rafaelcaricio/lvgl-rs
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Make use of embedded_graphics optional

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This commit is contained in:
Rafael Caricio 2021-06-06 16:17:29 +02:00
parent 085495ebc4
commit ac27d49c06
Signed by: rafaelcaricio
GPG key ID: 3C86DBCE8E93C947
8 changed files with 72 additions and 384 deletions
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39
examples/demo.rs
View file

@ -40,37 +40,14 @@ fn main() -> Result<(), LvError> {
// // static DISPLAY_REGISTRY: SingleDisplayRegistry = DisplayRegistry::empty(); // // static DISPLAY_REGISTRY: SingleDisplayRegistry = DisplayRegistry::empty();
// let display = DISPLAY_REGISTRY.register_shared(&DRAW_BUFFER, shared_native_display.clone())?; // let display = DISPLAY_REGISTRY.register_shared(&DRAW_BUFFER, shared_native_display.clone())?;
// Register your native display with LVGL. We use the `Display::register_shared()` method here, // Register your display update callback with LVGL. The closure you pass here will be called
// but that's because the Simulator needs a mutable reference to the display so it can draw // whenever LVGL has updates to be painted to the display.
// updates. On your embedded device code, you will use `Display::register()`. let display = Display::register(&DRAW_BUFFER, {
let shared_disp_inner = shared_native_display.clone(); let shared_disp_inner = SyncArc::clone(&shared_native_display);
let display = Display::register_shared(&DRAW_BUFFER, move |update| { move |update| {
// make this a `.into_pixels()` method in DisplayRefresh or `From<DisplayRefresh> for T where T: IntoIterator<Item = drawable::Pixel<C>>` let mut em_disp = shared_disp_inner.lock();
let area = &update.area; em_disp.draw_iter(update.as_pixels());
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.
let pixels = ys
.enumerate()
.map(|(iy, y)| {
xs.clone().map(move |(ix, x)| {
let color_len = x_len * iy + ix;
let raw_color = update.colors[color_len];
drawable::Pixel(Point::new(x as i32, y as i32), raw_color.into())
})
})
.flatten();
let mut em_disp = shared_disp_inner.lock();
em_disp.draw_iter(pixels);
})?; })?;
// Create screen and widgets // Create screen and widgets

15
lvgl/Cargo.toml
View file

@ -14,7 +14,7 @@ build = "build.rs"
[dependencies] [dependencies]
lvgl-sys = { version = "0.5.2", path = "../lvgl-sys" } lvgl-sys = { version = "0.5.2", path = "../lvgl-sys" }
cty = "0.2.1" cty = "0.2.1"
embedded-graphics = "0.6.2" embedded-graphics = { version = "0.6.2", optional = true }
cstr_core = "0.2.3" cstr_core = "0.2.3"
bitflags = "1.2.1" bitflags = "1.2.1"
parking_lot = "0.11.1" parking_lot = "0.11.1"
@ -22,6 +22,7 @@ heapless = "0.7.1"
[features] [features]
default = [] default = []
embedded_graphics = ["embedded-graphics"]
alloc = ["cstr_core/alloc"] alloc = ["cstr_core/alloc"]
lvgl_alloc = ["alloc"] lvgl_alloc = ["alloc"]
@ -37,29 +38,29 @@ embedded-graphics-simulator = "0.2.1"
[[example]] [[example]]
name = "app" name = "app"
path = "../examples/app.rs" path = "../examples/app.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]
[[example]] [[example]]
name = "demo" name = "demo"
path = "../examples/demo.rs" path = "../examples/demo.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]
[[example]] [[example]]
name = "bar" name = "bar"
path = "../examples/bar.rs" path = "../examples/bar.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]
[[example]] [[example]]
name = "button_click" name = "button_click"
path = "../examples/button_click.rs" path = "../examples/button_click.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]
[[example]] [[example]]
name = "gauge" name = "gauge"
path = "../examples/gauge.rs" path = "../examples/gauge.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]
[[example]] [[example]]
name = "arc" name = "arc"
path = "../examples/arc.rs" path = "../examples/arc.rs"
required-features = ["alloc"] required-features = ["alloc", "embedded_graphics"]

180
lvgl/src/display.rs
View file

@ -3,18 +3,12 @@ use crate::{disp_drv_register, disp_get_default, get_str_act};
use crate::{Box, RunOnce}; use crate::{Box, RunOnce};
use crate::{Color, Obj}; use crate::{Color, Obj};
use core::cell::RefCell; use core::cell::RefCell;
use core::marker::PhantomData;
use core::mem::MaybeUninit; use core::mem::MaybeUninit;
use core::ptr::NonNull; use core::ptr::NonNull;
use core::{ptr, result}; use core::{ptr, result};
use embedded_graphics::drawable;
use embedded_graphics::prelude::*;
use parking_lot::const_mutex; use parking_lot::const_mutex;
use parking_lot::Mutex; use parking_lot::Mutex;
#[cfg(feature = "alloc")]
use alloc::sync::Arc;
pub const DISP_HOR_RES: usize = lvgl_sys::LV_HOR_RES_MAX as usize; 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; pub const DISP_VER_RES: usize = lvgl_sys::LV_VER_RES_MAX as usize;
@ -27,9 +21,6 @@ pub enum DisplayError {
type Result<T> = result::Result<T, DisplayError>; type Result<T> = result::Result<T, DisplayError>;
#[cfg(feature = "alloc")]
pub type SharedNativeDisplay<T> = Arc<Mutex<T>>;
pub struct Display { pub struct Display {
pub(crate) disp: NonNull<lvgl_sys::lv_disp_t>, pub(crate) disp: NonNull<lvgl_sys::lv_disp_t>,
} }
@ -39,27 +30,14 @@ impl Display {
Self { disp } Self { disp }
} }
// pub fn register<T, C, const N: usize>( pub fn register<F, const N: usize>(
// draw_buffer: &'static DrawBuffer<N>,
// native_display: T,
// ) -> Result<Self>
// where
// T: DrawTarget<C>,
// C: PixelColor + From<Color>,
// {
// let mut display_diver = DisplayDriver::new(draw_buffer, native_display)?;
// Ok(disp_drv_register(&mut display_diver)?)
// }
#[cfg(feature = "alloc")]
pub fn register_shared<F, const N: usize>(
draw_buffer: &'static DrawBuffer<N>, draw_buffer: &'static DrawBuffer<N>,
display_update: F, display_update: F,
) -> Result<Self> ) -> Result<Self>
where where
F: FnMut(&DisplayRefresh<N>) + 'static, F: FnMut(&DisplayRefresh<N>) + 'static,
{ {
let mut display_diver = DisplayDriver::new_shared(draw_buffer, display_update)?; let mut display_diver = DisplayDriver::new(draw_buffer, display_update)?;
Ok(disp_drv_register(&mut display_diver)?) Ok(disp_drv_register(&mut display_diver)?)
} }
@ -125,45 +103,9 @@ pub struct DisplayDriver {
} }
impl DisplayDriver { impl DisplayDriver {
// pub fn new<const N: usize>( pub fn new<F, const N: usize>(
// draw_buffer: &'static DrawBuffer<N>,
// native_display: T,
// ) -> Result<Self> {
// 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)?;
//
// let native_display = DisplayUserData {
// display: native_display,
// phantom: PhantomData,
// };
// disp_drv.user_data =
// Box::into_raw(Box::new(native_display)) as *mut _ as lvgl_sys::lv_disp_drv_user_data_t;
//
// // Sets trampoline pointer to the function implementation using the types (T, C) that
// // are used in this instance of `DisplayDriver`.
// disp_drv.flush_cb = Some(disp_flush_trampoline::<T, C>);
//
// // We do not store any memory that can be accidentally deallocated by on the Rust side.
// Ok(Self {
// disp_drv,
// phantom_color: PhantomData,
// phantom_display: PhantomData,
// })
// }
#[cfg(feature = "alloc")]
pub fn new_shared<F, const N: usize>(
draw_buffer: &'static DrawBuffer<N>, draw_buffer: &'static DrawBuffer<N>,
display_update: F, display_update_callback: F,
) -> Result<Self> ) -> Result<Self>
where where
F: FnMut(&DisplayRefresh<N>) + 'static, F: FnMut(&DisplayRefresh<N>) + 'static,
@ -180,78 +122,19 @@ impl DisplayDriver {
.map(|ptr| Box::into_raw(ptr) as *mut _) .map(|ptr| Box::into_raw(ptr) as *mut _)
.ok_or(DisplayError::FailedToRegister)?; .ok_or(DisplayError::FailedToRegister)?;
disp_drv.user_data = disp_drv.user_data = Box::into_raw(Box::new(display_update_callback)) as *mut _
Box::into_raw(Box::new(display_update)) as *mut _ as lvgl_sys::lv_disp_drv_user_data_t; as lvgl_sys::lv_disp_drv_user_data_t;
// Sets trampoline pointer to the function implementation using the types (T, C) that // Sets trampoline pointer to the function implementation that uses the `F` type for a
// are used in this instance of `DisplayDriver`. // refresh buffer of size N specifically.
disp_drv.flush_cb = Some(shared_disp_flush_trampoline::<F, N>); 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. // We do not store any memory that can be accidentally deallocated by on the Rust side.
Ok(Self { disp_drv }) Ok(Self { disp_drv })
} }
} }
pub(crate) struct DisplayUserData<T, C> /// Represents a sub-area of the display that is being updated.
where
T: DrawTarget<C>,
C: PixelColor + From<Color>,
{
display: T,
phantom: PhantomData<C>,
}
unsafe extern "C" fn disp_flush_trampoline<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>,
{
let display_driver = *disp_drv;
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;
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::<C>(Point::new(x as i32, y as i32), raw_color.into())
})
})
.flatten();
let _ = user_data.display.draw_iter(pixels);
}
// Indicate to LVGL that we are ready with the flushing
lvgl_sys::lv_disp_flush_ready(disp_drv);
}
#[cfg(feature = "alloc")]
pub(crate) struct SharedDisplayUserData<T, C>
where
T: DrawTarget<C>,
C: PixelColor + From<Color>,
{
display: SharedNativeDisplay<T>,
phantom: PhantomData<C>,
}
pub struct Area { pub struct Area {
pub x1: i16, pub x1: i16,
pub x2: i16, pub x2: i16,
@ -259,13 +142,50 @@ pub struct Area {
pub y2: 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 struct DisplayRefresh<const N: usize> {
pub area: Area, pub area: Area,
pub colors: [Color; N], pub colors: [Color; N],
} }
#[cfg(feature = "alloc")] #[cfg(feature = "embedded_graphics")]
unsafe extern "C" fn shared_disp_flush_trampoline<F, const N: usize>( 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, disp_drv: *mut lvgl_sys::lv_disp_drv_t,
area: *const lvgl_sys::lv_area_t, area: *const lvgl_sys::lv_area_t,
color_p: *mut lvgl_sys::lv_color_t, color_p: *mut lvgl_sys::lv_color_t,
@ -279,7 +199,7 @@ unsafe extern "C" fn shared_disp_flush_trampoline<F, const N: usize>(
let mut colors = [Color::default(); N]; let mut colors = [Color::default(); N];
let mut color_len = 0; let mut color_len = 0;
for color in &mut colors { for color in &mut colors {
let lv_color = unsafe { *color_p.add(color_len) }; let lv_color = *color_p.add(color_len);
*color = Color::from_raw(lv_color); *color = Color::from_raw(lv_color);
color_len += 1; color_len += 1;
} }

3
lvgl/src/functions.rs
View file

@ -1,9 +1,8 @@
use crate::display::{Display, DisplayDriver}; use crate::display::{Display, DisplayDriver};
use crate::{Color, Obj, Widget}; use crate::{Obj, Widget};
use core::ptr::NonNull; use core::ptr::NonNull;
use core::time::Duration; use core::time::Duration;
use core::{ptr, result}; use core::{ptr, result};
use embedded_graphics::prelude::*;
#[derive(Debug, Copy, Clone, Eq, PartialEq)] #[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum CoreError { pub enum CoreError {

8
lvgl/src/lib.rs
View file

@ -48,13 +48,11 @@ mod display;
pub use display::*; pub use display::*;
mod functions; mod functions;
mod support; mod support;
mod ui;
pub mod widgets; pub mod widgets;
use core::sync::atomic::{AtomicBool, Ordering}; use core::sync::atomic::{AtomicBool, Ordering};
pub use functions::*; pub use functions::*;
pub use lv_core::*; pub use lv_core::*;
pub use support::*; pub use support::*;
pub use ui::*;
struct RunOnce(AtomicBool); struct RunOnce(AtomicBool);
@ -84,20 +82,16 @@ pub fn init() {
pub(crate) mod tests { pub(crate) mod tests {
use super::*; use super::*;
use crate::display::{Display, DrawBuffer}; use crate::display::{Display, DrawBuffer};
use embedded_graphics::mock_display::MockDisplay;
use embedded_graphics::pixelcolor::Rgb565;
pub(crate) fn initialize_test() { pub(crate) fn initialize_test() {
init(); init();
let embedded_graphics_display: MockDisplay<Rgb565> = Default::default();
const REFRESH_BUFFER_SIZE: usize = 64 * 64 / 10; const REFRESH_BUFFER_SIZE: usize = 64 * 64 / 10;
static DRAW_BUFFER: DrawBuffer<REFRESH_BUFFER_SIZE> = DrawBuffer::new(); static DRAW_BUFFER: DrawBuffer<REFRESH_BUFFER_SIZE> = DrawBuffer::new();
static ONCE_INIT: RunOnce = RunOnce::new(); static ONCE_INIT: RunOnce = RunOnce::new();
if ONCE_INIT.swap_and_check() { if ONCE_INIT.swap_and_check() {
let _ = Display::register(&DRAW_BUFFER, embedded_graphics_display).unwrap(); let _ = Display::register(&DRAW_BUFFER, |_| {}).unwrap();
} }
} }
} }

1
lvgl/src/lv_core/obj.rs
View file

@ -1,5 +1,4 @@
use crate::lv_core::style::Style; use crate::lv_core::style::Style;
use crate::Box;
use crate::{Align, LvError, LvResult}; use crate::{Align, LvError, LvResult};
use core::ptr; use core::ptr;

4
lvgl/src/support.rs
View file

@ -2,6 +2,8 @@ use crate::display::DisplayError;
use crate::Widget; use crate::Widget;
use core::convert::{TryFrom, TryInto}; use core::convert::{TryFrom, TryInto};
use core::ptr::NonNull; use core::ptr::NonNull;
#[cfg(feature = "embedded_graphics")]
use embedded_graphics::pixelcolor::{Rgb565, Rgb888}; use embedded_graphics::pixelcolor::{Rgb565, Rgb888};
pub type LvResult<T> = Result<T, LvError>; pub type LvResult<T> = Result<T, LvError>;
@ -53,6 +55,7 @@ impl Color {
} }
} }
#[cfg(feature = "embedded_graphics")]
impl From<Color> for Rgb888 { impl From<Color> for Rgb888 {
fn from(color: Color) -> Self { fn from(color: Color) -> Self {
unsafe { unsafe {
@ -65,6 +68,7 @@ impl From<Color> for Rgb888 {
} }
} }
#[cfg(feature = "embedded_graphics")]
impl From<Color> for Rgb565 { impl From<Color> for Rgb565 {
fn from(color: Color) -> Self { fn from(color: Color) -> Self {
unsafe { unsafe {

206
lvgl/src/ui.rs
View file

@ -1,206 +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::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, the memory "leaks" here since
// the `disp_drv` is dropped in the end of this method. This is not a problem
// since this should live for the whole lifetime of the program anyways.
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>);
// The memory of `display_data` is kept because of the reference in `self`
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>(&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)?)
}