Question

Does anyone know what the appropriate mechanism is when creating a custom compound control to apply state changes from the container down to all the children? It would seem to me there should be a straightforward way to set up a ViewGroup to forward all state changes (pressed, enabled, etc.) to each child.

For example, if I create a custom widget along the lines of:

public class MyWidget extends RelativeLayout {

    private TextView mTitleView, mValueView;
    private ImageView mImageView;

    public ValueButton(Context context) {
        this(context, null);
    }

    public ValueButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        //View setup, etc.
    }
}

In many cases, there are drawable or color state lists attached to the children that I want to toggle when changes apply to the overall widget as a whole. What do I need to add to a widget such as this so that when, for example, I call MyWidget.setEnabled() or when MyWidget is pressed those state changes filter down the hierarchy?

Thanks!

Answer 1

Add android:duplicateParentState="true" to each child (perhaps iterating through the childs using getChildAt(int index))

http://developer.android.com/reference/android/view/View.html#attr_android:duplicateParentState

Edit: you will need to set it up in the xml

Note: in the current implementation, setting this property to true after the view was added to a ViewGroup might have no effect at all. This property should always be used from XML or set to true before adding this view to a ViewGroup.