHeight)
              .backgroundColor(item.bgColor)
              .borderStyle(BorderStyle.Solid)
              .borderWidth(1)
              .borderColor(0xAFEEEE)
              .borderRadius(15)
                // Calculate the affine attributes of child components.
              .scale((this.getProgress(index) >= 0.4 && this.getProgress(index) <= 0.6) ?
                {
                  x: 1.1 - Math.abs(0.5 - this.getProgress(index)),
                  y: 1.1 - Math.abs(0.5 - this.getProgress(index))
                } :
                { x: 1, y: 1 })
              .animation({ curve: Curve.Smooth })
                // Apply a pan animation.
              .translate({ x: this.cardOffset })
              .animation({ curve: curves.springMotion() })
              .zIndex((this.getProgress(index) >= 0.4 && this.getProgress(index) <= 0.6) ? 2 : 1)
          }, (item:TaskData) => item.toString())
        }
        .width((this.cardWidth + this.cardSpace) * (taskDataArr.length + 1))
        .height('100%')
      }
      .gesture(
        GestureGroup(GestureMode.Parallel,
          PanGesture({ direction: PanDirection.Horizontal, distance: 5 })
            .onActionStart((event: GestureEvent|undefined) => {
              if(event){
                this.startTime = event.timestamp;
              }
            })
            .onActionUpdate((event: GestureEvent|undefined) => {
              if(event){
                this.cardOffset = this.lastCardOffset + event.offsetX;
              }
            })
            .onActionEnd((event: GestureEvent|undefined) => {
              if(event){
                let time = 0
                if(this.startTime){
                  time = event.timestamp - this.startTime;
                }
                let speed = event.offsetX / (time / 1000000000);
                let moveX = Math.pow(speed, 2) / 7000 * (speed > 0 ? 1 : -1);

                this.cardOffset += moveX;
                // When panning left to a position beyond the rightmost position
                let cardOffsetMax = -(taskDataArr.length - 1) * (this.displayWidth / 2);
                if (this.cardOffset < cardOffsetMax) {
                  this.cardOffset = cardOffsetMax;
                }
                // When panning right to a position beyond the rightmost position
                if (this.cardOffset > this.displayWidth / 4) {
                  this.cardOffset = this.displayWidth / 4;
                }

                // Processing when the pan distance is less than the minimum distance
                let remainMargin = this.cardOffset % (this.displayWidth / 2);
                if (remainMargin < 0) {
                  remainMargin = this.cardOffset % (this.displayWidth / 2) + this.displayWidth / 2;
                }
                if (remainMargin <= this.displayWidth / 4) {
                  this.cardOffset += this.displayWidth / 4 - remainMargin;
                } else {
                  this.cardOffset -= this.displayWidth / 4 - (this.displayWidth / 2 - remainMargin);
                }

                // Record the pan offset.
                this.lastCardOffset = this.cardOffset;
              }
            })
        ), GestureMask.IgnoreInternal)
      .scrollable(ScrollDirection.Horizontal)
      .scrollBar(BarState.Off)

      // Move to the beginning and end positions.
      Button('Move to first/last')
        .backgroundColor(0x888888)
        .margin({ bottom: 30 })
        .onClick(() => {
          this.clickIndex = !this.clickIndex;

          if (this.clickIndex) {
            this.cardOffset = this.displayWidth / 4;
          } else {
            this.cardOffset = this.displayWidth / 4 - (taskDataArr.length - 1) * this.displayWidth / 2;
          }
          this.lastCardOffset = this.cardOffset;
        })
    }
    .width('100%')
    .height('100%')
  }
}
```

![en-us_image_0000001599808406](figures/en-us_image_0000001599808406.gif)