Introduce `with_transformation` to `Renderer` trait

6 files changed, 145 insertions, 6 deletions

diff --git a/core/Cargo.toml b/core/Cargo.toml
index 32dd3df2..2360e822 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -12,6 +12,7 @@ keywords.workspace = true
 
 [dependencies]
 bitflags.workspace = true
+glam.workspace = true
 log.workspace = true
 num-traits.workspace = true
 smol_str.workspace = true
diff --git a/core/src/lib.rs b/core/src/lib.rs
index bbc973f0..002336ee 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -49,6 +49,7 @@ mod rectangle;
 mod shadow;
 mod shell;
 mod size;
+mod transformation;
 mod vector;
 
 pub use alignment::Alignment;
@@ -75,6 +76,7 @@ pub use shadow::Shadow;
 pub use shell::Shell;
 pub use size::Size;
 pub use text::Text;
+pub use transformation::Transformation;
 pub use vector::Vector;
 pub use widget::Widget;
 
diff --git a/core/src/mouse/interaction.rs b/core/src/mouse/interaction.rs
index 072033fd..6ad66229 100644
--- a/core/src/mouse/interaction.rs
+++ b/core/src/mouse/interaction.rs
@@ -13,4 +13,5 @@ pub enum Interaction {
     ResizingHorizontally,
     ResizingVertically,
     NotAllowed,
+    ZoomIn,
 }
diff --git a/core/src/renderer.rs b/core/src/renderer.rs
index 0af74bb3..1139b41c 100644
--- a/core/src/renderer.rs
+++ b/core/src/renderer.rs
@@ -5,7 +5,9 @@ mod null;
 #[cfg(debug_assertions)]
 pub use null::Null;
 
-use crate::{Background, Border, Color, Rectangle, Shadow, Size, Vector};
+use crate::{
+    Background, Border, Color, Rectangle, Shadow, Size, Transformation, Vector,
+};
 
 /// A component that can be used by widgets to draw themselves on a screen.
 pub trait Renderer: Sized {
@@ -14,12 +16,24 @@ pub trait Renderer: Sized {
     /// The layer will clip its contents to the provided `bounds`.
     fn with_layer(&mut self, bounds: Rectangle, f: impl FnOnce(&mut Self));
 
-    /// Applies a `translation` to the primitives recorded in the given closure.
+    /// Applies a [`Transformation`] to the primitives recorded in the given closure.
+    fn with_transformation(
+        &mut self,
+        transformation: Transformation,
+        f: impl FnOnce(&mut Self),
+    );
+
+    /// Applies a translation to the primitives recorded in the given closure.
     fn with_translation(
         &mut self,
         translation: Vector,
         f: impl FnOnce(&mut Self),
-    );
+    ) {
+        self.with_transformation(
+            Transformation::translate(translation.x, translation.y),
+            f,
+        );
+    }
 
     /// Fills a [`Quad`] with the provided [`Background`].
     fn fill_quad(&mut self, quad: Quad, background: impl Into<Background>);
diff --git a/core/src/renderer/null.rs b/core/src/renderer/null.rs
index 455daa42..75a3c8b6 100644
--- a/core/src/renderer/null.rs
+++ b/core/src/renderer/null.rs
@@ -1,7 +1,9 @@
 use crate::alignment;
 use crate::renderer::{self, Renderer};
 use crate::text::{self, Text};
-use crate::{Background, Color, Font, Pixels, Point, Rectangle, Size, Vector};
+use crate::{
+    Background, Color, Font, Pixels, Point, Rectangle, Size, Transformation,
+};
 
 use std::borrow::Cow;
 
@@ -21,9 +23,9 @@ impl Null {
 impl Renderer for Null {
     fn with_layer(&mut self, _bounds: Rectangle, _f: impl FnOnce(&mut Self)) {}
 
-    fn with_translation(
+    fn with_transformation(
         &mut self,
-        _translation: Vector,
+        _transformation: Transformation,
         _f: impl FnOnce(&mut Self),
     ) {
     }
diff --git a/core/src/transformation.rs b/core/src/transformation.rs
new file mode 100644
index 00000000..b2c488b0
--- /dev/null
+++ b/core/src/transformation.rs
@@ -0,0 +1,119 @@
+use crate::{Point, Rectangle, Size, Vector};
+
+use glam::{Mat4, Vec3, Vec4};
+use std::ops::Mul;
+
+/// A 2D transformation matrix.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct Transformation(Mat4);
+
+impl Transformation {
+    /// A [`Transformation`] that preserves whatever is transformed.
+    pub const IDENTITY: Self = Self(Mat4::IDENTITY);
+
+    /// Creates an orthographic projection.
+    #[rustfmt::skip]
+    pub fn orthographic(width: u32, height: u32) -> Transformation {
+        Transformation(Mat4::orthographic_rh_gl(
+            0.0, width as f32,
+            height as f32, 0.0,
+            -1.0, 1.0
+        ))
+    }
+
+    /// Creates a translate transformation.
+    pub fn translate(x: f32, y: f32) -> Transformation {
+        Transformation(Mat4::from_translation(Vec3::new(x, y, 0.0)))
+    }
+
+    /// Creates a uniform scaling transformation.
+    pub fn scale(scaling: f32) -> Transformation {
+        Transformation(Mat4::from_scale(Vec3::new(scaling, scaling, 1.0)))
+    }
+
+    /// Returns the scale factor of the [`Transformation`].
+    pub fn scale_factor(&self) -> f32 {
+        self.0.x_axis.x
+    }
+
+    /// Returns the translation of the [`Transformation`].
+    pub fn translation(&self) -> Vector {
+        Vector::new(self.0.w_axis.x, self.0.w_axis.y)
+    }
+}
+
+impl Mul for Transformation {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self {
+        Transformation(self.0 * rhs.0)
+    }
+}
+
+impl Mul<Transformation> for Point {
+    type Output = Self;
+
+    fn mul(self, transformation: Transformation) -> Self {
+        let point = transformation
+            .0
+            .mul_vec4(Vec4::new(self.x, self.y, 1.0, 1.0));
+
+        Point::new(point.x, point.y)
+    }
+}
+
+impl Mul<Transformation> for Vector {
+    type Output = Self;
+
+    fn mul(self, transformation: Transformation) -> Self {
+        let new_vector = transformation
+            .0
+            .mul_vec4(Vec4::new(self.x, self.y, 1.0, 0.0));
+
+        Vector::new(new_vector.x, new_vector.y)
+    }
+}
+
+impl Mul<Transformation> for Size {
+    type Output = Self;
+
+    fn mul(self, transformation: Transformation) -> Self {
+        let new_size = transformation.0.mul_vec4(Vec4::new(
+            self.width,
+            self.height,
+            1.0,
+            0.0,
+        ));
+
+        Size::new(new_size.x, new_size.y)
+    }
+}
+
+impl Mul<Transformation> for Rectangle {
+    type Output = Self;
+
+    fn mul(self, transformation: Transformation) -> Self {
+        let position = self.position();
+        let size = self.size();
+
+        Self::new(position * transformation, size * transformation)
+    }
+}
+
+impl AsRef<[f32; 16]> for Transformation {
+    fn as_ref(&self) -> &[f32; 16] {
+        self.0.as_ref()
+    }
+}
+
+impl From<Transformation> for [f32; 16] {
+    fn from(t: Transformation) -> [f32; 16] {
+        *t.as_ref()
+    }
+}
+
+impl From<Transformation> for Mat4 {
+    fn from(transformation: Transformation) -> Self {
+        transformation.0
+    }
+}