diff --git a/src/views/scroll_view.rs b/src/views/scroll_view.rs index 21010ac..1a779ce 100644 --- a/src/views/scroll_view.rs +++ b/src/views/scroll_view.rs @@ -89,22 +89,72 @@ impl ScrollView { } } -impl ScrollView where V: View { +impl ScrollView +where + V: View, +{ + /// Compute the size we would need. + /// + /// Given the constraints, and the axis that need scrollbars. + /// + /// Returns `(inner_size, size, scrollable)`. + fn sizes_when_scrolling( + &mut self, constraint: Vec2, scrollable: XY, + ) -> (Vec2, Vec2, XY) { + // This is the size taken by the scrollbars. + let scrollbar_size = scrollable + .select_or(self.scrollbar_padding + (1, 1), Vec2::zero()); - fn compute_size(&mut self, constraint: Vec2, scrollable: XY) -> (Vec2, XY) { - let scrollbar_size = scrollable - .select_or(self.scrollbar_padding + (1, 1), Vec2::zero()); + let available = constraint.saturating_sub(scrollbar_size); - let inner_size = self.inner - .required_size(constraint.saturating_sub(scrollbar_size)); + let inner_size = self.inner.required_size(available); - let size = self.enabled - .select_or(Vec2::min(inner_size, constraint), inner_size) - + scrollbar_size; + // Where we're "enabled", accept the constraints. + // Where we're not, just forward inner_size. + let size = self.enabled.select_or( + Vec2::min(inner_size + scrollbar_size, constraint), + inner_size + scrollbar_size, + ); - let new_scrollable = inner_size.zip_map(size, |i, s| i > s); + let new_scrollable = inner_size.zip_map(size, |i, s| i > s); - (size, new_scrollable) + (inner_size, size, new_scrollable) + } + + /// Computes the size we would need given the constraints. + /// + /// First be optimistic and try without scrollbars. + /// Then try with scrollbars if needed. + /// Then try again in case we now need to scroll both ways (!!!) + /// + /// Returns `(inner_size, size)` + fn sizes(&mut self, constraint: Vec2) -> (Vec2, Vec2) { + let (inner_size, size, scrollable) = + self.sizes_when_scrolling(constraint, XY::new(false, false)); + + // Did it work? + if scrollable.any() && self.show_scrollbars { + // Attempt 2: he wants to scroll? Sure! Try again with some space for the scrollbar. + let (inner_size, size, new_scrollable) = + self.sizes_when_scrolling(constraint, scrollable); + if scrollable != new_scrollable { + // Again? We're now scrolling in a new direction? + // There is no end to this! + let (inner_size, size, _) = + self.sizes_when_scrolling(constraint, new_scrollable); + + // That's enough. If the inner view changed again, ignore it! + // That'll teach it. + (inner_size, size) + } else { + // Yup, scrolling did it. We're goot to go now. + (inner_size, size) + } + } else { + // We're not showing any scrollbar, either because we don't scroll + // or because scrollbars are hidden. + (inner_size, size) + } } } @@ -169,10 +219,14 @@ where } fn layout(&mut self, size: Vec2) { + // Size is final now self.last_size = size; + let (inner_size, _) = self.sizes(size); + // Ask one more time - self.inner_size = self.inner.required_size(size).or_max(size); + self.inner_size = inner_size; + self.inner.layout(self.inner_size); // TODO: Refresh offset if needed! @@ -184,29 +238,9 @@ where fn required_size(&mut self, constraint: Vec2) -> Vec2 { // Attempt 1: try without scrollbars - let (size, scrollable) = self.compute_size(constraint, XY::new(false, false)); + let (_, size) = self.sizes(constraint); - // Did it work? - if scrollable.any() && self.show_scrollbars { - // Attempt 2: he wants to scroll? Sure! Try again with some space for the scrollbar. - let (size, new_scrollable) = self.compute_size(constraint, scrollable); - if scrollable != new_scrollable { - // Again? We're now scrolling in a new direction? - // There is no end to this! - let (size, _) = self.compute_size(constraint, new_scrollable); - - // That's enough. If the inner view changed again, ignore it! - // That'll teach it. - size - } else { - // Yup, scrolling did it. We're goot to go now. - size - } - } else { - // We're not showing any scrollbar, either because we don't scroll - // or because scrollbars are hidden. - size - } + size } fn call_on_any<'a>(&mut self, selector: &Selector, cb: AnyCb<'a>) {