[col] Add color methods

src/graphics/color.rs

@@ -0,0 +1,74 @@
+use byteorder::BigEndian;
+use crate::misc::emulator_error::EmulatorError;
+use crate::misc::endian::MemoryOperations;
+use crate::misc::result::EmulatorResult;
+
+pub struct Color(u8);
+
+const RED_MULT: u8 = 36;
+const GREEN_MULT: u8 = 6;
+
+impl Color {
+    /// Only first 216 color indices are used.
+    const COLOR_MAX:u8 = 215;
+    const COLOR_FACTOR_8_BIT: u8 = 0x33;
+    /// This constructs a valid color from rgb triplet
+    pub fn from_rgb(red: u8, green: u8, blue: u8) -> Color {
+        let red = red / Self::COLOR_FACTOR_8_BIT;
+        let green = green / Self::COLOR_FACTOR_8_BIT;
+        let blue = blue / Self::COLOR_FACTOR_8_BIT;
+        Color(red * RED_MULT + green * GREEN_MULT + blue)
+    }
+    pub fn try_new(in_mem_color: u8) -> EmulatorResult<Color> {
+        if in_mem_color > Self::COLOR_MAX {
+            return Err(EmulatorError::InvalidColorError(in_mem_color))
+        }
+        Ok(Color(in_mem_color))
+    }
+    pub fn get_mem_byte(&self) -> u8 {
+        self.0
+    }
+    /// This fetches the rgb triplet
+    pub fn get_rgb(self) -> [u8; 3] {
+        let r = self.0 / RED_MULT;
+        let gb_byte_remainder = self.0 % RED_MULT;
+        let g = gb_byte_remainder / GREEN_MULT;
+        let b = gb_byte_remainder % GREEN_MULT;
+        [r * Self::COLOR_FACTOR_8_BIT, g * Self::COLOR_FACTOR_8_BIT, b * Self::COLOR_FACTOR_8_BIT]
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use crate::graphics::color::Color;
+
+    #[test]
+    pub fn test_from_mem_zero() {
+        let color = Color::try_new(0).unwrap();
+        assert_eq!([0u8; 3], color.get_rgb())
+    }
+
+    #[test]
+    pub fn test_from_mem_invalid() {
+        let color = Color::try_new(0xff);
+        assert!(color.is_err())
+    }
+    #[test]
+    pub fn test_from_mem_max(){
+        let color = Color::try_new(Color::COLOR_MAX).unwrap();
+        assert_eq!([255u8;3],color.get_rgb())
+    }
+
+    #[test]
+    pub fn from_rgb_zero(){
+        let color = Color::from_rgb(0,0,0);
+        assert_eq!(0,color.get_mem_byte())
+    }
+    #[test]
+    pub fn from_rgb_max(){
+        let color = Color::from_rgb(255,255,255);
+        assert_eq!(Color::COLOR_MAX,color.get_mem_byte())
+    }
+
+}