How to make flutter custom drop down button?

Question

I want to Customise DropDownButton, so that it does not render the content of DropdownItem. Instead it should render my Custom layout/widget before and after selecting an item from DropDown. In simple Words, I want to customise my DropDownButton.

Thanks,

Checking how Dropdown is implemented, I think you will need to edit in the source implementation in order to do that as it checks if value=null or else value takes the item value and not a subset of it. — Shady Aziza
– Shady Aziza, Commented Feb 28, 2018 at 9:00
Can you be a little more clear about what you are trying to achive? — Hemanth Raj
– Hemanth Raj, Commented Feb 28, 2018 at 10:47
@HemanthRaj making dropdown value customization rather than reflecting the choice (choosing A will make dropdownButton value = A, what about if I choose A, the dropdownButton value = B instead) — Shady Aziza
– Shady Aziza, Commented Feb 28, 2018 at 11:26

Dmitriy · Accepted Answer · 2019-03-13 00:57:44Z

6

How to render DropdownButton items differently when it is dropped down?

I found a solution through DropdownMenuItem. Its build() is executed separately for closed and dropped down state. You can use the context to find out if it is closed or dropped down state. e.g you can check for an ancestor stateful widget.

I use something like this dummy code fragment:

DropdownButton<String>(
    value: selectedItem.id,
    items: items.map((item) {
        return DropdownMenuItem<String>(
            value: item.id,
            child: Builder(builder: (BuildContext context) {
                final bool isDropDown = context.ancestorStateOfType(TypeMatcher<PageState>()) == null;

                if (isDropDown) {
                    return Text(item.name);
                } else {
                    return Text(item.name, style: TextStyle(color: Colors.red));
                }
            },)
        );
    }).toList(),
);

Where items is a list of id-name instances, and PageState is the state of my own stateful widget.

edited Mar 13, 2019 at 0:57

Dmitriy

5,58512 gold badges27 silver badges39 bronze badges

answered Mar 13, 2019 at 0:30

bdi

1912 silver badges6 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

zack Over a year ago

so this works. the issue I'm having is getting the dropdown width to expand where the dropdown items ares larger than the button...

Collectives™ on Stack Overflow

How to make flutter custom drop down button?

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related