This package allows you to notify listener about the previous value and current value.

Features

• Get both previous and current value
• Listen to the value changes
• Build widget optimally by consider previous and current value

Usage

HistoryValueListenableListener

    HistoryValueListenableListener<int>(
      historyValueNotifier: counter,
      historyValueWidgetListener: (int prevValue, int value) {
        ScaffoldMessenger.of(context).showMaterialBanner(MaterialBanner(
            content: Text("Simple Prev $prevValue Curr $value"),
            actions: [
              GestureDetector(
                child: const Text("Cancel"),
                onTap: () {
                  ScaffoldMessenger.of(context).clearMaterialBanners();
                },
              )
            ]));
      },
      child: const Text(
        'Simple Listener',
      ),
    )

HistoryValueListenableBuilder

    HistoryValueListenableBuilder<int>(
      historyValueNotifier: counter,
      historyValueBuilder: (BuildContext context, int prevValue,
          int value, Widget? child) {
        return Text(
          "Prev $prevValue Curr $value",
        );
      },
    )

TransformerHistoryValueListenableBuilder

    TransformerHistoryValueListenableBuilder<int, int>(
      transformerHistoryValueNotifier: transformerHistoryValueNotifier,
      transformerHistoryValueBuilder: (BuildContext context,
          int? prevValue,
          int? prevTransformedValue,
          int value,
          int? transformedValue,
          Widget? child) {
        return Text(
          "Prev $prevValue PrevTransformed $prevTransformedValue Curr $value Transformed $transformedValue",
        );
      },
    )

TransformerHistoryValueListenableListener

    TransformerHistoryValueListenableListener<int, int>(
      transformerHistoryValueNotifier: transformerHistoryValueNotifier,
      transformerHistoryValueWidgetListener: (
        int? prevValue,
        int? prevTransformedValue,
        int value,
        int? transformedValue,
      ) {
        ScaffoldMessenger.of(context).clearSnackBars();
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
            content: Text(
          "Prev $prevValue PrevTransformed $prevTransformedValue "
          "Curr $value Transformed $transformedValue",
        )));
      },
      child: const Text(
        "Transformer Listener",
      ),
    )

Additional information

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