Add ColorBw for printer

showbits-thermal-printer/src/color.rs

@@ -0,0 +1,32 @@
+use palette::Srgb;
+use showbits_common::Color;
+
+#[derive(Clone, Copy)]
+pub enum PixelBw {
+    Black,
+    White,
+    Transparent,
+    Invert,
+}
+
+impl Color for PixelBw {
+    fn to_srgb(self) -> Srgb {
+        match self {
+            Self::Black => Srgb::new(0.0, 0.0, 0.0),
+            Self::White => Srgb::new(1.0, 1.0, 1.0),
+            _ => Srgb::new(1.0, 0.0, 1.0),
+        }
+    }
+
+    fn over(self, other: Self) -> Self {
+        match (self, other) {
+            (Self::Black, _) => Self::Black,
+            (Self::White, _) => Self::White,
+            (Self::Transparent, p) => p,
+            (Self::Invert, Self::Black) => Self::White,
+            (Self::Invert, Self::White) => Self::Black,
+            (Self::Invert, Self::Invert) => Self::Transparent,
+            (Self::Invert, Self::Transparent) => Self::Invert,
+        }
+    }
+}