build method

  1. @override
Widget build (BuildContext context)

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

The framework calls this method in a number of different situations:

  • After calling initState.
  • After calling didUpdateWidget.
  • After receiving a call to setState.
  • After a dependency of this State object changes (e.g., an InheritedWidget referenced by the previous build changes).
  • After calling deactivate and then reinserting the State object into the tree at another location.

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, the given BuildContext, and the internal state of this State object.

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. The BuildContext argument is always the same as the context property of this State object and will remain the same for the lifetime of this object. The BuildContext argument is provided redundantly here so that this method matches the signature for a WidgetBuilder.

Design discussion

Why is the build method on State, and not StatefulWidget?

Putting a Widget build(BuildContext context) method on State rather putting a Widget build(BuildContext context, State state) method on StatefulWidget gives developers more flexibility when subclassing StatefulWidget.

For example, AnimatedWidget is a subclass of StatefulWidget that introduces an abstract Widget build(BuildContext context) method for its subclasses to implement. If StatefulWidget already had a build method that took a State argument, AnimatedWidget would be forced to provide its State object to subclasses even though its State object is an internal implementation detail of AnimatedWidget.

Conceptually, StatelessWidget could also be implemented as a subclass of StatefulWidget in a similar manner. If the build method were on StatefulWidget rather than State, that would not be possible anymore.

Putting the build function on State rather than StatefulWidget also helps avoid a category of bugs related to closures implicitly capturing this. If you defined a closure in a build function on a StatefulWidget, that closure would implicitly capture this, which is the current widget instance, and would have the (immutable) fields of that instance in scope:

class MyButton extends StatefulWidget {
  ...
  final Color color;

  @override
  Widget build(BuildContext context, MyButtonState state) {
    ... () { print("color: $color"); } ...
  }
}

For example, suppose the parent builds MyButton with color being blue, the $color in the print function refers to blue, as expected. Now, suppose the parent rebuilds MyButton with green. The closure created by the first build still implicitly refers to the original widget and the $color still prints blue even through the widget has been updated to green.

In contrast, with the build function on the State object, closures created during build implicitly capture the State instance instead of the widget instance:

class MyButtonState extends State<MyButton> {
  ...
  @override
  Widget build(BuildContext context) {
    ... () { print("color: ${widget.color}"); } ...
  }
}

Now when the parent rebuilds MyButton with green, the closure created by the first build still refers to State object, which is preserved across rebuilds, but the framework has updated that State object's widget property to refer to the new MyButton instance and ${widget.color} prints green, as expected.

See also:

  • StatefulWidget, which contains the discussion on performance considerations.

Implementation

@override
Widget build(BuildContext context) {
  return Form(
    key: _formKey,
    //TODO: Allow user to update field value or validate based on changes in others (e.g. Summations, Confirm Password)
    onChanged: () {
      if (widget.onChanged != null) {
        _formKey.currentState.save();
        widget.onChanged(value);
      }
    },
    onWillPop: widget.onWillPop,
    autovalidate: widget.autovalidate,
    child: Column(
      children: this.formControls.map((FormBuilderInput formControl) {
        // GlobalKey<FormFieldState> _fieldKey = GlobalKey(debugLabel: formControl.attribute);
        // _fieldKeys[formControl.attribute] = _fieldKey;
        if (formControl != null) {
          switch (formControl.type) {
            case FormBuilderInput.TYPE_TEXT:
            case FormBuilderInput.TYPE_PASSWORD:
            case FormBuilderInput.TYPE_NUMBER:
            case FormBuilderInput.TYPE_PHONE:
            case FormBuilderInput.TYPE_EMAIL:
            case FormBuilderInput.TYPE_URL:
            case FormBuilderInput.TYPE_MULTILINE_TEXT:
              TextInputType keyboardType;
              switch (formControl.type) {
                case FormBuilderInput.TYPE_NUMBER:
                  keyboardType = TextInputType.number;
                  break;
                case FormBuilderInput.TYPE_EMAIL:
                  keyboardType = TextInputType.emailAddress;
                  break;
                case FormBuilderInput.TYPE_URL:
                  keyboardType = TextInputType.url;
                  break;
                case FormBuilderInput.TYPE_PHONE:
                  keyboardType = TextInputType.phone;
                  break;
                case FormBuilderInput.TYPE_MULTILINE_TEXT:
                  keyboardType = TextInputType.multiline;
                  break;
                default:
                  keyboardType = TextInputType.text;
                  break;
              }
              return TextFormField(
                // // key: _fieldKey,
                enabled: !(widget.readonly || formControl.readonly),
                style: (widget.readonly || formControl.readonly)
                    ? Theme.of(context).textTheme.subhead.copyWith(
                          color: Theme.of(context).disabledColor,
                        )
                    : null,
                focusNode: (widget.readonly || formControl.readonly)
                    ? AlwaysDisabledFocusNode()
                    : null,
                decoration: formControl.decoration.copyWith(
                  enabled: !(widget.readonly || formControl.readonly),
                ),
                autovalidate: formControl.autovalidate ?? false,
                initialValue:
                    formControl.value != null ? "${formControl.value}" : '',
                maxLines:
                    formControl.type == FormBuilderInput.TYPE_MULTILINE_TEXT
                        ? formControl.maxLines
                        : 1,
                keyboardType: keyboardType,
                obscureText:
                    formControl.type == FormBuilderInput.TYPE_PASSWORD
                        ? true
                        : false,
                onSaved: (val) {
                  value[formControl.attribute] =
                      formControl.type == FormBuilderInput.TYPE_NUMBER
                          ? num.tryParse(val)
                          : val;
                },
                onFieldSubmitted: (data) {
                  if (formControl.onChanged != null)
                    formControl.onChanged(data);
                },
                validator: (val) {
                  if (formControl.require && val.isEmpty)
                    return "${formControl.attribute} is required";

                  if (formControl.type == FormBuilderInput.TYPE_NUMBER) {
                    if (num.tryParse(val) == null && val.isNotEmpty)
                      return "$val is not a valid number";
                    if (formControl.max != null &&
                        num.tryParse(val) > formControl.max)
                      return "${formControl.attribute} should not be greater than ${formControl.max}";
                    if (formControl.min != null &&
                        num.tryParse(val) < formControl.min)
                      return "${formControl.attribute} should not be less than ${formControl.min}";
                  } else {
                    if (formControl.max != null &&
                        val.length > formControl.max)
                      return "${formControl.attribute} should have ${formControl.max} character(s) or less";
                    if (formControl.min != null &&
                        val.length < formControl.min)
                      return "${formControl.attribute} should have ${formControl.min} character(s) or more";
                  }

                  if (formControl.type == FormBuilderInput.TYPE_EMAIL &&
                      val.isNotEmpty) {
                    Pattern pattern =
                        r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
                    if (!RegExp(pattern).hasMatch(val))
                      return '$val is not a valid email address';
                  }

                  if (formControl.type == FormBuilderInput.TYPE_URL &&
                      val.isNotEmpty) {
                    Pattern pattern =
                        r"(https?|ftp)://([-A-Z0-9.]+)(/[-A-Z0-9+&@#/%=~_|!:,.;]*)?(\?[A-Z0-9+&@#/%=~_|!:‌​,.;]*)?";
                    if (!RegExp(pattern, caseSensitive: false).hasMatch(val))
                      return '$val is not a valid URL';
                  }

                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
                // autovalidate: ,
              );
              break;

            case FormBuilderInput.TYPE_DATE_TIME_PICKER:
              return DateTimePickerFormField(
                // key: _fieldKey,
                inputType: InputType.both,
                initialValue: formControl.value,
                format: formControl.format != null
                    ? DateFormat(formControl.format)
                    : _dateTimeFormats[InputType.both],
                enabled: !(formControl.readonly || widget.readonly),
                firstDate: formControl.firstDate,
                lastDate: formControl.lastDate,
                decoration: formControl.decoration.copyWith(
                  enabled: !(widget.readonly || formControl.readonly),
                ),
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                validator: (val) {
                  if (formControl.require && val == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
              );
              break;

            case FormBuilderInput.TYPE_DATE_PICKER:
              return DateTimePickerFormField(
                // key: _fieldKey,
                inputType: InputType.date,
                initialValue: formControl.value,
                format: formControl.format != null
                    ? DateFormat(formControl.format)
                    : _dateTimeFormats[InputType.date],
                enabled: !(formControl.readonly || widget.readonly),
                firstDate: formControl.firstDate,
                lastDate: formControl.lastDate,
                decoration: formControl.decoration.copyWith(
                  enabled: !(widget.readonly || formControl.readonly),
                ),
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                validator: (val) {
                  if (formControl.require && val == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
              );
              break;

            case FormBuilderInput.TYPE_TIME_PICKER:
              return DateTimePickerFormField(
                // key: _fieldKey,
                inputType: InputType.time,
                initialValue: formControl.value,
                format: formControl.format != null
                    ? DateFormat(formControl.format)
                    : _dateTimeFormats[InputType.time],
                enabled: !(formControl.readonly || widget.readonly),
                decoration: formControl.decoration.copyWith(
                  enabled: !(widget.readonly || formControl.readonly),
                ),
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                validator: (val) {
                  if (formControl.require && val == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
              );
              break;

            case FormBuilderInput.TYPE_TYPE_AHEAD:
              TextEditingController _typeAheadController =
                  TextEditingController(text: formControl.value);
              return TypeAheadFormField(
                // key: _fieldKey,
                textFieldConfiguration: TextFieldConfiguration(
                  enabled: !(widget.readonly || formControl.readonly),
                  controller: _typeAheadController,
                  style: (widget.readonly || formControl.readonly)
                      ? Theme.of(context).textTheme.subhead.copyWith(
                            color: Theme.of(context).disabledColor,
                          )
                      : null,
                  focusNode: (widget.readonly || formControl.readonly)
                      ? AlwaysDisabledFocusNode()
                      : null,
                  decoration: formControl.decoration.copyWith(
                    enabled: !(widget.readonly || formControl.readonly),
                  ),
                ),
                suggestionsCallback: formControl.suggestionsCallback,
                itemBuilder: formControl.itemBuilder,
                transitionBuilder: (context, suggestionsBox, controller) =>
                    suggestionsBox,
                onSuggestionSelected: (suggestion) {
                  _typeAheadController.text = suggestion;
                },
                validator: (val) {
                  if (formControl.require && val.isEmpty)
                    return '${formControl.attribute} is required';

                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
                onSaved: (val) => value[formControl.attribute] = val,
                getImmediateSuggestions: formControl.getImmediateSuggestions,
                errorBuilder: formControl.errorBuilder,
                noItemsFoundBuilder: formControl.noItemsFoundBuilder,
                loadingBuilder: formControl.loadingBuilder,
                debounceDuration: formControl.debounceDuration,
                suggestionsBoxDecoration:
                    formControl.suggestionsBoxDecoration,
                suggestionsBoxVerticalOffset:
                    formControl.suggestionsBoxVerticalOffset,
                // transitionBuilder: formControl.transitionBuilder,
                animationDuration: formControl.animationDuration,
                animationStart: formControl.animationStart,
                direction: formControl.direction,
                hideOnLoading: formControl.hideOnLoading,
                hideOnEmpty: formControl.hideOnEmpty,
                hideOnError: formControl.hideOnError,
                hideSuggestionsOnKeyboardHide:
                    formControl.hideSuggestionsOnKeyboardHide,
                keepSuggestionsOnLoading:
                    formControl.keepSuggestionsOnLoading,
                autoFlipDirection: formControl.autoFlipDirection,
                autovalidate:
                    (formControl.autovalidate || widget.autovalidate),
              );
              break;

            case FormBuilderInput.TYPE_DROPDOWN:
              return FormField(
                // key: _fieldKey,
                enabled: !(widget.readonly || formControl.readonly),
                initialValue: formControl.value,
                validator: (val) {
                  if (formControl.require && val == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(val);
                },
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                      contentPadding: EdgeInsets.only(top: 10.0, bottom: 0.0),
                      border: InputBorder.none,
                    ),
                    child: DropdownButton(
                      isExpanded: true,
                      // hint: Text(formControl.hint ?? ''), //TODO: Dropdown may require hint
                      items: formControl.options.map((option) {
                        return DropdownMenuItem(
                          child: Text("${option.label ?? option.value}"),
                          value: option.value,
                        );
                      }).toList(),
                      value: field.value,
                      onChanged: (widget.readonly || formControl.readonly)
                          ? null
                          : (value) {
                              field.didChange(value);
                            },
                    ),
                  );
                },
              );
              break;

            //TODO: For TYPE_CHECKBOX, TYPE_CHECKBOX_LIST, TYPE_RADIO allow user to choose if checkbox/radio to appear before or after Label
            case FormBuilderInput.TYPE_RADIO:
              return FormField(
                // key: _fieldKey,
                enabled: !widget.readonly && !formControl.readonly,
                initialValue: formControl.value,
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                builder: (FormFieldState<dynamic> field) {
                  List<Widget> radioList = [];
                  for (int i = 0; i < formControl.options.length; i++) {
                    radioList.addAll([
                      ListTile(
                        dense: true,
                        isThreeLine: false,
                        contentPadding: EdgeInsets.all(0.0),
                        leading: null,
                        title: Text(
                            "${formControl.options[i].label ?? formControl.options[i].value}"),
                        trailing: Radio<dynamic>(
                          value: formControl.options[i].value,
                          groupValue: field.value,
                          onChanged: (widget.readonly || formControl.readonly)
                              ? null
                              : (dynamic value) {
                                  field.didChange(value);
                                },
                        ),
                        onTap: (widget.readonly || formControl.readonly)
                            ? null
                            : () {
                                field.didChange(formControl.options[i].value);
                              },
                      ),
                      Divider(
                        height: 0.0,
                      ),
                    ]);
                  }
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                      contentPadding: EdgeInsets.only(top: 10.0, bottom: 0.0),
                      border: InputBorder.none,
                    ),
                    child: Column(
                      children: radioList,
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_SEGMENTED_CONTROL:
              return FormField(
                // key: _fieldKey,
                initialValue: formControl.value,
                enabled: !(widget.readonly || formControl.readonly),
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.require} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                      contentPadding:
                          EdgeInsets.only(top: 10.0, bottom: 10.0),
                      border: InputBorder.none,
                    ),
                    child: Padding(
                      padding: EdgeInsets.only(top: 10.0),
                      child: CupertinoSegmentedControl(
                        borderColor: (widget.readonly || formControl.readonly)
                            ? Theme.of(context).disabledColor
                            : Theme.of(context).primaryColor,
                        selectedColor:
                            (widget.readonly || formControl.readonly)
                                ? Theme.of(context).disabledColor
                                : Theme.of(context).primaryColor,
                        pressedColor:
                            (widget.readonly || formControl.readonly)
                                ? Theme.of(context).disabledColor
                                : Theme.of(context).primaryColor,
                        groupValue: field.value,
                        children: Map.fromIterable(
                          formControl.options,
                          key: (v) => v.value,
                          value: (v) => Padding(
                                padding: EdgeInsets.symmetric(vertical: 10.0),
                                child: Text("${v.label ?? v.value}"),
                              ),
                        ),
                        onValueChanged: (dynamic value) {
                          if (widget.readonly || formControl.readonly) {
                            field.reset();
                          } else
                            field.didChange(value);
                        },
                      ),
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_SWITCH:
              return FormField(
                  // key: _fieldKey,
                  enabled: !(widget.readonly || formControl.readonly),
                  initialValue: formControl.value ?? false,
                  validator: (value) {
                    if (formControl.require && value == null)
                      return "${formControl.attribute} is required";
                    /*if (formControl.validator != null)
                  return formControl.validator(value);*/
                  },
                  onSaved: (val) {
                    value[formControl.attribute] = val;
                  },
                  builder: (FormFieldState<dynamic> field) {
                    return InputDecorator(
                      decoration: formControl.decoration.copyWith(
                        enabled: !(widget.readonly || formControl.readonly),
                        errorText: field.errorText,
                      ),
                      child: ListTile(
                        dense: true,
                        isThreeLine: false,
                        contentPadding: EdgeInsets.all(0.0),
                        title: formControl.label,
                        trailing: Switch(
                          value: field.value,
                          onChanged: (widget.readonly || formControl.readonly)
                              ? null
                              : (bool value) {
                                  field.didChange(value);
                                },
                        ),
                        onTap: (widget.readonly || formControl.readonly)
                            ? null
                            : () {
                                bool newValue = !(field.value ?? false);
                                field.didChange(newValue);
                              },
                      ),
                    );
                  });
              break;

            case FormBuilderInput.TYPE_STEPPER:
              return FormField(
                enabled: !(widget.readonly || formControl.readonly),
                // key: _fieldKey,
                initialValue: formControl.value,
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                    ),
                    child: SyStepper(
                      value: field.value ?? 0,
                      step: formControl.step ?? 1,
                      min: formControl.min ?? 0,
                      max: formControl.max ?? 9999999,
                      size: 24.0,
                      onChange: (widget.readonly || formControl.readonly)
                          ? null
                          : (value) {
                              field.didChange(value);
                            },
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_RATE:
              return FormField(
                enabled: !(widget.readonly || formControl.readonly),
                // key: _fieldKey,
                initialValue: formControl.value ?? 1,
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                    ),
                    child: SyRate(
                      value: field.value,
                      total: formControl.max,
                      icon: formControl.icon,
                      //TODO: When disabled change icon color (Probably deep grey)
                      iconSize: formControl.iconSize ?? 24.0,
                      onTap: (widget.readonly || formControl.readonly)
                          ? null
                          : (value) {
                              field.didChange(value);
                            },
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_CHECKBOX:
              return FormField(
                // key: _fieldKey,
                enabled: !(widget.readonly || formControl.readonly),
                initialValue: formControl.value ?? false,
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                    ),
                    child: ListTile(
                      dense: true,
                      isThreeLine: false,
                      contentPadding: EdgeInsets.all(0.0),
                      title: formControl.label,
                      trailing: Checkbox(
                        value: field.value ?? false,
                        onChanged: (widget.readonly || formControl.readonly)
                            ? null
                            : (bool value) {
                                field.didChange(value);
                              },
                      ),
                      onTap: (widget.readonly || formControl.readonly)
                          ? null
                          : () {
                              bool newValue = !(field.value ?? false);
                              field.didChange(newValue);
                            },
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_SLIDER:
              return FormField(
                // key: _fieldKey,
                enabled: !(widget.readonly || formControl.readonly),
                initialValue: formControl.value,
                validator: (value) {
                  if (formControl.require && value == null)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                onSaved: (val) {
                  value[formControl.attribute] = val;
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                    ),
                    child: Container(
                      padding: EdgeInsets.only(top: 10.0),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Slider(
                            value: field.value,
                            min: formControl.min,
                            max: formControl.max,
                            divisions: formControl.divisions,
                            onChanged:
                                (widget.readonly || formControl.readonly)
                                    ? null
                                    : (double value) {
                                        field.didChange(value);
                                      },
                          ),
                          Row(
                            mainAxisAlignment: MainAxisAlignment.spaceBetween,
                            children: <Widget>[
                              Text("${formControl.min}"),
                              Text("${field.value}"),
                              Text("${formControl.max}"),
                            ],
                          ),
                        ],
                      ),
                    ),
                  );
                },
              );
              break;

            case FormBuilderInput.TYPE_CHECKBOX_LIST:
              return FormField(
                  // key: _fieldKey,
                  enabled: !(widget.readonly || formControl.readonly),
                  initialValue: formControl.value ?? [],
                  onSaved: (val) {
                    value[formControl.attribute] = val;
                  },
                  validator: formControl.validator,
                  builder: (FormFieldState<dynamic> field) {
                    List<Widget> checkboxList = [];
                    for (int i = 0; i < formControl.options.length; i++) {
                      checkboxList.addAll([
                        ListTile(
                          dense: true,
                          isThreeLine: false,
                          contentPadding: EdgeInsets.all(0.0),
                          leading: Checkbox(
                            value: field.value
                                .contains(formControl.options[i].value),
                            onChanged: (widget.readonly ||
                                    formControl.readonly)
                                ? null
                                : (bool value) {
                                    var currValue = field.value;
                                    if (value)
                                      currValue
                                          .add(formControl.options[i].value);
                                    else
                                      currValue.remove(
                                          formControl.options[i].value);
                                    field.didChange(currValue);
                                  },
                          ),
                          title: Text(
                              "${formControl.options[i].label ?? formControl.options[i].value}"),
                          onTap: (widget.readonly || formControl.readonly)
                              ? null
                              : () {
                                  var currentValue = field.value;
                                  if (!currentValue
                                      .contains(formControl.options[i].value))
                                    currentValue
                                        .add(formControl.options[i].value);
                                  else
                                    currentValue
                                        .remove(formControl.options[i].value);
                                  field.didChange(currentValue);
                                },
                        ),
                        Divider(
                          height: 0.0,
                        ),
                      ]);
                    }
                    return InputDecorator(
                      decoration: formControl.decoration.copyWith(
                        enabled: !(widget.readonly || formControl.readonly),
                        errorText: field.errorText,
                        contentPadding:
                            EdgeInsets.only(top: 10.0, bottom: 0.0),
                        border: InputBorder.none,
                      ),
                      child: Column(
                        children: checkboxList,
                      ),
                    );
                  });
              break;
            case FormBuilderInput.TYPE_CHIPS_INPUT:
              return SizedBox(
                // height: 200.0,
                child: FormField(
                  // key: _fieldKey,
                  enabled: !(widget.readonly || formControl.readonly),
                  initialValue: formControl.value ?? [],
                  onSaved: (val) {
                    value[formControl.attribute] = val;
                  },
                  validator: (value) {
                    if (formControl.require && value.length == 0)
                      return "${formControl.attribute} is required";
                    if (formControl.validator != null)
                      return formControl.validator(value);
                  },
                  builder: (FormFieldState<dynamic> field) {
                    return ChipsInput(
                      initialValue: field.value,
                      enabled: !(widget.readonly || formControl.readonly),
                      decoration: formControl.decoration.copyWith(
                        enabled: !(widget.readonly || formControl.readonly),
                        errorText: field.errorText,
                      ),
                      findSuggestions: formControl.suggestionsCallback,
                      onChanged: (data) {
                        field.didChange(data);
                      },
                      maxChips: formControl.max,
                      chipBuilder: formControl.chipBuilder,
                      suggestionBuilder: formControl.suggestionBuilder,
                    );
                  },
                ),
              );
              break;

            case FormBuilderInput.TYPE_SIGNATURE_PAD:
              var _signatureCanvas = Signature(
                points: formControl.points,
                width: formControl.width,
                height: formControl.height,
                backgroundColor: formControl.backgroundColor,
                penColor: formControl.penColor,
                penStrokeWidth: formControl.penStrokeWidth,
              );

              return FormField<Image>(
                key: Key(formControl.attribute),
                enabled: !(widget.readonly || formControl.readonly),
                initialValue: formControl.value,
                onSaved: (val) async {
                  Uint8List signature = await _signatureCanvas.exportBytes();
                  var image = Image.memory(signature).image;
                  value[formControl.attribute] = image;
                },
                validator: (value) {
                  if (formControl.require && _signatureCanvas.isEmpty)
                    return "${formControl.attribute} is required";
                  if (formControl.validator != null)
                    return formControl.validator(value);
                },
                builder: (FormFieldState<dynamic> field) {
                  return InputDecorator(
                    decoration: formControl.decoration.copyWith(
                      enabled: !(widget.readonly || formControl.readonly),
                      errorText: field.errorText,
                    ),
                    child: Column(
                      children: <Widget>[
                        Container(
                          decoration: BoxDecoration(
                            border: Border.all(color: Colors.grey),
                          ),
                          child: GestureDetector(
                            onVerticalDragUpdate: (_) {},
                            child: _signatureCanvas,
                          ),
                        ),
                        Row(
                          children: <Widget>[
                            Expanded(child: SizedBox()),
                            FlatButton(
                                onPressed: () {
                                  _signatureCanvas.clear();
                                  field.didChange(null);
                                },
                                child: Text('Clear')),
                          ],
                        ),
                      ],
                    ),
                  );
                },
              );
              break;
          }
        } else
          return Container();
      }).toList(),
    ),
  );
}