renderer: send frame callbacks on presented if no change (#14849)

some very picky clients like firefox expects a frame callback to
continue rendering and send buffers, if the frame is returning early
because no change its not going to recieve it, this becomes very
noticeable on a single firefox window and using new_render_scheduling
where it renders the monitor one extra time where occasionally nothing
had really changed.

src/helpers/Monitor.cpp

@@ -158,6 +158,17 @@ void CMonitor::onConnect(bool noRule) {
             });
         }
 
+        // if the monitor has no pending frames, we wont hit the no damage send frame callback path in rendermonitor
+        // this becomes really noticeable in new render scheduling. causing firefox to simply wait for a new frame callback.
+        // when nothing is scheduling new frames.
+        auto mon = m_self.lock();
+        if (!isMirror() && !g_pHyprRenderer->shouldRenderMonitor(mon)) {
+            auto const NOW = Time::steadyNow();
+            g_pHyprRenderer->sendFrameEventsToWorkspace(mon, m_activeWorkspace, NOW);
+            if (m_activeSpecialWorkspace)
+                g_pHyprRenderer->sendFrameEventsToWorkspace(mon, m_activeSpecialWorkspace, NOW);
+        }
+
         m_frameScheduler->onPresented();
 
         m_events.presented.emit();

src/render/Renderer.cpp

@@ -314,6 +314,16 @@ bool IHyprRenderer::shouldRenderWindow(PHLWINDOW pWindow) {
     return false;
 }
 
+bool IHyprRenderer::shouldRenderMonitor(PHLMONITOR monitor) {
+    static auto PDAMAGETRACKINGMODE = CConfigValue<Config::INTEGER>("debug:damage_tracking");
+    bool        hasChanged          = monitor->m_output->needsFrame || monitor->m_damage.hasChanged();
+
+    if (!hasChanged && *PDAMAGETRACKINGMODE != DAMAGE_TRACKING_NONE && monitor->m_forceFullFrames == 0)
+        return false;
+
+    return true;
+}
+
 void IHyprRenderer::renderWorkspaceWindowsFullscreen(PHLMONITOR pMonitor, PHLWORKSPACE pWorkspace, const Time::steady_tp& time) {
     PHLWINDOW pWorkspaceWindow = nullptr;
 
@@ -2036,10 +2046,7 @@ void IHyprRenderer::renderMonitor(PHLMONITOR pMonitor, bool commit) {
 
     const auto NOW = Time::steadyNow();
 
-    // check the damage
-    bool hasChanged = pMonitor->m_output->needsFrame || pMonitor->m_damage.hasChanged();
-
-    if (!hasChanged && *PDAMAGETRACKINGMODE != DAMAGE_TRACKING_NONE && pMonitor->m_forceFullFrames == 0 && damageBlinkCleanup == 0)
+    if (!shouldRenderMonitor(pMonitor) && damageBlinkCleanup == 0)
         return;
 
     if (*PDAMAGETRACKINGMODE == -1) {

src/render/Renderer.hpp

@@ -75,6 +75,7 @@ namespace Render {
         void                                damageMirrorsWith(PHLMONITOR, const CRegion&);
         bool                                shouldRenderWindow(PHLWINDOW, PHLMONITOR);
         bool                                shouldRenderWindow(PHLWINDOW);
+        bool                                shouldRenderMonitor(PHLMONITOR);
         void                                ensureCursorRenderingMode();
         bool                                shouldRenderCursor();
         void                                setCursorHidden(bool hide);
@@ -184,6 +185,8 @@ namespace Render {
         void                            pushMonitorTransformEnabled(bool enabled);
         void                            popMonitorTransformEnabled();
         bool                            monitorTransformEnabled();
+        void                            sendFrameEventsToWorkspace(PHLMONITOR pMonitor, PHLWORKSPACE pWorkspace,
+                                                                   const Time::steady_tp& now); // sends frame displayed events but doesn't actually render anything
 
         void                            setProjectionType(const Vector2D& fbSize);
         void                            setProjectionType(eRenderProjectionType projectionType);
@@ -253,8 +256,6 @@ namespace Render {
         void renderSessionLockSurface(WP<SSessionLockSurface>, PHLMONITOR, const Time::steady_tp&);
         void renderDragIcon(PHLMONITOR, const Time::steady_tp&);
         void renderIMEPopup(CInputPopup*, PHLMONITOR, const Time::steady_tp&);
-        void sendFrameEventsToWorkspace(PHLMONITOR pMonitor, PHLWORKSPACE pWorkspace,
-                                        const Time::steady_tp& now); // sends frame displayed events but doesn't actually render anything
         void renderSessionLockPrimer(PHLMONITOR pMonitor);
         void renderSessionLockMissing(PHLMONITOR pMonitor);
         void renderBackground(PHLMONITOR pMonitor);