Add layout run iterator

src/layout.rs

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+
+use super::CacheKey;
+
+/// A laid out glyph
+pub struct LayoutGlyph {
+    /// Start index of cluster in original line
+    pub start: usize,
+    /// End index of cluster in original line
+    pub end: usize,
+    /// X offset of hitbox
+    pub x: f32,
+    /// width of hitbox
+    pub w: f32,
+    /// True if the character is from an RTL script
+    pub rtl: bool,
+    /// Cache key, see [CacheKey]
+    pub cache_key: CacheKey,
+    /// Integer component of X offset in line
+    pub x_int: i32,
+    /// Integer component of Y offset in line
+    pub y_int: i32,
+}
+
+/// A line of laid out glyphs
+pub struct LayoutLine {
+    /// Glyphs in line
+    pub glyphs: Vec<LayoutGlyph>,
+}