Add display brightness control

src/main.rs

@@ -6,7 +6,7 @@ use std::{fs, path::PathBuf};
 use anyhow::{Context, Result};
 use badgemagic::{
     ble::Device as BleDevice,
-    protocol::{Mode, PayloadBuffer, Speed, Style},
+    protocol::{Brightness, Mode, PayloadBuffer, Speed, Style},
     usb_hid::Device as UsbDevice,
 };
 use base64::Engine;
@@ -63,6 +63,9 @@ enum TransportProtocol {
 #[derive(Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Config {
+    #[serde(default)]
+    brightness: Brightness,
+
     #[serde(rename = "message")]
     messages: Vec<Message>,
 }
@@ -148,6 +151,7 @@ fn gnerate_payload(args: &mut Args) -> Result<PayloadBuffer> {
     };
 
     let mut payload = PayloadBuffer::new();
+    payload.set_brightness(config.brightness);
 
     for message in config.messages {
         let mut style = Style::default();

src/protocol.rs

@@ -1,7 +1,5 @@
 //! Protocol used to update the badge
 
-use std::num::TryFromIntError;
-
 #[cfg(feature = "embedded-graphics")]
 use embedded_graphics::{
     draw_target::DrawTarget,
@@ -11,6 +9,7 @@ use embedded_graphics::{
     primitives::Rectangle,
     Drawable,
 };
+use std::{convert::Infallible, num::TryFromIntError};
 use time::OffsetDateTime;
 use zerocopy::{BigEndian, FromBytes, Immutable, IntoBytes, KnownLayout, U16};
 
@@ -54,7 +53,7 @@ impl Style {
         self
     }
 
-    /// Show a dotted border arround the display.
+    /// Show a dotted border around the display.
     /// ```
     /// use badgemagic::protocol::Style;
     /// # (
@@ -161,7 +160,7 @@ impl TryFrom<u8> for Speed {
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "snake_case"))]
 pub enum Mode {
-    /// Scroll thorugh the message from left to right
+    /// Scroll through the message from left to right
     #[default]
     Left,
 
@@ -193,14 +192,72 @@ pub enum Mode {
     Laser,
 }
 
+/// Display Brightness
+#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "serde", serde(try_from = "f32", into = "u8"))]
+pub enum Brightness {
+    #[default]
+    Full = 0x00,
+    ThreeQuarters = 0x10,
+    Half = 0x20,
+    OneQuarter = 0x30,
+}
+
+impl From<Brightness> for u8 {
+    fn from(value: Brightness) -> Self {
+        value as u8
+    }
+}
+
+impl TryFrom<u8> for Brightness {
+    type Error = TryFromIntError;
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        Ok(match value {
+            0x00 => Self::Full,
+            0x10 => Self::ThreeQuarters,
+            0x20 => Self::Half,
+            0x30 => Self::OneQuarter,
+            _ => return Err(u8::try_from(-1).unwrap_err()),
+        })
+    }
+}
+
+impl From<Brightness> for f32 {
+    fn from(value: Brightness) -> Self {
+        match value {
+            Brightness::Full => 1.0,
+            Brightness::ThreeQuarters => 0.75,
+            Brightness::Half => 0.5,
+            Brightness::OneQuarter => 0.25,
+        }
+    }
+}
+
+impl TryFrom<f32> for Brightness {
+    type Error = Infallible;
+    fn try_from(value: f32) -> Result<Self, Self::Error> {
+        if value < 0.375 {
+            Ok(Self::OneQuarter)
+        } else if value < 0.625 {
+            Ok(Self::Half)
+        } else if value < 0.875 {
+            Ok(Self::ThreeQuarters)
+        } else {
+            Ok(Self::Full)
+        }
+    }
+}
+
 const MSG_PADDING_ALIGN: usize = 64;
 
-const MAGIC: [u8; 6] = *b"wang\0\0";
+const MAGIC: [u8; 5] = *b"wang\0";
 
 #[derive(FromBytes, IntoBytes, Immutable, KnownLayout)]
 #[repr(C)]
 struct Header {
-    magic: [u8; 6],
+    magic: [u8; 5],
+    brightness: u8,
     blink: u8,
     border: u8,
     speed_and_mode: [u8; 8],
@@ -241,7 +298,7 @@ impl Timestamp {
 
 /// Buffer to create a payload
 ///
-/// A payload consits of up to 8 messages
+/// A payload consists of up to 8 messages
 /// ```
 /// # #[cfg(feature = "embedded-graphics")]
 /// # fn main() {
@@ -283,6 +340,7 @@ impl PayloadBuffer {
             num_messages: 0,
             data: Header {
                 magic: MAGIC,
+                brightness: Brightness::Full.into(),
                 blink: 0,
                 border: 0,
                 speed_and_mode: [0; 8],
@@ -300,6 +358,10 @@ impl PayloadBuffer {
         Header::mut_from_prefix(&mut self.data).unwrap().0
     }
 
+    pub fn set_brightness(&mut self, brightness: Brightness) {
+        self.header_mut().brightness = brightness.into();
+    }
+
     /// Return the current number of messages
     pub fn num_messages(&mut self) -> usize {
         self.num_messages as usize
@@ -368,7 +430,7 @@ impl PayloadBuffer {
         &self.data
     }
 
-    /// Convert the payload buffe into bytes (with padding)
+    /// Convert the payload buffer into bytes (with padding)
     #[allow(clippy::missing_panics_doc)] // should never panic
     #[must_use]
     pub fn into_padded_bytes(self) -> impl AsRef<[u8]> {
@@ -486,7 +548,7 @@ impl DrawTarget for MessageBuffer<'_> {
 mod test {
     use std::ops::Range;
 
-    use super::Speed;
+    use super::{Brightness, Speed};
 
     #[test]
     fn speed_to_u8_and_back() {
@@ -499,4 +561,26 @@ mod test {
             }
         }
     }
+
+    #[test]
+    fn u8_to_brightness_and_back() {
+        const VALID_BRIGHTNESS_VALUES: [u8; 4] = [0x00, 0x10, 0x20, 0x30];
+        for i in u8::MIN..u8::MAX {
+            if let Ok(brightness) = Brightness::try_from(i) {
+                assert_eq!(u8::from(brightness), i);
+            } else {
+                assert!(!VALID_BRIGHTNESS_VALUES.contains(&i));
+            }
+        }
+    }
+
+    #[test]
+    fn f32_to_brightness_and_back() {
+        const VALID_BRIGHTNESS_VALUES: [f32; 4] = [0.25, 0.5, 0.75, 1.0];
+        for i in i8::MIN..i8::MAX {
+            let i = f32::from(i) / 4f32;
+            let Ok(brightness) = Brightness::try_from(i);
+            assert!(VALID_BRIGHTNESS_VALUES.contains(&(f32::from(brightness))));
+        }
+    }
 }