Triple whammy to fix button alignment — I think this is good enough

crates/yakui-widgets/src/widgets/button.rs

@@ -147,11 +147,17 @@ impl Widget for ButtonWidget {
             text_style = style.text.clone();
         }
 
+        let align = match text_style.align {
+            TextAlignment::Start => Alignment::CENTER_LEFT,
+            TextAlignment::Center => Alignment::CENTER,
+            TextAlignment::End => Alignment::CENTER_RIGHT,
+        };
+
         let mut container = RoundRect::new(self.props.border_radius);
         container.color = color;
         container.show_children(|| {
             crate::pad(self.props.padding, || {
-                crate::align(Alignment::CENTER_LEFT, || {
+                crate::align(align, || {
                     RenderText::with_style(self.props.text.clone(), text_style).show();
                 });
             });

crates/yakui-widgets/src/widgets/render_text.rs

@@ -6,7 +6,7 @@ use yakui_core::widget::{LayoutContext, PaintContext, Widget};
 use yakui_core::{Response, TextureId};
 
 use crate::font::Fonts;
-use crate::style::TextStyle;
+use crate::style::{TextAlignment, TextStyle};
 use crate::text_renderer::{GlyphRender, Kind, TextGlobalState};
 use crate::util::widget;
 
@@ -59,6 +59,7 @@ impl RenderText {
 pub struct RenderTextWidget {
     props: RenderText,
     buffer: RefCell<Option<cosmic_text::Buffer>>,
+    line_offsets: RefCell<Vec<f32>>,
     size: Cell<Option<Vec2>>,
     last_text: RefCell<String>,
     max_size: Cell<Option<(Option<f32>, Option<f32>)>>,
@@ -75,6 +76,7 @@ impl Widget for RenderTextWidget {
         Self {
             props: RenderText::new(""),
             buffer: RefCell::default(),
+            line_offsets: RefCell::default(),
             size: Cell::default(),
             last_text: RefCell::new(String::new()),
             max_size: Cell::default(),
@@ -157,23 +159,43 @@ impl Widget for RenderTextWidget {
 
             buffer.shape_until_scroll(font_system, true);
 
-            let size = {
-                let size_x = buffer
-                    .layout_runs()
-                    .map(|layout| layout.line_w)
-                    .max_by(|a, b| a.total_cmp(b))
-                    .unwrap_or_default()
-                    .ceil();
+            let mut line_offsets = self.line_offsets.borrow_mut();
+            line_offsets.clear();
+
+            let widest_line = buffer
+                .layout_runs()
+                .map(|layout| layout.line_w)
+                .max_by(|a, b| a.total_cmp(b))
+                .unwrap_or_default()
+                .ceil()
+                .max(constraints.min.x * ctx.layout.scale_factor());
+
+            for run in buffer.layout_runs() {
+                let offset = match self.props.style.align {
+                    TextAlignment::Start => 0.0,
+                    TextAlignment::Center => (widest_line - run.line_w) / 2.0,
+                    TextAlignment::End => widest_line - run.line_w,
+                };
+
+                line_offsets.push(offset / ctx.layout.scale_factor());
+            }
 
+            let mut size = {
                 let size_y = buffer
                     .layout_runs()
                     .map(|layout| layout.line_height)
                     .sum::<f32>()
                     .ceil();
 
-                (Vec2::new(size_x, size_y) / ctx.layout.scale_factor()).round()
+                (Vec2::new(widest_line, size_y) / ctx.layout.scale_factor()).round()
             };
 
+            size.x = size.x.max(constraints.min.x);
+
+            if constraints.max.x.is_finite() {
+                size.x = size.x.max(constraints.max.x);
+            }
+
             let size = constraints.constrain(size);
             self.size.set(Some(size));
 
@@ -191,17 +213,18 @@ impl Widget for RenderTextWidget {
         };
 
         fonts.with_system(|font_system| {
+            let line_offsets = self.line_offsets.borrow();
             let text_global = ctx.dom.get_global_or_init(TextGlobalState::new);
 
-            for layout in buffer.layout_runs() {
+            for (layout, x_offset) in buffer.layout_runs().zip(line_offsets.iter().copied()) {
                 for glyph in layout.glyphs {
                     if let Some(render) = text_global.get_or_insert(ctx.paint, font_system, glyph) {
                         paint_text(
                             &mut ctx,
                             self.props.style.color,
                             glyph,
                             render,
-                            layout_node.rect.pos(),
+                            layout_node.rect.pos() + Vec2::new(x_offset, 0.0),
                             layout.line_y,
                         )
                     }

crates/yakui/examples/button_constrained.rs

@@ -0,0 +1,40 @@
+use yakui::style::TextAlignment;
+use yakui::widgets::{Button, List};
+use yakui::{constrained, Constraints, CrossAxisAlignment, Vec2};
+
+pub fn run() {
+    const ALIGNMENTS: &[TextAlignment] = &[
+        TextAlignment::Start,
+        TextAlignment::Center,
+        TextAlignment::End,
+    ];
+
+    let mut list = List::row();
+    list.cross_axis_alignment = CrossAxisAlignment::End;
+    list.item_spacing = 16.0;
+    list.show(|| {
+        for &alignment in ALIGNMENTS {
+            menu_button(alignment);
+        }
+    });
+}
+
+fn menu_button(alignment: TextAlignment) {
+    let constraints = Constraints {
+        min: Vec2::new(120.0, 0.0),
+        max: Vec2::new(f32::INFINITY, f32::INFINITY),
+    };
+
+    constrained(constraints, || {
+        let mut button = Button::styled(format!("Foo ({alignment:?})"));
+        button.style.text.font_size = 12.0;
+        button.style.text.align = alignment;
+        button.hover_style.text.align = alignment;
+        button.down_style.text.align = alignment;
+        button.show();
+    });
+}
+
+fn main() {
+    bootstrap::start(run as fn());
+}