From d20493c8a0cc6e2e250434ed4cb6f350ed39d7e8 Mon Sep 17 00:00:00 2001 From: Marien Zwart Date: Sun, 21 May 2023 23:41:26 +1000 Subject: Support conversion from Fn trait to custom theme ...instead of just from function pointers. I'm making this change not because I actually want to pass a closure, but to make passing a single fixed function work. This commit also simplifies the scrollable example slightly, and without the other half of this change that simplified example fails to compile with: ``` error[E0277]: the trait bound `iced::theme::ProgressBar: From fn(&'a Theme) -> iced::widget::progress_bar::Appearance {progress_bar_custom_style}>` is not satisfied --> examples/scrollable/src/main.rs:292:28 | 292 | .style(progress_bar_custom_style) | ----- ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `From fn(&'a Theme) -> iced::widget::progress_bar::Appearance {progress_bar_custom_style}>` is not implemented for `iced::theme::ProgressBar` | | | required by a bound introduced by this call | = help: the trait `From fn(&'a Theme) -> iced::widget::progress_bar::Appearance>` is implemented for `iced::theme::ProgressBar` = note: required for `for<'a> fn(&'a Theme) -> iced::widget::progress_bar::Appearance {progress_bar_custom_style}` to implement `Into` note: required by a bound in `iced::widget::ProgressBar::::style` --> /home/marienz/src/iced/widget/src/progress_bar.rs:77:21 | 77 | style: impl Into<::Style>, | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `ProgressBar::::style` ``` This happens because `progress_bar_custom_style` by itself is a function item, which is typically coerced to a function pointer when one is needed, but not in this case. It is possible to work around this on the caller's side, but especially since the compiler diagnostic for this is a bit rough (see https://github.com/rust-lang/rust/issues/100116) let's try to make it work out of the box. --- examples/scrollable/src/main.rs | 27 ++++++++------------------- 1 file changed, 8 insertions(+), 19 deletions(-) (limited to 'examples/scrollable/src') diff --git a/examples/scrollable/src/main.rs b/examples/scrollable/src/main.rs index 97344c94..9d57cb94 100644 --- a/examples/scrollable/src/main.rs +++ b/examples/scrollable/src/main.rs @@ -289,18 +289,13 @@ impl Application for ScrollableDemo { } Direction::Horizontal => { progress_bar(0.0..=1.0, self.current_scroll_offset.x) - .style(theme::ProgressBar::Custom(Box::new( - ProgressBarCustomStyle, - ))) + .style(progress_bar_custom_style) .into() } Direction::Multi => column![ progress_bar(0.0..=1.0, self.current_scroll_offset.y), - progress_bar(0.0..=1.0, self.current_scroll_offset.x).style( - theme::ProgressBar::Custom(Box::new( - ProgressBarCustomStyle, - )) - ) + progress_bar(0.0..=1.0, self.current_scroll_offset.x) + .style(progress_bar_custom_style) ] .spacing(10) .into(), @@ -372,16 +367,10 @@ impl scrollable::StyleSheet for ScrollbarCustomStyle { } } -struct ProgressBarCustomStyle; - -impl progress_bar::StyleSheet for ProgressBarCustomStyle { - type Style = Theme; - - fn appearance(&self, style: &Self::Style) -> progress_bar::Appearance { - progress_bar::Appearance { - background: style.extended_palette().background.strong.color.into(), - bar: Color::from_rgb8(250, 85, 134).into(), - border_radius: 0.0, - } +fn progress_bar_custom_style(theme: &Theme) -> progress_bar::Appearance { + progress_bar::Appearance { + background: theme.extended_palette().background.strong.color.into(), + bar: Color::from_rgb8(250, 85, 134).into(), + border_radius: 0.0, } } -- cgit