图片模糊

  final RxDouble blurStrength = 0.0.obs;
final ScrollController controller = ScrollController();
 @override
  void initState() {
    super.initState();
    controller.addListener(() {
      var offset = controller.offset;
      if (offset > 450.w) {
        bShowAppbarTitle.value = true;
      } else {
        bShowAppbarTitle.value = false;
      }
      if (offset > 1100.w) {
        bShowCover = false;
        blurStrength.value =10;
      } else {
        bShowCover = true;
        blurStrength.value =
            (controller.offset / 1100.w)*10; // 根据偏移量计算模糊强度
      }
      bShowClip.value = offset > 450.w;
      if (bLastShowCover != bShowCover) {
        logic.update(["background"]);
        bLastShowCover = bShowCover;
      }
    });
  }

  Widget _buildCover() {
    return Obx(() {
      return Stack(
        children: [
          // 原始图片
          LoadImage(
            logic.material?.appList.firstOrNull?.picList.firstOrNull?.icon ??
                "",
            width: 1080.w,
            height: 1100.w,
          ),
          // 动态模糊效果
          Positioned.fill(
            child: BackdropFilter(
              filter: ImageFilter.blur(
                  sigmaX: blurStrength.value, sigmaY: blurStrength.value),
              child: Container(
                color: Colors.black.withOpacity(0.3),
              ),
            ),
          ),
        ],
      );
    });
  }