Add troubleshooting messages for X11

rustfmt.toml

@@ -1 +1,2 @@
 max_width = 120
+fn_call_width = 100

src/client/gnome_client.rs

@@ -1,5 +1,5 @@
-use zbus::Connection;
 use crate::client::Client;
+use zbus::Connection;
 
 pub struct GnomeClient {
     connection: Option<Connection>,
@@ -7,9 +7,7 @@ pub struct GnomeClient {
 
 impl GnomeClient {
     pub fn new() -> GnomeClient {
-        GnomeClient {
-            connection: None,
-        }
+        GnomeClient { connection: None }
     }
 
     fn connect(&mut self) {
@@ -48,7 +46,7 @@ impl Client for GnomeClient {
         ) {
             if let Ok((_actor, json)) = message.body::<(bool, String)>() {
                 if let Ok(wm_class) = serde_json::from_str::<String>(&json) {
-                    return Some(wm_class)
+                    return Some(wm_class);
                 }
             }
         }

src/client/mod.rs

@@ -24,14 +24,10 @@ impl WMClient {
         if let None = self.supported {
             let supported = self.client.supported();
             self.supported = Some(supported);
-            println!(
-                "application-client: {} (supported: {})",
-                self.name,
-                supported
-            );
+            println!("application-client: {} (supported: {})", self.name, supported);
         }
         if !self.supported.unwrap() {
-            return None
+            return None;
         }
 
         let result = self.client.current_application();

src/client/sway_client.rs

@@ -10,9 +10,7 @@ pub struct SwayClient {
 
 impl SwayClient {
     pub fn new() -> SwayClient {
-        SwayClient {
-            connection: None,
-        }
+        SwayClient { connection: None }
     }
 
     fn connect(&mut self) {

src/client/x11_client.rs

@@ -1,4 +1,5 @@
 use crate::client::Client;
+use std::env;
 use x11_rs::xlib;
 
 pub struct X11Client {
@@ -7,16 +8,25 @@ pub struct X11Client {
 
 impl X11Client {
     pub fn new() -> X11Client {
-        X11Client {
-            display: None,
-        }
+        X11Client { display: None }
     }
 
     fn connect(&mut self) -> *mut xlib::Display {
         match self.display {
             Some(display) => display,
             None => {
+                if let Err(env::VarError::NotPresent) = env::var("DISPLAY") {
+                    println!("$DISPLAY is not set. Defaulting to DISPLAY=:0");
+                    env::set_var("DISPLAY", ":0");
+                }
+
                 let display = unsafe { xlib::XOpenDisplay(std::ptr::null()) };
+                if display.is_null() {
+                    let var = env::var("DISPLAY").unwrap();
+                    println!("warning: Failed to connect to X11.");
+                    println!("If you saw \"No protocol specified\", try running `xhost +SI:localuser:root`.");
+                    println!("If not, make sure `echo $DISPLAY` outputs xremap's $DISPLAY ({}).", var);
+                }
                 self.display = Some(display);
                 display
             }
@@ -77,14 +87,7 @@ impl Client for X11Client {
             let mut parent: xlib::Window = 0;
             let mut children: *mut xlib::Window = &mut 0;
             unsafe {
-                if xlib::XQueryTree(
-                    display,
-                    focused_window,
-                    &mut root,
-                    &mut parent,
-                    &mut children,
-                    &mut nchildren,
-                ) == 0
+                if xlib::XQueryTree(display, focused_window, &mut root, &mut parent, &mut children, &mut nchildren) == 0
                 {
                     break;
                 }

src/input.rs

@@ -140,7 +140,8 @@ fn is_keyboard(device: &Device) -> bool {
             keys.contains(Key::KEY_SPACE)
                 && keys.contains(Key::KEY_A)
                 && keys.contains(Key::KEY_Z)
-                && !keys.contains(Key::BTN_LEFT) // BTN_MOUSE
+                // BTN_MOUSE
+                && !keys.contains(Key::BTN_LEFT)
         }
         None => false,
     }