From 39a888c7baf4bd840de7d56dc45281488baf8adf Mon Sep 17 00:00:00 2001
From: Armin Friedl <dev@friedl.net>
Date: Mon, 6 Jun 2022 21:08:50 +0200
Subject: [PATCH] Center window on screen

---
 default.toml  |  7 +++--
 src/window.rs | 79 +++++++++++++++++++++++++++++++++------------------
 2 files changed, 55 insertions(+), 31 deletions(-)

diff --git a/default.toml b/default.toml
index 1d92d36..1ef885e 100644
--- a/default.toml
+++ b/default.toml
@@ -3,14 +3,15 @@ log_level = "trace"
 [completions]
 "e" = "emacs"
 "f" = "firefox"
-"t" = "terminal"
+"t" = "xfce4-terminal"
+"j" = "jetbrains"
 
 [sources.primary]
-matcher = "Flex"
+matcher = "Prefix"
 source = "Windows"
 
 [sources.additional]
-matcher = "Flex"
+matcher = "Fuse"
 source = ["Apps", "Shell", "Test"]
 
 [theme]
diff --git a/src/window.rs b/src/window.rs
index e1a2ab9..cb475f9 100644
--- a/src/window.rs
+++ b/src/window.rs
@@ -22,6 +22,7 @@ use winit::window::{Window, WindowBuilder};
 use xcb::ffi::xcb_connection_t;
 use xcb::x::{GrabMode, PropMode};
 use xcb::XidNew;
+use xcb_wm::ewmh;
 
 pub fn build_window() -> Result<(Window, EventLoop<()>)> {
     trace! {"Initialize `winit` event loop"}
@@ -32,7 +33,6 @@ pub fn build_window() -> Result<(Window, EventLoop<()>)> {
         .with_decorations(false)
         .with_transparent(true)
         .with_title("roftl")
-        .with_visible(true)
         .with_always_on_top(true)
         .with_override_redirect(true)
         .build(&event_loop)?;
@@ -49,11 +49,7 @@ fn postprocess_window(window: &Window) -> Result<()> {
     trace! {"Post-process window for x11"}
 
     trace! {"Get low level connection and data"}
-    let screen_id = window
-        .xlib_screen_id()
-        .ok_or(anyhow! {"Could not get X11 screen id for the window"})?;
-
-    let xcb_window: xcb::x::Window = unsafe {
+    let xcb_window = unsafe {
         xcb::x::Window::new(
             window
                 .xlib_window()
@@ -61,36 +57,67 @@ fn postprocess_window(window: &Window) -> Result<()> {
         )
     };
 
-    let xcb_conn_raw = window
-        .xcb_connection()
-        .ok_or(anyhow! {"Cannot get raw xcb connection"})?;
-
-    let xcb_conn = unsafe {
-        mem::ManuallyDrop::new(xcb::Connection::from_raw_conn(mem::transmute(xcb_conn_raw)))
+    let xcb_con = unsafe {
+        let con_raw = window
+            .xcb_connection()
+            .ok_or(anyhow! {"Cannot get raw xcb connection"})?;
+        let con = xcb::Connection::from_raw_conn(con_raw as *mut xcb_connection_t);
+        // xcb::Connection closes the underlying x connection on drop
+        // since the connection is actually owned by the window we have
+        // to prevent the drop
+        mem::ManuallyDrop::new(con)
     };
 
+    let ewmh_con = xcb_wm::ewmh::Connection::connect(&xcb_con);
+    let icccm_con = xcb_wm::icccm::Connection::connect(&xcb_con);
+
+    trace! {"Unmap window"}
     let req = xcb::x::UnmapWindow { window: xcb_window };
-    let cookie = xcb_conn.send_request_checked(&req);
-    xcb_conn.check_request(cookie)?;
+    xcb_con.send_and_check_request(&req)?;
 
     trace! {"Hide window from taskbar"}
-    let xcb_conn = unsafe { xcb::Connection::from_raw_conn(mem::transmute(xcb_conn_raw)) };
-    let ewmh_conn = xcb_wm::ewmh::Connection::connect(&xcb_conn);
-
     let window_state = xcb_wm::ewmh::proto::SendWmState::new(
-        &ewmh_conn,
+        &ewmh_con,
         xcb_window,
         PropMode::Append,
         [
-            ewmh_conn.atoms._NET_WM_STATE,
-            ewmh_conn.atoms._NET_WM_STATE_SKIP_TASKBAR,
+            ewmh_con.atoms._NET_WM_STATE,
+            ewmh_con.atoms._NET_WM_STATE_SKIP_TASKBAR,
         ],
         1,
     );
-    ewmh_conn.send_request(&window_state);
+    ewmh_con.send_request(&window_state);
 
-    let req = xcb::x::MapWindow { window: xcb_window };
-    xcb_conn.send_request(&req);
+    trace! {"Center window on screen"}
+    let screen_pixel = window
+        .current_monitor()
+        .ok_or(anyhow! {"Cannot get screen size"})?
+        .size();
+
+    // usually 0,0 except in multi-head settings (or large display (see icccm spec) which we actually don't consider)
+    let screen_position = window
+        .current_monitor()
+        .ok_or(anyhow! {"Cannot get screen position"})?
+        .position();
+
+    // Configure the window to the center with a size of 800x600 pixels.
+    let window_width = 800u32;
+    let window_height = 300u32;
+    let x = screen_position.x as i32 + (screen_pixel.width as i32 / 2 - window_width as i32 / 2);
+    let y = screen_position.y as i32 + (screen_pixel.height as i32 / 2 - window_height as i32 / 2);
+
+    xcb_con.send_and_check_request(&xcb::x::ConfigureWindow {
+        window: xcb_window,
+        value_list: &[
+            xcb::x::ConfigWindow::X(x),
+            xcb::x::ConfigWindow::Y(y),
+            xcb::x::ConfigWindow::Width(window_width),
+            xcb::x::ConfigWindow::Height(window_height),
+        ],
+    })?;
+
+    trace! {"Map window"}
+    xcb_con.send_and_check_request(&xcb::x::MapWindow { window: xcb_window })?;
 
     trace! {"Grab keyboard"}
     let req = xcb::x::GrabKeyboard {
@@ -100,11 +127,7 @@ fn postprocess_window(window: &Window) -> Result<()> {
         pointer_mode: GrabMode::Async,
         keyboard_mode: GrabMode::Async,
     };
-    xcb_conn.send_request(&req);
-
-    mem::forget(xcb_conn);
-
-    // trace! {"Center window on screen"}
+    xcb_con.send_request(&req);
 
     Ok(())
 }