Linux/x11 input handling (#7811)

Implements the basics of keyboard and mouse handling.
Some keys will need special treatment, like Backspace/Delete. In this
PR, all keys are treated as append-only. Leaving this for a follow-up.

I used @gabydd 's branch as a reference (thank you!) as well as
https://github.com/xkbcommon/libxkbcommon/blob/master/doc/quick-guide.md
For future work, I'll also use
https://github.com/xkbcommon/libxkbcommon/blob/master/tools/interactive-x11.c

All commits are separately compileable and reviewable.

Release Notes:
- N/A

---------

Co-authored-by: Mikayla Maki <mikayla@zed.dev>

crates/gpui/src/platform/linux/x11/window.rs

@@ -13,15 +13,12 @@ use std::{
 use blade_graphics as gpu;
 use parking_lot::Mutex;
 use raw_window_handle as rwh;
-use xcb::{
-    x::{self, StackMode},
-    Xid as _,
-};
+use xcb::{x, Xid as _};
 
 use crate::platform::linux::blade_renderer::BladeRenderer;
 use crate::{
-    Bounds, GlobalPixels, Pixels, PlatformDisplay, PlatformInputHandler, PlatformWindow, Point,
-    Size, WindowAppearance, WindowBounds, WindowOptions, X11Display,
+    Bounds, GlobalPixels, Pixels, PlatformDisplay, PlatformInput, PlatformInputHandler,
+    PlatformWindow, Point, Size, WindowAppearance, WindowBounds, WindowOptions, X11Display,
 };
 
 #[derive(Default)]
@@ -52,6 +49,7 @@ struct LinuxWindowInner {
     bounds: Bounds<i32>,
     scale_factor: f32,
     renderer: BladeRenderer,
+    input_handler: Option<PlatformInputHandler>,
 }
 
 impl LinuxWindowInner {
@@ -152,7 +150,19 @@ impl X11WindowState {
         let xcb_values = [
             x::Cw::BackPixel(screen.white_pixel()),
             x::Cw::EventMask(
-                x::EventMask::EXPOSURE | x::EventMask::STRUCTURE_NOTIFY | x::EventMask::KEY_PRESS,
+                x::EventMask::EXPOSURE
+                    | x::EventMask::STRUCTURE_NOTIFY
+                    | x::EventMask::KEY_PRESS
+                    | x::EventMask::KEY_RELEASE
+                    | x::EventMask::BUTTON_PRESS
+                    | x::EventMask::BUTTON_RELEASE
+                    | x::EventMask::POINTER_MOTION
+                    | x::EventMask::BUTTON1_MOTION
+                    | x::EventMask::BUTTON2_MOTION
+                    | x::EventMask::BUTTON3_MOTION
+                    | x::EventMask::BUTTON4_MOTION
+                    | x::EventMask::BUTTON5_MOTION
+                    | x::EventMask::BUTTON_MOTION,
             ),
         ];
 
@@ -238,7 +248,7 @@ impl X11WindowState {
 
         // Note: this has to be done after the GPU init, or otherwise
         // the sizes are immediately invalidated.
-        let gpu_extent = query_render_extent(&xcb_connection, x_window);
+        let gpu_extent = query_render_extent(xcb_connection, x_window);
 
         Self {
             xcb_connection: Arc::clone(xcb_connection),
@@ -250,6 +260,7 @@ impl X11WindowState {
                 bounds,
                 scale_factor: 1.0,
                 renderer: BladeRenderer::new(gpu, gpu_extent),
+                input_handler: None,
             }),
         }
     }
@@ -313,6 +324,20 @@ impl X11WindowState {
             })
             .unwrap();
     }
+
+    pub fn handle_input(&self, input: PlatformInput) {
+        if let Some(ref mut fun) = self.callbacks.lock().input {
+            if fun(input.clone()) {
+                return;
+            }
+        }
+        if let PlatformInput::KeyDown(event) = input {
+            let mut inner = self.inner.lock();
+            if let Some(ref mut input_handler) = inner.input_handler {
+                input_handler.replace_text_in_range(None, &event.keystroke.key);
+            }
+        }
+    }
 }
 
 impl PlatformWindow for X11Window {
@@ -356,12 +381,12 @@ impl PlatformWindow for X11Window {
         self
     }
 
-    //todo!(linux)
-    fn set_input_handler(&mut self, input_handler: PlatformInputHandler) {}
+    fn set_input_handler(&mut self, input_handler: PlatformInputHandler) {
+        self.0.inner.lock().input_handler = Some(input_handler);
+    }
 
-    //todo!(linux)
     fn take_input_handler(&mut self) -> Option<PlatformInputHandler> {
-        None
+        self.0.inner.lock().input_handler.take()
     }
 
     //todo!(linux)
@@ -378,7 +403,7 @@ impl PlatformWindow for X11Window {
     fn activate(&self) {
         self.0.xcb_connection.send_request(&x::ConfigureWindow {
             window: self.0.x_window,
-            value_list: &[x::ConfigWindow::StackMode(StackMode::Above)],
+            value_list: &[x::ConfigWindow::StackMode(x::StackMode::Above)],
         });
     }