From 97e35f7d37ed857fba9b8d831c82b2cc8cf7b31b Mon Sep 17 00:00:00 2001
From: Héctor Ramón Jiménez <hector@hecrj.dev>
Date: Fri, 12 Jul 2024 12:08:35 +0200
Subject: Add `on_press_with` method for `Button`
This allows using a closure to produce the message
only when the `Button` is actually pressed. Useful
when generating the message may be expensive.
---
widget/src/button.rs | 39 +++++++++++++++++++++++++++++++++++----
1 file changed, 35 insertions(+), 4 deletions(-)
diff --git a/widget/src/button.rs b/widget/src/button.rs
index 5d446fea..fb505d6e 100644
--- a/widget/src/button.rs
+++ b/widget/src/button.rs
@@ -52,7 +52,7 @@ where
Theme: Catalog,
{
content: Element<'a, Message, Theme, Renderer>,
- on_press: Option<Message>,
+ on_press: Option<OnPress<'a, Message>>,
width: Length,
height: Length,
padding: Padding,
@@ -60,6 +60,20 @@ where
class: Theme::Class<'a>,
}
+enum OnPress<'a, Message> {
+ Direct(Message),
+ Closure(Box<dyn Fn() -> Message + 'a>),
+}
+
+impl<'a, Message: Clone> OnPress<'a, Message> {
+ fn get(&self) -> Message {
+ match self {
+ OnPress::Direct(message) => message.clone(),
+ OnPress::Closure(f) => f(),
+ }
+ }
+}
+
impl<'a, Message, Theme, Renderer> Button<'a, Message, Theme, Renderer>
where
Renderer: crate::core::Renderer,
@@ -105,7 +119,23 @@ where
///
/// Unless `on_press` is called, the [`Button`] will be disabled.
pub fn on_press(mut self, on_press: Message) -> Self {
- self.on_press = Some(on_press);
+ self.on_press = Some(OnPress::Direct(on_press));
+ self
+ }
+
+ /// Sets the message that will be produced when the [`Button`] is pressed.
+ ///
+ /// This is analogous to [`Button::on_press`], but using a closure to produce
+ /// the message.
+ ///
+ /// This closure will only be called when the [`Button`] is actually pressed and,
+ /// therefore, this method is useful to reduce overhead if creating the resulting
+ /// message is slow.
+ pub fn on_press_with(
+ mut self,
+ on_press: impl Fn() -> Message + 'a,
+ ) -> Self {
+ self.on_press = Some(OnPress::Closure(Box::new(on_press)));
self
}
@@ -114,7 +144,7 @@ where
///
/// If `None`, the [`Button`] will be disabled.
pub fn on_press_maybe(mut self, on_press: Option<Message>) -> Self {
- self.on_press = on_press;
+ self.on_press = on_press.map(OnPress::Direct);
self
}
@@ -258,7 +288,8 @@ where
}
Event::Mouse(mouse::Event::ButtonReleased(mouse::Button::Left))
| Event::Touch(touch::Event::FingerLifted { .. }) => {
- if let Some(on_press) = self.on_press.clone() {
+ if let Some(on_press) = self.on_press.as_ref().map(OnPress::get)
+ {
let state = tree.state.downcast_mut::<State>();
if state.is_pressed {
--
cgit