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child: actions(
// bind intents to an actual method in your code
actions: <type, Action<Intent>>{
CreateNewItemIntent: CallbackAction<CreateNewItemIntent>(
onInvoke: (intent) => _createNewItem(),
),
},
// your sub-tree must be wrapped in a focusNode, so it can take focus.
child: focus(
autofocus: true,
child: container(),
),
),
);
}
<code_end>
the shortcuts widget is useful because it only
allows shortcuts to be fired when this widget tree
or one of its children has focus and is visible.
the final option is a global listener. this listener
can be used for always-on, app-wide shortcuts or for
panels that can accept shortcuts whenever they’re visible
(regardless of their focus state). adding global listeners
is easy with HardwareKeyboard:
<code_start>
@override
void initState() {
super.initState();
HardwareKeyboard.instance.addHandler(_handleKey);
}
@override
void dispose() {
HardwareKeyboard.instance.removeHandler(_handleKey);
super.dispose();
}
<code_end>
to check key combinations with the global listener,
you can use the HardwareKeyboard.instance.logicalKeysPressed set.
for example, a method like the following can check whether any
of the provided keys are being held down:
<code_start>
static bool isKeyDown(Set<LogicalKeyboardKey> keys) {
return keys
.intersection(hardwarekeyboard.instance.logicalkeyspressed)
.isnotempty;
}
<code_end>
putting these two things together,
you can fire an action when Shift+N is pressed:
<code_start>
bool _handleKey(KeyEvent event) {
bool isShiftDown = isKeyDown({
LogicalKeyboardKey.shiftLeft,
LogicalKeyboardKey.shiftRight,
});
if (isshiftdown && event.logicalKey == LogicalKeyboardKey.keyN) {
_createNewItem();
return true;
}
return false;
}
<code_end>
one note of caution when using the static listener,
is that you often need to disable it when the user
is typing in a field or when the widget it’s associated with
is hidden from view.
unlike with shortcuts or KeyboardListener,
this is your responsibility to manage. this can be especially
important when you’re binding a Delete/Backspace accelerator for
delete, but then have child TextFields that the user
might be typing in.
<topic_end>
<topic_start>
mouse enter, exit, and hover
on desktop, it’s common to change the mouse cursor
to indicate the functionality about the content the
mouse is hovering over. for example, you usually see
a hand cursor when you hover over a button,
or an i cursor when you hover over text.
the material component set has built-in support
for your standard button and text cursors.
to change the cursor from within your own widgets,
use MouseRegion:
<code_start>
// show hand cursor
return MouseRegion(
cursor: SystemMouseCursors.click,
// request focus when clicked
child: GestureDetector(
onTap: () {
Focus.of(context).requestFocus();
_submit();
},
child: Logo(showBorder: hasFocus),
),
);
<code_end>
MouseRegion is also useful for creating custom
rollover and hover effects:
<code_start>