[sf] Set visible regions change flag when layer starts drawing

If a layer state changes so it has a buffer or an effect like
color then, update the flags to indicate that visiblity of a
snapshot has changed. This will mark the visible regions
flag in CE args and force CE to rebuild its layer stack.
Without this flag, there was a scenario where CE
would get a null snapshot and crash.

Also crash early with traces if we ever pass a null snapshot to
CE.

Test: presubmit
Bug: 238781169, 295069311, 294889236
Change-Id: I355502fbe7f1be38c46a5ed25233b6b07c6b4eeb
diff --git a/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp b/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
index a5d5563..8a39cd6 100644
--- a/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
+++ b/services/surfaceflinger/FrontEnd/RequestedLayerState.cpp
@@ -150,7 +150,7 @@
 
     const bool hadSideStream = sidebandStream != nullptr;
     const layer_state_t& clientState = resolvedComposerState.state;
-    const bool hadBlur = hasBlur();
+    const bool hadSomethingToDraw = hasSomethingToDraw();
     uint64_t clientChanges = what | layer_state_t::diff(clientState);
     layer_state_t::merge(clientState);
     what = clientChanges;
@@ -228,11 +228,10 @@
                     RequestedLayerState::Changes::VisibleRegion;
         }
     }
-    if (what & (layer_state_t::eBackgroundBlurRadiusChanged | layer_state_t::eBlurRegionsChanged)) {
-        if (hadBlur != hasBlur()) {
-            changes |= RequestedLayerState::Changes::Visibility |
-                    RequestedLayerState::Changes::VisibleRegion;
-        }
+
+    if (hadSomethingToDraw != hasSomethingToDraw()) {
+        changes |= RequestedLayerState::Changes::Visibility |
+                RequestedLayerState::Changes::VisibleRegion;
     }
     if (clientChanges & layer_state_t::HIERARCHY_CHANGES)
         changes |= RequestedLayerState::Changes::Hierarchy;
@@ -579,6 +578,12 @@
     return externalTexture && externalTexture->getUsage() & GRALLOC_USAGE_PROTECTED;
 }
 
+bool RequestedLayerState::hasSomethingToDraw() const {
+    return externalTexture != nullptr || sidebandStream != nullptr || shadowRadius > 0.f ||
+            backgroundBlurRadius > 0 || blurRegions.size() > 0 ||
+            (color.r >= 0.0_hf && color.g >= 0.0_hf && color.b >= 0.0_hf);
+}
+
 void RequestedLayerState::clearChanges() {
     what = 0;
     changes.clear();
diff --git a/services/surfaceflinger/FrontEnd/RequestedLayerState.h b/services/surfaceflinger/FrontEnd/RequestedLayerState.h
index 8eff22b..09f33de 100644
--- a/services/surfaceflinger/FrontEnd/RequestedLayerState.h
+++ b/services/surfaceflinger/FrontEnd/RequestedLayerState.h
@@ -87,6 +87,7 @@
     bool backpressureEnabled() const;
     bool isSimpleBufferUpdate(const layer_state_t&) const;
     bool isProtected() const;
+    bool hasSomethingToDraw() const;
 
     // Layer serial number.  This gives layers an explicit ordering, so we
     // have a stable sort order when their layer stack and Z-order are
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index fa07001..32bb46c 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -134,6 +134,7 @@
 #include "FrontEnd/LayerCreationArgs.h"
 #include "FrontEnd/LayerHandle.h"
 #include "FrontEnd/LayerLifecycleManager.h"
+#include "FrontEnd/LayerLog.h"
 #include "FrontEnd/LayerSnapshot.h"
 #include "HdrLayerInfoReporter.h"
 #include "Layer.h"
@@ -2620,6 +2621,23 @@
     constexpr bool kCursorOnly = false;
     const auto layers = moveSnapshotsToCompositionArgs(refreshArgs, kCursorOnly);
 
+    if (mLayerLifecycleManagerEnabled && !refreshArgs.updatingGeometryThisFrame) {
+        for (const auto& [token, display] : FTL_FAKE_GUARD(mStateLock, mDisplays)) {
+            auto compositionDisplay = display->getCompositionDisplay();
+            if (!compositionDisplay->getState().isEnabled) continue;
+            for (auto outputLayer : compositionDisplay->getOutputLayersOrderedByZ()) {
+                LLOG_ALWAYS_FATAL_WITH_TRACE_IF(outputLayer->getLayerFE().getCompositionState() ==
+                                                        nullptr,
+                                                "Output layer %s for display %s %" PRIu64
+                                                " has a null "
+                                                "snapshot.",
+                                                outputLayer->getLayerFE().getDebugName(),
+                                                compositionDisplay->getName().c_str(),
+                                                compositionDisplay->getId().value);
+            }
+        }
+    }
+
     mCompositionEngine->present(refreshArgs);
     moveSnapshotsFromCompositionArgs(refreshArgs, layers);
 
diff --git a/services/surfaceflinger/tests/unittests/LayerLifecycleManagerTest.cpp b/services/surfaceflinger/tests/unittests/LayerLifecycleManagerTest.cpp
index e3c7837..d65277a 100644
--- a/services/surfaceflinger/tests/unittests/LayerLifecycleManagerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/LayerLifecycleManagerTest.cpp
@@ -389,4 +389,52 @@
     listener->expectLayersDestroyed({1, bgLayerId});
 }
 
+TEST_F(LayerLifecycleManagerTest, blurSetsVisibilityChangeFlag) {
+    // clear default color on layer so we start with a layer that does not draw anything.
+    setColor(1, {-1.f, -1.f, -1.f});
+    mLifecycleManager.commitChanges();
+
+    // layer has something to draw
+    setBackgroundBlurRadius(1, 2);
+    EXPECT_TRUE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+
+    // layer still has something to draw, so visibility shouldn't change
+    setBackgroundBlurRadius(1, 3);
+    EXPECT_FALSE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+
+    // layer has nothing to draw
+    setBackgroundBlurRadius(1, 0);
+    EXPECT_TRUE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+}
+
+TEST_F(LayerLifecycleManagerTest, colorSetsVisibilityChangeFlag) {
+    // clear default color on layer so we start with a layer that does not draw anything.
+    setColor(1, {-1.f, -1.f, -1.f});
+    mLifecycleManager.commitChanges();
+
+    // layer has something to draw
+    setColor(1, {2.f, 3.f, 4.f});
+    EXPECT_TRUE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+
+    // layer still has something to draw, so visibility shouldn't change
+    setColor(1, {0.f, 0.f, 0.f});
+    EXPECT_FALSE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+
+    // layer has nothing to draw
+    setColor(1, {-1.f, -1.f, -1.f});
+    EXPECT_TRUE(
+            mLifecycleManager.getGlobalChanges().test(RequestedLayerState::Changes::Visibility));
+    mLifecycleManager.commitChanges();
+}
+
 } // namespace android::surfaceflinger::frontend
diff --git a/services/surfaceflinger/tests/unittests/LayerSnapshotTest.cpp b/services/surfaceflinger/tests/unittests/LayerSnapshotTest.cpp
index 84c3775..c8eda12 100644
--- a/services/surfaceflinger/tests/unittests/LayerSnapshotTest.cpp
+++ b/services/surfaceflinger/tests/unittests/LayerSnapshotTest.cpp
@@ -349,16 +349,22 @@
 }
 
 TEST_F(LayerSnapshotTest, blurUpdatesWhenAlphaChanges) {
-    static constexpr int blurRadius = 42;
-    setBackgroundBlurRadius(1221, blurRadius);
+    int blurRadius = 42;
+    setBackgroundBlurRadius(1221, static_cast<uint32_t>(blurRadius));
 
     UPDATE_AND_VERIFY(mSnapshotBuilder, STARTING_ZORDER);
     EXPECT_EQ(getSnapshot({.id = 1221})->backgroundBlurRadius, blurRadius);
 
+    blurRadius = 21;
+    setBackgroundBlurRadius(1221, static_cast<uint32_t>(blurRadius));
+    UPDATE_AND_VERIFY(mSnapshotBuilder, STARTING_ZORDER);
+    EXPECT_EQ(getSnapshot({.id = 1221})->backgroundBlurRadius, blurRadius);
+
     static constexpr float alpha = 0.5;
     setAlpha(12, alpha);
     UPDATE_AND_VERIFY(mSnapshotBuilder, STARTING_ZORDER);
-    EXPECT_EQ(getSnapshot({.id = 1221})->backgroundBlurRadius, blurRadius * alpha);
+    EXPECT_EQ(getSnapshot({.id = 1221})->backgroundBlurRadius,
+              static_cast<int>(static_cast<float>(blurRadius) * alpha));
 }
 
 // Display Mirroring Tests