render: add a damage visualizer

src/cli/color.rs

@@ -0,0 +1,36 @@
+use {
+    crate::{theme::Color, utils::errorfmt::ErrorFmt},
+    std::ops::Range,
+};
+
+pub fn parse_color(string: &str) -> Color {
+    let hex = match string.strip_prefix("#") {
+        Some(s) => s,
+        _ => fatal!("Color must start with #"),
+    };
+    let d = |range: Range<usize>| match u8::from_str_radix(&hex[range.clone()], 16) {
+        Ok(n) => n,
+        Err(e) => {
+            fatal!(
+                "Could not parse color component {}: {}",
+                &hex[range],
+                ErrorFmt(e)
+            )
+        }
+    };
+    let s = |range: Range<usize>| {
+        let v = d(range);
+        (v << 4) | v
+    };
+    let (r, g, b, a) = match hex.len() {
+        3 => (s(0..1), s(1..2), s(2..3), u8::MAX),
+        4 => (s(0..1), s(1..2), s(2..3), s(3..4)),
+        6 => (d(0..2), d(2..4), d(4..6), u8::MAX),
+        8 => (d(0..2), d(2..4), d(4..6), d(6..8)),
+        _ => fatal!(
+            "Unexpected length of color string (should be 3, 4, 6, or 8): {}",
+            hex.len()
+        ),
+    };
+    jay_config::theme::Color::new_straight(r, g, b, a).into()
+}