Layout alignment

api/sixtyfps-cpp/include/sixtyfps.h

@@ -283,6 +283,7 @@ using cbindgen_private::solve_box_layout;
 using cbindgen_private::box_layout_info;
 using cbindgen_private::solve_path_layout;
 using cbindgen_private::Rect;
+using cbindgen_private::LayoutAlignment;
 
 inline LayoutInfo LayoutInfo::merge(const LayoutInfo &other) const {
     // Note: This "logic" is duplicated from LayoutInfo::merge in layout.rs.

docs/builtin_elements.md

@@ -187,6 +187,8 @@ they will be computed by the layout respecting the minimum and maximum sizes and
  * **`padding`** (*length*): the padding within the layout.
  * **`padding_left`**, **`padding_right`**, **`padding_top`** and **`padding_bottom`** (*length*):
     override the padding in specific sides.
+ * **`alignment`** (*FIXME enum*): Can be one of  `stretch`, `center`, `start`, `end`,
+    `space_between`, `space_around`. Defaults to `stretch`. Matches the CSS flex.
 
 ## Example
 

sixtyfps_compiler/generator/cpp.rs

@@ -1679,11 +1679,18 @@ impl crate::layout::gen::Language for CppLanguageLayoutGen {
             component,
         );
 
+        let alignment = if let Some(nr) = &box_layout.geometry.alignment {
+            format!("{}.get()", access_named_reference(nr, component, "self"))
+        } else {
+            "{}".into()
+        };
+
         LayoutTreeItem::BoxLayout {
             is_horizontal: box_layout.is_horizontal,
             geometry: &box_layout.geometry,
             spacing,
             padding,
+            alignment,
             var_creation_code: creation_code.join("\n"),
             cell_ref_variable,
         }
@@ -1703,11 +1710,12 @@ impl<'a> LayoutTreeItem<'a> {
                 spacing,
                 cell_ref_variable,
                 padding,
+                alignment,
                 is_horizontal,
                 ..
             } => format!(
-                "sixtyfps::box_layout_info(&{}, {}, &{}, {})",
+                "sixtyfps::box_layout_info(&{}, {}, &{}, {}, {})",
-                cell_ref_variable, spacing, padding, is_horizontal
+                cell_ref_variable, spacing, padding, alignment, is_horizontal
             ),
             LayoutTreeItem::PathLayout(_) => "{/*layout_info for path not implemented*/}".into(),
         }
@@ -1822,19 +1830,21 @@ impl<'a> LayoutTreeItem<'a> {
                 spacing,
                 cell_ref_variable,
                 padding,
+                alignment,
                 is_horizontal,
                 ..
             } => {
                 code_stream.push("    { ".into());
                 code_stream.push("    sixtyfps::BoxLayoutData box { ".into());
                 code_stream.push(format!(
-                    "        {w}, {h}, {x}, {y}, {s}, &{p},",
+                    "        {w}, {h}, {x}, {y}, {s}, &{p}, {a},",
                     w = layout_prop(&geometry.rect.width_reference),
                     h = layout_prop(&geometry.rect.height_reference),
                     x = layout_prop(&geometry.rect.x_reference),
                     y = layout_prop(&geometry.rect.y_reference),
                     s = spacing,
                     p = padding,
+                    a = alignment
                 ));
                 code_stream.push(format!("        {cv}", cv = cell_ref_variable));
                 code_stream.push("    };".to_owned());

sixtyfps_compiler/generator/rust.rs

@@ -47,6 +47,10 @@ fn rust_type(
             let inner = rust_type(&o, span)?;
             Ok(quote!(sixtyfps::re_exports::ModelHandle<#inner>))
         }
+        Type::Enumeration(e) => {
+            let e = format_ident!("{}", e.name);
+            Ok(quote!(sixtyfps::re_exports::#e))
+        }
         _ => Err(CompilerDiagnostic {
             message: format!("Cannot map property type {} to Rust", ty),
             span: span.clone(),
@@ -1513,6 +1517,13 @@ impl crate::layout::gen::Language for RustLanguageLayoutGen {
         let (padding, spacing, spacing_creation_code) =
             generate_layout_padding_and_spacing(&layout_tree, &box_layout.geometry, component);
 
+        let alignment = if let Some(expr) = &box_layout.geometry.alignment {
+            let p = access_named_reference(expr, component, quote!(_self));
+            quote!(#p.get())
+        } else {
+            quote!(::core::default::Default::default())
+        };
+
         LayoutTreeItem::BoxLayout {
             is_horizontal: box_layout.is_horizontal,
             geometry: &box_layout.geometry,
@@ -1520,6 +1531,7 @@ impl crate::layout::gen::Language for RustLanguageLayoutGen {
             cell_ref_variable: quote!(#cell_ref_variable),
             spacing,
             padding,
+            alignment,
         }
         .into()
     }
@@ -1537,10 +1549,11 @@ impl<'a> LayoutTreeItem<'a> {
                 cell_ref_variable,
                 spacing,
                 padding,
+                alignment,
                 is_horizontal,
                 ..
             } => {
-                quote!(box_layout_info(&Slice::from_slice(&#cell_ref_variable), #spacing, #padding, #is_horizontal))
+                quote!(box_layout_info(&Slice::from_slice(&#cell_ref_variable), #spacing, #padding, #alignment, #is_horizontal))
             }
             LayoutTreeItem::PathLayout(_) => quote!(todo!("layout_info for PathLayout in rust.rs")),
         }
@@ -1629,7 +1642,7 @@ impl<'a> LayoutTreeItem<'a> {
                 let p = access_named_reference(nr, component, quote!(_self));
                 quote!(#p.get())
             } else {
-                quote!(0.)
+                quote!(::core::default::Default::default())
             }
         };
         match self {
@@ -1645,8 +1658,8 @@ impl<'a> LayoutTreeItem<'a> {
                     solve_grid_layout(&GridLayoutData {
                         width: #width,
                         height: #height,
-                        x: #x_pos as _,
+                        x: #x_pos,
-                        y: #y_pos as _,
+                        y: #y_pos,
                         cells: Slice::from_slice(&#cell_ref_variable),
                         spacing: #spacing,
                         padding: #padding,
@@ -1658,6 +1671,7 @@ impl<'a> LayoutTreeItem<'a> {
                 cell_ref_variable,
                 spacing,
                 padding,
+                alignment,
                 is_horizontal,
                 ..
             } => {
@@ -1670,11 +1684,12 @@ impl<'a> LayoutTreeItem<'a> {
                     solve_box_layout(&BoxLayoutData {
                         width: #width,
                         height: #height,
-                        x: #x_pos as _,
+                        x: #x_pos,
-                        y: #y_pos as _,
+                        y: #y_pos,
                         cells: Slice::from_slice(&#cell_ref_variable),
                         spacing: #spacing,
                         padding: #padding,
+                        alignment: #alignment
                     }, #is_horizontal);
                 });
             }

sixtyfps_compiler/layout.rs

@@ -214,6 +214,7 @@ impl Padding {
 pub struct LayoutGeometry {
     pub rect: LayoutRect,
     pub spacing: Option<NamedReference>,
+    pub alignment: Option<NamedReference>,
     pub padding: Padding,
 }
 
@@ -221,6 +222,7 @@ impl LayoutGeometry {
     fn visit_named_references(&mut self, visitor: &mut impl FnMut(&mut NamedReference)) {
         self.rect.visit_named_references(visitor);
         self.spacing.as_mut().map(|e| visitor(&mut *e));
+        self.alignment.as_mut().map(|e| visitor(&mut *e));
         self.padding.visit_named_references(visitor);
     }
 }
@@ -254,6 +256,7 @@ impl LayoutGeometry {
     pub fn new(rect: LayoutRect, layout_element: &ElementRc) -> Self {
         let padding = || binding_reference(layout_element, "padding");
         let spacing = binding_reference(layout_element, "spacing");
+        let alignment = binding_reference(layout_element, "alignment");
 
         init_fake_property(layout_element, "width", || rect.width_reference.clone());
         init_fake_property(layout_element, "height", || rect.height_reference.clone());
@@ -271,7 +274,7 @@ impl LayoutGeometry {
             bottom: binding_reference(layout_element, "padding_bottom").or_else(padding),
         };
 
-        Self { rect, spacing, padding }
+        Self { rect, spacing, padding, alignment }
     }
 }
 
@@ -377,6 +380,7 @@ pub mod gen {
             geometry: &'a LayoutGeometry,
             spacing: L::CompiledCode,
             padding: L::CompiledCode,
+            alignment: L::CompiledCode,
             var_creation_code: L::CompiledCode,
             cell_ref_variable: L::CompiledCode,
             is_horizontal: bool,

sixtyfps_compiler/typeregister.rs

@@ -96,6 +96,10 @@ impl TypeRegister {
             declare_enum("TextHorizontalAlignment", &["align_left", "align_center", "align_right"]);
         let text_vertical_alignment =
             declare_enum("TextVerticalAlignment", &["align_top", "align_center", "align_bottom"]);
+        let layout_alignment = declare_enum(
+            "LayoutAlignment",
+            &["stretch", "center", "start", "end", "space_between", "space_around"],
+        );
 
         let native_class_with_member_functions =
             |tr: &mut TypeRegister,
@@ -296,9 +300,15 @@ impl TypeRegister {
         let mut horizontal_layout =
             BuiltinElement::new(Rc::new(NativeClass::new("HorizontalLayout")));
         horizontal_layout.properties.insert("spacing".to_owned(), Type::Length);
+        horizontal_layout
+            .properties
+            .insert("alignment".to_owned(), Type::Enumeration(layout_alignment.clone()));
         register.insert_type(Type::Builtin(Rc::new(horizontal_layout)));
         let mut vertical_layout = BuiltinElement::new(Rc::new(NativeClass::new("VerticalLayout")));
         vertical_layout.properties.insert("spacing".to_owned(), Type::Length);
+        vertical_layout
+            .properties
+            .insert("alignment".to_owned(), Type::Enumeration(layout_alignment));
         register.insert_type(Type::Builtin(Rc::new(vertical_layout)));
 
         let mut path_class = NativeClass::new("Path");

sixtyfps_runtime/corelib/layout.rs

@@ -382,6 +382,51 @@ pub extern "C" fn grid_layout_info<'a>(
     }
 }
 
+/// Enum representing the alignment property of a BoxLayout or HorizontalLayout
+#[derive(Copy, Clone, Debug, PartialEq, strum_macros::EnumString, strum_macros::Display)]
+#[repr(C)]
+#[allow(non_camel_case_types)]
+pub enum LayoutAlignment {
+    stretch,
+    center,
+    start,
+    end,
+    space_between,
+    space_around,
+}
+
+impl Default for LayoutAlignment {
+    fn default() -> Self {
+        Self::stretch
+    }
+}
+
+impl From<LayoutAlignment> for stretch::style::JustifyContent {
+    fn from(a: LayoutAlignment) -> Self {
+        match a {
+            LayoutAlignment::stretch => Self::FlexStart,
+            LayoutAlignment::center => Self::Center,
+            LayoutAlignment::start => Self::FlexStart,
+            LayoutAlignment::end => Self::FlexEnd,
+            LayoutAlignment::space_between => Self::SpaceBetween,
+            LayoutAlignment::space_around => Self::SpaceAround,
+        }
+    }
+}
+
+impl From<LayoutAlignment> for stretch::style::AlignContent {
+    fn from(a: LayoutAlignment) -> Self {
+        match a {
+            LayoutAlignment::stretch => Self::Stretch,
+            LayoutAlignment::center => Self::Center,
+            LayoutAlignment::start => Self::FlexStart,
+            LayoutAlignment::end => Self::FlexEnd,
+            LayoutAlignment::space_between => Self::SpaceBetween,
+            LayoutAlignment::space_around => Self::SpaceAround,
+        }
+    }
+}
+
 #[repr(C)]
 #[derive(Debug)]
 /// The BoxLayoutData is used to represent both a Horizontal and Vertical layout.
@@ -394,6 +439,7 @@ pub struct BoxLayoutData<'a> {
     pub y: Coord,
     pub spacing: Coord,
     pub padding: &'a Padding,
+    pub alignment: LayoutAlignment,
     pub cells: Slice<'a, BoxLayoutCellData<'a>>,
 }
 
@@ -418,10 +464,10 @@ pub extern "C" fn solve_box_layout(data: &BoxLayoutData, is_horizontal: bool) {
 
     let box_style = stretch::style::Style {
         size: Size { width: Dimension::Percent(1.), height: Dimension::Percent(1.) },
-        flex_grow: 1.,
-        display: Display::Flex,
         flex_direction: if is_horizontal { FlexDirection::Row } else { FlexDirection::Column },
         flex_basis: Dimension::Percent(1.),
+        justify_content: data.alignment.into(),
+        align_content: data.alignment.into(),
         ..Default::default()
     };
 
@@ -469,7 +515,13 @@ pub extern "C" fn solve_box_layout(data: &BoxLayoutData, is_horizontal: bool) {
         let cell_style = Style {
             min_size,
             max_size,
-            flex_grow: if let Some(s) = smaller_strecth { stretch_factor(cell) / s } else { 1. },
+            flex_grow: if data.alignment != LayoutAlignment::stretch {
+                0.
+            } else if let Some(s) = smaller_strecth {
+                stretch_factor(cell) / s
+            } else {
+                1.
+            },
             flex_basis: if is_horizontal { min_size.width } else { min_size.height },
             margin,
             align_self: AlignSelf::Stretch,
@@ -509,6 +561,7 @@ pub extern "C" fn box_layout_info<'a>(
     cells: &Slice<'a, BoxLayoutCellData<'a>>,
     spacing: Coord,
     padding: &Padding,
+    alignment: LayoutAlignment,
     is_horizontal: bool,
 ) -> LayoutInfo {
     let count = cells.len();
@@ -516,6 +569,7 @@ pub extern "C" fn box_layout_info<'a>(
         return LayoutInfo { max_width: 0., max_height: 0., ..LayoutInfo::default() };
     };
     let order_float = |a: &Coord, b: &Coord| a.partial_cmp(b).unwrap_or(core::cmp::Ordering::Equal);
+    let is_stretch = alignment == LayoutAlignment::stretch;
 
     if is_horizontal {
         let extra_w = padding.left + padding.right + spacing * (count - 1) as Coord;
@@ -527,7 +581,11 @@ pub extern "C" fn box_layout_info<'a>(
             + padding.top
             + padding.bottom;
         let min_width = cells.iter().map(|c| c.constraint.min_width).sum::<Coord>() + extra_w;
-        let max_width = cells.iter().map(|c| c.constraint.max_width).sum::<Coord>() + extra_w;
+        let max_width = if is_stretch {
+            cells.iter().map(|c| c.constraint.max_width).sum::<Coord>() + extra_w
+        } else {
+            f32::MAX
+        };
         let horizontal_stretch = cells.iter().map(|c| c.constraint.horizontal_stretch).sum::<f32>();
         let vertical_stretch =
             cells.iter().map(|c| c.constraint.vertical_stretch).min_by(order_float).unwrap();
@@ -549,7 +607,11 @@ pub extern "C" fn box_layout_info<'a>(
             + padding.left
             + padding.right;
         let min_height = cells.iter().map(|c| c.constraint.min_height).sum::<Coord>() + extra_h;
-        let max_height = cells.iter().map(|c| c.constraint.max_height).sum::<Coord>() + extra_h;
+        let max_height = if is_stretch {
+            cells.iter().map(|c| c.constraint.max_height).sum::<Coord>() + extra_h
+        } else {
+            f32::MAX
+        };
         let horizontal_stretch =
             cells.iter().map(|c| c.constraint.horizontal_stretch).min_by(order_float).unwrap();
         let vertical_stretch = cells.iter().map(|c| c.constraint.vertical_stretch).sum::<f32>();

sixtyfps_runtime/interpreter/dynamic_component.rs

@@ -593,7 +593,7 @@ fn generate_component<'id>(
         if decl.is_alias.is_some() {
             continue;
         }
-        let (prop, type_info) = match decl.property_type {
+        let (prop, type_info) = match &decl.property_type {
             Type::Float32 => animated_property_info::<f32>(),
             Type::Int32 => animated_property_info::<i32>(),
             Type::String => property_info::<SharedString>(),
@@ -611,6 +611,16 @@ fn generate_component<'id>(
             Type::Object { .. } => property_info::<eval::Value>(),
             Type::Array(_) => property_info::<eval::Value>(),
             Type::Percent => property_info::<f32>(),
+            Type::Enumeration(e) => match e.name.as_ref() {
+                "LayoutAlignment" => property_info::<sixtyfps_corelib::layout::LayoutAlignment>(),
+                "TextHorizontalAlignment" => {
+                    property_info::<sixtyfps_corelib::items::TextHorizontalAlignment>()
+                }
+                "TextVerticalAlignment" => {
+                    property_info::<sixtyfps_corelib::items::TextVerticalAlignment>()
+                }
+                _ => panic!("unkown enum"),
+            },
             _ => panic!("bad type"),
         };
         custom_properties.insert(
@@ -970,7 +980,11 @@ impl<'a> BoxLayoutCellTmpData<'a> {
 #[derive(derive_more::From)]
 enum LayoutTreeItem<'a> {
     GridLayout(LayoutWithCells<'a, GridLayoutCellData<'a>>),
-    BoxLayout(LayoutWithCells<'a, BoxLayoutCellTmpData<'a>>, bool),
+    BoxLayout(
+        LayoutWithCells<'a, BoxLayoutCellTmpData<'a>>,
+        bool,
+        sixtyfps_corelib::layout::LayoutAlignment,
+    ),
     PathLayout(&'a PathLayout),
 }
 
@@ -982,12 +996,13 @@ impl<'a> LayoutTreeItem<'a> {
                 grid_layout.spacing,
                 &grid_layout.padding,
             ),
-            LayoutTreeItem::BoxLayout(box_layout, is_horizontal) => {
+            LayoutTreeItem::BoxLayout(box_layout, is_horizontal, alignment) => {
                 let cells = BoxLayoutCellTmpData::into_cells(&box_layout.cells);
                 box_layout_info(
                     &Slice::from(cells.as_slice()),
                     box_layout.spacing,
                     &box_layout.padding,
+                    *alignment,
                     *is_horizontal,
                 )
             }
@@ -1154,9 +1169,21 @@ fn collect_layouts_recursively<'a, 'b>(
                 top: box_layout.geometry.padding.top.as_ref().map_or(0., expr_eval),
                 bottom: box_layout.geometry.padding.bottom.as_ref().map_or(0., expr_eval),
             };
+            let alignment = box_layout
+                .geometry
+                .alignment
+                .as_ref()
+                .map(|nr| {
+                    eval::load_property(component, &nr.element.upgrade().unwrap(), &nr.name)
+                        .unwrap()
+                        .try_into()
+                        .unwrap_or_default()
+                })
+                .unwrap_or_default();
             layout_tree.push(LayoutTreeItem::BoxLayout(
                 LayoutWithCells { geometry: &box_layout.geometry, cells, spacing, padding },
                 box_layout.is_horizontal,
+                alignment,
             ));
         }
         Layout::PathLayout(layout) => layout_tree.push(layout.into()),
@@ -1187,7 +1214,7 @@ impl<'a> LayoutTreeItem<'a> {
                     cells: Slice::from(grid_layout.cells.as_slice()),
                 });
             }
-            Self::BoxLayout(box_layout, is_horizontal) => {
+            Self::BoxLayout(box_layout, is_horizontal, alignment) => {
                 let cells = BoxLayoutCellTmpData::into_cells(&box_layout.cells);
                 solve_box_layout(
                     &BoxLayoutData {
@@ -1198,6 +1225,7 @@ impl<'a> LayoutTreeItem<'a> {
                         spacing: box_layout.spacing,
                         padding: &box_layout.padding,
                         cells: Slice::from(cells.as_slice()),
+                        alignment: *alignment,
                     },
                     *is_horizontal,
                 );

sixtyfps_runtime/interpreter/eval.rs

@@ -210,6 +210,7 @@ macro_rules! declare_value_enum_conversion {
 
 declare_value_enum_conversion!(corelib::items::TextHorizontalAlignment, TextHorizontalAlignment);
 declare_value_enum_conversion!(corelib::items::TextVerticalAlignment, TextVerticalAlignment);
+declare_value_enum_conversion!(corelib::layout::LayoutAlignment, LayoutAlignment);
 
 #[derive(Copy, Clone)]
 enum ComponentInstance<'a, 'id> {