Menu item API (#79)

* Add menu item api

* MenuItemKind implementation to add some protection around the checkbox and options items

* Removing unused menuItem handling constants

* Resolve soundness issue with dropping menu items

* clarify drop handling of menu items

* `System::remove_all_menu_items` no longer makes sense, removed

* remove menu_item tests from example

Cargo.toml

@@ -32,6 +32,11 @@ name = "hello_world"
 path = "examples/hello_world.rs"
 crate-type = ["staticlib", "cdylib"]
 
+[[example]]
+name = "menu_items"
+path = "examples/menu_items.rs"
+crate-type = ["staticlib", "cdylib"]
+
 [[example]]
 name = "life"
 path = "examples/life.rs"

examples/menu_items.rs

@@ -0,0 +1,108 @@
+#![no_std]
+
+extern crate alloc;
+
+use alloc::rc::Rc;
+use alloc::string::String;
+use alloc::vec;
+use alloc::vec::Vec;
+use core::cell::RefCell;
+
+use hashbrown::HashMap;
+
+use crankstart::system::MenuItemKind;
+use {
+    alloc::boxed::Box,
+    anyhow::Error,
+    crankstart::{
+        crankstart_game,
+        geometry::ScreenPoint,
+        graphics::{Graphics, LCDColor, LCDSolidColor},
+        log_to_console,
+        system::{MenuItem, System},
+        Game, Playdate,
+    },
+    euclid::point2,
+};
+
+struct State {
+    _menu_items: Rc<RefCell<HashMap<&'static str, MenuItem>>>,
+    text_location: ScreenPoint,
+}
+
+impl State {
+    pub fn new(_playdate: &Playdate) -> Result<Box<Self>, Error> {
+        crankstart::display::Display::get().set_refresh_rate(20.0)?;
+        let menu_items = Rc::new(RefCell::new(HashMap::new()));
+        let system = System::get();
+        let normal_item = {
+            system.add_menu_item(
+                "Select Me",
+                Box::new(|| {
+                    log_to_console!("Normal option picked");
+                }),
+            )?
+        };
+        let checkmark_item = {
+            let ref_menu_items = menu_items.clone();
+            system.add_checkmark_menu_item(
+                "Toggle Me",
+                false,
+                Box::new(move || {
+                    let value_of_item = {
+                        let menu_items = ref_menu_items.borrow();
+                        let this_menu_item = menu_items.get("checkmark").unwrap();
+                        System::get().get_menu_item_value(this_menu_item).unwrap() != 0
+                    };
+                    log_to_console!("Checked option picked: Value is now: {}", value_of_item);
+                }),
+            )?
+        };
+        let options_item = {
+            let ref_menu_items = menu_items.clone();
+            let options: Vec<String> = vec!["Small".into(), "Medium".into(), "Large".into()];
+            system.add_options_menu_item(
+                "Size",
+                options,
+                Box::new(move || {
+                    let value_of_item = {
+                        let menu_items = ref_menu_items.borrow();
+                        let this_menu_item = menu_items.get("options").unwrap();
+                        let idx = System::get().get_menu_item_value(this_menu_item).unwrap();
+                        match &this_menu_item.kind {
+                            MenuItemKind::Options(opts) => opts.get(idx).map(|s| s.clone()),
+                            _ => None,
+                        }
+                    };
+                    log_to_console!("Checked option picked: Value is now {:?}", value_of_item);
+                }),
+            )?
+        };
+        {
+            let mut menu_items = menu_items.borrow_mut();
+            menu_items.insert("normal", normal_item);
+            menu_items.insert("checkmark", checkmark_item);
+            menu_items.insert("options", options_item);
+        }
+        Ok(Box::new(Self {
+            _menu_items: menu_items,
+            text_location: point2(100, 100),
+        }))
+    }
+}
+
+impl Game for State {
+    fn update(&mut self, _playdate: &mut Playdate) -> Result<(), Error> {
+        let graphics = Graphics::get();
+        graphics.clear(LCDColor::Solid(LCDSolidColor::kColorWhite))?;
+        graphics
+            .draw_text("Menu Items", self.text_location)
+            .unwrap();
+
+        System::get().draw_fps(0, 0)?;
+
+        Ok(())
+    }
+}
+
+crankstart_game!(State);

src/system.rs

@@ -1,12 +1,19 @@
+use alloc::boxed::Box;
+use alloc::rc::Rc;
+use alloc::string::String;
+use alloc::vec::Vec;
+use core::cell::RefCell;
+
+use anyhow::anyhow;
+
+use crankstart_sys::ctypes::{c_char, c_int};
+pub use crankstart_sys::PDButtons;
+use crankstart_sys::{PDDateTime, PDLanguage, PDMenuItem, PDPeripherals};
 use {
-    crate::pd_func_caller, alloc::format, anyhow::Error, core::ptr, crankstart_sys::ctypes::c_void,
+    crate::pd_func_caller, anyhow::Error, core::ptr, crankstart_sys::ctypes::c_void,
     cstr_core::CString,
 };
 
-use crankstart_sys::ctypes::c_int;
-pub use crankstart_sys::PDButtons;
-use crankstart_sys::{PDDateTime, PDLanguage, PDPeripherals};
-
 static mut SYSTEM: System = System(ptr::null_mut());
 
 #[derive(Clone, Debug)]
@@ -47,6 +54,160 @@ impl System {
         Ok((current, pushed, released))
     }
 
+    extern "C" fn menu_item_callback(user_data: *mut core::ffi::c_void) {
+        unsafe {
+            let callback = user_data as *mut Box<dyn Fn()>;
+            (*callback)()
+        }
+    }
+
+    /// Adds a option to the menu. The callback is called when the option is selected.
+    pub fn add_menu_item(&self, title: &str, callback: Box<dyn Fn()>) -> Result<MenuItem, Error> {
+        let c_text = CString::new(title).map_err(|e| anyhow!("CString::new: {}", e))?;
+        let wrapped_callback = Box::new(callback);
+        let raw_callback_ptr = Box::into_raw(wrapped_callback);
+        let raw_menu_item = pd_func_caller!(
+            (*self.0).addMenuItem,
+            c_text.as_ptr() as *mut core::ffi::c_char,
+            Some(Self::menu_item_callback),
+            raw_callback_ptr as *mut c_void
+        )?;
+        Ok(MenuItem {
+            inner: Rc::new(RefCell::new(MenuItemInner {
+                item: raw_menu_item,
+                raw_callback_ptr,
+            })),
+            kind: MenuItemKind::Normal,
+        })
+    }
+
+    /// Adds a option to the menu that has a checkbox. The initial_checked_state is the initial
+    /// state of the checkbox. Callback will only be called when the menu is closed, not when the
+    /// option is toggled. Use `System::get_menu_item_value` to get the state of the checkbox when
+    /// the callback is called.
+    pub fn add_checkmark_menu_item(
+        &self,
+        title: &str,
+        initial_checked_state: bool,
+        callback: Box<dyn Fn()>,
+    ) -> Result<MenuItem, Error> {
+        let c_text = CString::new(title).map_err(|e| anyhow!("CString::new: {}", e))?;
+        let wrapped_callback = Box::new(callback);
+        let raw_callback_ptr = Box::into_raw(wrapped_callback);
+        let raw_menu_item = pd_func_caller!(
+            (*self.0).addCheckmarkMenuItem,
+            c_text.as_ptr() as *mut core::ffi::c_char,
+            initial_checked_state as c_int,
+            Some(Self::menu_item_callback),
+            raw_callback_ptr as *mut c_void
+        )?;
+
+        Ok(MenuItem {
+            inner: Rc::new(RefCell::new(MenuItemInner {
+                item: raw_menu_item,
+                raw_callback_ptr,
+            })),
+            kind: MenuItemKind::Checkmark,
+        })
+    }
+
+    /// Adds a option to the menu that has multiple values that can be cycled through. The initial
+    /// value is the first element in `options`. Callback will only be called when the menu is
+    /// closed, not when the option is toggled. Use `System::get_menu_item_value` to get the index
+    /// of the options list when the callback is called, which can be used to lookup the value.
+    pub fn add_options_menu_item(
+        &self,
+        title: &str,
+        options: Vec<String>,
+        callback: Box<dyn Fn()>,
+    ) -> Result<MenuItem, Error> {
+        let c_text = CString::new(title).map_err(|e| anyhow!("CString::new: {}", e))?;
+        let options_count = options.len() as c_int;
+        let c_options: Vec<CString> = options
+            .iter()
+            .map(|s| CString::new(s.clone()).map_err(|e| anyhow!("CString::new: {}", e)))
+            .collect::<Result<Vec<CString>, Error>>()?;
+        let c_options_ptrs: Vec<*const i8> = c_options.iter().map(|c| c.as_ptr()).collect();
+        let c_options_ptrs_ptr = c_options_ptrs.as_ptr();
+        let option_titles = c_options_ptrs_ptr as *mut *const c_char;
+        let wrapped_callback = Box::new(callback);
+        let raw_callback_ptr = Box::into_raw(wrapped_callback);
+        let raw_menu_item = pd_func_caller!(
+            (*self.0).addOptionsMenuItem,
+            c_text.as_ptr() as *mut core::ffi::c_char,
+            option_titles,
+            options_count,
+            Some(Self::menu_item_callback),
+            raw_callback_ptr as *mut c_void
+        )?;
+        Ok(MenuItem {
+            inner: Rc::new(RefCell::new(MenuItemInner {
+                item: raw_menu_item,
+                raw_callback_ptr,
+            })),
+            kind: MenuItemKind::Options(options),
+        })
+    }
+
+    /// Returns the state of a given menu item. The meaning depends on the type of menu item.
+    /// If it is the checkbox, the int represents the boolean checked state. If it's a option the
+    /// int represents the index of the option array.
+    pub fn get_menu_item_value(&self, item: &MenuItem) -> Result<usize, Error> {
+        let value = pd_func_caller!((*self.0).getMenuItemValue, item.inner.borrow().item)?;
+        Ok(value as usize)
+    }
+
+    /// set the value of a given menu item. The meaning depends on the type of menu item. Picking
+    /// the right value is left up to the caller, but is protected by the `MenuItemKind` of the
+    /// `item` passed
+    pub fn set_menu_item_value(&self, item: &MenuItem, new_value: usize) -> Result<(), Error> {
+        match &item.kind {
+            MenuItemKind::Normal => {}
+            MenuItemKind::Checkmark => {
+                if new_value > 1 {
+                    return Err(anyhow!(
+                        "Invalid value ({}) for checkmark menu item",
+                        new_value
+                    ));
+                }
+            }
+            MenuItemKind::Options(opts) => {
+                if new_value >= opts.len() {
+                    return Err(anyhow!(
+                        "Invalid value ({}) for options menu item, must be between 0 and {}",
+                        new_value,
+                        opts.len() - 1
+                    ));
+                }
+            }
+        }
+        pd_func_caller!(
+            (*self.0).setMenuItemValue,
+            item.inner.borrow().item,
+            new_value as c_int
+        )
+    }
+
+    /// Set the title of a given menu item
+    pub fn set_menu_item_title(&self, item: &MenuItem, new_title: &str) -> Result<(), Error> {
+        let c_text = CString::new(new_title).map_err(|e| anyhow!("CString::new: {}", e))?;
+        pd_func_caller!(
+            (*self.0).setMenuItemTitle,
+            item.inner.borrow().item,
+            c_text.as_ptr() as *mut c_char
+        )
+    }
+    pub fn remove_menu_item(&self, item: MenuItem) -> Result<(), Error> {
+        // Explicitly drops item. The actual calling of the removeMenuItem
+        // (via `remove_menu_item_internal`) is done in the drop impl to avoid calling it multiple
+        // times, even though that's been experimentally shown to be safe.
+        drop(item);
+        Ok(())
+    }
+    fn remove_menu_item_internal(&self, item_inner: &MenuItemInner) -> Result<(), Error> {
+        pd_func_caller!((*self.0).removeMenuItem, item_inner.item)
+    }
+
     pub fn set_peripherals_enabled(&self, peripherals: PDPeripherals) -> Result<(), Error> {
         pd_func_caller!((*self.0).setPeripheralsEnabled, peripherals)
     }
@@ -180,3 +341,32 @@ impl System {
         pd_func_caller!((*self.0).getLanguage)
     }
 }
+
+/// The kind of menu item. See `System::add_{,checkmark_,options_}menu_item` for more details.
+pub enum MenuItemKind {
+    Normal,
+    Checkmark,
+    Options(Vec<String>),
+}
+
+pub struct MenuItemInner {
+    item: *mut PDMenuItem,
+    raw_callback_ptr: *mut Box<dyn Fn()>,
+}
+
+impl Drop for MenuItemInner {
+    fn drop(&mut self) {
+        // We must remove the menu item on drop to avoid a memory or having the firmware read
+        // unmanaged memory.
+        System::get().remove_menu_item_internal(self).unwrap();
+        unsafe {
+            // Recast into box to let Box deal with freeing the right memory
+            let _ = Box::from_raw(self.raw_callback_ptr);
+        }
+    }
+}
+
+pub struct MenuItem {
+    inner: Rc<RefCell<MenuItemInner>>,
+    pub kind: MenuItemKind,
+}