A listener implemented by all two-way bindings to be notified when a triggering change happens.
For example, when there is a two-way binding for android:text, an implementation of
InverseBindingListener
will be generated in the layout's binding class.
private static class InverseListenerTextView implements InverseBindingListener {
@Override
public void onChange() {
mObj.setTextValue(mTextView.getText());
}
}
A
BindingAdapter should be used to assign the event listener.
For example, android:onTextChanged
will need to trigger the event listener
for the android:text
attribute.
@InverseBindingAdapter(attribute = "android:text", event = "android:textAttrChanged")
public static void captureTextValue(TextView view, ObservableField<CharSequence> value) {
CharSequence newValue = view.getText();
CharSequence oldValue = value.get();
if (oldValue == null) {
value.set(newValue);
} else if (!contentEquals(newValue, oldValue)) {
value.set(newValue);
}
}
@BindingAdapter(value = {"android:beforeTextChanged", "android:onTextChanged",
"android:afterTextChanged", "android:textAttrChanged"},
requireAll = false)
public static void setTextWatcher(TextView view, final BeforeTextChanged before,
final OnTextChanged on, final AfterTextChanged after,
final InverseBindingListener textAttrChanged) {
TextWatcher newValue = new TextWatcher() {
...
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (on != null) {
on.onTextChanged(s, start, before, count);
}
if (textAttrChanged != null) {
textAttrChanged.onChange();
}
}
}
TextWatcher oldValue = ListenerUtil.trackListener(view, newValue, R.id.textWatcher);
if (oldValue != null) {
view.removeTextChangedListener(oldValue);
}
view.addTextChangedListener(newValue);
}