Another pass at no_panic on Windows/MacOS/Linux.

Author: Narsil

examples/display.rs

@@ -1,6 +1,6 @@
 use rdev::display_size;
 fn main() {
-    let (w, h) = display_size();
+    let (w, h) = display_size().unwrap();
 
     println!("Your screen is {:?}x{:?}", w, h);
 }

src/lib.rs

@@ -62,7 +62,7 @@
 //! ```no_run
 //! use rdev::{display_size};
 //!
-//! let (w, h) = display_size();
+//! let (w, h) = display_size().unwrap();
 //! assert!(w > 0);
 //! assert!(h > 0);
 //! ```
@@ -82,7 +82,8 @@
 //! Serialization and deserialization. (Requires `serialize` feature).
 mod rdev;
 pub use crate::rdev::{
-    Button, Callback, Event, EventType, GrabCallback, GrabError, Key, ListenError, SimulateError,
+    Button, Callback, DisplayError, Event, EventType, GrabCallback, GrabError, Key, ListenError,
+    SimulateError,
 };
 
 #[cfg(target_os = "macos")]
@@ -169,10 +170,10 @@ pub fn simulate(event_type: &EventType) -> Result<(), SimulateError> {
 /// ```no_run
 /// use rdev::{display_size};
 ///
-/// let (w, h )= display_size();
+/// let (w, h) = display_size().unwrap();
 /// println!("My screen size : {:?}x{:?}", w, h);
 /// ```
-pub fn display_size() -> (u64, u64) {
+pub fn display_size() -> Result<(u64, u64), DisplayError> {
     _display_size()
 }
 

src/linux/common.rs

@@ -1,6 +1,7 @@
 use crate::linux::keyboard_state::KeyboardState;
 use crate::linux::keycodes::key_from_code;
 use crate::rdev::{Button, Event, EventType};
+use std::convert::TryInto;
 use std::os::raw::{c_int, c_uchar, c_uint};
 use std::ptr::null;
 use std::time::SystemTime;
@@ -67,29 +68,39 @@ pub fn convert(code: c_uint, state: c_uint, type_: c_int, x: f64, y: f64) -> Opt
     }
 }
 
-struct Display {
-    display: i32,
+pub struct Display {
+    display: *mut xlib::Display,
 }
 
 impl Display {
-    fn new() -> Option<Display> {
-        let display = xlib::XOpenDisplay(null());
-        if display.is_null() {
-            return None;
+    pub fn new() -> Option<Display> {
+        unsafe {
+            let display = xlib::XOpenDisplay(null());
+            if display.is_null() {
+                return None;
+            }
+            Some(Display { display })
         }
-        Some(Display { display })
     }
 
-    fn get_screen() -> Option<Screen> {
-        let screen_ptr = xlib::XDefaultScreenOfDisplay(dpy);
-        if screen_ptr.is_null() {
-            return None;
+    pub fn get_size(&self) -> Option<(u64, u64)> {
+        unsafe {
+            let screen_ptr = xlib::XDefaultScreenOfDisplay(self.display);
+            if screen_ptr.is_null() {
+                return None;
+            }
+            let screen = *screen_ptr;
+            Some((
+                screen.width.try_into().ok()?,
+                screen.height.try_into().ok()?,
+            ))
         }
-        Some(*screen_ptr);
     }
 }
 impl Drop for Display {
-    fn drop(&self) {
-        xlib::XCloseDisplay(self.display)
+    fn drop(&mut self) {
+        unsafe {
+            xlib::XCloseDisplay(self.display);
+        }
     }
 }

src/linux/display.rs

@@ -1,12 +1,7 @@
 use crate::linux::common::Display;
 use crate::rdev::DisplayError;
-use std::convert::TryInto;
 
 pub fn display_size() -> Result<(u64, u64), DisplayError> {
-    let dpy = Display::new().map_err(|| DisplayError::NoDisplay)?;
-    let screen = dpy.get_screen()?;
-    Ok(
-        screen.width.try_into().unwrap(),
-        screen.height.try_into().unwrap(),
-    )
+    let display = Display::new().ok_or(DisplayError::NoDisplay)?;
+    display.get_size().ok_or(DisplayError::NoDisplay)
 }

src/macos/display.rs

@@ -1,6 +1,7 @@
+use crate::rdev::DisplayError;
 use core_graphics::display::CGDisplay;
 
-pub fn display_size() -> (u64, u64) {
+pub fn display_size() -> Result<(u64, u64), DisplayError> {
     let main = CGDisplay::main();
-    (main.pixels_wide(), main.pixels_high())
+    Ok((main.pixels_wide(), main.pixels_high()))
 }

src/rdev.rs

@@ -40,9 +40,11 @@ pub enum GrabError {
     LinuxNotSupported,
 }
 /// Errors that occur when trying to get display size.
+#[non_exhaustive]
 #[derive(Debug)]
 pub enum DisplayError {
-    MissingDisplayError,
+    NoDisplay,
+    ConversionError,
 }
 
 /// Marking an error when we tried to simulate and event

src/windows/display.rs

@@ -1,8 +1,17 @@
+use crate::rdev::DisplayError;
 use std::convert::TryInto;
 use winapi::um::winuser::{GetSystemMetrics, SM_CXSCREEN, SM_CYSCREEN};
 
-pub fn display_size() -> (u64, u64) {
-    let w = unsafe { GetSystemMetrics(SM_CXSCREEN).try_into().unwrap() };
-    let h = unsafe { GetSystemMetrics(SM_CYSCREEN).try_into().unwrap() };
-    (w, h)
+pub fn display_size() -> Result<(u64, u64), DisplayError> {
+    let w = unsafe {
+        GetSystemMetrics(SM_CXSCREEN)
+            .try_into()
+            .map_err(|_| DisplayError::ConversionError)?
+    };
+    let h = unsafe {
+        GetSystemMetrics(SM_CYSCREEN)
+            .try_into()
+            .map_err(|_| DisplayError::ConversionError)?
+    };
+    Ok((w, h))
 }

src/windows/simulate.rs

@@ -118,6 +118,9 @@ pub fn simulate(event_type: &EventType) -> Result<(), SimulateError> {
         EventType::MouseMove { x, y } => {
             let width = unsafe { GetSystemMetrics(SM_CXVIRTUALSCREEN) };
             let height = unsafe { GetSystemMetrics(SM_CYVIRTUALSCREEN) };
+            if width == 0 || height == 0 {
+                return Err(SimulateError);
+            }
 
             sim_mouse_event(
                 MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE | MOUSEEVENTF_VIRTUALDESK,