How to get parent widget color in flutter tree widget?

Question

I want change a color of a button depending by background color of with:

computeLuminance()

So, I need to get parent widget located by button and get its color / any that can I calculate difference between the two colors.

Color calculateTextColor(Color background) {
    return background.computeLuminance() >= 0.5 ? Colors.black : Colors.white;
  }

I need to pass background color as exact parent color widget.

score 1 · Accepted Answer · answered Dec 26 '22 at 13:59

You can get a parent property ( color ) by referring to it using the BuildContext, and the findAncestorWidgetOfExactType method like this:

   Container(
          width: 200,
          height: 200,
          color: Colors.green,
          child: Builder(
            builder: (context) {
              return Text(
                "Hello",
                style: TextStyle(
                  color: context
                      .findAncestorWidgetOfExactType<Container>()
                      ?.color
                      ?.withGreen(255),
                  fontSize: 20,
                ),
              );
            },
          ),
        ),

As you see in the example, I wrapped the Text widget with a Builder to give it a new BuildContext so I can start searching from it ( not wrapping with the Builder widget will make the look-up start from the BuildContext of the build(), which exclude the current Widget tree, which is not what we want ).

Then, starting the lookup with findAncestorWidgetOfExactType<Container>(), In my example I have the parent as a Container so I set its type as generic.

this will give accessibility to its properties, and get me it the same color.

the withGreen() is just to clarify that it works.

How to get parent widget color in flutter tree widget?

1 Answers1