Add initial rich text example

src/attrs.rs

@@ -2,8 +2,28 @@
 
 pub use fontdb::{Family, Stretch, Style, Weight};
 
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub struct Color(pub u32);
+
+impl Color {
+    pub const fn rgb(r: u8, g: u8, b: u8) -> Self {
+        Self::rgba(r, g, b, 0xFF)
+    }
+
+    pub const fn rgba(r: u8, g: u8, b: u8, a: u8) -> Self {
+        Self(
+            ((a as u32) << 24) |
+            ((r as u32) << 16) |
+            ((g as u32) << 8) |
+            (b as u32)
+        )
+    }
+}
+
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub struct Attrs<'a> {
+    //TODO: should this be an option?
+    pub color_opt: Option<Color>,
     pub family: Family<'a>,
     pub monospaced: bool,
     pub stretch: Stretch,
@@ -14,6 +34,7 @@ pub struct Attrs<'a> {
 impl<'a> Attrs<'a> {
     pub fn new() -> Self {
         Self {
+            color_opt: None,
             family: Family::SansSerif,
             monospaced: false,
             stretch: Stretch::Normal,
@@ -22,6 +43,11 @@ impl<'a> Attrs<'a> {
         }
     }
 
+    pub fn color(mut self, color: Color) -> Self {
+        self.color_opt = Some(color);
+        self
+    }
+
     pub fn family(mut self, family: Family<'a>) -> Self {
         self.family = family;
         self
@@ -55,3 +81,9 @@ impl<'a> Attrs<'a> {
         (face.monospaced == self.monospaced || face.post_script_name.contains("Emoji"))
     }
 }
+
+pub struct AttrsSpan<'a> {
+    pub start: usize,
+    pub end: usize,
+    pub attrs: Attrs<'a>
+}