diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index 82a9ae2..b4fb51f 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -21,20 +21,18 @@
 // #define LOG_NDEBUG 0
 #include "VirtualDisplaySurface.h"
 
-#include <inttypes.h>
+#include <cinttypes>
 
 #include "HWComposer.h"
 #include "SurfaceFlinger.h"
 
+#include <ftl/Flags.h>
+#include <ftl/enum.h>
 #include <gui/BufferItem.h>
 #include <gui/BufferQueue.h>
 #include <gui/IProducerListener.h>
 #include <system/window.h>
 
-// ---------------------------------------------------------------------------
-namespace android {
-// ---------------------------------------------------------------------------
-
 #define VDS_LOGE(msg, ...) ALOGE("[%s] " msg, \
         mDisplayName.c_str(), ##__VA_ARGS__)
 #define VDS_LOGW_IF(cond, msg, ...) ALOGW_IF(cond, "[%s] " msg, \
@@ -42,20 +40,11 @@
 #define VDS_LOGV(msg, ...) ALOGV("[%s] " msg, \
         mDisplayName.c_str(), ##__VA_ARGS__)
 
-static const char* dbgCompositionTypeStr(compositionengine::DisplaySurface::CompositionType type) {
-    switch (type) {
-        case compositionengine::DisplaySurface::COMPOSITION_UNKNOWN:
-            return "UNKNOWN";
-        case compositionengine::DisplaySurface::COMPOSITION_GPU:
-            return "GPU";
-        case compositionengine::DisplaySurface::COMPOSITION_HWC:
-            return "HWC";
-        case compositionengine::DisplaySurface::COMPOSITION_MIXED:
-            return "MIXED";
-        default:
-            return "<INVALID>";
-    }
-}
+#define UNSUPPORTED()                                               \
+    VDS_LOGE("%s: Invalid operation on virtual display", __func__); \
+    return INVALID_OPERATION
+
+namespace android {
 
 VirtualDisplaySurface::VirtualDisplaySurface(HWComposer& hwc, VirtualDisplayId displayId,
                                              const sp<IGraphicBufferProducer>& sink,
@@ -76,14 +65,10 @@
         mQueueBufferOutput(),
         mSinkBufferWidth(0),
         mSinkBufferHeight(0),
-        mCompositionType(COMPOSITION_UNKNOWN),
         mFbFence(Fence::NO_FENCE),
         mOutputFence(Fence::NO_FENCE),
         mFbProducerSlot(BufferQueue::INVALID_BUFFER_SLOT),
         mOutputProducerSlot(BufferQueue::INVALID_BUFFER_SLOT),
-        mDbgState(DBG_STATE_IDLE),
-        mDbgLastCompositionType(COMPOSITION_UNKNOWN),
-        mMustRecompose(false),
         mForceHwcCopy(SurfaceFlinger::useHwcForRgbToYuv) {
     mSource[SOURCE_SINK] = sink;
     mSource[SOURCE_SCRATCH] = bqProducer;
@@ -131,9 +116,9 @@
 
     mMustRecompose = mustRecompose;
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_IDLE,
-            "Unexpected beginFrame() in %s state", dbgStateStr());
-    mDbgState = DBG_STATE_BEGUN;
+    VDS_LOGW_IF(mDebugState != DebugState::Idle, "Unexpected %s in %s state", __func__,
+                ftl::enum_string(mDebugState).c_str());
+    mDebugState = DebugState::Begun;
 
     return refreshOutputBuffer();
 }
@@ -143,12 +128,12 @@
         return NO_ERROR;
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_BEGUN,
-            "Unexpected prepareFrame() in %s state", dbgStateStr());
-    mDbgState = DBG_STATE_PREPARED;
+    VDS_LOGW_IF(mDebugState != DebugState::Begun, "Unexpected %s in %s state", __func__,
+                ftl::enum_string(mDebugState).c_str());
+    mDebugState = DebugState::Prepared;
 
     mCompositionType = compositionType;
-    if (mForceHwcCopy && mCompositionType == COMPOSITION_GPU) {
+    if (mForceHwcCopy && mCompositionType == CompositionType::Gpu) {
         // Some hardware can do RGB->YUV conversion more efficiently in hardware
         // controlled by HWC than in hardware controlled by the video encoder.
         // Forcing GPU-composed frames to go through an extra copy by the HWC
@@ -157,16 +142,16 @@
         //
         // On the other hand, when the consumer prefers RGB or can consume RGB
         // inexpensively, this forces an unnecessary copy.
-        mCompositionType = COMPOSITION_MIXED;
+        mCompositionType = CompositionType::Mixed;
     }
 
-    if (mCompositionType != mDbgLastCompositionType) {
-        VDS_LOGV("prepareFrame: composition type changed to %s",
-                dbgCompositionTypeStr(mCompositionType));
-        mDbgLastCompositionType = mCompositionType;
+    if (mCompositionType != mDebugLastCompositionType) {
+        VDS_LOGV("%s: composition type changed to %s", __func__,
+                 toString(mCompositionType).c_str());
+        mDebugLastCompositionType = mCompositionType;
     }
 
-    if (mCompositionType != COMPOSITION_GPU &&
+    if (mCompositionType != CompositionType::Gpu &&
         (mOutputFormat != mDefaultOutputFormat || mOutputUsage != GRALLOC_USAGE_HW_COMPOSER)) {
         // We must have just switched from GPU-only to MIXED or HWC
         // composition. Stop using the format and usage requested by the GPU
@@ -191,33 +176,32 @@
         return NO_ERROR;
     }
 
-    if (mCompositionType == COMPOSITION_HWC) {
-        VDS_LOGW_IF(mDbgState != DBG_STATE_PREPARED,
-                "Unexpected advanceFrame() in %s state on HWC frame",
-                dbgStateStr());
+    if (mCompositionType == CompositionType::Hwc) {
+        VDS_LOGW_IF(mDebugState != DebugState::Prepared, "Unexpected %s in %s state on HWC frame",
+                    __func__, ftl::enum_string(mDebugState).c_str());
     } else {
-        VDS_LOGW_IF(mDbgState != DBG_STATE_GPU_DONE,
-                    "Unexpected advanceFrame() in %s state on GPU/MIXED frame", dbgStateStr());
+        VDS_LOGW_IF(mDebugState != DebugState::GpuDone,
+                    "Unexpected %s in %s state on GPU/MIXED frame", __func__,
+                    ftl::enum_string(mDebugState).c_str());
     }
-    mDbgState = DBG_STATE_HWC;
+    mDebugState = DebugState::Hwc;
 
     if (mOutputProducerSlot < 0 ||
-            (mCompositionType != COMPOSITION_HWC && mFbProducerSlot < 0)) {
+        (mCompositionType != CompositionType::Hwc && mFbProducerSlot < 0)) {
         // Last chance bailout if something bad happened earlier. For example,
         // in a graphics API configuration, if the sink disappears then dequeueBuffer
         // will fail, the GPU driver won't queue a buffer, but SurfaceFlinger
         // will soldier on. So we end up here without a buffer. There should
         // be lots of scary messages in the log just before this.
-        VDS_LOGE("advanceFrame: no buffer, bailing out");
+        VDS_LOGE("%s: no buffer, bailing out", __func__);
         return NO_MEMORY;
     }
 
     sp<GraphicBuffer> fbBuffer = mFbProducerSlot >= 0 ?
             mProducerBuffers[mFbProducerSlot] : sp<GraphicBuffer>(nullptr);
     sp<GraphicBuffer> outBuffer = mProducerBuffers[mOutputProducerSlot];
-    VDS_LOGV("advanceFrame: fb=%d(%p) out=%d(%p)",
-            mFbProducerSlot, fbBuffer.get(),
-            mOutputProducerSlot, outBuffer.get());
+    VDS_LOGV("%s: fb=%d(%p) out=%d(%p)", __func__, mFbProducerSlot, fbBuffer.get(),
+             mOutputProducerSlot, outBuffer.get());
 
     const auto halDisplayId = HalVirtualDisplayId::tryCast(mDisplayId);
     LOG_FATAL_IF(!halDisplayId);
@@ -245,16 +229,16 @@
         return;
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_HWC,
-            "Unexpected onFrameCommitted() in %s state", dbgStateStr());
-    mDbgState = DBG_STATE_IDLE;
+    VDS_LOGW_IF(mDebugState != DebugState::Hwc, "Unexpected %s in %s state", __func__,
+                ftl::enum_string(mDebugState).c_str());
+    mDebugState = DebugState::Idle;
 
     sp<Fence> retireFence = mHwc.getPresentFence(*halDisplayId);
-    if (mCompositionType == COMPOSITION_MIXED && mFbProducerSlot >= 0) {
+    if (mCompositionType == CompositionType::Mixed && mFbProducerSlot >= 0) {
         // release the scratch buffer back to the pool
         Mutex::Autolock lock(mMutex);
         int sslot = mapProducer2SourceSlot(SOURCE_SCRATCH, mFbProducerSlot);
-        VDS_LOGV("onFrameCommitted: release scratch sslot=%d", sslot);
+        VDS_LOGV("%s: release scratch sslot=%d", __func__, sslot);
         addReleaseFenceLocked(sslot, mProducerBuffers[mFbProducerSlot],
                 retireFence);
         releaseBufferLocked(sslot, mProducerBuffers[mFbProducerSlot]);
@@ -263,7 +247,7 @@
     if (mOutputProducerSlot >= 0) {
         int sslot = mapProducer2SourceSlot(SOURCE_SINK, mOutputProducerSlot);
         QueueBufferOutput qbo;
-        VDS_LOGV("onFrameCommitted: queue sink sslot=%d", sslot);
+        VDS_LOGV("%s: queue sink sslot=%d", __func__, sslot);
         if (mMustRecompose) {
             status_t result = mSource[SOURCE_SINK]->queueBuffer(sslot,
                     QueueBufferInput(
@@ -308,8 +292,8 @@
         return mSource[SOURCE_SINK]->requestBuffer(pslot, outBuf);
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_GPU, "Unexpected requestBuffer pslot=%d in %s state", pslot,
-                dbgStateStr());
+    VDS_LOGW_IF(mDebugState != DebugState::Gpu, "Unexpected %s pslot=%d in %s state", __func__,
+                pslot, ftl::enum_string(mDebugState).c_str());
 
     *outBuf = mProducerBuffers[pslot];
     return NO_ERROR;
@@ -334,8 +318,8 @@
     if (result < 0)
         return result;
     int pslot = mapSource2ProducerSlot(source, *sslot);
-    VDS_LOGV("dequeueBuffer(%s): sslot=%d pslot=%d result=%d",
-            dbgSourceStr(source), *sslot, pslot, result);
+    VDS_LOGV("%s(%s): sslot=%d pslot=%d result=%d", __func__, ftl::enum_string(source).c_str(),
+             *sslot, pslot, result);
     uint64_t sourceBit = static_cast<uint64_t>(source) << pslot;
 
     // reset producer slot reallocation flag
@@ -363,10 +347,9 @@
             mSource[source]->cancelBuffer(*sslot, *fence);
             return result;
         }
-        VDS_LOGV("dequeueBuffer(%s): buffers[%d]=%p fmt=%d usage=%#" PRIx64,
-                dbgSourceStr(source), pslot, mProducerBuffers[pslot].get(),
-                mProducerBuffers[pslot]->getPixelFormat(),
-                mProducerBuffers[pslot]->getUsage());
+        VDS_LOGV("%s(%s): buffers[%d]=%p fmt=%d usage=%#" PRIx64, __func__,
+                 ftl::enum_string(source).c_str(), pslot, mProducerBuffers[pslot].get(),
+                 mProducerBuffers[pslot]->getPixelFormat(), mProducerBuffers[pslot]->getUsage());
 
         // propagate reallocation to VDS consumer
         mProducerSlotNeedReallocation |= 1ULL << pslot;
@@ -384,11 +367,11 @@
                                                    outTimestamps);
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_PREPARED,
-            "Unexpected dequeueBuffer() in %s state", dbgStateStr());
-    mDbgState = DBG_STATE_GPU;
+    VDS_LOGW_IF(mDebugState != DebugState::Prepared, "Unexpected %s in %s state", __func__,
+                ftl::enum_string(mDebugState).c_str());
+    mDebugState = DebugState::Gpu;
 
-    VDS_LOGV("dequeueBuffer %dx%d fmt=%d usage=%#" PRIx64, w, h, format, usage);
+    VDS_LOGV("%s %dx%d fmt=%d usage=%#" PRIx64, __func__, w, h, format, usage);
 
     status_t result = NO_ERROR;
     Source source = fbSourceForCompositionType(mCompositionType);
@@ -401,7 +384,7 @@
             // will fail, the GPU driver won't queue a buffer, but SurfaceFlinger
             // will soldier on. So we end up here without a buffer. There should
             // be lots of scary messages in the log just before this.
-            VDS_LOGE("dequeueBuffer: no buffer, bailing out");
+            VDS_LOGE("%s: no buffer, bailing out", __func__);
             return NO_MEMORY;
         }
 
@@ -417,12 +400,11 @@
                 (format != 0 && format != buf->getPixelFormat()) ||
                 (w != 0 && w != mSinkBufferWidth) ||
                 (h != 0 && h != mSinkBufferHeight)) {
-            VDS_LOGV("dequeueBuffer: dequeueing new output buffer: "
-                    "want %dx%d fmt=%d use=%#" PRIx64 ", "
-                    "have %dx%d fmt=%d use=%#" PRIx64,
-                    w, h, format, usage,
-                    mSinkBufferWidth, mSinkBufferHeight,
-                    buf->getPixelFormat(), buf->getUsage());
+            VDS_LOGV("%s: dequeueing new output buffer: "
+                     "want %dx%d fmt=%d use=%#" PRIx64 ", "
+                     "have %dx%d fmt=%d use=%#" PRIx64,
+                     __func__, w, h, format, usage, mSinkBufferWidth, mSinkBufferHeight,
+                     buf->getPixelFormat(), buf->getUsage());
             mOutputFormat = format;
             mOutputUsage = usage;
             result = refreshOutputBuffer();
@@ -452,21 +434,16 @@
     return result;
 }
 
-status_t VirtualDisplaySurface::detachBuffer(int /* slot */) {
-    VDS_LOGE("detachBuffer is not available for VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::detachBuffer(int) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::detachNextBuffer(
-        sp<GraphicBuffer>* /* outBuffer */, sp<Fence>* /* outFence */) {
-    VDS_LOGE("detachNextBuffer is not available for VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::detachNextBuffer(sp<GraphicBuffer>*, sp<Fence>*) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::attachBuffer(int* /* outSlot */,
-        const sp<GraphicBuffer>& /* buffer */) {
-    VDS_LOGE("attachBuffer is not available for VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::attachBuffer(int*, const sp<GraphicBuffer>&) {
+    UNSUPPORTED();
 }
 
 status_t VirtualDisplaySurface::queueBuffer(int pslot,
@@ -475,14 +452,14 @@
         return mSource[SOURCE_SINK]->queueBuffer(pslot, input, output);
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_GPU, "Unexpected queueBuffer(pslot=%d) in %s state", pslot,
-                dbgStateStr());
-    mDbgState = DBG_STATE_GPU_DONE;
+    VDS_LOGW_IF(mDebugState != DebugState::Gpu, "Unexpected %s(pslot=%d) in %s state", __func__,
+                pslot, ftl::enum_string(mDebugState).c_str());
+    mDebugState = DebugState::GpuDone;
 
-    VDS_LOGV("queueBuffer pslot=%d", pslot);
+    VDS_LOGV("%s pslot=%d", __func__, pslot);
 
     status_t result;
-    if (mCompositionType == COMPOSITION_MIXED) {
+    if (mCompositionType == CompositionType::Mixed) {
         // Queue the buffer back into the scratch pool
         QueueBufferOutput scratchQBO;
         int sslot = mapProducer2SourceSlot(SOURCE_SCRATCH, pslot);
@@ -498,15 +475,15 @@
         if (result != NO_ERROR)
             return result;
         VDS_LOGW_IF(item.mSlot != sslot,
-                "queueBuffer: acquired sslot %d from SCRATCH after queueing sslot %d",
-                item.mSlot, sslot);
+                    "%s: acquired sslot %d from SCRATCH after queueing sslot %d", __func__,
+                    item.mSlot, sslot);
         mFbProducerSlot = mapSource2ProducerSlot(SOURCE_SCRATCH, item.mSlot);
         mFbFence = mSlots[item.mSlot].mFence;
 
     } else {
-        LOG_FATAL_IF(mCompositionType != COMPOSITION_GPU,
-                     "Unexpected queueBuffer in state %s for compositionType %s", dbgStateStr(),
-                     dbgCompositionTypeStr(mCompositionType));
+        LOG_FATAL_IF(mCompositionType != CompositionType::Gpu,
+                     "Unexpected %s in state %s for composition type %s", __func__,
+                     ftl::enum_string(mDebugState).c_str(), toString(mCompositionType).c_str());
 
         // Extract the GPU release fence for HWC to acquire
         int64_t timestamp;
@@ -533,9 +510,9 @@
         return mSource[SOURCE_SINK]->cancelBuffer(mapProducer2SourceSlot(SOURCE_SINK, pslot), fence);
     }
 
-    VDS_LOGW_IF(mDbgState != DBG_STATE_GPU, "Unexpected cancelBuffer(pslot=%d) in %s state", pslot,
-                dbgStateStr());
-    VDS_LOGV("cancelBuffer pslot=%d", pslot);
+    VDS_LOGW_IF(mDebugState != DebugState::Gpu, "Unexpected %s(pslot=%d) in %s state", __func__,
+                pslot, ftl::enum_string(mDebugState).c_str());
+    VDS_LOGV("%s pslot=%d", __func__, pslot);
     Source source = fbSourceForCompositionType(mCompositionType);
     return mSource[source]->cancelBuffer(
             mapProducer2SourceSlot(source, pslot), fence);
@@ -573,8 +550,8 @@
     return mSource[SOURCE_SINK]->disconnect(api, mode);
 }
 
-status_t VirtualDisplaySurface::setSidebandStream(const sp<NativeHandle>& /*stream*/) {
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::setSidebandStream(const sp<NativeHandle>&) {
+    UNSUPPORTED();
 }
 
 void VirtualDisplaySurface::allocateBuffers(uint32_t /* width */,
@@ -586,40 +563,32 @@
     return INVALID_OPERATION;
 }
 
-status_t VirtualDisplaySurface::setGenerationNumber(uint32_t /* generation */) {
-    ALOGE("setGenerationNumber not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::setGenerationNumber(uint32_t) {
+    UNSUPPORTED();
 }
 
 String8 VirtualDisplaySurface::getConsumerName() const {
     return String8("VirtualDisplaySurface");
 }
 
-status_t VirtualDisplaySurface::setSharedBufferMode(bool /*sharedBufferMode*/) {
-    ALOGE("setSharedBufferMode not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::setSharedBufferMode(bool) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::setAutoRefresh(bool /*autoRefresh*/) {
-    ALOGE("setAutoRefresh not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::setAutoRefresh(bool) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::setDequeueTimeout(nsecs_t /* timeout */) {
-    ALOGE("setDequeueTimeout not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::setDequeueTimeout(nsecs_t) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::getLastQueuedBuffer(
-        sp<GraphicBuffer>* /*outBuffer*/, sp<Fence>* /*outFence*/,
-        float[16] /* outTransformMatrix*/) {
-    ALOGE("getLastQueuedBuffer not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::getLastQueuedBuffer(sp<GraphicBuffer>*, sp<Fence>*, float[16]) {
+    UNSUPPORTED();
 }
 
-status_t VirtualDisplaySurface::getUniqueId(uint64_t* /*outId*/) const {
-    ALOGE("getUniqueId not supported on VirtualDisplaySurface");
-    return INVALID_OPERATION;
+status_t VirtualDisplaySurface::getUniqueId(uint64_t*) const {
+    UNSUPPORTED();
 }
 
 status_t VirtualDisplaySurface::getConsumerUsage(uint64_t* outUsage) const {
@@ -633,7 +602,7 @@
 }
 
 void VirtualDisplaySurface::resetPerFrameState() {
-    mCompositionType = COMPOSITION_UNKNOWN;
+    mCompositionType = CompositionType::Unknown;
     mFbFence = Fence::NO_FENCE;
     mOutputFence = Fence::NO_FENCE;
     mOutputProducerSlot = -1;
@@ -682,39 +651,16 @@
     return mapSource2ProducerSlot(source, pslot);
 }
 
-VirtualDisplaySurface::Source
-VirtualDisplaySurface::fbSourceForCompositionType(CompositionType type) {
-    return type == COMPOSITION_MIXED ? SOURCE_SCRATCH : SOURCE_SINK;
+auto VirtualDisplaySurface::fbSourceForCompositionType(CompositionType type) -> Source {
+    return type == CompositionType::Mixed ? SOURCE_SCRATCH : SOURCE_SINK;
 }
 
-const char* VirtualDisplaySurface::dbgStateStr() const {
-    switch (mDbgState) {
-        case DBG_STATE_IDLE:
-            return "IDLE";
-        case DBG_STATE_PREPARED:
-            return "PREPARED";
-        case DBG_STATE_GPU:
-            return "GPU";
-        case DBG_STATE_GPU_DONE:
-            return "GPU_DONE";
-        case DBG_STATE_HWC:
-            return "HWC";
-        default:
-            return "INVALID";
-    }
+std::string VirtualDisplaySurface::toString(CompositionType type) {
+    using namespace std::literals;
+    return type == CompositionType::Unknown ? "Unknown"s : Flags(type).string();
 }
 
-const char* VirtualDisplaySurface::dbgSourceStr(Source s) {
-    switch (s) {
-        case SOURCE_SINK:    return "SINK";
-        case SOURCE_SCRATCH: return "SCRATCH";
-        default:             return "INVALID";
-    }
-}
-
-// ---------------------------------------------------------------------------
 } // namespace android
-// ---------------------------------------------------------------------------
 
 // TODO(b/129481165): remove the #pragma below and fix conversion issues
 #pragma clang diagnostic pop // ignored "-Wconversion"
diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
index bbb6306..7720713 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
-#define ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H
+#pragma once
 
 #include <optional>
 #include <string>
@@ -28,9 +27,7 @@
 
 #include "DisplayIdentification.h"
 
-// ---------------------------------------------------------------------------
 namespace android {
-// ---------------------------------------------------------------------------
 
 class HWComposer;
 class IProducerListener;
@@ -94,7 +91,13 @@
     virtual const sp<Fence>& getClientTargetAcquireFence() const override;
 
 private:
-    enum Source {SOURCE_SINK = 0, SOURCE_SCRATCH = 1};
+    enum Source : size_t {
+        SOURCE_SINK = 0,
+        SOURCE_SCRATCH = 1,
+
+        ftl_first = SOURCE_SINK,
+        ftl_last = SOURCE_SCRATCH,
+    };
 
     virtual ~VirtualDisplaySurface();
 
@@ -133,6 +136,8 @@
     // Utility methods
     //
     static Source fbSourceForCompositionType(CompositionType);
+    static std::string toString(CompositionType);
+
     status_t dequeueBuffer(Source, PixelFormat, uint64_t usage, int* sslot, sp<Fence>*);
     void updateQueueBufferOutput(QueueBufferOutput&&);
     void resetPerFrameState();
@@ -197,7 +202,7 @@
 
     // Composition type and graphics buffer source for the current frame.
     // Valid after prepareFrame(), cleared in onFrameCommitted.
-    CompositionType mCompositionType;
+    CompositionType mCompositionType = CompositionType::Unknown;
 
     // mFbFence is the fence HWC should wait for before reading the framebuffer
     // target buffer.
@@ -219,47 +224,42 @@
     // +-----------+-------------------+-------------+
     // | State     | Event             || Next State |
     // +-----------+-------------------+-------------+
-    // | IDLE      | beginFrame        || BEGUN      |
-    // | BEGUN     | prepareFrame      || PREPARED   |
-    // | PREPARED  | dequeueBuffer [1] || GPU        |
-    // | PREPARED  | advanceFrame [2]  || HWC        |
-    // | GPU       | queueBuffer       || GPU_DONE   |
-    // | GPU_DONE  | advanceFrame      || HWC        |
-    // | HWC       | onFrameCommitted  || IDLE       |
+    // | Idle      | beginFrame        || Begun      |
+    // | Begun     | prepareFrame      || Prepared   |
+    // | Prepared  | dequeueBuffer [1] || Gpu        |
+    // | Prepared  | advanceFrame [2]  || Hwc        |
+    // | Gpu       | queueBuffer       || GpuDone    |
+    // | GpuDone   | advanceFrame      || Hwc        |
+    // | Hwc       | onFrameCommitted  || Idle       |
     // +-----------+-------------------++------------+
-    // [1] COMPOSITION_GPU and COMPOSITION_MIXED frames.
-    // [2] COMPOSITION_HWC frames.
+    // [1] CompositionType::Gpu and CompositionType::Mixed frames.
+    // [2] CompositionType::Hwc frames.
     //
-    enum DbgState {
+    enum class DebugState {
         // no buffer dequeued, don't know anything about the next frame
-        DBG_STATE_IDLE,
+        Idle,
         // output buffer dequeued, framebuffer source not yet known
-        DBG_STATE_BEGUN,
+        Begun,
         // output buffer dequeued, framebuffer source known but not provided
         // to GPU yet.
-        DBG_STATE_PREPARED,
+        Prepared,
         // GPU driver has a buffer dequeued
-        DBG_STATE_GPU,
+        Gpu,
         // GPU driver has queued the buffer, we haven't sent it to HWC yet
-        DBG_STATE_GPU_DONE,
+        GpuDone,
         // HWC has the buffer for this frame
-        DBG_STATE_HWC,
+        Hwc,
+
+        ftl_last = Hwc
     };
-    DbgState mDbgState;
-    CompositionType mDbgLastCompositionType;
+    DebugState mDebugState = DebugState::Idle;
+    CompositionType mDebugLastCompositionType = CompositionType::Unknown;
 
-    const char* dbgStateStr() const;
-    static const char* dbgSourceStr(Source s);
-
-    bool mMustRecompose;
+    bool mMustRecompose = false;
 
     compositionengine::impl::HwcBufferCache mHwcBufferCache;
 
     bool mForceHwcCopy;
 };
 
-// ---------------------------------------------------------------------------
 } // namespace android
-// ---------------------------------------------------------------------------
-
-#endif // ANDROID_SF_VIRTUAL_DISPLAY_SURFACE_H