Add support for restricting HDR headroom for video

This is needed for allowing apps to vote for HDR headroom restrictions
for SurfaceView and SurfaceControl

Bug: 323964760
Test: manually poking at test app
Test: SurfaceViewTests
Test: SurfaceControlTest
Test: ASurfaceControlTest
Change-Id: Ie886e67879525462d49fdedc535aea659d69321a
diff --git a/services/surfaceflinger/FrontEnd/LayerSnapshot.cpp b/services/surfaceflinger/FrontEnd/LayerSnapshot.cpp
index 38974a2..8b200a2 100644
--- a/services/surfaceflinger/FrontEnd/LayerSnapshot.cpp
+++ b/services/surfaceflinger/FrontEnd/LayerSnapshot.cpp
@@ -380,6 +380,9 @@
         currentHdrSdrRatio = requested.currentHdrSdrRatio;
         desiredHdrSdrRatio = requested.desiredHdrSdrRatio;
     }
+    if (forceUpdate || requested.what & layer_state_t::eDesiredHdrHeadroomChanged) {
+        desiredHdrSdrRatio = requested.desiredHdrSdrRatio;
+    }
     if (forceUpdate || requested.what & layer_state_t::eCachingHintChanged) {
         cachingHint = requested.cachingHint;
     }
diff --git a/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp b/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
index 209df79..b72588a 100644
--- a/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
+++ b/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
@@ -98,7 +98,7 @@
     z = 0;
     layerStack = ui::DEFAULT_LAYER_STACK;
     transformToDisplayInverse = false;
-    desiredHdrSdrRatio = 1.f;
+    desiredHdrSdrRatio = -1.f;
     currentHdrSdrRatio = 1.f;
     dataspaceRequested = false;
     hdrMetadata.validTypes = 0;
@@ -603,7 +603,8 @@
             layer_state_t::eShadowRadiusChanged | layer_state_t::eFixedTransformHintChanged |
             layer_state_t::eTrustedOverlayChanged | layer_state_t::eStretchChanged |
             layer_state_t::eBufferCropChanged | layer_state_t::eDestinationFrameChanged |
-            layer_state_t::eDimmingEnabledChanged | layer_state_t::eExtendedRangeBrightnessChanged;
+            layer_state_t::eDimmingEnabledChanged | layer_state_t::eExtendedRangeBrightnessChanged |
+            layer_state_t::eDesiredHdrHeadroomChanged;
     if (changedFlags & deniedChanges) {
         ATRACE_FORMAT_INSTANT("%s: false [has denied changes flags 0x%" PRIx64 "]", __func__,
                               s.what & deniedChanges);
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 219a8e2..736fec6 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -3395,6 +3395,14 @@
     return true;
 }
 
+bool Layer::setDesiredHdrHeadroom(float desiredRatio) {
+    if (mDrawingState.desiredHdrSdrRatio == desiredRatio) return false;
+    mDrawingState.desiredHdrSdrRatio = desiredRatio;
+    mDrawingState.modified = true;
+    setTransactionFlags(eTransactionNeeded);
+    return true;
+}
+
 bool Layer::setCachingHint(gui::CachingHint cachingHint) {
     if (mDrawingState.cachingHint == cachingHint) return false;
     mDrawingState.cachingHint = cachingHint;
@@ -3991,6 +3999,13 @@
         }
     }
 
+    if (s.what & layer_state_t::eDesiredHdrHeadroomChanged) {
+        if (mDrawingState.desiredHdrSdrRatio != s.desiredHdrSdrRatio) {
+            ATRACE_FORMAT_INSTANT("%s: false [eDesiredHdrHeadroomChanged changed]", __func__);
+            return false;
+        }
+    }
+
     return true;
 }
 
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index dfd57c6..0ceecec 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -233,7 +233,7 @@
         bool autoRefresh = false;
         bool dimmingEnabled = true;
         float currentHdrSdrRatio = 1.f;
-        float desiredHdrSdrRatio = 1.f;
+        float desiredHdrSdrRatio = -1.f;
         gui::CachingHint cachingHint = gui::CachingHint::Enabled;
         int64_t latchedVsyncId = 0;
         bool useVsyncIdForRefreshRateSelection = false;
@@ -317,6 +317,7 @@
     void setDesiredPresentTime(nsecs_t /*desiredPresentTime*/, bool /*isAutoTimestamp*/);
     bool setDataspace(ui::Dataspace /*dataspace*/);
     bool setExtendedRangeBrightness(float currentBufferRatio, float desiredRatio);
+    bool setDesiredHdrHeadroom(float desiredRatio);
     bool setCachingHint(gui::CachingHint cachingHint);
     bool setHdrMetadata(const HdrMetadata& /*hdrMetadata*/);
     bool setSurfaceDamageRegion(const Region& /*surfaceDamage*/);
@@ -546,7 +547,7 @@
         sp<IBinder> mReleaseBufferEndpoint;
 
         bool mFrameLatencyNeeded{false};
-        float mDesiredHdrSdrRatio = 1.f;
+        float mDesiredHdrSdrRatio = -1.f;
     };
 
     BufferInfo mBufferInfo;
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 7626fe7..1a40bc2 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3119,6 +3119,7 @@
         for (auto& [compositionDisplay, listener] : hdrInfoListeners) {
             HdrLayerInfoReporter::HdrLayerInfo info;
             int32_t maxArea = 0;
+
             auto updateInfoFn =
                     [&](const std::shared_ptr<compositionengine::Display>& compositionDisplay,
                         const frontend::LayerSnapshot& snapshot, const sp<LayerFE>& layerFe) {
@@ -3129,7 +3130,7 @@
                                         compositionDisplay->getOutputLayerForLayer(layerFe);
                                 if (outputLayer) {
                                     const float desiredHdrSdrRatio =
-                                            snapshot.desiredHdrSdrRatio <= 1.f
+                                            snapshot.desiredHdrSdrRatio < 1.f
                                             ? std::numeric_limits<float>::infinity()
                                             : snapshot.desiredHdrSdrRatio;
                                     info.mergeDesiredRatio(desiredHdrSdrRatio);
@@ -5415,6 +5416,11 @@
             flags |= eTraversalNeeded;
         }
     }
+    if (what & layer_state_t::eDesiredHdrHeadroomChanged) {
+        if (layer->setDesiredHdrHeadroom(s.desiredHdrSdrRatio)) {
+            flags |= eTraversalNeeded;
+        }
+    }
     if (what & layer_state_t::eCachingHintChanged) {
         if (layer->setCachingHint(s.cachingHint)) {
             flags |= eTraversalNeeded;
@@ -5600,6 +5606,11 @@
             flags |= eTraversalNeeded;
         }
     }
+    if (what & layer_state_t::eDesiredHdrHeadroomChanged) {
+        if (layer->setDesiredHdrHeadroom(s.desiredHdrSdrRatio)) {
+            flags |= eTraversalNeeded;
+        }
+    }
     if (what & layer_state_t::eBufferChanged) {
         std::optional<ui::Transform::RotationFlags> transformHint = std::nullopt;
         frontend::LayerSnapshot* snapshot = mLayerSnapshotBuilder.getSnapshot(layer->sequence);