[TextInputLayout] Exposed the style of the ExposedDropDownMenu

[gabrielemariotti]

Currently the ExposedDropDownMenu provided by DropdownMenuEndIconDelegate doesn't use the shapeAppearance defined in the app theme and the corner radius are defined by code.

With this change:

• the ExposedDropDownMenu uses the shapeAppearance defined in the app theme
• there is a new attribute exposedDropDownMenuStyle defined in the TextInputLayout style with allows to customize the shapeAppearance /shapeAppearanceOverlay (and some other properties) of the ExposedDropDownMenu.

This change can be tested with the current catalog (changing the shapeAppearance).

[leticiarossi]

Thanks for the PR! I think it would be confusing to have a exposedDropDownMenuStyle since we have the TextInputLayout ExposedDropdownMenu styles and the AutoCompleteTextView styles.

Since we only want to affect the dropdown's popup background, I think it would make more sense to have an attribute like popupBackgroundShapeAppearance. I wonder if we could remove the logic that sets the background from the DropdownMenuEndIconDelegate and move it to the MaterialAutoCompleteTextView class instead, where it could read that attribute (that would then be set inside of the existent Widget.MaterialComponents.AutoCompleteTextView.* styles.

Would you be interested in trying that?

[gabrielemariotti]

Thanks for your feedback.
I will update the PR.

Are you interested to set in the Widget.MaterialComponents.AutoCompleteTextView.* styles also attributes like
popupVerticalPaddingand popupElevation?

[leticiarossi]

We already set android:dropDownVerticalOffset and android:popupElevation so it'd make sense to also read then in the class! I think it would also make sense to have popup*Padding attrs (right now we only set vertical padding but developers may want to set different paddings too)

[gabrielemariotti]

Moving all the logic that sets the background to the MaterialAutoCompleteTextView class, how do you prefer to set the popupBackground with an AppCompatAutoCompleteTextView (for example with a Bridge theme)?

[gabrielemariotti]

I've just updated the PR moving the all the logic that sets the background to the MaterialAutoCompleteTextView class.

[jsdeyro]

Will these be able to customize the ExposedDropDownMenu dropdown's popup background? If so, when this will be updated?