Merge pull request #141 from lvgl/obj-style-lifetimes

Lifetime tracking for objects and styles

Cargo.toml

@@ -4,3 +4,5 @@ members = [
     "lvgl-codegen",
     "lvgl-sys",
 ]
+
+resolver = "2"

lvgl-codegen/src/lib.rs

@@ -66,7 +66,7 @@ impl Rusty for LvWidget {
         Ok(quote! {
             define_object!(#widget_name);
 
-            impl #widget_name {
+            impl<'a> #widget_name<'a> {
                 #(#methods)*
             }
         })
@@ -122,7 +122,7 @@ impl Rusty for LvFunc {
                 }
 
                 pub fn new() -> crate::LvResult<Self> {
-                    let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+                    let mut parent = crate::display::get_scr_act()?;
                     Self::create(&mut parent)
                 }
 
@@ -613,7 +613,7 @@ mod test {
         let expected_code = quote! {
             define_object!(Arc);
 
-            impl Arc {
+            impl<'a> Arc<'a> {
 
             }
         };
@@ -645,7 +645,7 @@ mod test {
         let expected_code = quote! {
             define_object!(Arc);
 
-            impl Arc {
+            impl<'a> Arc<'a> {
                 pub fn create(parent: &mut impl crate::NativeObject) -> crate::LvResult<Self> {
                     unsafe {
                         let ptr = lvgl_sys::lv_arc_create(
@@ -661,7 +661,7 @@ mod test {
                 }
 
                 pub fn new() -> crate::LvResult<Self> {
-                    let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+                    let mut parent = crate::display::get_scr_act()?;
                     Self::create(&mut parent)
                 }
             }

lvgl-sys/src/lib.rs

@@ -23,10 +23,10 @@ mod tests {
             lv_init();
 
             let horizontal_resolution = lv_disp_get_hor_res(core::ptr::null_mut());
-            assert_eq!(horizontal_resolution, 0 as i16);
+            assert_eq!(horizontal_resolution, 0);
 
             let vertical_resolution = lv_disp_get_ver_res(core::ptr::null_mut());
-            assert_eq!(vertical_resolution, 0 as i16);
+            assert_eq!(vertical_resolution, 0);
         }
     }
 }

lvgl/src/display.rs

@@ -3,13 +3,13 @@ use crate::Screen;
 use crate::{disp_drv_register, disp_get_default, get_str_act, LvResult, NativeObject};
 use crate::{Box, Color};
 use core::convert::TryInto;
+#[cfg(feature = "nightly")]
+use core::error::Error;
+use core::fmt;
 use core::mem::{ManuallyDrop, MaybeUninit};
 use core::pin::Pin;
 use core::ptr::NonNull;
 use core::{ptr, result};
-use core::fmt;
-#[cfg(feature = "nightly")]
-use core::error::Error;
 
 /// Error in interacting with a `Display`.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
@@ -21,11 +21,15 @@ pub enum DisplayError {
 
 impl fmt::Display for DisplayError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "Display {}", match self {
-            DisplayError::NotAvailable => "not available",
-            DisplayError::FailedToRegister => "failed to register",
-            DisplayError::NotRegistered => "not registered",
-        })
+        write!(
+            f,
+            "Display {}",
+            match self {
+                DisplayError::NotAvailable => "not available",
+                DisplayError::FailedToRegister => "failed to register",
+                DisplayError::NotRegistered => "not registered",
+            }
+        )
     }
 }
 
@@ -63,18 +67,17 @@ impl<'a> Display {
         let disp_p = &mut display_diver.disp_drv;
         disp_p.hor_res = hor_res.try_into().unwrap_or(240);
         disp_p.ver_res = ver_res.try_into().unwrap_or(240);
-        let ret = Ok(disp_drv_register(&mut display_diver, None)?);
+        Ok(disp_drv_register(&mut display_diver, None)?)
         //display_diver.disp_drv.leak();
-        ret
     }
 
     /// Returns the current active screen.
-    pub fn get_scr_act(&self) -> Result<Screen> {
+    pub fn get_scr_act(&'a self) -> Result<Screen<'a>> {
         Ok(get_str_act(Some(self))?.try_into()?)
     }
 
     /// Sets a `Screen` as currently active.
-    pub fn set_scr_act(&mut self, screen: &mut Screen) -> LvResult<()> {
+    pub fn set_scr_act(&'a self, screen: &'a mut Screen) -> LvResult<()> {
         let scr_ptr = unsafe { screen.raw()?.as_mut() };
         unsafe { lvgl_sys::lv_disp_load_scr(scr_ptr) }
         Ok(())
@@ -152,14 +155,9 @@ impl Drop for Display {
     }
 }
 
-#[derive(Copy, Clone)]
-pub(crate) struct DefaultDisplay {}
-
-impl DefaultDisplay {
-    /// Gets the active screen of the default display.
-    pub(crate) fn get_scr_act() -> Result<Screen> {
-        Ok(get_str_act(None)?.try_into()?)
-    }
+/// Gets the active screen of the default display.
+pub(crate) fn get_scr_act() -> Result<Screen<'static>> {
+    Ok(get_str_act(None)?.try_into()?)
 }
 
 /// A buffer of size `N` representing `N` pixels. `N` can be smaller than the
@@ -401,8 +399,7 @@ mod tests {
         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");
+        let _screen_default = get_scr_act().expect("Return screen from the default display");
     }
 
     #[test]

lvgl/src/functions.rs

@@ -69,7 +69,10 @@ pub fn task_handler() {
 
 /// Directly send an event to a specific widget.
 #[inline]
-pub fn event_send<W: Widget>(obj: &mut W, event: Event<W::SpecialEvent>) -> LvResult<()> {
+pub fn event_send<W: for<'a> Widget<'a>>(
+    obj: &mut W,
+    event: Event<<W as Widget<'_>>::SpecialEvent>,
+) -> LvResult<()> {
     unsafe {
         lvgl_sys::lv_event_send(obj.raw()?.as_mut(), event.into(), ptr::null_mut());
     };

lvgl/src/lib.rs

@@ -109,8 +109,12 @@ fn once_init() {
     }
 }
 
-/// Initializes LVGL. Unless `unsafe_no_autoinit` is enabled, do not call
-/// without first calling `deinit()` and dropping all old values.
+/// Initializes LVGL.
+///
+/// # Safety
+///
+/// Unless `unsafe_no_autoinit` is enabled, do not call this function without
+/// first calling `deinit()` and dropping all old values.
 #[cfg(not(feature = "unsafe_no_autoinit"))]
 pub unsafe fn init() {
     unsafe {
@@ -119,6 +123,10 @@ pub unsafe fn init() {
 }
 
 /// Uninitializes LVGL. Make sure to reinitialize it before reusing it.
+///
+/// # Safety
+///
+/// This function should not be called if LVGL is already uninitialized.
 pub unsafe fn deinit() {
     unsafe { lvgl_sys::lv_deinit() }
 }

lvgl/src/lv_core/obj.rs

@@ -8,6 +8,7 @@
 use crate::lv_core::style::Style;
 use crate::{Align, LvError, LvResult};
 use core::fmt::{self, Debug};
+use core::marker::PhantomData;
 use core::ptr;
 
 /// Represents a native LVGL object.
@@ -19,13 +20,15 @@ pub trait NativeObject {
 /// Generic LVGL object.
 ///
 /// This is the parent object of all widget types. It stores the native LVGL raw pointer.
-pub struct Obj {
+pub struct Obj<'a> {
     // We use a raw pointer here because we do not control this memory address, it is controlled
     // by LVGL's global state.
     raw: *mut lvgl_sys::lv_obj_t,
+    // This is to ensure safety for style memory; it has no runtime impact
+    styles_used: PhantomData<&'a lvgl_sys::lv_style_t>,
 }
 
-impl Debug for Obj {
+impl Debug for Obj<'_> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         f.debug_struct("NativeObject")
             .field("raw", &"!! LVGL lv_obj_t ptr !!")
@@ -35,26 +38,29 @@ impl Debug for Obj {
 
 // We need to manually impl methods on Obj since widget codegen is defined in
 // terms of Obj
-impl Obj {
+impl Obj<'_> {
     pub fn create(parent: &mut impl NativeObject) -> LvResult<Self> {
         unsafe {
             let ptr = lvgl_sys::lv_obj_create(parent.raw()?.as_mut());
             if ptr::NonNull::new(ptr).is_some() {
                 //(*ptr).user_data = Box::new(UserDataObj::empty()).into_raw() as *mut _;
-                Ok(Self { raw: ptr })
+                Ok(Self {
+                    raw: ptr,
+                    styles_used: PhantomData,
+                })
             } else {
                 Err(LvError::InvalidReference)
             }
         }
     }
 
     pub fn new() -> crate::LvResult<Self> {
-        let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+        let mut parent = crate::display::get_scr_act()?;
         Self::create(&mut parent)
     }
 }
 
-impl NativeObject for Obj {
+impl NativeObject for Obj<'_> {
     fn raw(&self) -> LvResult<ptr::NonNull<lvgl_sys::lv_obj_t>> {
         if let Some(non_null_ptr) = ptr::NonNull::new(self.raw) {
             Ok(non_null_ptr)
@@ -65,7 +71,7 @@ impl NativeObject for Obj {
 }
 
 /// A wrapper for all LVGL common operations on generic objects.
-pub trait Widget: NativeObject + Sized {
+pub trait Widget<'a>: NativeObject + Sized + 'a {
     type SpecialEvent;
     type Part: Into<lvgl_sys::lv_part_t>;
 
@@ -79,7 +85,7 @@ pub trait Widget: NativeObject + Sized {
     unsafe fn from_raw(raw_pointer: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Option<Self>;
 
     /// Adds a `Style` to a given widget.
-    fn add_style(&mut self, part: Self::Part, style: &mut Style) -> LvResult<()> {
+    fn add_style(&mut self, part: Self::Part, style: &'a mut Style) -> LvResult<()> {
         unsafe {
             lvgl_sys::lv_obj_add_style(
                 self.raw()?.as_mut(),
@@ -144,19 +150,23 @@ pub trait Widget: NativeObject + Sized {
     }
 }
 
-impl Widget for Obj {
+impl<'a> Widget<'a> for Obj<'a> {
     type SpecialEvent = u32;
     type Part = Part;
 
     unsafe fn from_raw(raw: ptr::NonNull<lvgl_sys::lv_obj_t>) -> Option<Self> {
-        Some(Self { raw: raw.as_ptr() })
+        Some(Self {
+            raw: raw.as_ptr(),
+            styles_used: PhantomData,
+        })
     }
 }
 
-impl Default for Obj {
+impl Default for Obj<'_> {
     fn default() -> Self {
         Self {
             raw: unsafe { lvgl_sys::lv_obj_create(ptr::null_mut()) },
+            styles_used: PhantomData,
         }
     }
 }
@@ -176,22 +186,24 @@ macro_rules! define_object {
     };
     ($item:ident, event = $event_type:ty, part = $part_type:ty) => {
         #[derive(Debug)]
-        pub struct $item {
-            core: $crate::Obj,
+        pub struct $item<'a> {
+            core: $crate::Obj<'a>,
         }
 
-        impl $item {
+        impl<'a> $item<'a> {
             pub fn on_event<F>(&mut self, f: F) -> $crate::LvResult<()>
             where
-                F: FnMut(Self, $crate::support::Event<<Self as $crate::Widget>::SpecialEvent>),
+                F: FnMut(Self, $crate::support::Event<<Self as $crate::Widget<'a>>::SpecialEvent>),
             {
                 use $crate::NativeObject;
                 unsafe {
                     let obj = self.raw()?.as_mut();
                     obj.user_data = $crate::Box::into_raw($crate::Box::new(f)) as *mut _;
                     lvgl_sys::lv_obj_add_event_cb(
                         obj,
-                        lvgl_sys::lv_event_cb_t::Some($crate::support::event_callback::<Self, F>),
+                        lvgl_sys::lv_event_cb_t::Some(
+                            $crate::support::event_callback::<'a, Self, F>,
+                        ),
                         lvgl_sys::lv_event_code_t_LV_EVENT_ALL,
                         obj.user_data,
                     );
@@ -200,13 +212,13 @@ macro_rules! define_object {
             }
         }
 
-        impl $crate::NativeObject for $item {
+        impl $crate::NativeObject for $item<'_> {
             fn raw(&self) -> $crate::LvResult<core::ptr::NonNull<lvgl_sys::lv_obj_t>> {
                 self.core.raw()
             }
         }
 
-        impl $crate::Widget for $item {
+        impl<'a> $crate::Widget<'a> for $item<'a> {
             type SpecialEvent = $event_type;
             type Part = $part_type;
 
@@ -248,7 +260,7 @@ macro_rules! define_object {
 //     }
 //
 //     pub fn new() -> crate::LvResult<Self> {
-//         let mut parent = crate::display::DefaultDisplay::get_scr_act()?;
+//         let mut parent = crate::display::get_scr_act()?;
 //         Ok(Self::create_at(&mut parent)?)
 //     }
 // }