Restructure engine into modular layouter 🍂

1 files changed, 118 insertions, 0 deletions

diff --git a/src/layout/mod.rs b/src/layout/mod.rs
new file mode 100644
index 00000000..7bc62bd3
--- /dev/null
+++ b/src/layout/mod.rs
@@ -0,0 +1,118 @@
+//! Layouting engine.
+
+use crate::doc::Document;
+use crate::font::{Font, FontLoader, FontFamily, FontError};
+use crate::syntax::SyntaxTree;
+
+mod size;
+pub use size::Size;
+
+
+/// Layout a syntax tree given a context.
+#[allow(unused_variables)]
+pub fn layout(tree: &SyntaxTree, ctx: &LayoutContext) -> LayoutResult<Layout> {
+    Ok(Layout {})
+}
+
+/// A collection of layouted content.
+pub struct Layout {}
+
+impl Layout {
+    /// Convert this layout into a document given the list of fonts referenced by it.
+    pub fn into_document(self, fonts: Vec<Font>) -> Document {
+        Document {
+            pages: vec![],
+            fonts,
+        }
+    }
+}
+
+/// The context for layouting.
+pub struct LayoutContext<'a, 'p> {
+    pub loader: &'a FontLoader<'p>,
+}
+
+/// Default styles for pages.
+#[derive(Debug, Clone, PartialEq)]
+pub struct PageStyle {
+    /// The width of the paper.
+    pub width: Size,
+    /// The height of the paper.
+    pub height: Size,
+
+    /// The left margin of the paper.
+    pub margin_left: Size,
+    /// The top margin of the paper.
+    pub margin_top: Size,
+    /// The right margin of the paper.
+    pub margin_right: Size,
+    /// The bottom margin of the paper.
+    pub margin_bottom: Size,
+}
+
+impl Default for PageStyle {
+    fn default() -> PageStyle {
+        PageStyle {
+            // A4 paper.
+            width: Size::from_mm(210.0),
+            height: Size::from_mm(297.0),
+
+            // Margins. A bit more on top and bottom.
+            margin_left: Size::from_cm(3.0),
+            margin_top: Size::from_cm(3.0),
+            margin_right: Size::from_cm(3.0),
+            margin_bottom: Size::from_cm(3.0),
+        }
+    }
+}
+
+/// Default styles for texts.
+#[derive(Debug, Clone, PartialEq)]
+pub struct TextStyle {
+    /// A fallback list of font families to use.
+    pub font_families: Vec<FontFamily>,
+    /// The font size.
+    pub font_size: f32,
+    /// The line spacing (as a multiple of the font size).
+    pub line_spacing: f32,
+    /// The spacing for paragraphs (as a multiple of the line spacing).
+    pub paragraph_spacing: f32,
+}
+
+impl Default for TextStyle {
+    fn default() -> TextStyle {
+        use FontFamily::*;
+        TextStyle {
+            // Default font family, font size and line spacing.
+            font_families: vec![SansSerif, Serif, Monospace],
+            font_size: 11.0,
+            line_spacing: 1.25,
+            paragraph_spacing: 1.5,
+        }
+    }
+}
+
+/// The error type for layouting.
+pub enum LayoutError {
+    /// There was no suitable font.
+    MissingFont,
+    /// An error occured while gathering font data.
+    Font(FontError),
+}
+
+/// The result type for layouting.
+pub type LayoutResult<T> = Result<T, LayoutError>;
+
+error_type! {
+    err: LayoutError,
+    show: f => match err {
+        LayoutError::MissingFont => write!(f, "missing font"),
+        LayoutError::Font(err) => write!(f, "font error: {}", err),
+    },
+    source: match err {
+        LayoutError::Font(err) => Some(err),
+        _ => None,
+    },
+    from: (std::io::Error, LayoutError::Font(FontError::Io(err))),
+    from: (FontError, LayoutError::Font(err)),
+}