From 05e927d0a8ff47f2ae43045d03034c1426cc3d23 Mon Sep 17 00:00:00 2001
From: Zac Wilson <zac@zacjw.com>
Date: Thu, 18 Dec 2025 10:24:33 +0000
Subject: [PATCH] Added support for partial window tracking

---
 src/lib.rs | 141 +++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 132 insertions(+), 9 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index ef014a2..1682658 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,7 +1,7 @@
 #![no_std]
 
 //! This library is an embedded-hal based driver implementation for the GDEQ031T10 e-paper display.
-//! 
+//!
 //! **Note**: 9-bit SPI mode (where the data/command is designated with an extra bit for each byte)
 //! is not supported by this driver. Only the mode with a dedicated data/command line is supported.
 
@@ -27,7 +27,7 @@ pub struct EPaperDisplay<BusyPin, ResetPin, DcPin, SpiDevice, Delay> {
 /// An error that may occur during display initialisation.
 pub enum InitError<ResetError, DcError, SpiError> {
     /// This variant is for any error with setting the level of the reset pin.
-    /// 
+    ///
     /// This variant may be uninhabited if the `ResetPin` type parameter for [EPaperDisplay] is one that
     /// doesn't produce errors.
     ResetError(ResetError),
@@ -38,7 +38,7 @@ pub enum InitError<ResetError, DcError, SpiError> {
 /// An error when trying to communicate with the display controller.
 pub enum WriteError<DcError, SpiError> {
     /// This variant is for any error with setting the level of the DC (Data/Command) pin.
-    /// 
+    ///
     /// This variant may be uninhabited if the `DcPin` type parameter for [EPaperDisplay] is one that
     /// doesn't produce errors.
     DcError(DcError),
@@ -58,9 +58,10 @@ impl Frame {
     }
 }
 
-pub struct DoubleFrame {
+pub struct DoubleFrame<PartialWindow> {
     old: Frame,
     new: Frame,
+    partial_window: PartialWindow,
 }
 
 pub enum PixelColour {
@@ -68,13 +69,126 @@ pub enum PixelColour {
     White = 1,
 }
 
-impl DoubleFrame {
+pub trait ApplyParitalWindow: private::Sealed {
+    fn apply<
+        BusyPin: InputPin,
+        ResetPin: OutputPin,
+        DcPin: OutputPin,
+        Spi: SpiDevice,
+        Delay: DelayNs,
+    >(
+        &self,
+        display: &mut EPaperDisplay<BusyPin, ResetPin, DcPin, Spi, Delay>,
+    );
+
+    fn update_partial_window(&mut self, min_x: u16, max_x: u16, min_y: u16, max_y: u16);
+
+    fn reset_partial_window(&mut self);
+}
+
+mod private {
+    pub(super) trait Sealed {}
+
+    impl Sealed for super::NoPartialWindow {}
+
+    impl Sealed for super::AutomaticPartialWindow {}
+}
+
+pub struct NoPartialWindow;
+
+impl ApplyParitalWindow for NoPartialWindow {
+    fn apply<
+        BusyPin: InputPin,
+        ResetPin: OutputPin,
+        DcPin: OutputPin,
+        Spi: SpiDevice,
+        Delay: DelayNs,
+    >(
+        &self,
+        _display: &mut EPaperDisplay<BusyPin, ResetPin, DcPin, Spi, Delay>,
+    ) {
+    }
+
+    fn update_partial_window(&mut self, _min_x: u16, _max_x: u16, _min_y: u16, _max_y: u16) {}
+
+    fn reset_partial_window(&mut self) {}
+}
+
+pub struct AutomaticPartialWindow {
+    min_x: u16,
+    max_x: u16,
+    min_y: u16,
+    max_y: u16,
+}
+
+impl ApplyParitalWindow for AutomaticPartialWindow {
+    fn apply<
+        BusyPin: InputPin,
+        ResetPin: OutputPin,
+        DcPin: OutputPin,
+        Spi: SpiDevice,
+        Delay: DelayNs,
+    >(
+        &self,
+        display: &mut EPaperDisplay<BusyPin, ResetPin, DcPin, Spi, Delay>,
+    ) {
+        let hrst = self.min_x as u8 & 0b11111000;
+        let hred = self.max_x as u8 | 0b111;
+        let vrst = self.min_y & 0x1FF;
+        let vred = self.max_y & 0x1FF;
+        display.write_command(0x90);
+        display.write_data(hrst);
+        display.write_data(hred);
+        display.write_data((vrst >> 8) as u8);
+        display.write_data((vrst & 0xFF) as u8);
+        display.write_data((vred >> 8) as u8);
+        display.write_data((vred & 0xFF) as u8);
+        display.write_data(0x00);
+    }
+    
+    fn update_partial_window(&mut self, min_x: u16, max_x: u16, min_y: u16, max_y: u16) {
+        self.min_x = core::cmp::min(self.min_x, min_x);
+        self.max_x = core::cmp::max(self.max_x, max_x);
+        self.min_y = core::cmp::min(self.min_y, min_y);
+        self.max_y = core::cmp::max(self.max_y, max_y);
+    }
+    
+    fn reset_partial_window(&mut self) {
+        *self = AutomaticPartialWindow {
+            min_x: EPD_WIDTH as u16,
+            max_x: 0,
+            min_y: EPD_HEIGHT as u16,
+            max_y: 0,
+        }
+    }
+}
+
+impl DoubleFrame<NoPartialWindow> {
     pub fn new(old: Frame, new: Frame) -> Self {
-        Self { old, new }
+        Self {
+            old,
+            new,
+            partial_window: NoPartialWindow,
+        }
     }
 
     pub fn draw_pixel(&mut self, x: usize, y: usize, colour: PixelColour) {
+        todo!()
+    }
+}
 
+impl DoubleFrame<AutomaticPartialWindow> {
+    pub fn new_with_automatic_partial_window(old: Frame, new: Frame) -> Self {
+        Self {
+            old,
+            new,
+            partial_window: AutomaticPartialWindow {
+                min_x: EPD_WIDTH as u16,
+                max_x: 0,
+                min_y: EPD_HEIGHT as u16,
+                max_y: 0,
+            },
+        }
     }
 }
 
@@ -158,7 +272,8 @@ impl<BusyPin: InputPin, ResetPin: OutputPin, DcPin: OutputPin, Spi: SpiDevice, D
         self.wait_for_display();
     }
 
-    pub fn draw_full_frame(&mut self, double_frame: &mut DoubleFrame) {
+    pub fn draw_full_frame<PartialWindow: ApplyParitalWindow>(&mut self, double_frame: &mut DoubleFrame<PartialWindow>) {
+        double_frame.partial_window.apply(self);
         self.write_command(0x10);
         for byte in double_frame.old.0 {
             self.write_data(byte);
@@ -175,12 +290,20 @@ impl<BusyPin: InputPin, ResetPin: OutputPin, DcPin: OutputPin, Spi: SpiDevice, D
     }
 
     /// Puts the display into deep sleep mode which effectively deinitialises the display controller.
-    /// 
+    ///
     /// Reinitialising the display with [EPaperDisplay::new] is sufficient to wake the display back up.
-    /// 
+    ///
     /// All display controller registers will be reset by this process.
     pub fn deep_sleep(mut self) {
         self.write_command(0x07);
         self.write_data(0xA5);
     }
+
+    pub fn enable_partial_mode(&mut self) {
+        self.write_command(0x91);
+    }
+
+    pub fn disable_partial_mode(&mut self) {
+        self.write_command(0x92);
+    }
 }