build method

@override Widget build(BuildContext context)

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:

• the fields of the widget, which themselves must not change over time, and
• any ambient state obtained from the context using BuildContext.dependOnInheritedWidgetOfExactType.

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 Scaffold(
    backgroundColor: Colors.transparent,
    body: Column(
      children: [
        // header of the dialog which contains the image and big title
        Expanded(
          child: LayoutBuilder(
            builder: (context, con) {
              return Container(
                width: con.maxWidth,
                decoration: BoxDecoration(
                  color: color,
                  borderRadius: const BorderRadius.only(
                    topLeft: Radius.circular(25),
                    topRight: Radius.circular(25),
                  ),
                ),
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  children: [
                    // the image of the dialog
                    Center(
                      child: Image.asset(
                        image,
                        width: 100,
                        height: 100,
                      ),
                    ),

                    // the big header text
                    Text(
                      bigHeader,
                      style: const TextStyle(
                        color: Colors.white,
                        fontSize: 26,
                        height: 2,
                        fontWeight: FontWeight.bold,
                      ),
                    ),
                  ],
                ),
              );
            },
          ),
        ),

        // the body of the dialog which contains the title and the body
        Expanded(
          child: Container(
            padding: const EdgeInsets.all(10),
            child: Column(
              children: [
                // the title or head of the body section
                // if the title widget not passed we show our widget and take the header title
                if (centerTitleWidget == null)
                  Text(
                    headerText,
                    style: const TextStyle(
                      fontSize: 20,
                      fontWeight: FontWeight.bold,
                    ),
                  ),

                // if the title widget passed we just show it
                if (centerTitleWidget != null) centerTitleWidget!,
                const SizedBox(
                  height: 10,
                ),

                // the text of the body if the center body not passed as widget
                // we show our body and take the body text
                if (centerBodyWidget == null)
                  Text(
                    bodyText,
                    style: const TextStyle(
                      fontSize: 16,
                    ),
                  ),

                // if the body widget passed we just show it
                if (centerBodyWidget != null) centerBodyWidget!,
              ],
            ),
          ),
        ),

        // the bottom section which contains the buttons
        Container(
          padding: const EdgeInsets.all(10),
          child: Row(
            children: [
              // show our button if it's a notify dialog
              // and also the ok button not passed
              if (isNotifyDialog && okButtonWidget == null)
                OutlinedButton(
                  onPressed: onOkButtonPressed == null
                      ? null
                      : () => onOkButtonPressed,
                  child: Text(okButtonText),
                ),

              // if it's notify dialog and also ok button is passed
              // we sho the ok button
              if (isNotifyDialog && okButtonWidget != null) okButtonWidget!,

              const SizedBox(
                width: 20,
              ),

              // if cancel button is not passed we show our text button
              if (cancelButtonWidget == null)
                TextButton(
                  onPressed: onCloseButtonPressed == null
                      ? () {
                          Navigator.pop(context);
                        }
                      : () => onCloseButtonPressed,
                  child: Text(closeButtonText),
                ),

              // if cancel button passed we show it and hide our button
              if (cancelButtonWidget != null) cancelButtonWidget!,
            ],
          ),
        ),
      ],
    ),
  );
}