Merge "SF TimeStats: add a debug function for global present to present time"
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 1e910ce..f3182be 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -1021,6 +1021,10 @@
 uint32_t Layer::doTransaction(uint32_t flags) {
     ATRACE_CALL();
 
+    if (mLayerDetached) {
+        return 0;
+    }
+
     pushPendingState();
     State c = getCurrentState();
     if (!applyPendingStates(&c)) {
@@ -1553,6 +1557,9 @@
         return false;
     }
 
+    if (attachChildren()) {
+        setTransactionFlags(eTransactionNeeded);
+    }
     for (const sp<Layer>& child : mCurrentChildren) {
         newParent->addChild(child);
 
@@ -1597,6 +1604,13 @@
         client->updateParent(newParent);
     }
 
+    if (mLayerDetached) {
+        mLayerDetached = false;
+        setTransactionFlags(eTransactionNeeded);
+    }
+    if (attachChildren()) {
+        setTransactionFlags(eTransactionNeeded);
+    }
     return true;
 }
 
@@ -1605,7 +1619,7 @@
         sp<Client> parentClient = mClientRef.promote();
         sp<Client> client(child->mClientRef.promote());
         if (client != nullptr && parentClient != client) {
-            client->detachLayer(child.get());
+            child->mLayerDetached = true;
             child->detachChildren();
         }
     }
@@ -1613,6 +1627,23 @@
     return true;
 }
 
+bool Layer::attachChildren() {
+    bool changed = false;
+    for (const sp<Layer>& child : mCurrentChildren) {
+        sp<Client> parentClient = mClientRef.promote();
+        sp<Client> client(child->mClientRef.promote());
+        if (client != nullptr && parentClient != client) {
+            if (child->mLayerDetached) {
+                child->mLayerDetached = false;
+                changed = true;
+            }
+            changed |= child->attachChildren();
+        }
+    }
+
+    return changed;
+}
+
 bool Layer::setColorTransform(const mat4& matrix) {
     static const mat4 identityMatrix = mat4();
 
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 40ebe1e..ed51c61 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -263,6 +263,8 @@
     virtual void setChildrenDrawingParent(const sp<Layer>& layer);
     virtual bool reparent(const sp<IBinder>& newParentHandle);
     virtual bool detachChildren();
+    bool attachChildren();
+    bool isLayerDetached() const { return mLayerDetached; }
     virtual bool setColorTransform(const mat4& matrix);
     virtual const mat4& getColorTransform() const;
     virtual bool hasColorTransform() const;
@@ -355,7 +357,6 @@
     // to avoid grabbing the lock again to avoid deadlock
     virtual bool isCreatedFromMainThread() const { return false; }
 
-
     bool isRemovedFromCurrentState() const;
 
     void writeToProto(LayerProto* layerInfo,
@@ -776,6 +777,9 @@
 
     mutable LayerBE mBE;
 
+    // Can only be accessed with the SF state lock held.
+    bool mLayerDetached{false};
+
 private:
     /**
      * Returns an unsorted vector of all layers that are part of this tree.
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 7150660..2f5ee8a 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -3198,6 +3198,10 @@
 }
 
 status_t SurfaceFlinger::removeLayerLocked(const Mutex& lock, const sp<Layer>& layer) {
+    if (layer->isLayerDetached()) {
+        return NO_ERROR;
+    }
+
     const auto& p = layer->getParent();
     ssize_t index;
     if (p != nullptr) {
diff --git a/services/surfaceflinger/tests/Transaction_test.cpp b/services/surfaceflinger/tests/Transaction_test.cpp
index 988454a..a600a0a 100644
--- a/services/surfaceflinger/tests/Transaction_test.cpp
+++ b/services/surfaceflinger/tests/Transaction_test.cpp
@@ -3356,6 +3356,61 @@
     }
 }
 
+TEST_F(ChildLayerTest, DetachChildrenThenAttach) {
+    sp<SurfaceComposerClient> newComposerClient = new SurfaceComposerClient;
+    sp<SurfaceControl> childNewClient =
+            newComposerClient->createSurface(String8("New Child Test Surface"), 10, 10,
+                                             PIXEL_FORMAT_RGBA_8888, 0, mFGSurfaceControl.get());
+
+    ASSERT_TRUE(childNewClient != nullptr);
+    ASSERT_TRUE(childNewClient->isValid());
+
+    fillSurfaceRGBA8(childNewClient, 200, 200, 200);
+
+    Transaction()
+            .hide(mChild)
+            .show(childNewClient)
+            .setPosition(childNewClient, 10, 10)
+            .setPosition(mFGSurfaceControl, 64, 64)
+            .apply();
+
+    {
+        mCapture = screenshot();
+        // Top left of foreground must now be visible
+        mCapture->expectFGColor(64, 64);
+        // But 10 pixels in we should see the child surface
+        mCapture->expectChildColor(74, 74);
+        // And 10 more pixels we should be back to the foreground surface
+        mCapture->expectFGColor(84, 84);
+    }
+
+    Transaction().detachChildren(mFGSurfaceControl).apply();
+    Transaction().hide(childNewClient).apply();
+
+    // Nothing should have changed.
+    {
+        mCapture = screenshot();
+        mCapture->expectFGColor(64, 64);
+        mCapture->expectChildColor(74, 74);
+        mCapture->expectFGColor(84, 84);
+    }
+
+    sp<SurfaceControl> newParentSurface = createLayer(String8("New Parent Surface"), 32, 32, 0);
+    fillLayerColor(ISurfaceComposerClient::eFXSurfaceBufferQueue, newParentSurface, Color::RED, 32,
+                   32);
+    Transaction()
+            .setLayer(newParentSurface, INT32_MAX - 1)
+            .show(newParentSurface)
+            .setPosition(newParentSurface, 20, 20)
+            .reparent(childNewClient, newParentSurface->getHandle())
+            .apply();
+    {
+        mCapture = screenshot();
+        // Child is now hidden.
+        mCapture->expectColor(Rect(20, 20, 52, 52), Color::RED);
+    }
+}
+
 TEST_F(ChildLayerTest, ChildrenInheritNonTransformScalingFromParent) {
     asTransaction([&](Transaction& t) {
         t.show(mChild);