Support wm_class for X11

Cargo.lock

@@ -120,6 +120,12 @@ dependencies = [
  "memoffset",
 ]
 
+[[package]]
+name = "pkg-config"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "58893f751c9b0412871a09abd62ecd2a00298c6c83befa223ef98c52aef40cbe"
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.34"
@@ -220,6 +226,16 @@ dependencies = [
  "tap",
 ]
 
+[[package]]
+name = "x11"
+version = "2.19.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dd0565fa8bfba8c5efe02725b14dff114c866724eff2cfd44d76cea74bcd87a"
+dependencies = [
+ "libc",
+ "pkg-config",
+]
+
 [[package]]
 name = "xremap"
 version = "0.1.0"
@@ -230,6 +246,7 @@ dependencies = [
  "nix",
  "serde",
  "serde_yaml",
+ "x11",
 ]
 
 [[package]]

Cargo.toml

@@ -12,3 +12,4 @@ lazy_static = "1.4.0"
 nix = "0.23.1"
 serde = { version = "1.0", features = ["derive"] }
 serde_yaml = "0.8"
+x11 = { version = "2.19.1", features = ["xlib"] }

example/config.yml

@@ -106,12 +106,12 @@ keymap:
       # workaround prefix key bug
       M-r:
         remap:
-          3: C-M-3
-          0: C-M-0
+          '3': C-M-3
+          '0': C-M-0
 
   - name: Chrome, Slack (modified from Default)
     wm_class:
-      not: [Google-chrome, Slack]
+      only: [Google-chrome, Slack]
     remap:
       # Emacs basic
       C-b: left
@@ -185,10 +185,10 @@ keymap:
     wm_class:
       only: Nocturn
     remap:
-      Super-j: M-j,
-      Super-k: M-k,
-      Super-o: M-o,
-      Super-p: M-p,
+      Super-j: M-j
+      Super-k: M-k
+      Super-o: M-o
+      Super-p: M-p
       Super-Enter: Shift-Enter
 
   - name: Slack

example/test.yml

@@ -4,7 +4,7 @@
 #       a: b
 keymap:
   - name: Global
+    wm_class:
+      only: Slack
     remap:
-      C-i:
-        remap:
-          C-a: C-u
+      C-i: C-u

src/client/mod.rs

@@ -0,0 +1 @@
+pub mod x11_client;

src/client/x11_client.rs

@@ -0,0 +1,116 @@
+pub struct X11Client {
+    // Both of them are lazily initialized
+    display: Option<*mut x11::xlib::Display>,
+    supported: Option<bool>,
+    last_wm_class: String,
+}
+
+impl X11Client {
+    pub fn new() -> X11Client {
+        X11Client {
+            display: None,
+            supported: None,
+            last_wm_class: String::new(),
+        }
+    }
+
+    pub fn supported(&mut self) -> bool {
+        match self.supported {
+            Some(supported) => supported,
+            None => {
+                let display = self.display();
+                let mut focused_window = 0;
+                let mut focus_state = 0;
+                unsafe { x11::xlib::XGetInputFocus(display, &mut focused_window, &mut focus_state) };
+                let supported = focused_window > 0;
+                self.supported = Some(supported);
+                supported
+            },
+        }
+    }
+
+    pub fn current_wm_class(&mut self) -> Option<String> {
+        if !self.supported() {
+            return None
+        }
+
+        let display = self.display();
+        let mut focused_window = 0;
+        let mut focus_state = 0;
+        unsafe { x11::xlib::XGetInputFocus(display, &mut focused_window, &mut focus_state) };
+
+        let mut x_class_hint = x11::xlib::XClassHint {
+            res_name: std::ptr::null_mut(),
+            res_class: std::ptr::null_mut(),
+        };
+        loop {
+            unsafe {
+                if x11::xlib::XGetClassHint(display, focused_window, &mut x_class_hint) == 1 {
+                    break;
+                }
+            }
+
+            let mut nchildren: u32 = 0;
+            let mut root: x11::xlib::Window = 0;
+            let mut parent: x11::xlib::Window = 0;
+            let mut children: *mut x11::xlib::Window = &mut 0;
+            unsafe {
+                if x11::xlib::XQueryTree(
+                    display,
+                    focused_window,
+                    &mut root,
+                    &mut parent,
+                    &mut children,
+                    &mut nchildren,
+                ) == 0
+                {
+                    break;
+                }
+            }
+            if !children.is_null() {
+                unsafe {
+                    x11::xlib::XFree(children as *mut std::ffi::c_void);
+                }
+            }
+
+            // The root client's parent is NULL. Avoid querying it to prevent SEGV on XGetClientHint.
+            if parent == 0 {
+                return None;
+            }
+            focused_window = parent;
+        }
+
+        if !x_class_hint.res_name.is_null() {
+            unsafe {
+                x11::xlib::XFree(x_class_hint.res_name as *mut std::ffi::c_void);
+            }
+        }
+
+        if !x_class_hint.res_class.is_null() {
+            let wm_class = unsafe {
+                // Note: This seems to free `x_class_hint.res_class`. So XFree on it would double-free it.
+                std::ffi::CString::from_raw(x_class_hint.res_class as *mut i8)
+                    .into_string()
+                    .unwrap()
+            };
+            if &self.last_wm_class != &wm_class {
+                self.last_wm_class = wm_class.clone();
+                println!("wm_class: {}", &wm_class);
+            }
+            Some(wm_class)
+        } else {
+            None
+        }
+    }
+
+    fn display(&mut self) -> *mut x11::xlib::Display {
+        match self.display {
+            Some(display) => display,
+            None => {
+                let display = unsafe { x11::xlib::XOpenDisplay(std::ptr::null()) };
+                self.display = Some(display);
+                display
+            }
+        }
+    }
+}

src/config/key_press.rs

@@ -1,7 +1,7 @@
 use crate::config::key::parse_key;
 use evdev::Key;
 use serde::de;
-use serde::de::Visitor;
+use serde::de::{Visitor};
 use serde::{Deserialize, Deserializer};
 use std::error;
 use std::fmt::Formatter;

src/event_handler.rs

@@ -6,9 +6,11 @@ use evdev::{EventType, InputEvent, Key};
 use lazy_static::lazy_static;
 use std::collections::HashMap;
 use std::error::Error;
+use crate::client::x11_client::X11Client;
 
 pub struct EventHandler {
     device: VirtualDevice,
+    x11_client: X11Client,
     override_remap: Option<HashMap<KeyPress, Vec<Action>>>,
     shift: bool,
     control: bool,
@@ -20,6 +22,7 @@ impl EventHandler {
     pub fn new(device: VirtualDevice) -> EventHandler {
         EventHandler {
             device,
+            x11_client: X11Client::new(),
             override_remap: None,
             shift: false,
             control: false,
@@ -69,6 +72,7 @@ impl EventHandler {
         if !is_pressed(value) {
             return None;
         }
+        let mut wm_class_cache: Option<String> = None;
 
         let key_press = KeyPress {
             key: key.clone(),
@@ -86,6 +90,28 @@ impl EventHandler {
         }
         for keymap in &config.keymap {
             if let Some(actions) = keymap.remap.get(&key_press) {
+                // Lazily check wm_class as needed
+                if let Some(wm_class_matcher) = &keymap.wm_class {
+                    if let None = &wm_class_cache {
+                        match self.x11_client.current_wm_class() {
+                            Some(wm_class) => wm_class_cache = Some(wm_class),
+                            None => wm_class_cache = Some(String::new()),
+                        }
+                    }
+                    if let Some(wm_class) = &wm_class_cache {
+                        if let Some(wm_class_only) = &wm_class_matcher.only {
+                            if !wm_class_only.contains(wm_class) {
+                                continue;
+                            }
+                        }
+                        if let Some(wm_class_not) = &wm_class_matcher.not {
+                            if wm_class_not.contains(wm_class) {
+                                continue;
+                            }
+                        }
+                    }
+                }
+
                 return Some(actions.iter().map(|a| a.clone()).collect());
             }
         }

src/main.rs

@@ -6,6 +6,7 @@ use std::process::exit;
 
 extern crate getopts;
 
+mod client;
 mod config;
 mod event_handler;
 mod input;