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 +63,8 @@ enum TransportProtocol {
 #[derive(Deserialize)]
 #[serde(deny_unknown_fields)]
 struct Config {
+    #[serde(default)]
+    brightness: Option<Brightness>,
     #[serde(rename = "message")]
     messages: Vec<Message>,
 }
@@ -148,6 +150,7 @@ fn gnerate_payload(args: &mut Args) -> Result<PayloadBuffer> {
     };
 
     let mut payload = PayloadBuffer::new();
+    payload.set_brightness(config.brightness.unwrap_or_default());
 
     for message in config.messages {
         let mut style = Style::default();

src/protocol.rs

@@ -54,7 +54,7 @@ impl Style {
         self
     }
 
-    /// Show a dotted border arround the display.
+    /// Show a dotted border around the display.
     /// ```
     /// use badgemagic::protocol::Style;
     /// # (
@@ -161,7 +161,7 @@ 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 +193,47 @@ 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(rename_all = "snake_case"))]
+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()),
+        })
+    }
+}
+
 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 +274,7 @@ 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() {
@@ -252,7 +285,7 @@ impl Timestamp {
 ///     primitives::{PrimitiveStyle, Rectangle, Styled},
 /// };
 ///
-/// let mut buffer = PayloadBuffer::new();
+/// let mut buffer = PayloadBuffer::default();
 /// buffer.add_message_drawable(
 ///     Style::default(),
 ///     &Styled::new(
@@ -283,6 +316,7 @@ impl PayloadBuffer {
             num_messages: 0,
             data: Header {
                 magic: MAGIC,
+                brightness: 0,
                 blink: 0,
                 border: 0,
                 speed_and_mode: [0; 8],
@@ -300,6 +334,10 @@ 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 +406,7 @@ 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 +524,7 @@ 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 +537,18 @@ mod test {
             }
         }
     }
+
+    #[test]
+    fn brightness_to_u8() {
+        const VALID_BRIGHTNESS_VALUES: [(Brightness, u8); 4] = [
+            (Brightness::Full, 0x00),
+            (Brightness::ThreeQuarters, 0x10),
+            (Brightness::Half, 0x20),
+            (Brightness::OneQuarter, 0x30),
+        ];
+
+        for (value, raw) in VALID_BRIGHTNESS_VALUES {
+            assert_eq!(u8::from(value), raw);
+        }
+    }
 }