Attempt to print to device

lvgl/Cargo.toml

@@ -13,5 +13,6 @@ keywords = ["littlevgl", "lvgl", "graphical_interfaces"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-lvgl-sys = {path="../lvgl-sys", version="0.1.1"}
-cty = "0.2.1"
+lvgl-sys = {path="../lvgl-sys", version="0.1"}
+cty = "0.2"
+embedded-graphics = "0.6"

lvgl/src/display.rs

@@ -1,5 +1,115 @@
 use crate::objx::ObjectX;
 use core::ptr;
+use embedded_graphics;
+use embedded_graphics::prelude::*;
+use embedded_graphics::{drawable, DrawTarget};
+use core::mem::MaybeUninit;
+use embedded_graphics::pixelcolor::{PixelColor, raw::RawData, raw::RawU32};
+use core::marker::PhantomData;
+
+
+struct DisplayDriver<F, C>
+    where
+        F: FnMut(drawable::Pixel<C>),
+        C: PixelColor
+{
+    pub raw: lvgl_sys::lv_disp_drv_t,
+    callback: F,
+    display_buffer: MaybeUninit<lvgl_sys::lv_disp_buf_t>,
+    refresh_buffer: [MaybeUninit<lvgl_sys::lv_color_t>; lvgl_sys::LV_HOR_RES_MAX as usize * 10],
+    phantom: PhantomData<C>,
+}
+
+impl<F, C> DisplayDriver<F, C> where
+    F: FnMut(drawable::Pixel<C>),
+    C: PixelColor {
+
+    pub fn new<T>(mut device: T) -> Self
+        where
+        T: DrawTarget<C>
+    {
+        let mut callback = move |pixel: drawable::Pixel<C>| {
+            let _ = device.draw_pixel(pixel);
+        };
+
+        // Create a display buffer for LittlevGL
+        let mut display_buffer = MaybeUninit::<lvgl_sys::lv_disp_buf_t>::uninit();
+        // Declare a buffer for 10 lines
+        let mut refresh_buffer: [MaybeUninit<lvgl_sys::lv_color_t>;
+            lvgl_sys::LV_HOR_RES_MAX as usize * 10] =
+            unsafe { MaybeUninit::uninit().assume_init() };
+        // Initialize the display buffer
+        unsafe {
+            lvgl_sys::lv_disp_buf_init(
+                display_buffer.as_mut_ptr(),
+                refresh_buffer.as_mut_ptr() as *mut cty::c_void,
+                core::ptr::null_mut(),
+                (lvgl_sys::LV_HOR_RES_MAX * 10) as u32,
+            );
+        }
+        let mut disp_drv = unsafe {
+            // Descriptor of a display driver
+            let mut disp_drv = MaybeUninit::<lvgl_sys::lv_disp_drv_t>::uninit().assume_init();
+            // Basic initialization
+            lvgl_sys::lv_disp_drv_init(&mut disp_drv);
+            // Set your driver function
+            disp_drv.flush_cb = Some(display_callback_wrapper::<F, C>);
+            disp_drv.user_data = &mut callback as *mut _ as *mut cty::c_void;
+            disp_drv
+        };
+        // Assign the buffer to the display
+        disp_drv.buffer = display_buffer.as_mut_ptr();
+        // Finally register the driver
+        unsafe {
+            lvgl_sys::lv_disp_drv_register(&mut disp_drv);
+        }
+        Self {
+            raw: disp_drv,
+            callback,
+            display_buffer,
+            refresh_buffer,
+            phantom: PhantomData,
+        }
+    }
+
+    fn get_active_screen(&mut self) -> ObjectX<'static> {
+        get_active_screen()
+    }
+}
+
+unsafe extern "C" fn display_callback_wrapper<F, C>(
+    disp_drv: *mut lvgl_sys::lv_disp_drv_t,
+    area: *const lvgl_sys::lv_area_t,
+    color_p: *mut lvgl_sys::lv_color_t,
+) where
+    F: FnMut(drawable::Pixel<C>),
+    C: PixelColor
+{
+    // We need to make sure panics can't escape across the FFI boundary.
+    //let _ = panic::catch_unwind(|| {
+        let mut i = 0;
+        let disp = *disp_drv;
+
+        // Rust code closure reference
+        let closure = &mut *(disp.user_data as *mut F);
+
+        for y in (*area).y1..=(*area).y2 {
+            for x in (*area).x1..=(*area).x2 {
+                // Convert C color representation to high-level Rust
+                let raw_color = *color_p.add(i);
+                // let color = Rgb888::new(raw_color.ch.red,
+                //                         raw_color.ch.green,
+                //                         raw_color.ch.blue);
+                let color = C::Raw::from_u32(raw_color.full);
+                i = i + 1;
+                // Callback the Rust closure to flush the new points to the screen
+                closure(drawable::Pixel(Point::new(x as i32, y as i32), color));
+            }
+        }
+        // Indicate to LittlevGL that you are ready with the flushing
+        lvgl_sys::lv_disp_flush_ready(disp_drv);
+    //}); // end of panic::catch_unwind
+}
 
 pub fn get_active_screen() -> ObjectX<'static> {
     let raw =