Add Align2 helpers (#8485)

Add utilities to make it easier to construct and use `Align2`

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

crates/egui/src/atomics/atom_layout.rs

@@ -345,9 +345,7 @@ impl<'a> AtomLayout<'a> {
 
         let mut shrink_item = None;
 
-        let align2 = align2.unwrap_or_else(|| {
+        let align2 = align2.unwrap_or_else(|| ui.layout().align2());
-            Align2([ui.layout().horizontal_align(), ui.layout().vertical_align()])
-        });
 
         if atoms.len() > 1 {
             let gap_space = gap * (atoms.len() as f32 - 1.0);

crates/egui/src/layout.rs

@@ -348,8 +348,8 @@ impl Layout {
     }
 
     /// e.g. for when aligning text within a button.
-    fn align2(&self) -> Align2 {
+    pub fn align2(&self) -> Align2 {
-        Align2([self.horizontal_align(), self.vertical_align()])
+        Align2::new(self.horizontal_align(), self.vertical_align())
     }
 
     pub fn horizontal_justify(&self) -> bool {
@@ -614,10 +614,10 @@ impl Layout {
         }
 
         let align2 = match self.main_dir {
-            Direction::LeftToRight => Align2([Align::LEFT, self.vertical_align()]),
+            Direction::LeftToRight => self.align2().with_x(Align::LEFT),
-            Direction::RightToLeft => Align2([Align::RIGHT, self.vertical_align()]),
+            Direction::RightToLeft => self.align2().with_x(Align::RIGHT),
-            Direction::TopDown => Align2([self.horizontal_align(), Align::TOP]),
+            Direction::TopDown => self.align2().with_y(Align::TOP),
-            Direction::BottomUp => Align2([self.horizontal_align(), Align::BOTTOM]),
+            Direction::BottomUp => self.align2().with_y(Align::BOTTOM),
         };
 
         let mut frame_rect = align2.align_size_within_rect(frame_size, available_rect);
@@ -818,22 +818,22 @@ impl Layout {
             Direction::LeftToRight => {
                 painter.line_segment([cursor.left_top(), cursor.left_bottom()], stroke);
                 painter.arrow(next_pos, vec2(l, 0.0), stroke);
-                Align2([Align::LEFT, self.vertical_align()])
+                self.align2().with_x(Align::LEFT)
             }
             Direction::RightToLeft => {
                 painter.line_segment([cursor.right_top(), cursor.right_bottom()], stroke);
                 painter.arrow(next_pos, vec2(-l, 0.0), stroke);
-                Align2([Align::RIGHT, self.vertical_align()])
+                self.align2().with_x(Align::RIGHT)
             }
             Direction::TopDown => {
                 painter.line_segment([cursor.left_top(), cursor.right_top()], stroke);
                 painter.arrow(next_pos, vec2(0.0, l), stroke);
-                Align2([self.horizontal_align(), Align::TOP])
+                self.align2().with_y(Align::TOP)
             }
             Direction::BottomUp => {
                 painter.line_segment([cursor.left_bottom(), cursor.right_bottom()], stroke);
                 painter.arrow(next_pos, vec2(0.0, -l), stroke);
-                Align2([self.horizontal_align(), Align::BOTTOM])
+                self.align2().with_y(Align::BOTTOM)
             }
         };
 

crates/egui/src/widgets/slider.rs

@@ -860,7 +860,7 @@ impl Slider<'_> {
             SliderOrientation::Horizontal => rect.x_range().shrink(handle_radius),
             // The vertical case has to be flipped because the largest slider value maps to the
             // lowest y value (which is at the top)
-            SliderOrientation::Vertical => rect.y_range().shrink(handle_radius).flip(),
+            SliderOrientation::Vertical => rect.y_range().shrink(handle_radius).flipped(),
         }
     }
 

crates/egui_demo_lib/src/demo/text_edit.rs

@@ -75,10 +75,10 @@ impl crate::View for TextEditDemo {
         let output = egui::TextEdit::multiline(text)
             .hint_text("Type something!")
             // Atoms are centered by default, so we need to pass the right align here:
-            .prefix("🔎".atom_align(Align2([Align::LEFT, *valign])))
+            .prefix("🔎".atom_align(Align2::new(Align::LEFT, *valign)))
             .suffix(
                 egui::Atom::custom(clear_id, clear_size)
-                    .atom_align(Align2([Align::RIGHT, *valign])),
+                    .atom_align(Align2::new(Align::RIGHT, *valign)),
             )
             .horizontal_align(*halign)
             .vertical_align(*valign)

crates/emath/src/align.rs

@@ -52,7 +52,8 @@ impl Align {
 
     /// Returns the inverse alignment.
     /// `Min` becomes `Max`, `Center` stays the same, `Max` becomes `Min`.
-    pub fn flip(self) -> Self {
+    #[must_use]
+    pub fn flipped(self) -> Self {
         match self {
             Self::Min => Self::Max,
             Self::Center => Self::Center,
@@ -60,6 +61,14 @@ impl Align {
         }
     }
 
+    /// Returns the inverse alignment.
+    /// `Min` becomes `Max`, `Center` stays the same, `Max` becomes `Min`.
+    #[must_use]
+    #[deprecated = "Renamed to `flipped`"]
+    pub fn flip(self) -> Self {
+        self.flipped()
+    }
+
     /// Returns a range of given size within a specified range.
     ///
     /// If the requested `size` is bigger than the size of `range`, then the returned
@@ -163,6 +172,37 @@ impl Align2 {
 }
 
 impl Align2 {
+    #[inline(always)]
+    pub fn new(x: Align, y: Align) -> Self {
+        Self([x, y])
+    }
+
+    /// Set align on the horizontal axis.
+    #[inline]
+    pub fn with_x(mut self, x: Align) -> Self {
+        self.set_x(x);
+        self
+    }
+
+    /// Set align on the vertical axis.
+    #[inline]
+    pub fn with_y(mut self, y: Align) -> Self {
+        self.set_y(y);
+        self
+    }
+
+    /// Set align on the horizontal axis.
+    #[inline(always)]
+    pub fn set_x(&mut self, x: Align) {
+        self.0[0] = x;
+    }
+
+    /// Set align on the vertical axis.
+    #[inline(always)]
+    pub fn set_y(&mut self, y: Align) {
+        self.0[1] = y;
+    }
+
     /// Returns an alignment by the X (horizontal) axis
     #[inline(always)]
     pub fn x(self) -> Align {
@@ -182,20 +222,47 @@ impl Align2 {
 
     /// Flip on the x-axis
     /// e.g. `TOP_LEFT` -> `TOP_RIGHT`
+    #[must_use]
+    pub fn flipped_x(self) -> Self {
+        self.with_x(self.x().flipped())
+    }
+
+    /// Flip on the x-axis
+    /// e.g. `TOP_LEFT` -> `TOP_RIGHT`
+    #[must_use]
+    #[deprecated = "Renamed to `flipped_x`"]
     pub fn flip_x(self) -> Self {
-        Self([self.x().flip(), self.y()])
+        self.flipped_x()
     }
 
     /// Flip on the y-axis
     /// e.g. `TOP_LEFT` -> `BOTTOM_LEFT`
+    #[must_use]
+    pub fn flipped_y(self) -> Self {
+        self.with_y(self.y().flipped())
+    }
+
+    /// Flip on the y-axis
+    /// e.g. `TOP_LEFT` -> `BOTTOM_LEFT`
+    #[must_use]
+    #[deprecated = "Renamed to `flipped_y`"]
     pub fn flip_y(self) -> Self {
-        Self([self.x(), self.y().flip()])
+        self.flipped_y()
     }
 
     /// Flip on both axes
     /// e.g. `TOP_LEFT` -> `BOTTOM_RIGHT`
+    #[must_use]
+    pub fn flipped(self) -> Self {
+        Self::new(self.x().flipped(), self.y().flipped())
+    }
+
+    /// Flip on both axes
+    /// e.g. `TOP_LEFT` -> `BOTTOM_RIGHT`
+    #[must_use]
+    #[deprecated = "Renamed to `flipped`"]
     pub fn flip(self) -> Self {
-        Self([self.x().flip(), self.y().flip()])
+        self.flipped()
     }
 
     /// Used e.g. to anchor a piece of text to a part of the rectangle.

crates/emath/src/range.rs

@@ -102,13 +102,21 @@ impl Rangef {
     /// Flip the min and the max
     #[inline]
     #[must_use]
-    pub fn flip(self) -> Self {
+    pub fn flipped(self) -> Self {
         Self {
             min: self.max,
             max: self.min,
         }
     }
 
+    /// Flip the min and the max
+    #[inline]
+    #[must_use]
+    #[deprecated = "Renamed to `flipped`"]
+    pub fn flip(self) -> Self {
+        self.flipped()
+    }
+
     /// The overlap of two ranges, i.e. the range that is contained by both.
     ///
     /// If the ranges do not overlap, returns a range with `span() < 0.0`.

crates/emath/src/rect_align.rs

@@ -161,7 +161,7 @@ impl RectAlign {
     pub fn outside(align: Align2) -> Self {
         Self {
             parent: align,
-            child: align.flip(),
+            child: align.flipped(),
         }
     }
 
@@ -206,33 +206,58 @@ impl RectAlign {
     }
 
     /// Flip the alignment on the x-axis.
-    pub fn flip_x(self) -> Self {
+    #[must_use]
+    pub fn flipped_x(self) -> Self {
         Self {
-            parent: self.parent.flip_x(),
+            parent: self.parent.flipped_x(),
-            child: self.child.flip_x(),
+            child: self.child.flipped_x(),
+        }
+    }
+
+    /// Flip the alignment on the x-axis.
+    #[must_use]
+    #[deprecated = "Renamed to `flipped_x`"]
+    pub fn flip_x(self) -> Self {
+        self.flipped_x()
+    }
+
+    /// Flip the alignment on the y-axis.
+    #[must_use]
+    pub fn flipped_y(self) -> Self {
+        Self {
+            parent: self.parent.flipped_y(),
+            child: self.child.flipped_y(),
         }
     }
 
     /// Flip the alignment on the y-axis.
+    #[must_use]
+    #[deprecated = "Renamed to `flipped_y`"]
     pub fn flip_y(self) -> Self {
+        self.flipped_y()
+    }
+
+    /// Flip the alignment on both axes.
+    #[must_use]
+    pub fn flipped(self) -> Self {
         Self {
-            parent: self.parent.flip_y(),
+            parent: self.parent.flipped(),
-            child: self.child.flip_y(),
+            child: self.child.flipped(),
         }
     }
 
     /// Flip the alignment on both axes.
+    #[must_use]
+    #[deprecated = "Renamed to `flipped`"]
     pub fn flip(self) -> Self {
-        Self {
+        self.flipped()
-            parent: self.parent.flip(),
-            child: self.child.flip(),
-        }
     }
 
     /// Returns the 3 alternative [`RectAlign`]s that are flipped in various ways, for use
     /// with [`RectAlign::find_best_align`].
+    #[must_use]
     pub fn symmetries(self) -> [Self; 3] {
-        [self.flip_x(), self.flip_y(), self.flip()]
+        [self.flipped_x(), self.flipped_y(), self.flipped()]
     }
 
     /// Look for the first alternative [`RectAlign`] that allows the child rect to fit