From 827577c179f78c9fb82a46142d2cdb9e61f4662b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?H=C3=A9ctor=20Ram=C3=B3n?= Date: Fri, 4 Jun 2021 19:39:08 +0700 Subject: [PATCH] Introduce `snap_to` and `unsnap` to `scrollable::State` --- native/src/widget/scrollable.rs | 325 ++++++++++++++------------------ 1 file changed, 140 insertions(+), 185 deletions(-) diff --git a/native/src/widget/scrollable.rs b/native/src/widget/scrollable.rs index 374dcf76..28d695ba 100644 --- a/native/src/widget/scrollable.rs +++ b/native/src/widget/scrollable.rs @@ -10,7 +10,7 @@ use crate::{ Rectangle, Size, Vector, Widget, }; -use std::{cell::RefCell, f32, hash::Hash, u32}; +use std::{f32, hash::Hash, u32}; /// A widget that can vertically display an infinite amount of content with a /// scrollbar. @@ -24,8 +24,6 @@ pub struct Scrollable<'a, Message, Renderer: self::Renderer> { scroller_width: u16, content: Column<'a, Message, Renderer>, style: Renderer::Style, - on_scroll: Option Message>>, - snap_to_bottom: bool, } impl<'a, Message, Renderer: self::Renderer> Scrollable<'a, Message, Renderer> { @@ -40,36 +38,9 @@ impl<'a, Message, Renderer: self::Renderer> Scrollable<'a, Message, Renderer> { scroller_width: 10, content: Column::new(), style: Renderer::Style::default(), - on_scroll: None, - snap_to_bottom: false, } } - /// Whether to set the [`Scrollable`] to snap to bottom when the user - /// scrolls to bottom or not. This will keep the scrollable at the bottom - /// even if new content is added to the scrollable. - /// - /// [`Scrollable`]: struct.Scrollable.html - pub fn snap_to_bottom(mut self, snap: bool) -> Self { - self.snap_to_bottom = snap; - self - } - - /// Sets a function to call when the [`Scrollable`] is scrolled. - /// - /// The function takes two `f32` as arguments. First is the percentage of - /// where the scrollable is at right now. Second is the percentage of where - /// the scrollable was *before*. `0.0` means top and `1.0` means bottom. - /// - /// [`Scrollable`]: struct.Scrollable.html - pub fn on_scroll(mut self, message_constructor: F) -> Self - where - F: 'static + Fn(f32, f32) -> Message, - { - self.on_scroll = Some(Box::new(message_constructor)); - self - } - /// Sets the vertical spacing _between_ elements. /// /// Custom margins per element do not exist in Iced. You should use this @@ -215,7 +186,7 @@ where .map(|scrollbar| scrollbar.is_mouse_over(cursor_position)) .unwrap_or(false); - let mut event_status = { + let event_status = { let cursor_position = if is_mouse_over && !is_mouse_over_scrollbar { Point::new( cursor_position.x, @@ -240,78 +211,99 @@ where ) }; - if let event::Status::Ignored = event_status { - self.state.prev_offset = self.state.offset(bounds, content_bounds); + if let event::Status::Captured = event_status { + return event::Status::Captured; + } + + if is_mouse_over { + match event { + Event::Mouse(mouse::Event::WheelScrolled { delta }) => { + match delta { + mouse::ScrollDelta::Lines { y, .. } => { + // TODO: Configurable speed (?) + self.state.scroll(y * 60.0, bounds, content_bounds); + } + mouse::ScrollDelta::Pixels { y, .. } => { + self.state.scroll(y, bounds, content_bounds); + } + } + + return event::Status::Captured; + } + Event::Touch(event) => { + match event { + touch::Event::FingerPressed { .. } => { + self.state.scroll_box_touched_at = + Some(cursor_position); + } + touch::Event::FingerMoved { .. } => { + if let Some(scroll_box_touched_at) = + self.state.scroll_box_touched_at + { + let delta = + cursor_position.y - scroll_box_touched_at.y; - if is_mouse_over { - match event { - Event::Mouse(mouse::Event::WheelScrolled { delta }) => { - match delta { - mouse::ScrollDelta::Lines { y, .. } => { - // TODO: Configurable speed (?) self.state.scroll( - y * 60.0, + delta, bounds, content_bounds, ); - } - mouse::ScrollDelta::Pixels { y, .. } => { - self.state.scroll(y, bounds, content_bounds); - } - } - event_status = event::Status::Captured; - } - Event::Touch(event) => { - match event { - touch::Event::FingerPressed { .. } => { self.state.scroll_box_touched_at = Some(cursor_position); } - touch::Event::FingerMoved { .. } => { - if let Some(scroll_box_touched_at) = - self.state.scroll_box_touched_at - { - let delta = cursor_position.y - - scroll_box_touched_at.y; - - self.state.scroll( - delta, - bounds, - content_bounds, - ); - - self.state.scroll_box_touched_at = - Some(cursor_position); - } - } - touch::Event::FingerLifted { .. } - | touch::Event::FingerLost { .. } => { - self.state.scroll_box_touched_at = None; - } } - - event_status = event::Status::Captured; + touch::Event::FingerLifted { .. } + | touch::Event::FingerLost { .. } => { + self.state.scroll_box_touched_at = None; + } } - _ => {} + + return event::Status::Captured; } + _ => {} } + } - if self.state.is_scroller_grabbed() { - match event { - Event::Mouse(mouse::Event::ButtonReleased( - mouse::Button::Left, - )) - | Event::Touch(touch::Event::FingerLifted { .. }) - | Event::Touch(touch::Event::FingerLost { .. }) => { - self.state.scroller_grabbed_at = None; + if self.state.is_scroller_grabbed() { + match event { + Event::Mouse(mouse::Event::ButtonReleased( + mouse::Button::Left, + )) + | Event::Touch(touch::Event::FingerLifted { .. }) + | Event::Touch(touch::Event::FingerLost { .. }) => { + self.state.scroller_grabbed_at = None; - event_status = event::Status::Captured; + return event::Status::Captured; + } + Event::Mouse(mouse::Event::CursorMoved { .. }) + | Event::Touch(touch::Event::FingerMoved { .. }) => { + if let (Some(scrollbar), Some(scroller_grabbed_at)) = + (scrollbar, self.state.scroller_grabbed_at) + { + self.state.scroll_to( + scrollbar.scroll_percentage( + scroller_grabbed_at, + cursor_position, + ), + bounds, + content_bounds, + ); + + return event::Status::Captured; } - Event::Mouse(mouse::Event::CursorMoved { .. }) - | Event::Touch(touch::Event::FingerMoved { .. }) => { - if let (Some(scrollbar), Some(scroller_grabbed_at)) = - (scrollbar, self.state.scroller_grabbed_at) + } + _ => {} + } + } else if is_mouse_over_scrollbar { + match event { + Event::Mouse(mouse::Event::ButtonPressed( + mouse::Button::Left, + )) + | Event::Touch(touch::Event::FingerPressed { .. }) => { + if let Some(scrollbar) = scrollbar { + if let Some(scroller_grabbed_at) = + scrollbar.grab_scroller(cursor_position) { self.state.scroll_to( scrollbar.scroll_percentage( @@ -322,71 +314,18 @@ where content_bounds, ); - event_status = event::Status::Captured; + self.state.scroller_grabbed_at = + Some(scroller_grabbed_at); + + return event::Status::Captured; } } - _ => {} - } - } else if is_mouse_over_scrollbar { - match event { - Event::Mouse(mouse::Event::ButtonPressed( - mouse::Button::Left, - )) - | Event::Touch(touch::Event::FingerPressed { .. }) => { - if let Some(scrollbar) = scrollbar { - if let Some(scroller_grabbed_at) = - scrollbar.grab_scroller(cursor_position) - { - self.state.scroll_to( - scrollbar.scroll_percentage( - scroller_grabbed_at, - cursor_position, - ), - bounds, - content_bounds, - ); - - self.state.scroller_grabbed_at = - Some(scroller_grabbed_at); - - event_status = event::Status::Captured; - } - } - } - _ => {} } + _ => {} } } - if let event::Status::Captured = event_status { - if self.snap_to_bottom { - let new_offset = self.state.offset(bounds, content_bounds); - - if new_offset < self.state.prev_offset { - self.state.snap_to_bottom = false; - } else { - let scroll_perc = new_offset as f32 - / (content_bounds.height - bounds.height); - - if scroll_perc >= 1.0 - f32::EPSILON { - self.state.snap_to_bottom = true; - } - } - } - - if let Some(on_scroll) = &self.on_scroll { - messages.push(on_scroll( - self.state.offset(bounds, content_bounds) as f32 - / (content_bounds.height - bounds.height), - self.state.prev_offset as f32 - / (content_bounds.height - bounds.height), - )); - } - - event::Status::Captured - } else { - event::Status::Ignored - } + event::Status::Ignored } fn draw( @@ -400,15 +339,6 @@ where let bounds = layout.bounds(); let content_layout = layout.children().next().unwrap(); let content_bounds = content_layout.bounds(); - - if self.state.snap_to_bottom { - self.state.scroll_to(1.0, bounds, content_bounds); - } - - if let Some(scroll_to) = self.state.scroll_to.borrow_mut().take() { - self.state.scroll_to(scroll_to, bounds, content_bounds); - } - let offset = self.state.offset(bounds, content_bounds); let scrollbar = renderer.scrollbar( bounds, @@ -488,14 +418,44 @@ where } /// The local state of a [`Scrollable`]. -#[derive(Debug, Clone, Default)] +#[derive(Debug, Clone, Copy)] pub struct State { scroller_grabbed_at: Option, scroll_box_touched_at: Option, - prev_offset: u32, - snap_to_bottom: bool, - offset: RefCell, - scroll_to: RefCell>, + offset: Offset, +} + +impl Default for State { + fn default() -> Self { + Self { + scroller_grabbed_at: None, + scroll_box_touched_at: None, + offset: Offset::Absolute(0.0), + } + } +} + +/// The local state of a [`Scrollable`]. +#[derive(Debug, Clone, Copy)] +enum Offset { + Absolute(f32), + Relative(f32), +} + +impl Offset { + fn absolute(self, bounds: Rectangle, content_bounds: Rectangle) -> f32 { + match self { + Self::Absolute(absolute) => { + let hidden_content = + (content_bounds.height - bounds.height).max(0.0); + + absolute.min(hidden_content) + } + Self::Relative(percentage) => { + ((content_bounds.height - bounds.height) * percentage).max(0.0) + } + } + } } impl State { @@ -516,51 +476,46 @@ impl State { return; } - let offset_val = *self.offset.borrow(); - *self.offset.borrow_mut() = (offset_val - delta_y) - .max(0.0) - .min((content_bounds.height - bounds.height) as f32); + self.offset = Offset::Absolute( + (self.offset.absolute(bounds, content_bounds) - delta_y) + .max(0.0) + .min((content_bounds.height - bounds.height) as f32), + ); } - /// Moves the scroll position to a relative amount, given the bounds of - /// the [`Scrollable`] and its contents. + /// Scrolls the [`Scrollable`] to a relative amount. /// /// `0` represents scrollbar at the top, while `1` represents scrollbar at /// the bottom. pub fn scroll_to( - &self, + &mut self, percentage: f32, bounds: Rectangle, content_bounds: Rectangle, ) { - *self.offset.borrow_mut() = - ((content_bounds.height - bounds.height) * percentage).max(0.0); + self.snap_to(percentage); + self.unsnap(bounds, content_bounds); } - /// Marks the scrollable to scroll to `perc` percentage (between 0.0 and 1.0) - /// in the next `draw` call. + /// Snaps the scroll position to a relative amount. /// - /// [`Scrollable`]: struct.Scrollable.html - /// [`State`]: struct.State.html - pub fn scroll_to_percentage(&mut self, perc: f32) { - *self.scroll_to.borrow_mut() = Some(perc.max(0.0).min(1.0)); + /// `0` represents scrollbar at the top, while `1` represents scrollbar at + /// the bottom. + pub fn snap_to(&mut self, percentage: f32) { + self.offset = Offset::Relative(percentage.max(0.0).min(1.0)); } - /// Marks the scrollable to scroll to bottom in the next `draw` call. - /// - /// [`Scrollable`]: struct.Scrollable.html - /// [`State`]: struct.State.html - pub fn scroll_to_bottom(&mut self) { - self.scroll_to_percentage(1.0); + /// Unsnaps the current scroll position, if snapped, given the bounds of the + /// [`Scrollable`] and its contents. + pub fn unsnap(&mut self, bounds: Rectangle, content_bounds: Rectangle) { + self.offset = + Offset::Absolute(self.offset.absolute(bounds, content_bounds)); } /// Returns the current scrolling offset of the [`State`], given the bounds /// of the [`Scrollable`] and its contents. pub fn offset(&self, bounds: Rectangle, content_bounds: Rectangle) -> u32 { - let hidden_content = - (content_bounds.height - bounds.height).max(0.0).round() as u32; - - self.offset.borrow().min(hidden_content as f32) as u32 + self.offset.absolute(bounds, content_bounds) as u32 } /// Returns whether the scroller is currently grabbed or not.