From 0e8ed8aa4046868d3e2cd32eb564c65f0b8a76c7 Mon Sep 17 00:00:00 2001
From: alex-ds13 <145657253+alex-ds13@users.noreply.github.com>
Date: Wed, 2 Apr 2025 19:44:22 +0100
Subject: [PATCH] feat(wm): apply wallpapers per monitor

---
 komorebi/src/monitor.rs        |  3 ++-
 komorebi/src/window_manager.rs |  7 +++++++
 komorebi/src/windows_api.rs    | 20 ++++++++++++++++++--
 komorebi/src/workspace.rs      | 10 +++++-----
 4 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/komorebi/src/monitor.rs b/komorebi/src/monitor.rs
index 26f447ec..5664d335 100644
--- a/komorebi/src/monitor.rs
+++ b/komorebi/src/monitor.rs
@@ -177,9 +177,10 @@ impl Monitor {
 
     pub fn load_focused_workspace(&mut self, mouse_follows_focus: bool) -> Result<()> {
         let focused_idx = self.focused_workspace_idx();
+        let hmonitor = self.id();
         for (i, workspace) in self.workspaces_mut().iter_mut().enumerate() {
             if i == focused_idx {
-                workspace.restore(mouse_follows_focus)?;
+                workspace.restore(mouse_follows_focus, hmonitor)?;
             } else {
                 workspace.hide(None);
             }
diff --git a/komorebi/src/window_manager.rs b/komorebi/src/window_manager.rs
index 4ccf2a1f..d6eae048 100644
--- a/komorebi/src/window_manager.rs
+++ b/komorebi/src/window_manager.rs
@@ -1014,6 +1014,7 @@ impl WindowManager {
             let focused_workspace_idx = monitor.focused_workspace_idx();
             monitor.update_workspace_globals(focused_workspace_idx, offset);
 
+            let hmonitor = monitor.id();
             let workspace = monitor
                 .focused_workspace_mut()
                 .ok_or_else(|| anyhow!("there is no workspace"))?;
@@ -1025,6 +1026,12 @@ impl WindowManager {
                 }
             }
 
+            if workspace.wallpaper().is_some() {
+                if let Err(error) = workspace.apply_wallpaper(hmonitor) {
+                    tracing::error!("failed to apply wallpaper: {}", error);
+                }
+            }
+
             workspace.update()?;
         }
 
diff --git a/komorebi/src/windows_api.rs b/komorebi/src/windows_api.rs
index 7281ff0d..b76b8ad0 100644
--- a/komorebi/src/windows_api.rs
+++ b/komorebi/src/windows_api.rs
@@ -1008,6 +1008,16 @@ impl WindowsApi {
         Ok(ex_info)
     }
 
+    pub fn monitor_device_path(hmonitor: isize) -> Option<String> {
+        for display in win32_display_data::connected_displays_all().flatten() {
+            if display.hmonitor == hmonitor {
+                return Some(display.device_path.clone());
+            }
+        }
+
+        None
+    }
+
     pub fn monitor(hmonitor: isize) -> Result<Monitor> {
         for mut display in win32_display_data::connected_displays_all().flatten() {
             if display.hmonitor == hmonitor {
@@ -1352,7 +1362,7 @@ impl WindowsApi {
         unsafe { WTSRegisterSessionNotification(HWND(as_ptr!(hwnd)), 1) }.process()
     }
 
-    pub fn set_wallpaper(path: &Path) -> Result<()> {
+    pub fn set_wallpaper(path: &Path, hmonitor: isize) -> Result<()> {
         let path = path.canonicalize()?;
 
         let wallpaper: IDesktopWallpaper =
@@ -1363,9 +1373,15 @@ impl WindowsApi {
             wallpaper.SetPosition(DWPOS_FILL)?;
         }
 
+        let monitor_id = if let Some(path) = Self::monitor_device_path(hmonitor) {
+            PCWSTR::from_raw(HSTRING::from(path).as_ptr())
+        } else {
+            PCWSTR::null()
+        };
+
         // Set the wallpaper
         unsafe {
-            wallpaper.SetWallpaper(PCWSTR::null(), PCWSTR::from_raw(wallpaper_path.as_ptr()))?;
+            wallpaper.SetWallpaper(monitor_id, PCWSTR::from_raw(wallpaper_path.as_ptr()))?;
         }
         Ok(())
     }
diff --git a/komorebi/src/workspace.rs b/komorebi/src/workspace.rs
index 540a1ec7..4aaaa41e 100644
--- a/komorebi/src/workspace.rs
+++ b/komorebi/src/workspace.rs
@@ -302,9 +302,9 @@ impl Workspace {
         }
     }
 
-    pub fn apply_wallpaper(&self) -> Result<()> {
+    pub fn apply_wallpaper(&self, hmonitor: isize) -> Result<()> {
         if let Some(wallpaper) = &self.wallpaper {
-            if let Err(error) = WindowsApi::set_wallpaper(&wallpaper.path) {
+            if let Err(error) = WindowsApi::set_wallpaper(&wallpaper.path, hmonitor) {
                 tracing::error!("failed to set wallpaper: {error}");
             }
 
@@ -419,12 +419,12 @@ impl Workspace {
         Ok(())
     }
 
-    pub fn restore(&mut self, mouse_follows_focus: bool) -> Result<()> {
+    pub fn restore(&mut self, mouse_follows_focus: bool, hmonitor: isize) -> Result<()> {
         if let Some(container) = self.monocle_container() {
             if let Some(window) = container.focused_window() {
                 container.restore();
                 window.focus(mouse_follows_focus)?;
-                return self.apply_wallpaper();
+                return self.apply_wallpaper(hmonitor);
             }
         }
 
@@ -468,7 +468,7 @@ impl Workspace {
             floating_window.focus(mouse_follows_focus)?;
         }
 
-        self.apply_wallpaper()
+        self.apply_wallpaper(hmonitor)
     }
 
     pub fn update(&mut self) -> Result<()> {