Add ability to convert from a hex string to Color32 using macros (#1596)

Cargo.lock

@@ -608,6 +608,12 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "color-hex"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ecdffb913a326b6c642290a0d0ec8e8d6597291acdc07cc4c9cb4b3635d44cf9"
+
 [[package]]
 name = "color_quant"
 version = "1.1.0"
@@ -1347,6 +1353,7 @@ dependencies = [
  "atomic_refcell",
  "bytemuck",
  "cint",
+ "color-hex",
  "criterion",
  "emath",
  "nohash-hasher",

egui/src/lib.rs

@@ -323,7 +323,7 @@ pub use epaint::emath;
 
 pub use emath::{lerp, pos2, remap, remap_clamp, vec2, Align, Align2, NumExt, Pos2, Rect, Vec2};
 pub use epaint::{
-    color, mutex,
+    color, hex_color, mutex,
     text::{FontData, FontDefinitions, FontFamily, FontId, FontTweak},
     textures::TexturesDelta,
     ClippedPrimitive, Color32, ColorImage, FontImage, ImageData, Mesh, PaintCallback,

epaint/CHANGELOG.md

@@ -4,7 +4,7 @@ All notable changes to the epaint crate will be documented in this file.
 
 ## Unreleased
 * Optimize tessellation of filled circles by 10x or more ([#1616](https://github.com/emilk/egui/pull/1616)).
-
+* Added `epaint::hex_rgb*!()` macros to create Color32's from hex strings ([#1596](https://github.com/emilk/egui/pull/1596)).
 
 ## 0.18.1 - 2022-05-01
 * Change `Shape::Callback` from `&dyn Any` to `&mut dyn Any` to support more backends.

epaint/Cargo.toml

@@ -47,13 +47,14 @@ mint = ["emath/mint"]
 # implement serde on most types.
 serde = ["dep:serde", "ahash/serde", "emath/serde"]
 
-
 [dependencies]
 emath = { version = "0.18.0", path = "../emath" }
 
 ab_glyph = "0.2.11"
 nohash-hasher = "0.2"
 
+color-hex = "0.2.0"
+
 # Optional:
 ahash = { version = "0.7", default-features = false, features = ["std"] }
 bytemuck = { version = "1.7.2", optional = true, features = ["derive"] }

epaint/src/color.rs

@@ -125,27 +125,27 @@ impl Color32 {
     }
 
     #[inline(always)]
-    pub fn is_opaque(&self) -> bool {
+    pub const fn is_opaque(&self) -> bool {
         self.a() == 255
     }
 
     #[inline(always)]
-    pub fn r(&self) -> u8 {
+    pub const fn r(&self) -> u8 {
         self.0[0]
     }
 
     #[inline(always)]
-    pub fn g(&self) -> u8 {
+    pub const fn g(&self) -> u8 {
         self.0[1]
     }
 
     #[inline(always)]
-    pub fn b(&self) -> u8 {
+    pub const fn b(&self) -> u8 {
         self.0[2]
     }
 
     #[inline(always)]
-    pub fn a(&self) -> u8 {
+    pub const fn a(&self) -> u8 {
         self.0[3]
     }
 
@@ -156,20 +156,20 @@ impl Color32 {
 
     /// Returns an additive version of self
     #[inline(always)]
-    pub fn additive(self) -> Self {
+    pub const fn additive(self) -> Self {
         let [r, g, b, _] = self.to_array();
         Self([r, g, b, 0])
     }
 
     /// Premultiplied RGBA
     #[inline(always)]
-    pub fn to_array(&self) -> [u8; 4] {
+    pub const fn to_array(&self) -> [u8; 4] {
         [self.r(), self.g(), self.b(), self.a()]
     }
 
     /// Premultiplied RGBA
     #[inline(always)]
-    pub fn to_tuple(&self) -> (u8, u8, u8, u8) {
+    pub const fn to_tuple(&self) -> (u8, u8, u8, u8) {
         (self.r(), self.g(), self.b(), self.a())
     }
 
@@ -186,6 +186,42 @@ impl Color32 {
     }
 }
 
+/// Construct a [`Color32`] from a hex RGB or RGBA string.
+///
+/// ```ignore
+/// assert_eq!(hex_color!("#202122"), Color32::from_rgb(0x20, 0x21, 0x22));
+/// assert_eq!(hex_color!("#abcdef12"), Color32::from_rgba_unmultiplied(0xab, 0xcd, 0xef, 0x12));
+/// ```
+#[macro_export]
+macro_rules! hex_color {
+    ($s:literal) => {{
+        let array = $crate::color_hex::color_from_hex!($s);
+        if array.len() == 3 {
+            $crate::Color32::from_rgb(array[0], array[1], array[2])
+        } else {
+            #[allow(unconditional_panic)]
+            $crate::Color32::from_rgba_unmultiplied(array[0], array[1], array[2], array[3])
+        }
+    }};
+}
+
+#[test]
+fn test_from_rgb_hex() {
+    assert_eq!(Color32::from_rgb(0x20, 0x21, 0x22), hex_color!("#202122"));
+    assert_eq!(
+        Color32::from_rgb_additive(0x20, 0x21, 0x22),
+        hex_color!("#202122").additive()
+    );
+}
+
+#[test]
+fn test_from_rgba_hex() {
+    assert_eq!(
+        Color32::from_rgba_unmultiplied(0x20, 0x21, 0x22, 0x50),
+        hex_color!("20212250")
+    );
+}
+
 // ----------------------------------------------------------------------------
 
 /// 0-1 linear space `RGBA` color with premultiplied alpha.

epaint/src/lib.rs

@@ -49,6 +49,8 @@ pub use emath::{pos2, vec2, Pos2, Rect, Vec2};
 pub use ahash;
 pub use emath;
 
+pub use color_hex;
+
 /// The UV coordinate of a white region of the texture mesh.
 /// The default egui texture has the top-left corner pixel fully white.
 /// You need need use a clamping texture sampler for this to work