鸿蒙实现自定义Tabbar样式，显示数字红点提示

前言：

DevEco Studio版本：4.0.0.600

Tabs的链接参考：OpenHarmony Tabs

TabContent的链接参考：OpenHarmony TabContent

通过查看链接参考我们知道可以通过TabContent的tabBar来实现自定义TabBar样式（CustomBuilder）

实现效果：

具体实现逻辑：

1、自定义样式

@Builder
tabBuilder(index: number, name: string) {
   RelativeContainer() {
      Text(name)
         .id("textTab")
         .fontColor(this.currentIndex === index ? this.selectedFontColor : this.fontColor)
         .fontSize(16)
         .fontWeight(this.currentIndex === index ? 8 : 4)
         .margin({ top: 17, bottom: 7 })
         .alignRules({
            center: { anchor: '__container__', align: VerticalAlign.Center }, //竖直居中
            middle: { anchor: '__container__', align: HorizontalAlign.Center }//水平居中
         })
      Text("5")
         .id("textDot")
         .textAlign(TextAlign.Center)
         .backgroundColor(Color.Red)
         .borderRadius(10)
         .fontSize(12)
         .fontColor(Color.White)
         .width(20)
         .height(20)
         .alignRules({
            left: { anchor: 'textTab', align: HorizontalAlign.End },
            center: { anchor: 'textTab', align: VerticalAlign.Center }
         })

      Divider()
         .id("dividerTab")
         .strokeWidth(this.strokeWidth)
         .color('#007DFF')
         .opacity(this.currentIndex === index ? 1 : 0)
         .alignRules({
            bottom: { anchor: '__container__', align: VerticalAlign.Bottom }, //竖直居中
            middle: { anchor: '__container__', align: HorizontalAlign.Center }//水平居中
         })
   }.width('100%')
}

2、完整代码：

@Entry
@Component
struct Index {
   @State fontColor: string = '#111111'
   @State selectedFontColor: string = '#007DFF'
   @State currentIndex: number = 0
   private controller: TabsController = new TabsController()
   @State strokeWidth: number = 3 //下划线的宽度

@Builder
tabBuilder(index: number, name: string) {
   RelativeContainer() {
      Text(name)
         .id("textTab")
         .fontColor(this.currentIndex === index ? this.selectedFontColor : this.fontColor)
         .fontSize(16)
         .fontWeight(this.currentIndex === index ? 8 : 4)
         .margin({ top: 17, bottom: 7 })
         .alignRules({
            center: { anchor: '__container__', align: VerticalAlign.Center }, //竖直居中
            middle: { anchor: '__container__', align: HorizontalAlign.Center }//水平居中
         })
      Text("5")
         .id("textDot")
         .textAlign(TextAlign.Center)
         .backgroundColor(Color.Red)
         .borderRadius(10)
         .fontSize(12)
         .fontColor(Color.White)
         .width(20)
         .height(20)
         .alignRules({
            left: { anchor: 'textTab', align: HorizontalAlign.End },
            center: { anchor: 'textTab', align: VerticalAlign.Center }
         })

      Divider()
         .id("dividerTab")
         .strokeWidth(this.strokeWidth)
         .color('#007DFF')
         .opacity(this.currentIndex === index ? 1 : 0)
         .alignRules({
            bottom: { anchor: '__container__', align: VerticalAlign.Bottom }, //竖直居中
            middle: { anchor: '__container__', align: HorizontalAlign.Center }//水平居中
         })
   }.width('100%')
}

   build() {
      Column() {
         Tabs({ barPosition: BarPosition.Start, index: this.currentIndex, controller: this.controller }) {
            TabContent() {
               Column().width('100%').height('100%').backgroundColor('#00CB87')
            }.tabBar(this.tabBuilder(0, 'green'))

            TabContent() {
               Column().width('100%').height('100%').backgroundColor('#007DFF')
            }.tabBar(this.tabBuilder(1, 'blue'))

            TabContent() {
               Column().width('100%').height('100%').backgroundColor('#FFBF00')
            }.tabBar(this.tabBuilder(2, 'yellow'))

            TabContent() {
               Column().width('100%').height('100%').backgroundColor('#E67C92')
            }.tabBar(this.tabBuilder(3, 'pink'))
         }
         .vertical(false)
         .barMode(BarMode.Fixed)
         .barHeight(56)
         .animationDuration(400)
         .onChange((index: number) => {
            this.currentIndex = index
         })
         .width('100%')
         .height('100%')
         .backgroundColor('#F1F3F5')
      }.width('100%')
   }
}