renderer: Tearing implementation (#3441)

src/helpers/Monitor.cpp

@@ -40,6 +40,8 @@ void CMonitor::onConnect(bool noRule) {
     hyprListener_monitorCommit.initCallback(&output->events.commit, &Events::listener_monitorCommit, this);
     hyprListener_monitorBind.initCallback(&output->events.bind, &Events::listener_monitorBind, this);
 
+    canTear = wlr_backend_is_drm(output->backend); // tearing only works on drm
+
     if (m_bEnabled) {
         wlr_output_enable(output, 1);
         wlr_output_commit(output);

src/helpers/Monitor.hpp

@@ -81,6 +81,13 @@ class CMonitor {
 
     CRegion                lastFrameDamage; // stores last frame damage
 
+    // for tearing
+    CWindow* solitaryClient           = nullptr;
+    bool     canTear                  = false;
+    bool     nextRenderTorn           = false;
+    bool     ignoreNextFlipEvent      = false;
+    bool     renderingFromVblankEvent = false;
+
     // for the special workspace. 0 means not open.
     int                                                        specialWorkspaceID = 0;
 

src/helpers/SubsurfaceTree.cpp

@@ -245,6 +245,15 @@ void Events::listener_commitSubsurface(void* owner, void* data) {
 
     if (pNode->pSurface && pNode->pSurface->exists())
         g_pHyprRenderer->damageSurface(pNode->pSurface->wlr(), lx, ly, SCALE);
+
+    if (pNode->pWindowOwner) {
+        // tearing: if solitary, redraw it. This still might be a single surface window
+        const auto PMONITOR = g_pCompositor->getMonitorFromID(pNode->pWindowOwner->m_iMonitorID);
+        if (PMONITOR->solitaryClient == pNode->pWindowOwner && pNode->pWindowOwner->canBeTorn() && PMONITOR->canTear) {
+            PMONITOR->nextRenderTorn = true;
+            g_pHyprRenderer->renderMonitor(PMONITOR);
+        }
+    }
 }
 
 void Events::listener_destroySubsurface(void* owner, void* data) {

src/helpers/WLClasses.hpp

@@ -180,7 +180,7 @@ struct SConstraint {
     Vector2D getLogicConstraintSize();
 
     bool     operator==(const SConstraint& b) const {
-            return constraint == b.constraint;
+        return constraint == b.constraint;
     }
 };
 
@@ -393,3 +393,14 @@ struct SSwitchDevice {
         return pWlrDevice == other.pWlrDevice;
     }
 };
+
+struct STearingController {
+    wlr_tearing_control_v1* pWlrHint = nullptr;
+
+    DYNLISTENER(set);
+    DYNLISTENER(destroy);
+
+    bool operator==(const STearingController& other) {
+        return pWlrHint == other.pWlrHint;
+    }
+};