diff --git a/include/gui/ISurfaceComposer.h b/include/gui/ISurfaceComposer.h
index 824e5c4..ff04e2f 100644
--- a/include/gui/ISurfaceComposer.h
+++ b/include/gui/ISurfaceComposer.h
@@ -157,7 +157,7 @@
     virtual status_t captureScreen(const sp<IBinder>& display,
             const sp<IGraphicBufferProducer>& producer,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform,
             Rotation rotation = eRotateNone) = 0;
 
diff --git a/include/gui/SurfaceComposerClient.h b/include/gui/SurfaceComposerClient.h
index 183b42d..4356a58 100644
--- a/include/gui/SurfaceComposerClient.h
+++ b/include/gui/SurfaceComposerClient.h
@@ -142,7 +142,7 @@
     status_t    show(const sp<IBinder>& id);
     status_t    setFlags(const sp<IBinder>& id, uint32_t flags, uint32_t mask);
     status_t    setTransparentRegionHint(const sp<IBinder>& id, const Region& transparent);
-    status_t    setLayer(const sp<IBinder>& id, uint32_t layer);
+    status_t    setLayer(const sp<IBinder>& id, int32_t layer);
     status_t    setLayerInfo(const sp<IBinder>& id, uint32_t type, uint32_t appid);
     status_t    setAlpha(const sp<IBinder>& id, float alpha=1.0f);
     status_t    setMatrix(const sp<IBinder>& id, float dsdx, float dtdx, float dsdy, float dtdy);
@@ -213,12 +213,12 @@
             const sp<IBinder>& display,
             const sp<IGraphicBufferProducer>& producer,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform);
     static status_t captureToBuffer(
             const sp<IBinder>& display,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform,
             uint32_t rotation,
             sp<GraphicBuffer>* outbuffer);
@@ -242,11 +242,11 @@
             bool useIdentityTransform);
     status_t update(const sp<IBinder>& display,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform);
     status_t update(const sp<IBinder>& display,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform, uint32_t rotation);
 
     sp<CpuConsumer> getCpuConsumer() const;
diff --git a/include/gui/SurfaceControl.h b/include/gui/SurfaceControl.h
index 456bde4..62217ad 100644
--- a/include/gui/SurfaceControl.h
+++ b/include/gui/SurfaceControl.h
@@ -61,7 +61,7 @@
     void        disconnect();
 
     status_t    setLayerStack(uint32_t layerStack);
-    status_t    setLayer(uint32_t layer);
+    status_t    setLayer(int32_t layer);
     status_t    setLayerInfo(uint32_t type, uint32_t appid);
     status_t    setPosition(float x, float y);
     status_t    setSize(uint32_t w, uint32_t h);
diff --git a/include/private/gui/LayerState.h b/include/private/gui/LayerState.h
index b648751..b3481d6 100644
--- a/include/private/gui/LayerState.h
+++ b/include/private/gui/LayerState.h
@@ -84,7 +84,7 @@
             uint32_t        what;
             float           x;
             float           y;
-            uint32_t        z;
+            int32_t         z;
             uint32_t        w;
             uint32_t        h;
             uint32_t        layerStack;
diff --git a/libs/gui/ISurfaceComposer.cpp b/libs/gui/ISurfaceComposer.cpp
index fa2f59a..74c3bed 100644
--- a/libs/gui/ISurfaceComposer.cpp
+++ b/libs/gui/ISurfaceComposer.cpp
@@ -104,7 +104,7 @@
     virtual status_t captureScreen(const sp<IBinder>& display,
             const sp<IGraphicBufferProducer>& producer,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform,
             ISurfaceComposer::Rotation rotation)
     {
@@ -115,8 +115,8 @@
         data.write(sourceCrop);
         data.writeUint32(reqWidth);
         data.writeUint32(reqHeight);
-        data.writeUint32(minLayerZ);
-        data.writeUint32(maxLayerZ);
+        data.writeInt32(minLayerZ);
+        data.writeInt32(maxLayerZ);
         data.writeInt32(static_cast<int32_t>(useIdentityTransform));
         data.writeInt32(static_cast<int32_t>(rotation));
         remote()->transact(BnSurfaceComposer::CAPTURE_SCREEN, data, &reply);
@@ -544,8 +544,8 @@
             data.read(sourceCrop);
             uint32_t reqWidth = data.readUint32();
             uint32_t reqHeight = data.readUint32();
-            uint32_t minLayerZ = data.readUint32();
-            uint32_t maxLayerZ = data.readUint32();
+            int32_t minLayerZ = data.readInt32();
+            int32_t maxLayerZ = data.readInt32();
             bool useIdentityTransform = static_cast<bool>(data.readInt32());
             int32_t rotation = data.readInt32();
 
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 3949186..16bf324 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -28,7 +28,7 @@
     output.writeUint32(what);
     output.writeFloat(x);
     output.writeFloat(y);
-    output.writeUint32(z);
+    output.writeInt32(z);
     output.writeUint32(w);
     output.writeUint32(h);
     output.writeUint32(layerStack);
@@ -54,7 +54,7 @@
     what = input.readUint32();
     x = input.readFloat();
     y = input.readFloat();
-    z = input.readUint32();
+    z = input.readInt32();
     w = input.readUint32();
     h = input.readUint32();
     layerStack = input.readUint32();
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index 3346a83..540dbd9 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -148,7 +148,7 @@
     status_t setSize(const sp<SurfaceComposerClient>& client, const sp<IBinder>& id,
             uint32_t w, uint32_t h);
     status_t setLayer(const sp<SurfaceComposerClient>& client, const sp<IBinder>& id,
-            uint32_t z);
+            int32_t z);
     status_t setLayerInfo(const sp<SurfaceComposerClient>& client, const sp<IBinder>& id,
             uint32_t type, uint32_t appid);
     status_t setFlags(const sp<SurfaceComposerClient>& client, const sp<IBinder>& id,
@@ -327,7 +327,7 @@
 }
 
 status_t Composer::setLayer(const sp<SurfaceComposerClient>& client,
-        const sp<IBinder>& id, uint32_t z) {
+        const sp<IBinder>& id, int32_t z) {
     Mutex::Autolock _l(mLock);
     layer_state_t* s = getLayerStateLocked(client, id);
     if (!s)
@@ -714,7 +714,7 @@
     return getComposer().setSize(this, id, w, h);
 }
 
-status_t SurfaceComposerClient::setLayer(const sp<IBinder>& id, uint32_t z) {
+status_t SurfaceComposerClient::setLayer(const sp<IBinder>& id, int32_t z) {
     return getComposer().setLayer(this, id, z);
 }
 
@@ -871,7 +871,7 @@
         const sp<IBinder>& display,
         const sp<IGraphicBufferProducer>& producer,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ, bool useIdentityTransform) {
+        int32_t minLayerZ, int32_t maxLayerZ, bool useIdentityTransform) {
     sp<ISurfaceComposer> s(ComposerService::getComposerService());
     if (s == NULL) return NO_INIT;
     return s->captureScreen(display, producer, sourceCrop,
@@ -880,7 +880,7 @@
 
 status_t ScreenshotClient::captureToBuffer(const sp<IBinder>& display,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ, bool useIdentityTransform,
+        int32_t minLayerZ, int32_t maxLayerZ, bool useIdentityTransform,
         uint32_t rotation,
         sp<GraphicBuffer>* outBuffer) {
     sp<ISurfaceComposer> s(ComposerService::getComposerService());
@@ -926,7 +926,7 @@
 
 status_t ScreenshotClient::update(const sp<IBinder>& display,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform, uint32_t rotation) {
     sp<ISurfaceComposer> s(ComposerService::getComposerService());
     if (s == NULL) return NO_INIT;
@@ -953,7 +953,7 @@
 
 status_t ScreenshotClient::update(const sp<IBinder>& display,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform) {
 
     return ScreenshotClient::update(display, sourceCrop, reqWidth, reqHeight,
@@ -962,14 +962,16 @@
 
 status_t ScreenshotClient::update(const sp<IBinder>& display, Rect sourceCrop,
         bool useIdentityTransform) {
-    return ScreenshotClient::update(display, sourceCrop, 0, 0, 0, -1U,
+    return ScreenshotClient::update(display, sourceCrop, 0, 0,
+            INT32_MIN, INT32_MAX,
             useIdentityTransform, ISurfaceComposer::eRotateNone);
 }
 
 status_t ScreenshotClient::update(const sp<IBinder>& display, Rect sourceCrop,
         uint32_t reqWidth, uint32_t reqHeight, bool useIdentityTransform) {
     return ScreenshotClient::update(display, sourceCrop, reqWidth, reqHeight,
-            0, -1U, useIdentityTransform, ISurfaceComposer::eRotateNone);
+            INT32_MIN, INT32_MAX,
+            useIdentityTransform, ISurfaceComposer::eRotateNone);
 }
 
 void ScreenshotClient::release() {
diff --git a/libs/gui/SurfaceControl.cpp b/libs/gui/SurfaceControl.cpp
index b47e434..c82f6a7 100644
--- a/libs/gui/SurfaceControl.cpp
+++ b/libs/gui/SurfaceControl.cpp
@@ -102,7 +102,7 @@
     if (err < 0) return err;
     return mClient->setLayerStack(mHandle, layerStack);
 }
-status_t SurfaceControl::setLayer(uint32_t layer) {
+status_t SurfaceControl::setLayer(int32_t layer) {
     status_t err = validate();
     if (err < 0) return err;
     return mClient->setLayer(mHandle, layer);
diff --git a/libs/gui/tests/Surface_test.cpp b/libs/gui/tests/Surface_test.cpp
index e40b4eb..7b78175 100644
--- a/libs/gui/tests/Surface_test.cpp
+++ b/libs/gui/tests/Surface_test.cpp
@@ -398,7 +398,7 @@
     status_t captureScreen(const sp<IBinder>& /*display*/,
             const sp<IGraphicBufferProducer>& /*producer*/,
             Rect /*sourceCrop*/, uint32_t /*reqWidth*/, uint32_t /*reqHeight*/,
-            uint32_t /*minLayerZ*/, uint32_t /*maxLayerZ*/,
+            int32_t /*minLayerZ*/, int32_t /*maxLayerZ*/,
             bool /*useIdentityTransform*/,
             Rotation /*rotation*/) override { return NO_ERROR; }
     status_t clearAnimationFrameStats() override { return NO_ERROR; }
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index b388448..5f32119 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -482,7 +482,7 @@
 }
 
 #ifdef USE_HWC2
-void Layer::setGeometry(const sp<const DisplayDevice>& displayDevice)
+void Layer::setGeometry(const sp<const DisplayDevice>& displayDevice, uint32_t z)
 #else
 void Layer::setGeometry(
     const sp<const DisplayDevice>& hw,
@@ -602,9 +602,9 @@
             "%s (%d)", mName.string(), s.alpha, to_string(error).c_str(),
             static_cast<int32_t>(error));
 
-    error = hwcLayer->setZOrder(s.z);
+    error = hwcLayer->setZOrder(z);
     ALOGE_IF(error != HWC2::Error::None, "[%s] Failed to set Z %u: %s (%d)",
-            mName.string(), s.z, to_string(error).c_str(),
+            mName.string(), z, to_string(error).c_str(),
             static_cast<int32_t>(error));
 #else
     if (!frame.intersect(hw->getViewport(), &frame)) {
@@ -1585,7 +1585,7 @@
     return true;
 }
 
-bool Layer::setLayer(uint32_t z) {
+bool Layer::setLayer(int32_t z) {
     if (mCurrentState.z == z)
         return false;
     mCurrentState.sequence++;
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 1654a51..3959341 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -109,7 +109,7 @@
     struct State {
         Geometry active;
         Geometry requested;
-        uint32_t z;
+        int32_t z;
         uint32_t layerStack;
 #ifdef USE_HWC2
         float alpha;
@@ -154,7 +154,7 @@
 
     // modify current state
     bool setPosition(float x, float y, bool immediate);
-    bool setLayer(uint32_t z);
+    bool setLayer(int32_t z);
     bool setSize(uint32_t w, uint32_t h);
 #ifdef USE_HWC2
     bool setAlpha(float alpha);
@@ -234,7 +234,7 @@
     // -----------------------------------------------------------------------
 
 #ifdef USE_HWC2
-    void setGeometry(const sp<const DisplayDevice>& displayDevice);
+    void setGeometry(const sp<const DisplayDevice>& displayDevice, uint32_t z);
     void forceClientComposition(int32_t hwcId);
     void setPerFrameData(const sp<const DisplayDevice>& displayDevice);
 
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 5f25ef5..8b10344 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1416,7 +1416,8 @@
                 const Vector<sp<Layer>>& currentLayers(
                         displayDevice->getVisibleLayersSortedByZ());
                 bool foundLayerWithoutHwc = false;
-                for (auto& layer : currentLayers) {
+                for (size_t i = 0; i < currentLayers.size(); i++) {
+                    auto const& layer = currentLayers[i];
                     if (!layer->hasHwcLayer(hwcId)) {
                         auto hwcLayer = mHwc->createLayer(hwcId);
                         if (hwcLayer) {
@@ -1428,7 +1429,7 @@
                         }
                     }
 
-                    layer->setGeometry(displayDevice);
+                    layer->setGeometry(displayDevice, i);
                     if (mDebugDisableHWC || mDebugRegion) {
                         layer->forceClientComposition(hwcId);
                     }
@@ -3582,7 +3583,7 @@
 status_t SurfaceFlinger::captureScreen(const sp<IBinder>& display,
         const sp<IGraphicBufferProducer>& producer,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform, ISurfaceComposer::Rotation rotation) {
 
     if (CC_UNLIKELY(display == 0))
@@ -3633,7 +3634,7 @@
                 const sp<IBinder>& display,
                 const sp<IGraphicBufferProducer>& producer,
                 Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-                uint32_t minLayerZ, uint32_t maxLayerZ,
+                int32_t minLayerZ, int32_t maxLayerZ,
                 bool useIdentityTransform,
                 Transform::orientation_flags rotation,
                 bool isLocalScreenshot)
@@ -3682,7 +3683,7 @@
 void SurfaceFlinger::renderScreenImplLocked(
         const sp<const DisplayDevice>& hw,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool yswap, bool useIdentityTransform, Transform::orientation_flags rotation)
 {
     ATRACE_CALL();
@@ -3750,7 +3751,7 @@
         const sp<const DisplayDevice>& hw,
         const sp<IGraphicBufferProducer>& producer,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform, Transform::orientation_flags rotation,
         bool isLocalScreenshot)
 {
@@ -3911,7 +3912,7 @@
 }
 
 void SurfaceFlinger::checkScreenshot(size_t w, size_t s, size_t h, void const* vaddr,
-        const sp<const DisplayDevice>& hw, uint32_t minLayerZ, uint32_t maxLayerZ) {
+        const sp<const DisplayDevice>& hw, int32_t minLayerZ, int32_t maxLayerZ) {
     if (DEBUG_SCREENSHOTS) {
         for (size_t y=0 ; y<h ; y++) {
             uint32_t const * p = (uint32_t const *)vaddr + y*s;
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index f7f9ef5..bb44a36 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -206,7 +206,7 @@
     virtual status_t captureScreen(const sp<IBinder>& display,
             const sp<IGraphicBufferProducer>& producer,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform, ISurfaceComposer::Rotation rotation);
     virtual status_t getDisplayStats(const sp<IBinder>& display,
             DisplayStatInfo* stats);
@@ -333,14 +333,14 @@
     void renderScreenImplLocked(
             const sp<const DisplayDevice>& hw,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool yswap, bool useIdentityTransform, Transform::orientation_flags rotation);
 
     status_t captureScreenImplLocked(
             const sp<const DisplayDevice>& hw,
             const sp<IGraphicBufferProducer>& producer,
             Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-            uint32_t minLayerZ, uint32_t maxLayerZ,
+            int32_t minLayerZ, int32_t maxLayerZ,
             bool useIdentityTransform, Transform::orientation_flags rotation,
             bool isLocalScreenshot);
 
@@ -441,7 +441,7 @@
     void appendSfConfigString(String8& result) const;
     void checkScreenshot(size_t w, size_t s, size_t h, void const* vaddr,
             const sp<const DisplayDevice>& hw,
-            uint32_t minLayerZ, uint32_t maxLayerZ);
+            int32_t minLayerZ, int32_t maxLayerZ);
 
     void logFrameStats();
 
diff --git a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
index fcf0185..217ba1b 100644
--- a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
+++ b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
@@ -3459,7 +3459,7 @@
 status_t SurfaceFlinger::captureScreen(const sp<IBinder>& display,
         const sp<IGraphicBufferProducer>& producer,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform, ISurfaceComposer::Rotation rotation) {
 
     if (CC_UNLIKELY(display == 0))
@@ -3500,7 +3500,7 @@
         sp<IGraphicBufferProducer> producer;
         Rect sourceCrop;
         uint32_t reqWidth, reqHeight;
-        uint32_t minLayerZ,maxLayerZ;
+        int32_t minLayerZ,maxLayerZ;
         bool useIdentityTransform;
         Transform::orientation_flags rotation;
         status_t result;
@@ -3510,7 +3510,7 @@
                 const sp<IBinder>& display,
                 const sp<IGraphicBufferProducer>& producer,
                 Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-                uint32_t minLayerZ, uint32_t maxLayerZ,
+                int32_t minLayerZ, int32_t maxLayerZ,
                 bool useIdentityTransform,
                 Transform::orientation_flags rotation,
                 bool isLocalScreenshot)
@@ -3559,7 +3559,7 @@
 void SurfaceFlinger::renderScreenImplLocked(
         const sp<const DisplayDevice>& hw,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool yswap, bool useIdentityTransform, Transform::orientation_flags rotation)
 {
     ATRACE_CALL();
@@ -3629,7 +3629,7 @@
         const sp<const DisplayDevice>& hw,
         const sp<IGraphicBufferProducer>& producer,
         Rect sourceCrop, uint32_t reqWidth, uint32_t reqHeight,
-        uint32_t minLayerZ, uint32_t maxLayerZ,
+        int32_t minLayerZ, int32_t maxLayerZ,
         bool useIdentityTransform, Transform::orientation_flags rotation,
         bool isLocalScreenshot)
 {
@@ -3782,7 +3782,7 @@
 }
 
 void SurfaceFlinger::checkScreenshot(size_t w, size_t s, size_t h, void const* vaddr,
-        const sp<const DisplayDevice>& hw, uint32_t minLayerZ, uint32_t maxLayerZ) {
+        const sp<const DisplayDevice>& hw, int32_t minLayerZ, int32_t maxLayerZ) {
     if (DEBUG_SCREENSHOTS) {
         for (size_t y=0 ; y<h ; y++) {
             uint32_t const * p = (uint32_t const *)vaddr + y*s;