Merge pull request #354 from hecrj/feature/glow-renderer

OpenGL renderer and backend-agnostic graphics subcrate

1 files changed, 367 insertions, 0 deletions

diff --git a/graphics/src/widget/canvas/frame.rs b/graphics/src/widget/canvas/frame.rs
new file mode 100644
index 00000000..48d28d95
--- /dev/null
+++ b/graphics/src/widget/canvas/frame.rs
@@ -0,0 +1,367 @@
+use iced_native::{Point, Rectangle, Size, Vector};
+
+use crate::{
+    canvas::{Fill, Geometry, Path, Stroke, Text},
+    triangle, Primitive,
+};
+
+/// The frame of a [`Canvas`].
+///
+/// [`Canvas`]: struct.Canvas.html
+#[derive(Debug)]
+pub struct Frame {
+    size: Size,
+    buffers: lyon::tessellation::VertexBuffers<triangle::Vertex2D, u32>,
+    primitives: Vec<Primitive>,
+    transforms: Transforms,
+}
+
+#[derive(Debug)]
+struct Transforms {
+    previous: Vec<Transform>,
+    current: Transform,
+}
+
+#[derive(Debug, Clone, Copy)]
+struct Transform {
+    raw: lyon::math::Transform,
+    is_identity: bool,
+}
+
+impl Frame {
+    /// Creates a new empty [`Frame`] with the given dimensions.
+    ///
+    /// The default coordinate system of a [`Frame`] has its origin at the
+    /// top-left corner of its bounds.
+    ///
+    /// [`Frame`]: struct.Frame.html
+    pub fn new(size: Size) -> Frame {
+        Frame {
+            size,
+            buffers: lyon::tessellation::VertexBuffers::new(),
+            primitives: Vec::new(),
+            transforms: Transforms {
+                previous: Vec::new(),
+                current: Transform {
+                    raw: lyon::math::Transform::identity(),
+                    is_identity: true,
+                },
+            },
+        }
+    }
+
+    /// Returns the width of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn width(&self) -> f32 {
+        self.size.width
+    }
+
+    /// Returns the width of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn height(&self) -> f32 {
+        self.size.height
+    }
+
+    /// Returns the dimensions of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn size(&self) -> Size {
+        self.size
+    }
+
+    /// Returns the coordinate of the center of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn center(&self) -> Point {
+        Point::new(self.size.width / 2.0, self.size.height / 2.0)
+    }
+
+    /// Draws the given [`Path`] on the [`Frame`] by filling it with the
+    /// provided style.
+    ///
+    /// [`Path`]: path/struct.Path.html
+    /// [`Frame`]: struct.Frame.html
+    pub fn fill(&mut self, path: &Path, fill: impl Into<Fill>) {
+        use lyon::tessellation::{
+            BuffersBuilder, FillOptions, FillTessellator,
+        };
+
+        let mut buffers = BuffersBuilder::new(
+            &mut self.buffers,
+            FillVertex(match fill.into() {
+                Fill::Color(color) => color.into_linear(),
+            }),
+        );
+
+        let mut tessellator = FillTessellator::new();
+
+        let result = if self.transforms.current.is_identity {
+            tessellator.tessellate_path(
+                path.raw(),
+                &FillOptions::default(),
+                &mut buffers,
+            )
+        } else {
+            let path = path.transformed(&self.transforms.current.raw);
+
+            tessellator.tessellate_path(
+                path.raw(),
+                &FillOptions::default(),
+                &mut buffers,
+            )
+        };
+
+        let _ = result.expect("Tessellate path");
+    }
+
+    /// Draws an axis-aligned rectangle given its top-left corner coordinate and
+    /// its `Size` on the [`Frame`] by filling it with the provided style.
+    ///
+    /// [`Frame`]: struct.Frame.html
+    pub fn fill_rectangle(
+        &mut self,
+        top_left: Point,
+        size: Size,
+        fill: impl Into<Fill>,
+    ) {
+        use lyon::tessellation::{BuffersBuilder, FillOptions};
+
+        let mut buffers = BuffersBuilder::new(
+            &mut self.buffers,
+            FillVertex(match fill.into() {
+                Fill::Color(color) => color.into_linear(),
+            }),
+        );
+
+        let top_left =
+            self.transforms.current.raw.transform_point(
+                lyon::math::Point::new(top_left.x, top_left.y),
+            );
+
+        let size =
+            self.transforms.current.raw.transform_vector(
+                lyon::math::Vector::new(size.width, size.height),
+            );
+
+        let _ = lyon::tessellation::basic_shapes::fill_rectangle(
+            &lyon::math::Rect::new(top_left, size.into()),
+            &FillOptions::default(),
+            &mut buffers,
+        )
+        .expect("Fill rectangle");
+    }
+
+    /// Draws the stroke of the given [`Path`] on the [`Frame`] with the
+    /// provided style.
+    ///
+    /// [`Path`]: path/struct.Path.html
+    /// [`Frame`]: struct.Frame.html
+    pub fn stroke(&mut self, path: &Path, stroke: impl Into<Stroke>) {
+        use lyon::tessellation::{
+            BuffersBuilder, StrokeOptions, StrokeTessellator,
+        };
+
+        let stroke = stroke.into();
+
+        let mut buffers = BuffersBuilder::new(
+            &mut self.buffers,
+            StrokeVertex(stroke.color.into_linear()),
+        );
+
+        let mut tessellator = StrokeTessellator::new();
+
+        let mut options = StrokeOptions::default();
+        options.line_width = stroke.width;
+        options.start_cap = stroke.line_cap.into();
+        options.end_cap = stroke.line_cap.into();
+        options.line_join = stroke.line_join.into();
+
+        let result = if self.transforms.current.is_identity {
+            tessellator.tessellate_path(path.raw(), &options, &mut buffers)
+        } else {
+            let path = path.transformed(&self.transforms.current.raw);
+
+            tessellator.tessellate_path(path.raw(), &options, &mut buffers)
+        };
+
+        let _ = result.expect("Stroke path");
+    }
+
+    /// Draws the characters of the given [`Text`] on the [`Frame`], filling
+    /// them with the given color.
+    ///
+    /// __Warning:__ Text currently does not work well with rotations and scale
+    /// transforms! The position will be correctly transformed, but the
+    /// resulting glyphs will not be rotated or scaled properly.
+    ///
+    /// Additionally, all text will be rendered on top of all the layers of
+    /// a [`Canvas`]. Therefore, it is currently only meant to be used for
+    /// overlays, which is the most common use case.
+    ///
+    /// Support for vectorial text is planned, and should address all these
+    /// limitations.
+    ///
+    /// [`Text`]: struct.Text.html
+    /// [`Frame`]: struct.Frame.html
+    /// [`Canvas`]: struct.Canvas.html
+    pub fn fill_text(&mut self, text: impl Into<Text>) {
+        use std::f32;
+
+        let text = text.into();
+
+        let position = if self.transforms.current.is_identity {
+            text.position
+        } else {
+            let transformed = self.transforms.current.raw.transform_point(
+                lyon::math::Point::new(text.position.x, text.position.y),
+            );
+
+            Point::new(transformed.x, transformed.y)
+        };
+
+        // TODO: Use vectorial text instead of primitive
+        self.primitives.push(Primitive::Text {
+            content: text.content,
+            bounds: Rectangle {
+                x: position.x,
+                y: position.y,
+                width: f32::INFINITY,
+                height: f32::INFINITY,
+            },
+            color: text.color,
+            size: text.size,
+            font: text.font,
+            horizontal_alignment: text.horizontal_alignment,
+            vertical_alignment: text.vertical_alignment,
+        });
+    }
+
+    /// Stores the current transform of the [`Frame`] and executes the given
+    /// drawing operations, restoring the transform afterwards.
+    ///
+    /// This method is useful to compose transforms and perform drawing
+    /// operations in different coordinate systems.
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn with_save(&mut self, f: impl FnOnce(&mut Frame)) {
+        self.transforms.previous.push(self.transforms.current);
+
+        f(self);
+
+        self.transforms.current = self.transforms.previous.pop().unwrap();
+    }
+
+    /// Applies a translation to the current transform of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn translate(&mut self, translation: Vector) {
+        self.transforms.current.raw = self
+            .transforms
+            .current
+            .raw
+            .pre_translate(lyon::math::Vector::new(
+                translation.x,
+                translation.y,
+            ));
+        self.transforms.current.is_identity = false;
+    }
+
+    /// Applies a rotation to the current transform of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn rotate(&mut self, angle: f32) {
+        self.transforms.current.raw = self
+            .transforms
+            .current
+            .raw
+            .pre_rotate(lyon::math::Angle::radians(-angle));
+        self.transforms.current.is_identity = false;
+    }
+
+    /// Applies a scaling to the current transform of the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    #[inline]
+    pub fn scale(&mut self, scale: f32) {
+        self.transforms.current.raw =
+            self.transforms.current.raw.pre_scale(scale, scale);
+        self.transforms.current.is_identity = false;
+    }
+
+    /// Produces the [`Geometry`] representing everything drawn on the [`Frame`].
+    ///
+    /// [`Frame`]: struct.Frame.html
+    /// [`Geometry`]: struct.Geometry.html
+    pub fn into_geometry(mut self) -> Geometry {
+        if !self.buffers.indices.is_empty() {
+            self.primitives.push(Primitive::Mesh2D {
+                buffers: triangle::Mesh2D {
+                    vertices: self.buffers.vertices,
+                    indices: self.buffers.indices,
+                },
+                size: self.size,
+            });
+        }
+
+        Geometry::from_primitive(Primitive::Group {
+            primitives: self.primitives,
+        })
+    }
+}
+
+struct FillVertex([f32; 4]);
+
+impl lyon::tessellation::BasicVertexConstructor<triangle::Vertex2D>
+    for FillVertex
+{
+    fn new_vertex(
+        &mut self,
+        position: lyon::math::Point,
+    ) -> triangle::Vertex2D {
+        triangle::Vertex2D {
+            position: [position.x, position.y],
+            color: self.0,
+        }
+    }
+}
+
+impl lyon::tessellation::FillVertexConstructor<triangle::Vertex2D>
+    for FillVertex
+{
+    fn new_vertex(
+        &mut self,
+        position: lyon::math::Point,
+        _attributes: lyon::tessellation::FillAttributes<'_>,
+    ) -> triangle::Vertex2D {
+        triangle::Vertex2D {
+            position: [position.x, position.y],
+            color: self.0,
+        }
+    }
+}
+
+struct StrokeVertex([f32; 4]);
+
+impl lyon::tessellation::StrokeVertexConstructor<triangle::Vertex2D>
+    for StrokeVertex
+{
+    fn new_vertex(
+        &mut self,
+        position: lyon::math::Point,
+        _attributes: lyon::tessellation::StrokeAttributes<'_, '_>,
+    ) -> triangle::Vertex2D {
+        triangle::Vertex2D {
+            position: [position.x, position.y],
+            color: self.0,
+        }
+    }
+}