build method

  1. @override
Widget build(
  1. BuildContext context
)
override

Describes the part of the user interface represented by this widget.

The framework calls this method when this widget is inserted into the tree in a given BuildContext and when the dependencies of this widget change (e.g., an InheritedWidget referenced by this widget changes). This method can potentially be called in every frame and should not have any side effects beyond building a widget.

The framework replaces the subtree below this widget with the widget returned by this method, either by updating the existing subtree or by removing the subtree and inflating a new subtree, depending on whether the widget returned by this method can update the root of the existing subtree, as determined by calling Widget.canUpdate.

Typically implementations return a newly created constellation of widgets that are configured with information from this widget's constructor and from the given BuildContext.

The given BuildContext contains information about the location in the tree at which this widget is being built. For example, the context provides the set of inherited widgets for this location in the tree. A given widget might be built with multiple different BuildContext arguments over time if the widget is moved around the tree or if the widget is inserted into the tree in multiple places at once.

The implementation of this method must only depend on:

If a widget's build method is to depend on anything else, use a StatefulWidget instead.

See also:

  • StatelessWidget, which contains the discussion on performance considerations.

Implementation

@override
Widget build(BuildContext context) {
  return Center(
    child: Column(
      children: [
        Row(
          mainAxisAlignment: MainAxisAlignment.end,
          children: [
            Container(
              decoration: BoxDecoration(
                color: Theme.of(context).colorScheme.onTertiary,
                borderRadius: BorderRadius.circular(20.0),
              ),
              child: Row(
                children: [
                  SizedBox(
                    width: 15.0,
                  ),
                  Text(
                    "Theme",
                    style: TextStyle(
                      fontSize: 15.0,
                    ),
                  ),
                  IconButton(
                    icon: Obx(
                      () {
                        var themeMode = Get.find<ThemeController>().themeMode;
                        IconData icon;

                        if (themeMode == ThemeMode.dark) {
                          icon = Icons.dark_mode;
                        } else if (themeMode == ThemeMode.light) {
                          icon = Icons.light_mode;
                        } else {
                          icon = Icons.brightness_auto;
                        }

                        return Icon(icon, size: 20.0);
                      },
                    ),
                    onPressed: () {
                      var themeController = Get.find<ThemeController>();
                      ThemeMode currentMode = themeController.themeMode;

                      // Cycle through System → Dark → Light → System
                      ThemeMode newMode;
                      if (currentMode == ThemeMode.system) {
                        newMode = ThemeMode.dark;
                      } else if (currentMode == ThemeMode.dark) {
                        newMode = ThemeMode.light;
                      } else {
                        newMode = ThemeMode.system;
                      }

                      themeController.setThemeMode(newMode);
                    },
                  ),
                ],
              ),
            ),
          ],
        ),
        SizedBox(
          height: 80.0,
        ),
        Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              'SLNIC Decoder',
              style: Theme.of(context).textTheme.bodyLarge,
            ),
            const SizedBox(height: 100.0),
            TextField(
              // Define the controller for the TextField
              controller: textNicController,
              style: Theme.of(context).textTheme.labelMedium,
              textAlign: TextAlign.center,
              decoration: InputDecoration(
                suffixIcon: IconButton(
                  icon: Icon(Icons.clear_rounded),
                  iconSize: 18.0,
                  onPressed: () {
                    textNicController.clear();
                  },
                ),
                hintText: 'Enter your NIC Number here',
              ),
            ),
            const SizedBox(height: 20.0),
            ElevatedButton(
              onPressed: () {
                // Check if the input is empty
                if (textNicController.text.isEmpty) {
                  _showSnackBar(context, "Please Enter an NIC number!");
                  return;
                }

                // Remove extra spaces
                String nicVal = textNicController.text.trim();

                // Check if the NIC number is of the correct length
                if (nicVal.length != 10 && nicVal.length != 12) {
                  _showSnackBar(
                      context, "NIC number entered is wrong length!");
                  return;
                }

                // Further validate 9 digit NIC number
                if (nicVal.length == 10) {
                  String checkString = nicVal.substring(0, nicVal.length - 1);
                  String checkLetter = nicVal.substring(9).toLowerCase();

                  // Check if the last letter is valid
                  if (!["x", "v"].contains(checkLetter)) {
                    _showSnackBar(context, "$checkLetter is invalid");
                    return;
                  }

                  // Check if the remaning part is a number
                  if (int.tryParse(checkString) == null) {
                    _showSnackBar(
                        context, "Please Enter a valid NIC number!");
                    return;
                  }
                }

                // Decode the NIC number using the nicController
                nicController.decodeNic(nicVal);
                Get.to(() => ResultPage());
              },
              child: Text(
                'Decode',
              ),
            ),
          ],
        ),
      ],
    ),
  );
}