feat(x11): Add Window::drag_resize_window (#2515)

src/platform_impl/linux/mod.rs

@@ -34,8 +34,8 @@ use crate::{
     },
     icon::Icon,
     window::{
-        CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes, WindowButtons,
-        WindowLevel,
+        CursorGrabMode, CursorIcon, ResizeDirection, Theme, UserAttentionType, WindowAttributes,
+        WindowButtons, WindowLevel,
     },
 };
 
@@ -424,6 +424,11 @@ impl Window {
         x11_or_wayland!(match self; Window(window) => window.drag_window())
     }
 
+    #[inline]
+    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+        x11_or_wayland!(match self; Window(window) => window.drag_resize_window(direction))
+    }
+
     #[inline]
     pub fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
         x11_or_wayland!(match self; Window(w) => w.set_cursor_hittest(hittest))

src/platform_impl/linux/wayland/window/mod.rs

@@ -19,7 +19,8 @@ use crate::platform_impl::{
     PlatformSpecificWindowBuilderAttributes as PlatformAttributes,
 };
 use crate::window::{
-    CursorGrabMode, CursorIcon, Theme, UserAttentionType, WindowAttributes, WindowButtons,
+    CursorGrabMode, CursorIcon, ResizeDirection, Theme, UserAttentionType, WindowAttributes,
+    WindowButtons,
 };
 
 use super::env::WindowingFeatures;
@@ -560,6 +561,11 @@ impl Window {
         Ok(())
     }
 
+    #[inline]
+    pub fn drag_resize_window(&self, _direction: ResizeDirection) -> Result<(), ExternalError> {
+        Err(ExternalError::NotSupported(NotSupportedError::new()))
+    }
+
     #[inline]
     pub fn set_cursor_hittest(&self, hittest: bool) -> Result<(), ExternalError> {
         self.send_request(WindowRequest::PassthroughMouseInput(!hittest));

src/platform_impl/linux/x11/util/wm.rs

@@ -4,6 +4,17 @@ use once_cell::sync::Lazy;
 
 use super::*;
 
+// https://specifications.freedesktop.org/wm-spec/latest/ar01s04.html#idm46075117309248
+pub const MOVERESIZE_TOPLEFT: isize = 0;
+pub const MOVERESIZE_TOP: isize = 1;
+pub const MOVERESIZE_TOPRIGHT: isize = 2;
+pub const MOVERESIZE_RIGHT: isize = 3;
+pub const MOVERESIZE_BOTTOMRIGHT: isize = 4;
+pub const MOVERESIZE_BOTTOM: isize = 5;
+pub const MOVERESIZE_BOTTOMLEFT: isize = 6;
+pub const MOVERESIZE_LEFT: isize = 7;
+pub const MOVERESIZE_MOVE: isize = 8;
+
 // This info is global to the window manager.
 static SUPPORTED_HINTS: Lazy<Mutex<Vec<ffi::Atom>>> =
     Lazy::new(|| Mutex::new(Vec::with_capacity(0)));

src/platform_impl/linux/x11/window.rs

@@ -21,8 +21,8 @@ use crate::{
         PlatformSpecificWindowBuilderAttributes, VideoMode as PlatformVideoMode,
     },
     window::{
-        CursorGrabMode, CursorIcon, Icon, Theme, UserAttentionType, WindowAttributes,
-        WindowButtons, WindowLevel,
+        CursorGrabMode, CursorIcon, Icon, ResizeDirection, Theme, UserAttentionType,
+        WindowAttributes, WindowButtons, WindowLevel,
     },
 };
 
@@ -1433,7 +1433,27 @@ impl UnownedWindow {
         Err(ExternalError::NotSupported(NotSupportedError::new()))
     }
 
+    /// Moves the window while it is being dragged.
     pub fn drag_window(&self) -> Result<(), ExternalError> {
+        self.drag_initiate(util::MOVERESIZE_MOVE)
+    }
+
+    /// Resizes the window while it is being dragged.
+    pub fn drag_resize_window(&self, direction: ResizeDirection) -> Result<(), ExternalError> {
+        self.drag_initiate(match direction {
+            ResizeDirection::East => util::MOVERESIZE_RIGHT,
+            ResizeDirection::North => util::MOVERESIZE_TOP,
+            ResizeDirection::NorthEast => util::MOVERESIZE_TOPRIGHT,
+            ResizeDirection::NorthWest => util::MOVERESIZE_TOPLEFT,
+            ResizeDirection::South => util::MOVERESIZE_BOTTOM,
+            ResizeDirection::SouthEast => util::MOVERESIZE_BOTTOMRIGHT,
+            ResizeDirection::SouthWest => util::MOVERESIZE_BOTTOMLEFT,
+            ResizeDirection::West => util::MOVERESIZE_LEFT,
+        })
+    }
+
+    /// Initiates a drag operation while the left mouse button is pressed.
+    fn drag_initiate(&self, action: isize) -> Result<(), ExternalError> {
         let pointer = self
             .xconn
             .query_pointer(self.xwindow, util::VIRTUAL_CORE_POINTER)
@@ -1464,7 +1484,7 @@ impl UnownedWindow {
                 [
                     (window.x as c_long + pointer.win_x as c_long),
                     (window.y as c_long + pointer.win_y as c_long),
-                    8, // _NET_WM_MOVERESIZE_MOVE
+                    action.try_into().unwrap(),
                     ffi::Button1 as c_long,
                     1,
                 ],