From 63218a9db6dc80393d02221bf7039cfa1997eddf Mon Sep 17 00:00:00 2001 From: lucasmerlin Date: Tue, 2 Jun 2026 17:17:30 +0200 Subject: [PATCH] Add `AtomLayout::direction` --- crates/egui/src/atomics/atom_layout.rs | 188 +++++++++++++++++++------ 1 file changed, 142 insertions(+), 46 deletions(-) diff --git a/crates/egui/src/atomics/atom_layout.rs b/crates/egui/src/atomics/atom_layout.rs index 1f83e757c..272c0c737 100644 --- a/crates/egui/src/atomics/atom_layout.rs +++ b/crates/egui/src/atomics/atom_layout.rs @@ -1,6 +1,6 @@ use crate::{ - AtomKind, Atoms, FontSelection, Frame, Id, Image, IntoAtoms, Response, Sense, SizedAtom, - SizedAtomKind, Ui, Widget, + AtomKind, Atoms, Direction, FontSelection, Frame, Id, Image, IntoAtoms, Response, Sense, + SizedAtom, SizedAtomKind, Ui, Widget, }; use emath::{Align2, GuiRounding as _, NumExt as _, Rect, Vec2}; use epaint::text::TextWrapMode; @@ -9,6 +9,47 @@ use smallvec::SmallVec; use std::ops::{Deref, DerefMut}; use std::sync::Arc; +/// The main-axis component of `v` for `direction` (x for horizontal, y for vertical). +#[inline] +fn main_axis(direction: Direction, v: Vec2) -> f32 { + if direction.is_horizontal() { + v.x + } else { + v.y + } +} + +/// The cross-axis component of `v` for `direction` (y for horizontal, x for vertical). +#[inline] +fn cross_axis(direction: Direction, v: Vec2) -> f32 { + if direction.is_horizontal() { + v.y + } else { + v.x + } +} + +/// Build a [`Vec2`] from `main`/`cross` components for `direction`. +#[inline] +fn main_cross_vec(direction: Direction, main: f32, cross: f32) -> Vec2 { + if direction.is_horizontal() { + Vec2::new(main, cross) + } else { + Vec2::new(cross, main) + } +} + +/// Build a cell [`Rect`] spanning `block` fully on the cross axis and `[min_main, max_main]` +/// along the main axis. +#[inline] +fn main_cross_rect(direction: Direction, block: Rect, min_main: f32, max_main: f32) -> Rect { + if direction.is_horizontal() { + Rect::from_x_y_ranges(min_main..=max_main, block.y_range()) + } else { + Rect::from_x_y_ranges(block.x_range(), min_main..=max_main) + } +} + /// Intra-widget layout utility. /// /// Used to lay out and paint [`crate::Atom`]s. @@ -30,7 +71,7 @@ use std::sync::Arc; /// [`AllocatedAtomLayout`] for interaction styling. #[derive(Clone)] pub struct AtomLayout<'a> { - id: Option, + pub(crate) id: Option, pub atoms: Atoms<'a>, gap: Option, pub(crate) frame: Frame, @@ -41,6 +82,7 @@ pub struct AtomLayout<'a> { max_size: Vec2, wrap_mode: Option, align2: Option, + direction: Direction, } impl Default for AtomLayout<'_> { @@ -63,6 +105,7 @@ impl<'a> AtomLayout<'a> { max_size: Vec2::INFINITY, wrap_mode: None, align2: None, + direction: Direction::LeftToRight, } } @@ -173,6 +216,20 @@ impl<'a> AtomLayout<'a> { self } + /// Set the [`Direction`] the [`crate::Atom`]s are laid out along. + /// + /// The default is [`Direction::LeftToRight`] (a horizontal row). Use + /// [`Direction::TopDown`] (or [`Direction::BottomUp`]) to stack atoms vertically. + /// + /// The main axis (the direction) is where `grow`/`shrink` and the gap apply; the cross axis + /// is sized to the largest atom. [`Self::align2`] positions the whole block within the + /// allocated [`Rect`]. + #[inline] + pub fn direction(mut self, direction: Direction) -> Self { + self.direction = direction; + self + } + /// [`AtomLayout::allocate`] and [`AllocatedAtomLayout::paint`] in one go. pub fn show(self, ui: &mut Ui) -> AtomLayoutResponse { self.allocate(ui).paint(ui) @@ -202,6 +259,7 @@ impl<'a> AtomLayout<'a> { wrap_mode, align2, fallback_font, + direction, } = self; let fallback_font = fallback_font.unwrap_or_default(); @@ -230,8 +288,13 @@ impl<'a> AtomLayout<'a> { // max_size has no effect in justified layouts. If we'd limit the available size here, // the content would be sized differently than the frame which would look weird. - if ui.layout().horizontal_justify() { - max_size.x = f32::INFINITY; + // This only applies along the main axis (the direction we lay atoms out along). + if direction.is_horizontal() { + if ui.layout().horizontal_justify() { + max_size.x = f32::INFINITY; + } + } else if ui.layout().vertical_justify() { + max_size.y = f32::INFINITY; } let available_size = available_size.at_most(max_size).at_least(min_size); @@ -239,14 +302,18 @@ impl<'a> AtomLayout<'a> { // The size available for the content let available_inner_size = available_size - frame.total_margin().sum(); - let mut inner_width = 0.0; + // We work in main/cross axis terms so the same code handles horizontal and vertical + // layouts. For a horizontal `direction`, main = x and cross = y; for vertical it's + // swapped. `grow`/`shrink`/`gap` apply along the main axis; the cross axis is sized to + // the largest atom. + let mut inner_main = 0.0; - // intrinsic width / height is the ideal size of the widget, e.g. the size where the + // intrinsic main / cross is the ideal size of the widget, e.g. the size where the // text is not wrapped. Used to set Response::intrinsic_size. - let mut intrinsic_width = 0.0; - let mut intrinsic_height = 0.0; + let mut intrinsic_main = 0.0; + let mut intrinsic_cross: f32 = 0.0; - let mut height: f32 = 0.0; + let mut cross_size: f32 = 0.0; let mut sized_items = Vec::new(); @@ -260,8 +327,8 @@ impl<'a> AtomLayout<'a> { if atoms.len() > 1 { let gap_space = gap * (atoms.len() as f32 - 1.0); - inner_width += gap_space; - intrinsic_width += gap_space; + inner_main += gap_space; + intrinsic_main += gap_space; } for (idx, item) in atoms.into_iter().enumerate() { @@ -286,19 +353,22 @@ impl<'a> AtomLayout<'a> { ); let size = sized.size; - inner_width += size.x; - intrinsic_width += sized.intrinsic_size.x; + inner_main += main_axis(direction, size); + intrinsic_main += main_axis(direction, sized.intrinsic_size); - height = height.at_least(size.y); - intrinsic_height = intrinsic_height.at_least(sized.intrinsic_size.y); + cross_size = cross_size.at_least(cross_axis(direction, size)); + intrinsic_cross = intrinsic_cross.at_least(cross_axis(direction, sized.intrinsic_size)); sized_items.push(sized); } if let Some((index, item)) = shrink_item { - // The `shrink` item gets the remaining space - let available_size_for_shrink_item = - Vec2::new(available_inner_size.x - inner_width, available_inner_size.y); + // The `shrink` item gets the remaining space along the main axis. + let available_size_for_shrink_item = main_cross_vec( + direction, + main_axis(direction, available_inner_size) - inner_main, + cross_axis(direction, available_inner_size), + ); let sized = item.into_sized( ui, @@ -308,20 +378,21 @@ impl<'a> AtomLayout<'a> { ); let size = sized.size; - inner_width += size.x; - intrinsic_width += sized.intrinsic_size.x; + inner_main += main_axis(direction, size); + intrinsic_main += main_axis(direction, sized.intrinsic_size); - height = height.at_least(size.y); - intrinsic_height = intrinsic_height.at_least(sized.intrinsic_size.y); + cross_size = cross_size.at_least(cross_axis(direction, size)); + intrinsic_cross = intrinsic_cross.at_least(cross_axis(direction, sized.intrinsic_size)); sized_items.insert(index, sized); } let margin = frame.total_margin(); - let inner_size = Vec2::new(inner_width, height); + let inner_size = main_cross_vec(direction, inner_main, cross_size); let outer_size = (inner_size + margin.sum()).at_least(min_size); - let intrinsic_size = - (Vec2::new(intrinsic_width, intrinsic_height) + margin.sum()).at_least(min_size); + let intrinsic_size = (main_cross_vec(direction, intrinsic_main, intrinsic_cross) + + margin.sum()) + .at_least(min_size); SizedAtomLayout { sized_atoms: sized_items, @@ -335,6 +406,7 @@ impl<'a> AtomLayout<'a> { inner_size, align2, gap, + direction, } } @@ -394,6 +466,9 @@ pub struct SizedAtomLayout<'a> { /// The gap between each [`crate::Atom`] gap: f32, + + /// The axis the atoms are laid out along. The main axis carries `grow`/`shrink`/`gap`. + direction: Direction, } /// Instructions for painting an [`AtomLayout`]. @@ -489,13 +564,14 @@ impl<'atom> SizedAtomLayout<'atom> { /// becomes the base of the returned [`AtomLayoutResponse`]. pub fn paint_at(self, ui: &Ui, rect: Rect, response: Response) -> AtomLayoutResponse { let Self { - sized_atoms, + mut sized_atoms, frame, fallback_text_color, grow_count, inner_size, align2, gap, + direction, .. } = self; @@ -503,17 +579,30 @@ impl<'atom> SizedAtomLayout<'atom> { ui.painter().add(frame.paint(inner_rect)); - let width_to_fill = inner_rect.width(); - let extra_space = f32::max(width_to_fill - inner_size.x, 0.0); - let grow_width = f32::max(extra_space / grow_count as f32, 0.0).floor_ui(); + // We position atoms along the main axis (the `direction`) and span the cross axis. + let main_to_fill = main_axis(direction, inner_rect.size()); + let inner_main = main_axis(direction, inner_size); + let extra_space = f32::max(main_to_fill - inner_main, 0.0); + let grow_main = f32::max(extra_space / grow_count as f32, 0.0).floor_ui(); - let aligned_rect = if grow_count > 0 { - align2.align_size_within_rect(Vec2::new(width_to_fill, inner_size.y), inner_rect) + // When something grows, the block fills the available main extent; otherwise it's the + // content's inner size. `align2` then positions the block within `inner_rect`. + let block_main = if grow_count > 0 { + main_to_fill } else { - align2.align_size_within_rect(inner_size, inner_rect) + inner_main }; + let block_size = main_cross_vec(direction, block_main, cross_axis(direction, inner_size)); + let aligned_rect = align2.align_size_within_rect(block_size, inner_rect); - let mut cursor = aligned_rect.left(); + // For reversed directions the first atom sits at the far end, so we lay them out in + // reverse and otherwise share the same forward cursor logic. + if matches!(direction, Direction::RightToLeft | Direction::BottomUp) { + sized_atoms.reverse(); + } + + // The cursor walks the main axis from the start (left/top) of the aligned block. + let mut cursor = main_axis(direction, aligned_rect.min.to_vec2()); let mut response = AtomLayoutResponse::empty(response); @@ -521,34 +610,41 @@ impl<'atom> SizedAtomLayout<'atom> { let size = sized.size; // TODO(lucasmerlin): This is not ideal, since this might lead to accumulated rounding errors // https://github.com/emilk/egui/pull/5830#discussion_r2079627864 - let growth = if sized.is_grow() { grow_width } else { 0.0 }; + let growth = if sized.is_grow() { grow_main } else { 0.0 }; - let frame = aligned_rect - .with_min_x(cursor) - .with_max_x(cursor + size.x + growth); - cursor = frame.right() + gap; - let rect = sized.align.align_size_within_rect(size, frame); + let atom_main = main_axis(direction, size) + growth; + + // The cell spans the cross axis fully and `atom_main` along the main axis. + let cell = main_cross_rect(direction, aligned_rect, cursor, cursor + atom_main); + cursor += atom_main + gap; + let item_rect = sized.align.align_size_within_rect(size, cell); if let Some(id) = sized.id { debug_assert!( !response.custom_rects.iter().any(|(i, _)| *i == id), "Duplicate custom id" ); - response.custom_rects.push((id, rect)); + response.custom_rects.push((id, item_rect)); } match sized.kind { SizedAtomKind::Text(galley) => { - ui.painter().galley(rect.min, galley, fallback_text_color); + ui.painter() + .galley(item_rect.min, galley, fallback_text_color); } SizedAtomKind::Image { image, size: _ } => { - image.paint_at(ui, rect); + image.paint_at(ui, item_rect); } SizedAtomKind::Empty { .. } => {} SizedAtomKind::Layout(layout) => { - // TODO(lucasmerlin): Add some kind of justify flag to AtomLayout - let layout_response = ui.interact(frame, layout.id, layout.sense); - layout.paint_at(ui, frame, layout_response); + // Hand the nested layout the full (possibly grown) cell extent along the main + // axis so its own `grow` atoms can expand, while keeping its measured cross + // size and honoring this atom's alignment within the cell. + let layout_size = + main_cross_vec(direction, atom_main, cross_axis(direction, size)); + let layout_rect = sized.align.align_size_within_rect(layout_size, cell); + let layout_response = ui.interact(cell, layout.id, layout.sense); + layout.paint_at(ui, cell, layout_response); } } }