windows: honor xdg_toplevel_set_fullscreen output hint (#8965)

Co-authored-by: Dardo D Kleiner <dardo.kleiner@nrl.navy.mil>

src/desktop/Window.cpp

@@ -1382,15 +1382,26 @@ void CWindow::activate(bool force) {
 }
 
 void CWindow::onUpdateState() {
-    std::optional<bool> requestsFS = m_pXDGSurface ? m_pXDGSurface->toplevel->state.requestsFullscreen : m_pXWaylandSurface->state.requestsFullscreen;
+    std::optional<bool>      requestsFS = m_pXDGSurface ? m_pXDGSurface->toplevel->state.requestsFullscreen : m_pXWaylandSurface->state.requestsFullscreen;
-    std::optional<bool> requestsMX = m_pXDGSurface ? m_pXDGSurface->toplevel->state.requestsMaximize : m_pXWaylandSurface->state.requestsMaximize;
+    std::optional<MONITORID> requestsID = m_pXDGSurface ? m_pXDGSurface->toplevel->state.requestsFullscreenMonitor : MONITOR_INVALID;
+    std::optional<bool>      requestsMX = m_pXDGSurface ? m_pXDGSurface->toplevel->state.requestsMaximize : m_pXWaylandSurface->state.requestsMaximize;
 
     if (requestsFS.has_value() && !(m_eSuppressedEvents & SUPPRESS_FULLSCREEN)) {
-        bool fs = requestsFS.value();
+        if (requestsID.has_value() && (requestsID.value() != MONITOR_INVALID) && !(m_eSuppressedEvents & SUPPRESS_FULLSCREEN_OUTPUT)) {
-        if (m_bIsMapped) {
+            if (m_bIsMapped) {
-            g_pCompositor->changeWindowFullscreenModeClient(m_pSelf.lock(), FSMODE_FULLSCREEN, requestsFS.value());
+                const auto monitor = g_pCompositor->getMonitorFromID(requestsID.value());
+                g_pCompositor->moveWindowToWorkspaceSafe(m_pSelf.lock(), monitor->activeWorkspace);
+                g_pCompositor->setActiveMonitor(monitor);
+            }
+
+            if (!m_bIsMapped)
+                m_iWantsInitialFullscreenMonitor = requestsID.value();
         }
 
+        bool fs = requestsFS.value();
+        if (m_bIsMapped)
+            g_pCompositor->changeWindowFullscreenModeClient(m_pSelf.lock(), FSMODE_FULLSCREEN, requestsFS.value());
+
         if (!m_bIsMapped)
             m_bWantsInitialFullscreen = fs;
     }

src/desktop/Window.hpp

@@ -57,6 +57,7 @@ enum eSuppressEvents : uint8_t {
     SUPPRESS_MAXIMIZE           = 1 << 1,
     SUPPRESS_ACTIVATE           = 1 << 2,
     SUPPRESS_ACTIVATE_FOCUSONLY = 1 << 3,
+    SUPPRESS_FULLSCREEN_OUTPUT  = 1 << 4,
 };
 
 class IWindowTransformer;
@@ -288,7 +289,8 @@ class CWindow {
     bool m_bNoInitialFocus = false;
 
     // Fullscreen and Maximize
-    bool m_bWantsInitialFullscreen = false;
+    bool      m_bWantsInitialFullscreen        = false;
+    MONITORID m_iWantsInitialFullscreenMonitor = MONITOR_INVALID;
 
     // bitfield eSuppressEvents
     uint64_t m_eSuppressedEvents = SUPPRESS_NONE;

src/events/Windows.cpp

@@ -131,6 +131,7 @@ void Events::listener_mapWindow(void* owner, void* data) {
     std::optional<SFullscreenState> requestedFSState;
     if (PWINDOW->m_bWantsInitialFullscreen || (PWINDOW->m_bIsX11 && PWINDOW->m_pXWaylandSurface->fullscreen))
         requestedClientFSMode = FSMODE_FULLSCREEN;
+    MONITORID requestedFSMonitor = PWINDOW->m_iWantsInitialFullscreenMonitor;
 
     for (auto const& r : PWINDOW->m_vMatchedRules) {
         switch (r->ruleType) {
@@ -168,6 +169,7 @@ void Events::listener_mapWindow(void* owner, void* data) {
                     PWORKSPACE            = PWINDOW->m_pWorkspace;
 
                     Debug::log(LOG, "Rule monitor, applying to {:mw}", PWINDOW);
+                    requestedFSMonitor = MONITOR_INVALID;
                 } catch (std::exception& e) { Debug::log(ERR, "Rule monitor failed, rule: {} -> {} | err: {}", r->szRule, r->szValue, e.what()); }
                 break;
             }
@@ -186,6 +188,7 @@ void Events::listener_mapWindow(void* owner, void* data) {
                     requestedWorkspace = "";
 
                 Debug::log(LOG, "Rule workspace matched by {}, {} applied.", PWINDOW, r->szValue);
+                requestedFSMonitor = MONITOR_INVALID;
                 break;
             }
             case CWindowRule::RULE_FLOAT: {
@@ -227,6 +230,8 @@ void Events::listener_mapWindow(void* owner, void* data) {
                         PWINDOW->m_eSuppressedEvents |= SUPPRESS_ACTIVATE;
                     else if (vars[i] == "activatefocus")
                         PWINDOW->m_eSuppressedEvents |= SUPPRESS_ACTIVATE_FOCUSONLY;
+                    else if (vars[i] == "fullscreenoutput")
+                        PWINDOW->m_eSuppressedEvents |= SUPPRESS_FULLSCREEN_OUTPUT;
                     else
                         Debug::log(ERR, "Error while parsing suppressevent windowrule: unknown event type {}", vars[i]);
                 }
@@ -337,10 +342,30 @@ void Events::listener_mapWindow(void* owner, void* data) {
 
                 PMONITOR = g_pCompositor->m_pLastMonitor.lock();
             }
+
+            requestedFSMonitor = MONITOR_INVALID;
         } else
             workspaceSilent = false;
     }
 
+    if (PWINDOW->m_eSuppressedEvents & SUPPRESS_FULLSCREEN_OUTPUT)
+        requestedFSMonitor = MONITOR_INVALID;
+    else if (requestedFSMonitor != MONITOR_INVALID) {
+        if (const auto PM = g_pCompositor->getMonitorFromID(requestedFSMonitor); PM)
+            PWINDOW->m_pMonitor = PM;
+
+        const auto PMONITORFROMID = PWINDOW->m_pMonitor.lock();
+
+        if (PWINDOW->m_pMonitor != PMONITOR) {
+            g_pKeybindManager->m_mDispatchers["focusmonitor"](std::to_string(PWINDOW->monitorID()));
+            PMONITOR = PMONITORFROMID;
+        }
+        PWINDOW->m_pWorkspace = PMONITOR->activeSpecialWorkspace ? PMONITOR->activeSpecialWorkspace : PMONITOR->activeWorkspace;
+        PWORKSPACE            = PWINDOW->m_pWorkspace;
+
+        Debug::log(LOG, "Requested monitor, applying to {:mw}", PWINDOW);
+    }
+
     if (PWORKSPACE->m_bDefaultFloating)
         PWINDOW->m_bIsFloating = true;
 

src/protocols/XDGShell.cpp

@@ -5,6 +5,7 @@
 #include "../managers/SeatManager.hpp"
 #include "core/Seat.hpp"
 #include "core/Compositor.hpp"
+#include "protocols/core/Output.hpp"
 #include <cstring>
 #include <ranges>
 
@@ -191,9 +192,14 @@ CXDGToplevelResource::CXDGToplevelResource(SP<CXdgToplevel> resource_, SP<CXDGSu
     });
 
     resource->setSetFullscreen([this](CXdgToplevel* r, wl_resource* output) {
+        if (output)
+            if (const auto PM = CWLOutputResource::fromResource(output)->monitor; PM)
+                state.requestsFullscreenMonitor = PM->ID;
+
         state.requestsFullscreen = true;
         events.stateChanged.emit();
         state.requestsFullscreen.reset();
+        state.requestsFullscreenMonitor.reset();
     });
 
     resource->setUnsetFullscreen([this](CXdgToplevel* r) {
@@ -205,7 +211,7 @@ CXDGToplevelResource::CXDGToplevelResource(SP<CXdgToplevel> resource_, SP<CXDGSu
     resource->setSetMinimized([this](CXdgToplevel* r) {
         state.requestsMinimize = true;
         events.stateChanged.emit();
-        state.requestsFullscreen.reset();
+        state.requestsMinimize.reset();
     });
 
     resource->setSetParent([this](CXdgToplevel* r, wl_resource* parentR) {

src/protocols/XDGShell.hpp

@@ -123,9 +123,10 @@ class CXDGToplevelResource {
         std::string appid;
 
         // volatile state: is reset after the stateChanged signal fires
-        std::optional<bool> requestsMaximize;
+        std::optional<bool>      requestsMaximize;
-        std::optional<bool> requestsFullscreen;
+        std::optional<bool>      requestsFullscreen;
-        std::optional<bool> requestsMinimize;
+        std::optional<MONITORID> requestsFullscreenMonitor;
+        std::optional<bool>      requestsMinimize;
     } state;
 
     struct {