core: Accumulate render damage

[PlasmaPower]

Describe your PR, what does it fix/add?

If a client commits multiple times before we next render, we should accumulate damage instead of replacing it.

Is there anything you want to mention? (unchecked code, possible bugs, found problems, breaking compatibility, etc.)

Nope

Is it ready for merging, or does it need work?

Ready for merging

[ikalco]

I think you can just keep track of damage in surface.current, something like this

diff --git a/src/desktop/WLSurface.cpp b/src/desktop/WLSurface.cpp
index 11da7b68..4f8e7429 100644
--- a/src/desktop/WLSurface.cpp
+++ b/src/desktop/WLSurface.cpp
@@ -99,6 +99,7 @@ CRegion CWLSurface::computeDamage() const {
         return {};
 
     CRegion damage = m_pResource->current.accumulateBufferDamage();
+    m_pResource->current.bufferDamage.clear();
     damage.transform(wlTransformToHyprutils(m_pResource->current.transform), m_pResource->current.bufferSize.x, m_pResource->current.bufferSize.y);
 
     const auto BUFSIZE    = m_pResource->current.bufferSize;
diff --git a/src/protocols/types/SurfaceState.cpp b/src/protocols/types/SurfaceState.cpp
old mode 100644
new mode 100755
index a97f69b4..f81c6bb0
--- a/src/protocols/types/SurfaceState.cpp
+++ b/src/protocols/types/SurfaceState.cpp
@@ -74,8 +74,8 @@ void SSurfaceState::updateFrom(SSurfaceState& ref) {
     }
 
     if (ref.updated.damage) {
-        damage       = ref.damage;
-        bufferDamage = ref.bufferDamage;
+        damage.add(ref.damage);
+        bufferDamage.add(ref.bufferDamage);
     }
 
     if (ref.updated.input)
diff --git a/src/protocols/types/SurfaceState.hpp b/src/protocols/types/SurfaceState.hpp
index 07ade832..b58aa9a8 100644
--- a/src/protocols/types/SurfaceState.hpp
+++ b/src/protocols/types/SurfaceState.hpp
@@ -55,7 +55,7 @@ struct SSurfaceState {
     void         updateSynchronousTexture(SP<CTexture> lastTexture);
 
     // helpers
-    CRegion accumulateBufferDamage();       // transforms state.damage and merges it into state.bufferDamage
+    CRegion accumulateBufferDamage();       // returns total damage in buffer coords
     void    updateFrom(SSurfaceState& ref); // updates this state based on a reference state.
     void    reset();                        // resets pending state after commit
 };

[PlasmaPower]

That breaks the damage passed to updating the shm texture and cursor.

[gulafaran]

no regressions here, lgtm.

[vaxerski]

this is incredibly unintuitive and not documented

[PlasmaPower]

It's already documented in the comment I added to computeRenderDamage in the .hpp. Should I rename the method or add additional documentation?

[vaxerski]

I would just not do this. Why? Maybe add another method to explicitly clear render damage

[PlasmaPower]

Sorry I forgot about this. I added the separate method.

[PlasmaPower]

Actually I don't think this is necessary, because it looks like the surface should be damaged per commit not per render