118.HarmonyOS NEXT 跑马灯组件详解(六)：事件处理机制

.onAreaChange((oldValue, newValue) => {
    logger.info(`TextArea oldValue:${JSON.stringify(oldValue)},
                newValue:${JSON.stringify(newValue)}`);
    
    // 获取组件尺寸
    let modePosition = componentUtils.getRectangleById('marquee');
    
    // 更新宽度信息
    this.updateWidthInfo(modePosition, newValue);
    
    // 处理文本偏移
    this.handleTextOffset();
})

private updateWidthInfo(modePosition: any, newValue: any) {
    this.ticketCheckScrollWidth = Number(px2vp(modePosition.size.width));
    this.ticketCheckTextWidth = Number(newValue.width);
}

.onAppear(() => {
    // 开始滚动动画
    this.scrollAnimation();
})

private initializeAnimation() {
    if (this.ticketCheckTextWidth < this.ticketCheckScrollWidth) {
        return;
    }
    this.scrollAnimation();
}

onFinish: () => {
    // 重置偏移量
    this.resetOffset();
    
    // 处理循环逻辑
    this.handleIteration();
    
    // 设置下一次动画
    this.scheduleNextAnimation();
}

private handleIteration() {
    if (this.marqueeAnimationModifier.iterations > 1) {
        if (this.count === this.marqueeAnimationModifier.iterations) {
            this.count = 1;
            return;
        }
        this.count++;
    }
}

aboutToAppear(): void {
    // 清除定时器
    clearTimeout(this.timer);
}

aboutToDisappear(): void {
    // 清理资源
    this.cleanup();
}

private resetOffset() {
    this.ticketCheckTextOffset = 
        this.marqueeAnimationModifier.playMode === PlayMode.Normal ? 
        0 : 
        -(2 * this.ticketCheckTextWidth + 
          this.marqueeScrollModifier.space - 
          this.ticketCheckScrollWidth);
}

private scheduleNextAnimation() {
    this.timer = setTimeout(() => {
        this.scrollAnimation();
    }, this.marqueeAnimationModifier.delayTime);
}

try {
    this.handleAreaChange(oldValue, newValue);
} catch (error) {
    logger.error('Area change error:', error.toString());
}

private validateParameters(value: any): boolean {
    if (!value || typeof value.width !== 'number') {
        logger.warn('Invalid parameter');
        return false;
    }
    return true;
}

// 使用防抖处理频繁事件
private debounce(func: Function, wait: number) {
    let timeout: number;
    return (...args: any[]) => {
        clearTimeout(timeout);
        timeout = setTimeout(() => {
            func.apply(this, args);
        }, wait);
    };
}

private cleanup() {
    // 清除定时器
    clearTimeout(this.timer);
    
    // 重置状态
    this.count = 1;
    this.ticketCheckTextOffset = 0;
}