.github/workflows/rust.yml

@@ -30,4 +30,5 @@ jobs:
         run: cargo build --verbose
 
       - name: Run tests
-        run: cargo test --verbose
+        # LVGL is not thread safe, we need to run tests sequentially
+        run: cargo test --verbose -- --nocapture --test-threads 1

examples/app.rs

@@ -0,0 +1,40 @@
+use embedded_graphics::pixelcolor::Rgb565;
+use embedded_graphics::prelude::*;
+use embedded_graphics_simulator::{OutputSettingsBuilder, SimulatorDisplay, Window};
+use lvgl;
+use lvgl::widgets::Label;
+use lvgl::{Display, DrawBuffer};
+use parking_lot::Mutex;
+use std::cell::RefCell;
+use std::sync::Arc;
+
+type ColorSpace = Rgb565;
+
+fn main() {
+    let embedded_graphics_display: SimulatorDisplay<ColorSpace> = SimulatorDisplay::new(Size::new(
+        lvgl::DISP_HOR_RES as u32,
+        lvgl::DISP_VER_RES as u32,
+    ));
+
+    let output_settings = OutputSettingsBuilder::new().scale(2).build();
+    let mut window = Window::new("App Example", &output_settings);
+
+    let mut shared_native_display = Arc::new(Mutex::new(embedded_graphics_display));
+
+    // LVGL usage
+    lvgl::init();
+
+    const REFRESH_BUFFER_SIZE: usize = lvgl::DISP_HOR_RES * lvgl::DISP_VER_RES / 10;
+    static DRAW_BUFFER: DrawBuffer<REFRESH_BUFFER_SIZE> = DrawBuffer::new();
+
+    let display = Display::register(&DRAW_BUFFER, {
+        let shared_display = Arc::clone(&shared_native_display);
+        move |update| {
+            let mut embedded_graphics_display = shared_display.lock();
+            embedded_graphics_display.draw_iter(update.as_pixels());
+        }
+    })
+    .unwrap();
+
+    let label: Label = "Nice!".into();
+}

examples/arc.rs

@@ -4,12 +4,16 @@ use embedded_graphics::prelude::*;
 use embedded_graphics_simulator::{
     OutputSettingsBuilder, SimulatorDisplay, SimulatorEvent, Window,
 };
+use lvgl::display::Display;
 use lvgl::style::Style;
 use lvgl::widgets::{Arc, Label, LabelAlign};
-use lvgl::{self, Align, Color, Part, State, UI};
+use lvgl::{self, Align, Color, Part, State};
 use lvgl::{LvError, Widget};
 use lvgl_sys;
-use std::time::Instant;
+use parking_lot::Mutex;
+use std::sync::Arc as SyncArc;
+use std::thread;
+use std::time::{Duration, Instant};
 
 fn mem_info() -> lvgl_sys::lv_mem_monitor_t {
     let mut info = lvgl_sys::lv_mem_monitor_t {
@@ -36,7 +40,9 @@ fn main() -> Result<(), LvError> {
 }
 
 fn run_arc_demo() -> Result<(), LvError> {
-    let display: SimulatorDisplay<Rgb565> = SimulatorDisplay::new(Size::new(
+    lvgl::init();
+
+    let embedded_graphics_display: SimulatorDisplay<Rgb565> = SimulatorDisplay::new(Size::new(
         lvgl_sys::LV_HOR_RES_MAX,
         lvgl_sys::LV_VER_RES_MAX,
     ));
@@ -44,52 +50,60 @@ fn run_arc_demo() -> Result<(), LvError> {
     let output_settings = OutputSettingsBuilder::new().scale(2).build();
     let mut window = Window::new("Arc Example", &output_settings);
 
-    let mut ui = UI::init()?;
+    let shared_native_display = SyncArc::new(Mutex::new(embedded_graphics_display));
+    let display = Display::register_shared(&shared_native_display)?;
 
-    // Implement and register your display:
-    ui.disp_drv_register(display)?;
-
-    // Create screen and widgets
-    let mut screen = ui.scr_act()?;
+    let mut screen = display.get_str_act()?;
 
     let mut screen_style = Style::default();
     screen_style.set_bg_color(State::DEFAULT, Color::from_rgb((255, 255, 255)));
     screen_style.set_radius(State::DEFAULT, 0);
-    screen.add_style(Part::Main, screen_style)?;
+    screen.add_style(Part::Main, &mut screen_style)?;
 
     // Create the arc object
-    let mut arc = Arc::new(&mut screen)?;
+    let mut arc = Arc::new()?;
     arc.set_size(150, 150)?;
     arc.set_align(&mut screen, Align::Center, 0, 10)?;
     arc.set_start_angle(135)?;
     arc.set_end_angle(135)?;
 
-    let mut loading_lbl = Label::new(&mut screen)?;
+    let mut loading_lbl = Label::new()?;
     loading_lbl.set_text(CString::new("Loading...").unwrap().as_c_str())?;
     loading_lbl.set_align(&mut arc, Align::OutTopMid, 0, -10)?;
     loading_lbl.set_label_align(LabelAlign::Center)?;
 
     let mut loading_style = Style::default();
     loading_style.set_text_color(State::DEFAULT, Color::from_rgb((0, 0, 0)));
-    loading_lbl.add_style(Part::Main, loading_style)?;
+    loading_lbl.add_style(Part::Main, &mut loading_style)?;
 
     let mut angle = 0;
     let mut forward = true;
     let mut i = 0;
 
-    let mut loop_started = Instant::now();
+    // LVGL timer thread
+    thread::spawn(|| {
+        let interval = Duration::from_millis(5);
+        loop {
+            thread::sleep(interval);
+            lvgl::tick_inc(interval);
+        }
+    });
+
     'running: loop {
         if i > 270 {
             forward = if forward { false } else { true };
             i = 1;
-            println!("meminfo running: {:?}", mem_info());
+            println!("mem info running: {:?}", mem_info());
         }
         angle = if forward { angle + 1 } else { angle - 1 };
         arc.set_end_angle(angle + 135)?;
         i += 1;
 
-        ui.task_handler();
-        window.update(ui.get_display_ref().unwrap());
+        lvgl::task_handler();
+        {
+            let eg_display = shared_native_display.lock();
+            window.update(&eg_display);
+        }
 
         for event in window.events() {
             match event {
@@ -97,9 +111,7 @@ fn run_arc_demo() -> Result<(), LvError> {
                 _ => {}
             }
         }
-
-        ui.tick_inc(loop_started.elapsed());
-        loop_started = Instant::now();
+        thread::sleep(Duration::from_millis(15));
     }
 
     Ok(())

examples/demo.rs

@@ -1,4 +1,5 @@
 use cstr_core::CString;
+use embedded_graphics::drawable;
 use embedded_graphics::pixelcolor::Rgb565;
 use embedded_graphics::prelude::*;
 use embedded_graphics_simulator::{
@@ -7,61 +8,91 @@ use embedded_graphics_simulator::{
 use lvgl;
 use lvgl::style::Style;
 use lvgl::widgets::{Label, LabelAlign};
-use lvgl::{Align, Color, LvError, Part, State, Widget, UI};
+use lvgl::{Align, Color, DefaultDisplay, Display, DrawBuffer, LvError, Part, State, Widget};
 use lvgl_sys;
+use parking_lot::Mutex;
+use std::sync::Arc as SyncArc;
+use std::thread;
 use std::thread::sleep;
 use std::time::{Duration, Instant};
 
 fn main() -> Result<(), LvError> {
-    let display: SimulatorDisplay<Rgb565> = SimulatorDisplay::new(Size::new(
-        lvgl_sys::LV_HOR_RES_MAX,
-        lvgl_sys::LV_VER_RES_MAX,
+    let embedded_graphics_display: SimulatorDisplay<Rgb565> = SimulatorDisplay::new(Size::new(
+        lvgl::DISP_HOR_RES as u32,
+        lvgl::DISP_VER_RES as u32,
     ));
 
-    let output_settings = OutputSettingsBuilder::new().scale(2).build();
+    let output_settings = OutputSettingsBuilder::new().scale(1).build();
     let mut window = Window::new("PineTime", &output_settings);
 
-    let mut ui = UI::init()?;
+    let shared_native_display = SyncArc::new(Mutex::new(embedded_graphics_display));
 
-    // Implement and register your display:
-    ui.disp_drv_register(display).unwrap();
+    // LVGL-rs usage starts here
+    lvgl::init();
+
+    // LVGL will render the graphics here first, and seed the rendered image to the
+    // display. The buffer size can be set freely but 1/10 screen size is a good starting point.
+    const REFRESH_BUFFER_SIZE: usize = lvgl::DISP_HOR_RES * lvgl::DISP_VER_RES / 10;
+    static DRAW_BUFFER: DrawBuffer<REFRESH_BUFFER_SIZE> = DrawBuffer::new();
+    //
+    // const NUMBER_OF_DISPLAYS: usize = 1;
+    // static DISPLAY_REGISTRY: DisplayRegistry<NUMBER_OF_DISPLAYS> = DisplayRegistry::empty();
+    // // static DISPLAY_REGISTRY: SingleDisplayRegistry = DisplayRegistry::empty();
+    // let display = DISPLAY_REGISTRY.register_shared(&DRAW_BUFFER, shared_native_display.clone())?;
+
+    // Register your display update callback with LVGL. The closure you pass here will be called
+    // whenever LVGL has updates to be painted to the display.
+    let display = Display::register(&DRAW_BUFFER, {
+        let shared_disp_inner = SyncArc::clone(&shared_native_display);
+        move |update| {
+            let mut em_disp = shared_disp_inner.lock();
+            em_disp.draw_iter(update.as_pixels());
+        }
+    })?;
 
     // Create screen and widgets
-    let mut screen = ui.scr_act()?;
+    let mut screen = display.get_scr_act()?;
+
+    println!("Before all widgets: {:?}", mem_info());
 
     let mut screen_style = Style::default();
     screen_style.set_bg_color(State::DEFAULT, Color::from_rgb((0, 0, 0)));
     screen_style.set_radius(State::DEFAULT, 0);
-    screen.add_style(Part::Main, screen_style)?;
+    screen.add_style(Part::Main, &mut screen_style)?;
 
-    let mut time = Label::new(&mut screen)?;
+    let mut time = Label::from("20:46");
     let mut style_time = Style::default();
-    //style_time.set_text_font(font_noto_sans_numeric_28);
+    // style_time.set_text_font(font_noto_sans_numeric_28);
     style_time.set_text_color(State::DEFAULT, Color::from_rgb((255, 255, 255)));
-    time.add_style(Part::Main, style_time)?;
+    time.add_style(Part::Main, &mut style_time)?;
     time.set_align(&mut screen, Align::Center, 0, 0)?;
-    time.set_text(CString::new("20:46").unwrap().as_c_str())?;
     time.set_width(240)?;
     time.set_height(240)?;
 
-    let mut bt = Label::new(&mut screen)?;
+    let mut bt = Label::from("#5794f2 \u{F293}#");
     bt.set_width(50)?;
     bt.set_height(80)?;
     bt.set_recolor(true)?;
-    bt.set_text(CString::new("#5794f2 \u{F293}#").unwrap().as_c_str())?;
     bt.set_label_align(LabelAlign::Left)?;
     bt.set_align(&mut screen, Align::InTopLeft, 0, 0)?;
 
-    let mut power = Label::new(&mut screen)?;
+    let mut power: Label = "#fade2a 20%#".into();
     power.set_recolor(true)?;
     power.set_width(80)?;
     power.set_height(20)?;
-    power.set_text(CString::new("#fade2a 20%#").unwrap().as_c_str())?;
     power.set_label_align(LabelAlign::Right)?;
     power.set_align(&mut screen, Align::InTopRight, 0, 0)?;
 
+    // LVGL timer thread
+    thread::spawn(|| {
+        let interval = Duration::from_millis(5);
+        loop {
+            thread::sleep(interval);
+            lvgl::tick_inc(interval);
+        }
+    });
+
     let mut i = 0;
-    let mut loop_started = Instant::now();
     'running: loop {
         if i > 59 {
             i = 0;
@@ -70,8 +101,11 @@ fn main() -> Result<(), LvError> {
         time.set_text(&val)?;
         i = 1 + i;
 
-        ui.task_handler();
-        window.update(ui.get_display_ref().unwrap());
+        lvgl::task_handler();
+        {
+            let native_display = shared_native_display.lock();
+            window.update(&native_display);
+        }
 
         for event in window.events() {
             match event {
@@ -79,12 +113,12 @@ fn main() -> Result<(), LvError> {
                 _ => {}
             }
         }
+        println!("During run: {:?}", mem_info());
         sleep(Duration::from_secs(1));
-
-        ui.tick_inc(loop_started.elapsed());
-        loop_started = Instant::now();
     }
 
+    println!("Final part of demo app: {:?}", mem_info());
+
     Ok(())
 }
 
@@ -99,3 +133,20 @@ fn main() -> Result<(), LvError> {
 extern "C" {
     pub static mut noto_sans_numeric_80: lvgl_sys::lv_font_t;
 }
+
+fn mem_info() -> lvgl_sys::lv_mem_monitor_t {
+    let mut info = lvgl_sys::lv_mem_monitor_t {
+        total_size: 0,
+        free_cnt: 0,
+        free_size: 0,
+        free_biggest_size: 0,
+        used_cnt: 0,
+        max_used: 0,
+        used_pct: 0,
+        frag_pct: 0,
+    };
+    unsafe {
+        lvgl_sys::lv_mem_monitor(&mut info as *mut _);
+    }
+    info
+}

examples/include/lv_conf.h

@@ -1,6 +1,6 @@
 /**
  * @file lv_conf.h
- *
+ * Configuration file for v7.10.1
  */
 
 /*
@@ -80,9 +80,9 @@ typedef int16_t lv_coord_t;
 #define LV_MEM_CUSTOM      0
 #if LV_MEM_CUSTOM == 0
 /* Size of the memory used by `lv_mem_alloc` in bytes (>= 2kB)*/
-#  define LV_MEM_SIZE    (1048576U) // 1Mb
+#  define LV_MEM_SIZE    (14U * 1024U)
 
-/* Complier prefix for a big array declaration */
+/* Compiler prefix for a big array declaration */
 #  define LV_MEM_ATTR
 
 /* Set an address for the memory pool instead of allocating it as an array.
@@ -97,6 +97,10 @@ typedef int16_t lv_coord_t;
 #  define LV_MEM_CUSTOM_FREE    free         /*Wrapper to free*/
 #endif     /*LV_MEM_CUSTOM*/
 
+/* Use the standard memcpy and memset instead of LVGL's own functions.
+ * The standard functions might or might not be faster depending on their implementation. */
+#define LV_MEMCPY_MEMSET_STD    0
+
 /* Garbage Collector settings
  * Used if lvgl is binded to higher level language and the memory is managed by that language */
 #define LV_ENABLE_GC 0
@@ -123,14 +127,13 @@ typedef int16_t lv_coord_t;
 #define LV_INDEV_DEF_DRAG_THROW           10
 
 /* Long press time in milliseconds.
- * Time to send `LV_EVENT_LONG_PRESSSED`) */
+ * Time to send `LV_EVENT_LONG_PRESSED`) */
 #define LV_INDEV_DEF_LONG_PRESS_TIME      400
 
 /* Repeated trigger period in long press [ms]
  * Time between `LV_EVENT_LONG_PRESSED_REPEAT */
 #define LV_INDEV_DEF_LONG_PRESS_REP_TIME  100
 
-
 /* Gesture threshold in pixels */
 #define LV_INDEV_DEF_GESTURE_LIMIT        50
 
@@ -150,7 +153,7 @@ typedef void * lv_anim_user_data_t;
 
 #endif
 
-/* 1: Enable shadow drawing*/
+/* 1: Enable shadow drawing on rectangles*/
 #define LV_USE_SHADOW           1
 #if LV_USE_SHADOW
 /* Allow buffering some shadow calculation
@@ -160,6 +163,15 @@ typedef void * lv_anim_user_data_t;
 #define LV_SHADOW_CACHE_SIZE    0
 #endif
 
+/*1: enable outline drawing on rectangles*/
+#define LV_USE_OUTLINE  1
+
+/*1: enable pattern drawing on rectangles*/
+#define LV_USE_PATTERN  1
+
+/*1: enable value string drawing on rectangles*/
+#define LV_USE_VALUE_STR    1
+
 /* 1: Use other blend modes than normal (`LV_BLEND_MODE_...`)*/
 #define LV_USE_BLEND_MODES      1
 
@@ -178,6 +190,22 @@ typedef void * lv_group_user_data_t;
 /* 1: Enable GPU interface*/
 #define LV_USE_GPU              1   /*Only enables `gpu_fill_cb` and `gpu_blend_cb` in the disp. drv- */
 #define LV_USE_GPU_STM32_DMA2D  0
+/*If enabling LV_USE_GPU_STM32_DMA2D, LV_GPU_DMA2D_CMSIS_INCLUDE must be defined to include path of CMSIS header of target processor
+e.g. "stm32f769xx.h" or "stm32f429xx.h" */
+#define LV_GPU_DMA2D_CMSIS_INCLUDE
+
+/*1: Use PXP for CPU off-load on NXP RTxxx platforms */
+#define LV_USE_GPU_NXP_PXP      0
+
+/*1: Add default bare metal and FreeRTOS interrupt handling routines for PXP (lv_gpu_nxp_pxp_osa.c)
+ *   and call lv_gpu_nxp_pxp_init() automatically during lv_init(). Note that symbol FSL_RTOS_FREE_RTOS
+ *   has to be defined in order to use FreeRTOS OSA, otherwise bare-metal implementation is selected.
+ *0: lv_gpu_nxp_pxp_init() has to be called manually before lv_init()
+ * */
+#define LV_USE_GPU_NXP_PXP_AUTO_INIT 0
+
+/*1: Use VG-Lite for CPU offload on NXP RTxxx platforms */
+#define LV_USE_GPU_NXP_VG_LITE   0
 
 /* 1: Enable file system (might be required for images */
 #define LV_USE_FILESYSTEM       1
@@ -194,6 +222,7 @@ typedef void * lv_fs_drv_user_data_t;
 
 /*1: Use the functions and types from the older API if possible */
 #define LV_USE_API_EXTENSION_V6  1
+#define LV_USE_API_EXTENSION_V7  1
 
 /*========================
  * Image decoder and cache
@@ -210,7 +239,7 @@ typedef void * lv_fs_drv_user_data_t;
  * (I.e. no new image decoder is added)
  * With complex image decoders (e.g. PNG or JPG) caching can save the continuous open/decode of images.
  * However the opened images might consume additional RAM.
- * LV_IMG_CACHE_DEF_SIZE must be >= 1 */
+ * Set it to 0 to disable caching */
 #define LV_IMG_CACHE_DEF_SIZE       1
 
 /*Declare the type of the user data of image decoder (can be e.g. `void *`, `int`, `struct`)*/
@@ -219,6 +248,10 @@ typedef void * lv_img_decoder_user_data_t;
 /*=====================
  *  Compiler settings
  *====================*/
+
+/* For big endian systems set to 1 */
+#define LV_BIG_ENDIAN_SYSTEM    0
+
 /* Define a custom attribute to `lv_tick_inc` function */
 #define LV_ATTRIBUTE_TICK_INC
 
@@ -228,9 +261,14 @@ typedef void * lv_img_decoder_user_data_t;
 /* Define a custom attribute to `lv_disp_flush_ready` function */
 #define LV_ATTRIBUTE_FLUSH_READY
 
+/* Required alignment size for buffers */
+#define LV_ATTRIBUTE_MEM_ALIGN_SIZE
+
 /* With size optimization (-Os) the compiler might not align data to
- * 4 or 8 byte boundary. This alignment will be explicitly applied where needed.
- * E.g. __attribute__((aligned(4))) */
+ * 4 or 8 byte boundary. Some HW may need even 32 or 64 bytes.
+ * This alignment will be explicitly applied where needed.
+ * LV_ATTRIBUTE_MEM_ALIGN_SIZE should be used to specify required align size.
+ * E.g. __attribute__((aligned(LV_ATTRIBUTE_MEM_ALIGN_SIZE))) */
 #define LV_ATTRIBUTE_MEM_ALIGN
 
 /* Attribute to mark large constant arrays for example
@@ -249,6 +287,10 @@ typedef void * lv_img_decoder_user_data_t;
  */
 #define LV_EXPORT_CONST_INT(int_value) struct _silence_gcc_warning
 
+/* Prefix variables that are used in GPU accelerated operations, often these need to be
+ * placed in RAM sections that are DMA accessible */
+#define LV_ATTRIBUTE_DMA
+
 /*===================
  *  HAL settings
  *==================*/
@@ -257,8 +299,8 @@ typedef void * lv_img_decoder_user_data_t;
  * It removes the need to manually update the tick with `lv_tick_inc`) */
 #define LV_TICK_CUSTOM     0
 #if LV_TICK_CUSTOM == 1
-#define LV_TICK_CUSTOM_INCLUDE  "something.h"       /*Header for the sys time function*/
-#define LV_TICK_CUSTOM_SYS_TIME_EXPR (millis())     /*Expression evaluating to current systime in ms*/
+#define LV_TICK_CUSTOM_INCLUDE  "Arduino.h"         /*Header for the system time function*/
+#define LV_TICK_CUSTOM_SYS_TIME_EXPR (millis())     /*Expression evaluating to current system time in ms*/
 #endif   /*LV_TICK_CUSTOM*/
 
 typedef void * lv_disp_drv_user_data_t;             /*Type of user data in the display driver*/
@@ -293,7 +335,7 @@ typedef void * lv_indev_drv_user_data_t;            /*Type of user data in the i
  * If an invalid parameter is found an error log message is printed and
  * the MCU halts at the error. (`LV_USE_LOG` should be enabled)
  * If you are debugging the MCU you can pause
- * the debugger to see exactly where  the issue is.
+ * the debugger to see exactly where the issue is.
  *
  * The behavior of asserts can be overwritten by redefining them here.
  * E.g. #define LV_ASSERT_MEM(p)  <my_assert_code>
@@ -328,17 +370,19 @@ typedef void * lv_indev_drv_user_data_t;            /*Type of user data in the i
  *    FONT USAGE
  *===================*/
 
-/* The built-in fonts contains the ASCII range and some Symbols with  4 bit-per-pixel.
+/* The built-in fonts contains the ASCII range and some Symbols with 4 bit-per-pixel.
  * The symbols are available via `LV_SYMBOL_...` defines
- * More info about fonts: https://docs.lvgl.com/#Fonts
+ * More info about fonts: https://docs.lvgl.io/v7/en/html/overview/font.html
  * To create a new font go to: https://lvgl.com/ttf-font-to-c-array
  */
 
 /* Montserrat fonts with bpp = 4
  * https://fonts.google.com/specimen/Montserrat  */
+#define LV_FONT_MONTSERRAT_8     0
+#define LV_FONT_MONTSERRAT_10    0
 #define LV_FONT_MONTSERRAT_12    0
-#define LV_FONT_MONTSERRAT_14    0
-#define LV_FONT_MONTSERRAT_16    1
+#define LV_FONT_MONTSERRAT_14    1
+#define LV_FONT_MONTSERRAT_16    0
 #define LV_FONT_MONTSERRAT_18    0
 #define LV_FONT_MONTSERRAT_20    0
 #define LV_FONT_MONTSERRAT_22    0
@@ -365,6 +409,7 @@ typedef void * lv_indev_drv_user_data_t;            /*Type of user data in the i
 /*Pixel perfect monospace font
  * http://pelulamu.net/unscii/ */
 #define LV_FONT_UNSCII_8     0
+#define LV_FONT_UNSCII_16     0
 
 /* Optionally declare your custom fonts here.
  * You can use these fonts as default font too
@@ -379,11 +424,20 @@ typedef void * lv_indev_drv_user_data_t;            /*Type of user data in the i
  * but with > 10,000 characters if you see issues probably you need to enable it.*/
 #define LV_FONT_FMT_TXT_LARGE   0
 
+/* Enables/disables support for compressed fonts. If it's disabled, compressed
+ * glyphs cannot be processed by the library and won't be rendered.
+ */
+#define LV_USE_FONT_COMPRESSED 1
+
+/* Enable subpixel rendering */
+#define LV_USE_FONT_SUBPX 1
+#if LV_USE_FONT_SUBPX
 /* Set the pixel order of the display.
  * Important only if "subpx fonts" are used.
  * With "normal" font it doesn't matter.
  */
 #define LV_FONT_SUBPX_BGR    0
+#endif
 
 /*Declare the type of the user data of fonts (can be e.g. `void *`, `int`, `struct`)*/
 typedef void * lv_font_user_data_t;
@@ -396,34 +450,37 @@ typedef void * lv_font_user_data_t;
 
 /* No theme, you can apply your styles as you need
  * No flags. Set LV_THEME_DEFAULT_FLAG 0 */
- #define LV_USE_THEME_EMPTY       1
+#define LV_USE_THEME_EMPTY       1
 
 /*Simple to the create your theme based on it
  * No flags. Set LV_THEME_DEFAULT_FLAG 0 */
- #define LV_USE_THEME_TEMPLATE    1
+#define LV_USE_THEME_TEMPLATE    1
 
 /* A fast and impressive theme.
  * Flags:
  * LV_THEME_MATERIAL_FLAG_LIGHT: light theme
- * LV_THEME_MATERIAL_FLAG_DARK: dark theme*/
- #define LV_USE_THEME_MATERIAL    1
+ * LV_THEME_MATERIAL_FLAG_DARK: dark theme
+ * LV_THEME_MATERIAL_FLAG_NO_TRANSITION: disable transitions (state change animations)
+ * LV_THEME_MATERIAL_FLAG_NO_FOCUS: disable indication of focused state)
+ * */
+#define LV_USE_THEME_MATERIAL    1
 
 /* Mono-color theme for monochrome displays.
  * If LV_THEME_DEFAULT_COLOR_PRIMARY is LV_COLOR_BLACK the
  * texts and borders will be black and the background will be
  * white. Else the colors are inverted.
  * No flags. Set LV_THEME_DEFAULT_FLAG 0 */
- #define LV_USE_THEME_MONO        1
+#define LV_USE_THEME_MONO        1
 
 #define LV_THEME_DEFAULT_INCLUDE            <stdint.h>      /*Include a header for the init. function*/
 #define LV_THEME_DEFAULT_INIT               lv_theme_material_init
-#define LV_THEME_DEFAULT_COLOR_PRIMARY      LV_COLOR_RED
-#define LV_THEME_DEFAULT_COLOR_SECONDARY    LV_COLOR_BLUE
+#define LV_THEME_DEFAULT_COLOR_PRIMARY      lv_color_hex(0x01a2b1)
+#define LV_THEME_DEFAULT_COLOR_SECONDARY    lv_color_hex(0x44d1b6)
 #define LV_THEME_DEFAULT_FLAG               LV_THEME_MATERIAL_FLAG_LIGHT
-#define LV_THEME_DEFAULT_FONT_SMALL         &lv_font_montserrat_16
-#define LV_THEME_DEFAULT_FONT_NORMAL        &lv_font_montserrat_16
-#define LV_THEME_DEFAULT_FONT_SUBTITLE      &lv_font_montserrat_16
-#define LV_THEME_DEFAULT_FONT_TITLE         &lv_font_montserrat_16
+#define LV_THEME_DEFAULT_FONT_SMALL         &lv_font_montserrat_14
+#define LV_THEME_DEFAULT_FONT_NORMAL        &lv_font_montserrat_14
+#define LV_THEME_DEFAULT_FONT_SUBTITLE      &lv_font_montserrat_14
+#define LV_THEME_DEFAULT_FONT_TITLE         &lv_font_montserrat_14
 
 /*=================
  *  Text settings
@@ -456,7 +513,7 @@ typedef void * lv_font_user_data_t;
 
 /* Support bidirectional texts.
  * Allows mixing Left-to-Right and Right-to-Left texts.
- * The direction will be processed according to the Unicode Bidirectioanl Algorithm:
+ * The direction will be processed according to the Unicode Bidirectional Algorithm:
  * https://www.w3.org/International/articles/inline-bidi-markup/uba-basics*/
 #define LV_USE_BIDI     0
 #if LV_USE_BIDI
@@ -498,7 +555,7 @@ typedef void * lv_obj_user_data_t;
 #endif
 #endif
 
-/*1: enable `lv_obj_realaign()` based on `lv_obj_align()` parameters*/
+/*1: enable `lv_obj_realign()` based on `lv_obj_align()` parameters*/
 #define LV_USE_OBJ_REALIGN          1
 
 /* Enable to make the object clickable on a larger area.
@@ -529,6 +586,9 @@ typedef void * lv_obj_user_data_t;
 
 /*Calendar (dependencies: -)*/
 #define LV_USE_CALENDAR 1
+#if LV_USE_CALENDAR
+#  define LV_CALENDAR_WEEK_STARTS_MONDAY    0
+#endif
 
 /*Canvas (dependencies: lv_img)*/
 #define LV_USE_CANVAS   1
@@ -613,7 +673,7 @@ typedef void * lv_obj_user_data_t;
  * 1: Some extra precision
  * 2: Best precision
  */
-#  define LV_LINEMETER_PRECISE    0
+#  define LV_LINEMETER_PRECISE    1
 #endif
 
 /*Mask (dependencies: -)*/
@@ -667,6 +727,7 @@ typedef void * lv_obj_user_data_t;
 #define LV_USE_TABLE    1
 #if LV_USE_TABLE
 #  define LV_TABLE_COL_MAX    12
+#  define LV_TABLE_CELL_STYLE_CNT 4
 #endif
 
 /*Tab (dependencies: lv_page, lv_btnm)*/

lvgl-codegen/src/analysis.rs

@@ -0,0 +1,66 @@
+/// A parameter of C functions.
+///
+/// This struct represents all relevant information we can extract from the C function declaration
+/// of a LVGL public interface. We can use this information to do inference for how the parameter
+/// should be represented in a safe Rust API.
+#[derive(Clone, Debug)]
+pub struct CParameter {
+    /// The name of the parameter in the C code.
+    pub name: String,
+
+    /// This is the raw representation of the Rust equivalent of the C type.
+    pub c_type: String,
+
+    /// Takes a pointer to a type that is referenced by the LVGL code permanently.
+    pub scope: ParameterScope,
+
+    /// The pointer is not marked as `*const` so the referenced object can be mutated.
+    pub mutable: bool,
+
+    /// We need to check if the value is optional in the C code. We need to check
+    /// the function comments for this information.
+    ///     - "if NULL then"
+    ///     - "if not NULL then"
+    ///     - "NULL to"
+    pub allow_none: bool,
+
+    /// Comment associated with the parameter, if exists.
+    pub comment: Option<String>,
+}
+
+#[derive(Clone, Debug)]
+pub enum ParameterScope {
+    Call,
+    Static,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum FunctionKind {
+    Constructor,
+    Method,
+    Function,
+}
+
+/// Inference from a LVGL C API function.
+#[derive(Clone, Debug)]
+pub struct Function {
+    /// Name of the function in the LVGL C API.
+    pub name: String,
+
+    /// Comment associated with the function, if exists.
+    pub comment: Option<String>,
+
+    pub kind: FunctionKind,
+
+    pub parameters: Vec<CParameter>,
+
+    pub ret: Return,
+}
+
+#[derive(Clone, Debug)]
+pub enum Return {
+    Value(Option<CParameter>),
+
+    /// If the return is a LVGL result
+    ResultError(CParameter),
+}

lvgl-codegen/src/lib.rs

@@ -1,3 +1,5 @@
+mod analysis;
+
 use inflector::cases::pascalcase::to_pascal_case;
 use lazy_static::lazy_static;
 use proc_macro2::{Ident, TokenStream};
@@ -44,6 +46,12 @@ pub struct LvWidget {
     methods: Vec<LvFunc>,
 }
 
+impl LvWidget {
+    fn pascal_name(&self) -> String {
+        to_pascal_case(&self.name)
+    }
+}
+
 impl Rusty for LvWidget {
     type Parent = ();
 
@@ -53,7 +61,7 @@ impl Rusty for LvWidget {
             return Err(WrapperError::Skip);
         }
 
-        let widget_name = format_ident!("{}", to_pascal_case(self.name.as_str()));
+        let widget_name = format_ident!("{}", self.pascal_name());
         let methods: Vec<TokenStream> = self.methods.iter().flat_map(|m| m.code(self)).collect();
         Ok(quote! {
             define_object!(#widget_name);
@@ -90,6 +98,7 @@ impl Rusty for LvFunc {
     type Parent = LvWidget;
 
     fn code(&self, parent: &Self::Parent) -> WrapperResult<TokenStream> {
+        let widget_name = format_ident!("{}", parent.pascal_name());
         let templ = format!("{}{}_", LIB_PREFIX, parent.name.as_str());
         let new_name = self.name.replace(templ.as_str(), "");
         let func_name = format_ident!("{}", new_name);
@@ -99,12 +108,12 @@ impl Rusty for LvFunc {
         if new_name.as_str().eq("create") {
             return Ok(quote! {
 
-                pub fn new<C>(parent: &mut C) -> crate::LvResult<Self>
-                where
-                    C: crate::NativeObject,
-                {
+                pub fn create(parent: &mut impl crate::NativeObject, copy: Option<&#widget_name>) -> crate::LvResult<Self> {
                     unsafe {
-                        let ptr = lvgl_sys::#original_func_name(parent.raw()?.as_mut(), core::ptr::null_mut());
+                        let ptr = lvgl_sys::#original_func_name(
+                            parent.raw()?.as_mut(),
+                            copy.map(|c| c.raw().unwrap().as_mut() as *mut lvgl_sys::lv_obj_t).unwrap_or(core::ptr::null_mut() as *mut lvgl_sys::lv_obj_t),
+                        );
                         if let Some(raw) = core::ptr::NonNull::new(ptr) {
                             let core = <crate::Obj as crate::Widget>::from_raw(raw);
                             Ok(Self { core })
@@ -114,6 +123,15 @@ impl Rusty for LvFunc {
                     }
                 }
 
+                pub fn create_at(parent: &mut impl crate::NativeObject) -> crate::LvResult<Self> {
+                    Ok(Self::create(parent, None)?)
+                }
+
+                pub fn new() -> crate::LvResult<Self> {
+                    let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+                    Ok(Self::create_at(&mut parent)?)
+                }
+
             });
         }
 
@@ -338,6 +356,9 @@ impl Rusty for LvType {
             Some(name) => {
                 let val = if self.is_str() {
                     quote!(&cstr_core::CStr)
+                } else if self.literal_name.contains("lv_") {
+                    let ident = format_ident!("{}", name);
+                    quote!(&#ident)
                 } else {
                     let ident = format_ident!("{}", name);
                     quote!(#ident)
@@ -631,13 +652,12 @@ mod test {
             define_object!(Arc);
 
             impl Arc {
-                pub fn new<C>(parent: &mut C) -> crate::LvResult<Self>
-                where
-                    C: crate::NativeObject,
-                {
-
+                pub fn create(parent: &mut impl crate::NativeObject, copy: Option<&Arc>) -> crate::LvResult<Self> {
                     unsafe {
-                        let ptr = lvgl_sys::lv_arc_create(parent.raw()?.as_mut(), core::ptr::null_mut());
+                        let ptr = lvgl_sys::lv_arc_create(
+                            parent.raw()?.as_mut(),
+                            copy.map(|c| c.raw().unwrap().as_mut() as *mut lvgl_sys::lv_obj_t).unwrap_or(core::ptr::null_mut() as *mut lvgl_sys::lv_obj_t),
+                        );
                         if let Some(raw) = core::ptr::NonNull::new(ptr) {
                             let core = <crate::Obj as crate::Widget>::from_raw(raw);
                             Ok(Self { core })
@@ -646,6 +666,15 @@ mod test {
                         }
                     }
                 }
+
+                pub fn create_at(parent: &mut impl crate::NativeObject) -> crate::LvResult<Self> {
+                    Ok(Self::create(parent, None)?)
+                }
+
+                pub fn new() -> crate::LvResult<Self> {
+                    let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+                    Ok(Self::create_at(&mut parent)?)
+                }
             }
         };
 

lvgl-sys/build.rs

@@ -114,6 +114,7 @@ fn main() {
     let bindings = bindgen::Builder::default()
         .header(shims_dir.join("lvgl_sys.h").to_str().unwrap())
         .generate_comments(false)
+        .derive_default(true)
         .layout_tests(false)
         .use_core()
         .rustfmt_bindings(true)

lvgl/Cargo.toml

@@ -14,11 +14,14 @@ build = "build.rs"
 [dependencies]
 lvgl-sys = { version = "0.5.2", path = "../lvgl-sys" }
 cty = "0.2.1"
-embedded-graphics = "0.6.2"
 cstr_core = "0.2.3"
 bitflags = "1.2.1"
+parking_lot = "0.11.1"
+embedded-graphics = { version = "0.6.2", optional = true }
 
 [features]
+default = []
+embedded_graphics = ["embedded-graphics"]
 alloc = ["cstr_core/alloc"]
 lvgl_alloc = ["alloc"]
 
@@ -30,28 +33,33 @@ lvgl-sys = { version = "0.5.2", path = "../lvgl-sys" }
 
 [dev-dependencies]
 embedded-graphics-simulator = "0.2.1"
-heapless = "0.5.5"
+
+[[example]]
+name = "app"
+path = "../examples/app.rs"
+required-features = ["alloc", "embedded_graphics"]
 
 [[example]]
 name = "demo"
 path = "../examples/demo.rs"
-required-features = ["alloc"]
+required-features = ["alloc", "embedded_graphics"]
 
 [[example]]
 name = "bar"
 path = "../examples/bar.rs"
-required-features = ["alloc"]
+required-features = ["alloc", "embedded_graphics"]
 
 [[example]]
 name = "button_click"
 path = "../examples/button_click.rs"
-required-features = ["alloc"]
+required-features = ["alloc", "embedded_graphics"]
 
 [[example]]
 name = "gauge"
 path = "../examples/gauge.rs"
+required-features = ["alloc", "embedded_graphics"]
 
 [[example]]
 name = "arc"
 path = "../examples/arc.rs"
-required-features = ["lvgl_alloc"]
+required-features = ["alloc", "embedded_graphics"]

lvgl/src/allocator.rs

@@ -9,12 +9,12 @@ pub struct LvglAlloc;
 unsafe impl GlobalAlloc for LvglAlloc {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         // Make sure LVGL is initialized!
-        crate::lvgl_init();
+        crate::init();
         lvgl_sys::lv_mem_alloc(layout.size() as lvgl_sys::size_t) as *mut u8
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
-        crate::lvgl_init();
+        crate::init();
         lvgl_sys::lv_mem_free(ptr as *const cty::c_void)
     }
 }

lvgl/src/display.rs

@@ -0,0 +1,268 @@
+use crate::functions::CoreError;
+use crate::{disp_drv_register, disp_get_default, get_str_act};
+use crate::{Box, RunOnce};
+use crate::{Color, Obj};
+use core::cell::RefCell;
+use core::mem::MaybeUninit;
+use core::ptr::NonNull;
+use core::{ptr, result};
+use parking_lot::const_mutex;
+use parking_lot::Mutex;
+
+pub const DISP_HOR_RES: usize = lvgl_sys::LV_HOR_RES_MAX as usize;
+pub const DISP_VER_RES: usize = lvgl_sys::LV_VER_RES_MAX as usize;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum DisplayError {
+    NotAvailable,
+    FailedToRegister,
+    NotRegistered,
+}
+
+type Result<T> = result::Result<T, DisplayError>;
+
+pub struct Display {
+    pub(crate) disp: NonNull<lvgl_sys::lv_disp_t>,
+}
+
+impl Display {
+    pub(crate) fn from_raw(disp: NonNull<lvgl_sys::lv_disp_t>) -> Self {
+        Self { disp }
+    }
+
+    pub fn register<F, const N: usize>(
+        draw_buffer: &'static DrawBuffer<N>,
+        display_update: F,
+    ) -> Result<Self>
+    where
+        F: FnMut(&DisplayRefresh<N>) + 'static,
+    {
+        let mut display_diver = DisplayDriver::new(draw_buffer, display_update)?;
+        Ok(disp_drv_register(&mut display_diver)?)
+    }
+
+    pub fn get_scr_act(&self) -> Result<Obj> {
+        Ok(get_str_act(Some(&self))?)
+    }
+}
+
+impl Default for Display {
+    fn default() -> Self {
+        disp_get_default().expect("LVGL must be INITIALIZED")
+    }
+}
+
+#[derive(Copy, Clone)]
+pub struct DefaultDisplay {}
+
+impl DefaultDisplay {
+    /// Gets the screen active of the default display.
+    pub fn get_scr_act() -> Result<Obj> {
+        Ok(get_str_act(None)?)
+    }
+}
+
+pub struct DrawBuffer<const N: usize> {
+    initialized: RunOnce,
+    refresh_buffer: Mutex<RefCell<[MaybeUninit<lvgl_sys::lv_color_t>; N]>>,
+}
+
+impl<const N: usize> DrawBuffer<N> {
+    pub const fn new() -> Self {
+        Self {
+            initialized: RunOnce::new(),
+            refresh_buffer: const_mutex(RefCell::new([MaybeUninit::uninit(); N])),
+        }
+    }
+
+    fn get_ptr(&self) -> Option<Box<lvgl_sys::lv_disp_buf_t>> {
+        if self.initialized.swap_and_check() {
+            // TODO: needs to be 'static somehow
+            // Cannot be in the DrawBuffer struct because the type `lv_disp_buf_t` contains a raw
+            // pointer and raw pointers are not Send and consequently cannot be in `static` variables.
+            let mut inner: MaybeUninit<lvgl_sys::lv_disp_buf_t> = MaybeUninit::uninit();
+            let primary_buffer_guard = self.refresh_buffer.lock();
+            let draw_buf = unsafe {
+                lvgl_sys::lv_disp_buf_init(
+                    inner.as_mut_ptr(),
+                    primary_buffer_guard.borrow_mut().as_mut_ptr() as *mut _ as *mut cty::c_void,
+                    ptr::null_mut(),
+                    N as u32,
+                );
+                inner.assume_init()
+            };
+            Some(Box::new(draw_buf))
+        } else {
+            None
+        }
+    }
+}
+
+pub struct DisplayDriver {
+    pub(crate) disp_drv: lvgl_sys::lv_disp_drv_t,
+}
+
+impl DisplayDriver {
+    pub fn new<F, const N: usize>(
+        draw_buffer: &'static DrawBuffer<N>,
+        display_update_callback: F,
+    ) -> Result<Self>
+    where
+        F: FnMut(&DisplayRefresh<N>) + 'static,
+    {
+        let mut disp_drv = unsafe {
+            let mut inner = MaybeUninit::uninit();
+            lvgl_sys::lv_disp_drv_init(inner.as_mut_ptr());
+            inner.assume_init()
+        };
+
+        // Safety: The variable `draw_buffer` is statically allocated, no need to worry about this being dropped.
+        disp_drv.buffer = draw_buffer
+            .get_ptr()
+            .map(|ptr| Box::into_raw(ptr) as *mut _)
+            .ok_or(DisplayError::FailedToRegister)?;
+
+        disp_drv.user_data = Box::into_raw(Box::new(display_update_callback)) as *mut _
+            as lvgl_sys::lv_disp_drv_user_data_t;
+
+        // Sets trampoline pointer to the function implementation that uses the `F` type for a
+        // refresh buffer of size N specifically.
+        disp_drv.flush_cb = Some(disp_flush_trampoline::<F, N>);
+
+        // We do not store any memory that can be accidentally deallocated by on the Rust side.
+        Ok(Self { disp_drv })
+    }
+}
+
+/// Represents a sub-area of the display that is being updated.
+pub struct Area {
+    pub x1: i16,
+    pub x2: i16,
+    pub y1: i16,
+    pub y2: i16,
+}
+
+/// It's a update to the display information, contains the area that is being updated and the color
+/// of the pixels that need to be updated. The colors are represented in a contiguous array.
+pub struct DisplayRefresh<const N: usize> {
+    pub area: Area,
+    pub colors: [Color; N],
+}
+
+#[cfg(feature = "embedded_graphics")]
+mod embedded_graphics_impl {
+    use crate::{Color, DisplayRefresh};
+    use embedded_graphics::drawable;
+    use embedded_graphics::prelude::*;
+
+    impl<const N: usize> DisplayRefresh<N> {
+        pub fn as_pixels<C>(&self) -> impl IntoIterator<Item = drawable::Pixel<C>> + '_
+        where
+            C: PixelColor + From<Color>,
+        {
+            let area = &self.area;
+            let x1 = area.x1;
+            let x2 = area.x2;
+            let y1 = area.y1;
+            let y2 = area.y2;
+
+            let ys = y1..=y2;
+            let xs = (x1..=x2).enumerate();
+            let x_len = (x2 - x1 + 1) as usize;
+
+            // We use iterators here to ensure that the Rust compiler can apply all possible
+            // optimizations at compile time.
+            ys.enumerate()
+                .map(move |(iy, y)| {
+                    xs.clone().map(move |(ix, x)| {
+                        let color_len = x_len * iy + ix;
+                        let raw_color = self.colors[color_len];
+                        drawable::Pixel(Point::new(x as i32, y as i32), raw_color.into())
+                    })
+                })
+                .flatten()
+        }
+    }
+}
+
+unsafe extern "C" fn disp_flush_trampoline<F, const N: usize>(
+    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(&DisplayRefresh<N>) + 'static,
+{
+    let display_driver = *disp_drv;
+    if !display_driver.user_data.is_null() {
+        let callback = &mut *(display_driver.user_data as *mut F);
+
+        let mut colors = [Color::default(); N];
+        let mut color_len = 0;
+        for color in &mut colors {
+            let lv_color = *color_p.add(color_len);
+            *color = Color::from_raw(lv_color);
+            color_len += 1;
+        }
+
+        let update = DisplayRefresh {
+            area: Area {
+                x1: (*area).x1,
+                x2: (*area).x2,
+                y1: (*area).y1,
+                y2: (*area).y2,
+            },
+            colors,
+        };
+        callback(&update);
+    }
+
+    // Indicate to LVGL that we are ready with the flushing
+    lvgl_sys::lv_disp_flush_ready(disp_drv);
+}
+
+impl From<CoreError> for DisplayError {
+    fn from(err: CoreError) -> Self {
+        use DisplayError::*;
+        match err {
+            CoreError::ResourceNotAvailable => NotAvailable,
+            CoreError::OperationFailed => NotAvailable,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tests;
+
+    #[test]
+    fn get_scr_act_return_display() {
+        tests::initialize_test();
+        let _screen = get_str_act(None).expect("We can get the active screen");
+    }
+
+    #[test]
+    fn get_default_display() {
+        tests::initialize_test();
+        let display = Display::default();
+
+        let _screen_direct = display
+            .get_scr_act()
+            .expect("Return screen directly from the display instance");
+
+        let _screen_default =
+            DefaultDisplay::get_scr_act().expect("Return screen from the default display");
+    }
+
+    #[test]
+    fn register_display_directly() -> Result<()> {
+        tests::initialize_test();
+        let display = Display::default();
+
+        let _screen = display
+            .get_scr_act()
+            .expect("Return screen directly from the display instance");
+
+        Ok(())
+    }
+}

lvgl/src/functions.rs

@@ -0,0 +1,56 @@
+use crate::display::{Display, DisplayDriver};
+use crate::{Obj, Widget};
+use core::ptr::NonNull;
+use core::time::Duration;
+use core::{ptr, result};
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum CoreError {
+    ResourceNotAvailable,
+    OperationFailed,
+}
+
+type Result<T> = result::Result<T, CoreError>;
+
+/// Register own buffer
+pub(crate) fn disp_drv_register(disp_drv: &mut DisplayDriver) -> Result<Display> {
+    let disp_ptr = unsafe { lvgl_sys::lv_disp_drv_register(&mut disp_drv.disp_drv as *mut _) };
+    Ok(Display::from_raw(
+        NonNull::new(disp_ptr).ok_or(CoreError::OperationFailed)?,
+    ))
+}
+
+pub(crate) fn disp_get_default() -> Result<Display> {
+    let disp_ptr = unsafe { lvgl_sys::lv_disp_get_default() };
+    Ok(Display::from_raw(
+        NonNull::new(disp_ptr).ok_or(CoreError::OperationFailed)?,
+    ))
+}
+
+pub(crate) fn get_str_act(disp: Option<&Display>) -> Result<Obj> {
+    let scr_ptr = unsafe {
+        lvgl_sys::lv_disp_get_scr_act(
+            disp.map(|d| d.disp.as_ptr())
+                .unwrap_or(ptr::null_mut() as *mut lvgl_sys::lv_disp_t),
+        )
+    };
+    Ok(Obj::from_raw(
+        NonNull::new(scr_ptr).ok_or(CoreError::ResourceNotAvailable)?,
+    ))
+}
+
+/// You have to call this function periodically.
+/// Expects a `tick_period` duration as argument which is the call period of this
+/// function in milliseconds.
+#[inline]
+pub fn tick_inc(tick_period: Duration) {
+    unsafe {
+        lvgl_sys::lv_tick_inc(tick_period.as_millis() as u32);
+    }
+}
+
+/// Call it periodically to handle tasks.
+#[inline]
+pub fn task_handler() {
+    unsafe { lvgl_sys::lv_task_handler() };
+}

lvgl/src/lib.rs

@@ -17,7 +17,10 @@
 #[macro_use]
 extern crate bitflags;
 
-#[cfg(feature = "lvgl_alloc")]
+#[macro_use]
+mod lv_core;
+
+#[cfg(feature = "alloc")]
 extern crate alloc;
 
 // We can ONLY use `alloc::boxed::Box` if `lvgl_alloc` is enabled.
@@ -31,12 +34,6 @@ use ::alloc::boxed::Box;
 #[cfg(feature = "lvgl_alloc")]
 mod allocator;
 
-mod support;
-mod ui;
-#[macro_use]
-mod lv_core;
-pub mod widgets;
-
 #[cfg(not(feature = "lvgl_alloc"))]
 pub(crate) mod mem;
 
@@ -47,22 +44,54 @@ pub(crate) mod mem;
 #[cfg(not(feature = "lvgl_alloc"))]
 use crate::mem::Box;
 
+mod display;
+pub use display::*;
+mod functions;
+mod support;
+pub mod widgets;
+use core::sync::atomic::{AtomicBool, Ordering};
+pub use functions::*;
 pub use lv_core::*;
 pub use support::*;
-pub use ui::*;
 
-use core::sync::atomic::{AtomicBool, Ordering};
+struct RunOnce(AtomicBool);
 
-// Initialize LVGL only once.
-static LVGL_INITIALIZED: AtomicBool = AtomicBool::new(false);
+impl RunOnce {
+    const fn new() -> Self {
+        Self(AtomicBool::new(false))
+    }
 
-pub(crate) fn lvgl_init() {
-    if LVGL_INITIALIZED
-        .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
-        .is_ok()
-    {
+    fn swap_and_check(&self) -> bool {
+        self.0
+            .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
+            .is_ok()
+    }
+}
+
+static LVGL_INITIALIZED: RunOnce = RunOnce::new();
+
+pub fn init() {
+    if LVGL_INITIALIZED.swap_and_check() {
         unsafe {
             lvgl_sys::lv_init();
         }
     }
 }
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use super::*;
+    use crate::display::{Display, DrawBuffer};
+
+    pub(crate) fn initialize_test() {
+        init();
+
+        const REFRESH_BUFFER_SIZE: usize = 64 * 64 / 10;
+        static DRAW_BUFFER: DrawBuffer<REFRESH_BUFFER_SIZE> = DrawBuffer::new();
+        static ONCE_INIT: RunOnce = RunOnce::new();
+
+        if ONCE_INIT.swap_and_check() {
+            let _ = Display::register(&DRAW_BUFFER, |_| {}).unwrap();
+        }
+    }
+}

lvgl/src/lv_core/obj.rs

@@ -1,5 +1,4 @@
 use crate::lv_core::style::Style;
-use crate::Box;
 use crate::{Align, LvError, LvResult};
 use core::ptr;
 
@@ -35,14 +34,15 @@ pub trait Widget: NativeObject {
 
     /// Construct an instance of the object from a raw pointer.
     ///
-    /// # Safety
-    /// Provided the LVGL library can allocate memory this should be safe.
-    ///
-    unsafe fn from_raw(raw_pointer: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self;
+    fn from_raw(raw_pointer: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self;
 
-    fn add_style(&self, part: Self::Part, style: Style) -> LvResult<()> {
+    fn add_style(&self, part: Self::Part, style: &mut Style) -> LvResult<()> {
         unsafe {
-            lvgl_sys::lv_obj_add_style(self.raw()?.as_mut(), part.into(), Box::into_raw(style.raw));
+            lvgl_sys::lv_obj_add_style(
+                self.raw()?.as_mut(),
+                part.into(),
+                style.raw.as_mut() as *mut _,
+            );
         };
         Ok(())
     }
@@ -104,7 +104,7 @@ impl Widget for Obj {
     type SpecialEvent = ();
     type Part = Part;
 
-    unsafe fn from_raw(raw: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self {
+    fn from_raw(raw: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self {
         Self { raw: raw.as_ptr() }
     }
 }
@@ -167,7 +167,7 @@ macro_rules! define_object {
             type SpecialEvent = $event_type;
             type Part = $part_type;
 
-            unsafe fn from_raw(raw_pointer: core::ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self {
+            fn from_raw(raw_pointer: core::ptr::NonNull<lvgl_sys::lv_obj_t>) -> Self {
                 Self {
                     core: $crate::Obj::from_raw(raw_pointer),
                 }
@@ -176,6 +176,38 @@ macro_rules! define_object {
     };
 }
 
+// define_object!(Rafael);
+//
+// impl Rafael {
+//     pub fn create(
+//         parent: &mut impl crate::NativeObject,
+//         copy: Option<&Rafael>,
+//     ) -> crate::LvResult<Self> {
+//         unsafe {
+//             let ptr = lvgl_sys::lv_arc_create(
+//                 parent.raw()?.as_mut(),
+//                 copy.map(|c| c.raw().unwrap().as_mut() as *mut lvgl_sys::lv_obj_t)
+//                     .unwrap_or(core::ptr::null_mut() as *mut lvgl_sys::lv_obj_t),
+//             );
+//             if let Some(raw) = core::ptr::NonNull::new(ptr) {
+//                 let core = <crate::Obj as crate::Widget>::from_raw(raw);
+//                 Ok(Self { core })
+//             } else {
+//                 Err(crate::LvError::InvalidReference)
+//             }
+//         }
+//     }
+//
+//     pub fn create_at(parent: &mut impl crate::NativeObject) -> crate::LvResult<Self> {
+//         Ok(Self::create(parent, None)?)
+//     }
+//
+//     pub fn new() -> crate::LvResult<Self> {
+//         let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+//         Ok(Self::create_at(&mut parent)?)
+//     }
+// }
+
 bitflags! {
     pub struct State: u32 {
         /// Normal, released

lvgl/src/mem.rs

@@ -11,7 +11,7 @@ pub(crate) struct Box<T>(NonNull<T>);
 
 impl<T> Box<T> {
     /// Allocate memory using LVGL memory API and place `T` in the LVGL tracked memory.
-    pub fn new(value: T) -> Box<T> {
+    pub fn new(value: T) -> Self {
         let size = mem::size_of::<T>();
         let inner = unsafe {
             let ptr = lvgl_sys::lv_mem_alloc(size as lvgl_sys::size_t) as *mut T;
@@ -29,10 +29,10 @@ impl<T> Box<T> {
                     p
                 })
                 .unwrap_or_else(|| {
-                    panic!("Could not allocate memory {} bytes", size);
+                    panic!("Could not allocate memory {} bytes: {:?}", size, mem_info());
                 })
         };
-        Box(inner)
+        Self(inner)
     }
 
     pub fn into_raw(self) -> *mut T {
@@ -69,14 +69,33 @@ impl<T> AsMut<T> for Box<T> {
     }
 }
 
+fn mem_info() -> lvgl_sys::lv_mem_monitor_t {
+    let mut info = lvgl_sys::lv_mem_monitor_t {
+        total_size: 0,
+        free_cnt: 0,
+        free_size: 0,
+        free_biggest_size: 0,
+        used_cnt: 0,
+        max_used: 0,
+        used_pct: 0,
+        frag_pct: 0,
+    };
+    unsafe {
+        lvgl_sys::lv_mem_monitor(&mut info as *mut _);
+    }
+    info
+}
+
 #[cfg(test)]
 mod test {
     use super::*;
+    use crate::mem::mem_info;
+    use crate::*;
     use std::vec::Vec;
 
     #[test]
     fn place_value_in_lv_mem() {
-        crate::lvgl_init();
+        tests::initialize_test();
 
         let v = Box::new(5);
         drop(v);
@@ -86,7 +105,7 @@ mod test {
 
     #[test]
     fn place_complex_value_in_lv_mem() {
-        crate::lvgl_init();
+        tests::initialize_test();
 
         #[repr(C)]
         #[derive(Debug)]
@@ -135,21 +154,4 @@ mod test {
         // If this fails, we are leaking memory! BOOM! \o/
         assert_eq!(initial_mem_info.free_size, final_info.free_size)
     }
-
-    fn mem_info() -> lvgl_sys::lv_mem_monitor_t {
-        let mut info = lvgl_sys::lv_mem_monitor_t {
-            total_size: 0,
-            free_cnt: 0,
-            free_size: 0,
-            free_biggest_size: 0,
-            used_cnt: 0,
-            max_used: 0,
-            used_pct: 0,
-            frag_pct: 0,
-        };
-        unsafe {
-            lvgl_sys::lv_mem_monitor(&mut info as *mut _);
-        }
-        info
-    }
 }

lvgl/src/support.rs

@@ -1,6 +1,9 @@
+use crate::display::DisplayError;
 use crate::Widget;
 use core::convert::{TryFrom, TryInto};
 use core::ptr::NonNull;
+
+#[cfg(feature = "embedded_graphics")]
 use embedded_graphics::pixelcolor::{Rgb565, Rgb888};
 
 pub type LvResult<T> = Result<T, LvError>;
@@ -13,7 +16,18 @@ pub enum LvError {
     AlreadyInUse,
 }
 
-#[derive(Clone)]
+impl From<DisplayError> for LvError {
+    fn from(err: DisplayError) -> Self {
+        use LvError::*;
+        match err {
+            DisplayError::NotAvailable => Uninitialized,
+            DisplayError::FailedToRegister => InvalidReference,
+            DisplayError::NotRegistered => Uninitialized,
+        }
+    }
+}
+
+#[derive(Copy, Clone, Default)]
 pub struct Color {
     pub(crate) raw: lvgl_sys::lv_color_t,
 }
@@ -41,6 +55,7 @@ impl Color {
     }
 }
 
+#[cfg(feature = "embedded_graphics")]
 impl From<Color> for Rgb888 {
     fn from(color: Color) -> Self {
         unsafe {
@@ -53,6 +68,7 @@ impl From<Color> for Rgb888 {
     }
 }
 
+#[cfg(feature = "embedded_graphics")]
 impl From<Color> for Rgb565 {
     fn from(color: Color) -> Self {
         unsafe {

lvgl/src/ui.rs

@@ -1,203 +0,0 @@
-use crate::Box;
-use crate::{Color, Event, LvError, LvResult, Obj, Widget};
-use core::marker::PhantomData;
-use core::mem::MaybeUninit;
-use core::ptr;
-use core::ptr::NonNull;
-use core::sync::atomic::{AtomicBool, Ordering};
-use core::time::Duration;
-use embedded_graphics::pixelcolor::PixelColor;
-use embedded_graphics::prelude::*;
-use embedded_graphics::{drawable, DrawTarget};
-
-// There can only be a single reference to LVGL library.
-static LVGL_IN_USE: AtomicBool = AtomicBool::new(false);
-
-// TODO: Make this an external configuration
-const REFRESH_BUFFER_LEN: usize = 2;
-// Declare a buffer for the refresh rate
-pub(crate) const BUF_SIZE: usize = lvgl_sys::LV_HOR_RES_MAX as usize * REFRESH_BUFFER_LEN;
-
-pub struct UI<T, C>
-where
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-    // LVGL is not thread-safe by default.
-    _not_sync: PhantomData<*mut ()>,
-    // Later we can add possibility to have multiple displays by using `heapless::Vec`
-    display_data: Option<DisplayUserData<T, C>>,
-}
-
-// LVGL does not use thread locals.
-unsafe impl<T, C> Send for UI<T, C>
-where
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-}
-
-impl<T, C> UI<T, C>
-where
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-    pub fn init() -> LvResult<Self> {
-        if LVGL_IN_USE
-            .compare_exchange(false, true, Ordering::Relaxed, Ordering::Relaxed)
-            .is_ok()
-        {
-            crate::lvgl_init();
-            Ok(Self {
-                _not_sync: PhantomData,
-                display_data: None,
-            })
-        } else {
-            Err(LvError::AlreadyInUse)
-        }
-    }
-
-    pub fn disp_drv_register(&mut self, display: T) -> LvResult<()> {
-        self.display_data = Some(DisplayUserData {
-            display,
-            phantom: PhantomData,
-        });
-
-        let refresh_buffer1 = [Color::from_rgb((0, 0, 0)).raw; BUF_SIZE];
-        let refresh_buffer2 = [Color::from_rgb((0, 0, 0)).raw; BUF_SIZE];
-
-        let mut disp_buf = MaybeUninit::<lvgl_sys::lv_disp_buf_t>::uninit();
-        let mut disp_drv = MaybeUninit::<lvgl_sys::lv_disp_drv_t>::uninit();
-
-        unsafe {
-            // Initialize the display buffer
-            lvgl_sys::lv_disp_buf_init(
-                disp_buf.as_mut_ptr(),
-                Box::into_raw(Box::new(refresh_buffer1)) as *mut cty::c_void,
-                Box::into_raw(Box::new(refresh_buffer2)) as *mut cty::c_void,
-                lvgl_sys::LV_HOR_RES_MAX * REFRESH_BUFFER_LEN as u32,
-            );
-            // Basic initialization of the display driver
-            lvgl_sys::lv_disp_drv_init(disp_drv.as_mut_ptr());
-            let mut disp_drv = Box::new(disp_drv.assume_init());
-            // Assign the buffer to the display
-            disp_drv.buffer = Box::into_raw(Box::new(disp_buf.assume_init()));
-            // Set your driver function
-            disp_drv.flush_cb = Some(display_callback_wrapper::<T, C>);
-            disp_drv.user_data = &mut self.display_data as *mut _ as *mut cty::c_void;
-            // We need to remember to deallocate the `disp_drv` memory when dropping UI
-            lvgl_sys::lv_disp_drv_register(Box::into_raw(disp_drv));
-        };
-
-        Ok(())
-    }
-
-    pub fn get_display_ref(&self) -> Option<&T> {
-        match self.display_data.as_ref() {
-            None => None,
-            Some(v) => Some(&v.display),
-        }
-    }
-
-    pub fn scr_act(&self) -> LvResult<Obj> {
-        unsafe {
-            let screen = lvgl_sys::lv_disp_get_scr_act(ptr::null_mut());
-            if let Some(v) = NonNull::new(screen) {
-                Ok(Obj::from_raw(v))
-            } else {
-                Err(LvError::InvalidReference)
-            }
-        }
-    }
-
-    pub fn event_send<W>(&mut self, obj: &mut W, event: Event<W::SpecialEvent>) -> LvResult<()>
-    where
-        W: Widget,
-    {
-        unsafe {
-            lvgl_sys::lv_event_send(obj.raw()?.as_mut(), event.into(), ptr::null_mut());
-        }
-        Ok(())
-    }
-
-    pub fn tick_inc(&mut self, tick_period: Duration) {
-        unsafe {
-            lvgl_sys::lv_tick_inc(tick_period.as_millis() as u32);
-        }
-    }
-
-    pub fn task_handler(&mut self) {
-        unsafe {
-            lvgl_sys::lv_task_handler();
-        }
-    }
-}
-
-pub(crate) struct DisplayUserData<T, C>
-where
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-    display: T,
-    phantom: PhantomData<C>,
-}
-
-unsafe extern "C" fn display_callback_wrapper<T, 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
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-    // In the `std` world we would make sure to capture panics here and make them not escape across
-    // the FFI boundary. Since this library is focused on embedded platforms, we don't
-    // have an standard unwinding mechanism to rely upon.
-    let display_driver = *disp_drv;
-    // Rust code closure reference
-    if !display_driver.user_data.is_null() {
-        let user_data = &mut *(display_driver.user_data as *mut DisplayUserData<T, C>);
-        let x1 = (*area).x1;
-        let x2 = (*area).x2;
-        let y1 = (*area).y1;
-        let y2 = (*area).y2;
-        // TODO: Can we do anything when there is a error while flushing?
-        let _ = display_flush(&mut user_data.display, (x1, x2), (y1, y2), color_p);
-    }
-    // Indicate to LVGL that we are ready with the flushing
-    lvgl_sys::lv_disp_flush_ready(disp_drv);
-}
-
-// We separate this display flush function to reduce the amount of unsafe code we need to write.
-// This also provides a good separation of concerns, what is necessary from LVGL to work and
-// what is the lvgl-rs wrapper responsibility.
-fn display_flush<T, C>(
-    display: &mut T,
-    (x1, x2): (i16, i16),
-    (y1, y2): (i16, i16),
-    color_p: *mut lvgl_sys::lv_color_t,
-) -> Result<(), T::Error>
-where
-    T: DrawTarget<C>,
-    C: PixelColor + From<Color>,
-{
-    let ys = y1..=y2;
-    let xs = (x1..=x2).enumerate();
-    let x_len = (x2 - x1 + 1) as usize;
-
-    // We use iterators here to ensure that the Rust compiler can apply all possible
-    // optimizations at compile time.
-    let pixels = ys
-        .enumerate()
-        .map(|(iy, y)| {
-            xs.clone().map(move |(ix, x)| {
-                let color_len = x_len * iy + ix;
-                let lv_color = unsafe { *color_p.add(color_len) };
-                let raw_color = Color::from_raw(lv_color);
-                drawable::Pixel(Point::new(x as i32, y as i32), raw_color.into())
-            })
-        })
-        .flatten();
-
-    Ok(display.draw_iter(pixels)?)
-}

lvgl/src/widgets/label.rs

@@ -10,6 +10,37 @@ impl Label {
     }
 }
 
+#[cfg(feature = "alloc")]
+mod alloc_imp {
+    use crate::widgets::Label;
+    use crate::LvError;
+    use cstr_core::CString;
+    use core::convert::TryFrom;
+
+    impl<S: AsRef<str>> From<S> for Label {
+        fn from(text: S) -> Self {
+            // text.try_into().unwrap()
+            let text_cstr = CString::new(text.as_ref()).unwrap();
+            let mut label = Label::new().unwrap();
+            label.set_text(text_cstr.as_c_str()).unwrap();
+            label
+        }
+    }
+
+    // Issue link: https://github.com/rust-lang/rust/issues/50133
+    //
+    // impl<S: AsRef<str>> TryFrom<S> for Label {
+    //     type Error = LvError;
+    //     fn try_from(text: S) -> Result<Self, Self::Error> {
+    //         let text_cstr = CString::new(text.as_ref())?;
+    //         let mut label = Label::new()?;
+    //         label.set_text(text_cstr.as_c_str())?;
+    //         Ok(label)
+    //     }
+    // }
+}
+
+
 #[derive(Debug, Copy, Clone, PartialEq)]
 #[repr(u8)]
 pub enum LabelAlign {