SF: Consolidate layer-to-output filtering

Add ui::LayerFilter for less repetitive CE plumbing. Make ui::LayerStack
a type, and (unlike the alias) use it everywhere. Remove redundant state
in CE's DisplayCreationArgs.

Bug: 182939859
Test: Display cutout is excluded in screenshots.
Test: libcompositionengine_test
Test: libsurfaceflinger_unittest
Test: SurfaceFlinger_test
Test: libgui_test
Change-Id: Ib854d354af7aef7168001c34297e875b71d53622
diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 23895c0..95a2f60 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -41,7 +41,6 @@
         z(0),
         w(0),
         h(0),
-        layerStack(0),
         alpha(0),
         flags(0),
         mask(0),
@@ -86,7 +85,7 @@
     SAFE_PARCEL(output.writeInt32, z);
     SAFE_PARCEL(output.writeUint32, w);
     SAFE_PARCEL(output.writeUint32, h);
-    SAFE_PARCEL(output.writeUint32, layerStack);
+    SAFE_PARCEL(output.writeUint32, layerStack.id);
     SAFE_PARCEL(output.writeFloat, alpha);
     SAFE_PARCEL(output.writeUint32, flags);
     SAFE_PARCEL(output.writeUint32, mask);
@@ -187,7 +186,7 @@
     SAFE_PARCEL(input.readInt32, &z);
     SAFE_PARCEL(input.readUint32, &w);
     SAFE_PARCEL(input.readUint32, &h);
-    SAFE_PARCEL(input.readUint32, &layerStack);
+    SAFE_PARCEL(input.readUint32, &layerStack.id);
     SAFE_PARCEL(input.readFloat, &alpha);
 
     SAFE_PARCEL(input.readUint32, &flags);
@@ -314,21 +313,14 @@
     return state.read(input);
 }
 
-DisplayState::DisplayState()
-      : what(0),
-        layerStack(0),
-        flags(0),
-        layerStackSpaceRect(Rect::EMPTY_RECT),
-        orientedDisplaySpaceRect(Rect::EMPTY_RECT),
-        width(0),
-        height(0) {}
+DisplayState::DisplayState() = default;
 
 status_t DisplayState::write(Parcel& output) const {
     SAFE_PARCEL(output.writeStrongBinder, token);
     SAFE_PARCEL(output.writeStrongBinder, IInterface::asBinder(surface));
     SAFE_PARCEL(output.writeUint32, what);
-    SAFE_PARCEL(output.writeUint32, layerStack);
     SAFE_PARCEL(output.writeUint32, flags);
+    SAFE_PARCEL(output.writeUint32, layerStack.id);
     SAFE_PARCEL(output.writeUint32, toRotationInt(orientation));
     SAFE_PARCEL(output.write, layerStackSpaceRect);
     SAFE_PARCEL(output.write, orientedDisplaySpaceRect);
@@ -344,8 +336,8 @@
     surface = interface_cast<IGraphicBufferProducer>(tmpBinder);
 
     SAFE_PARCEL(input.readUint32, &what);
-    SAFE_PARCEL(input.readUint32, &layerStack);
     SAFE_PARCEL(input.readUint32, &flags);
+    SAFE_PARCEL(input.readUint32, &layerStack.id);
     uint32_t tmpUint = 0;
     SAFE_PARCEL(input.readUint32, &tmpUint);
     orientation = ui::toRotation(tmpUint);
diff --git a/libs/gui/SurfaceComposerClient.cpp b/libs/gui/SurfaceComposerClient.cpp
index f620f5a..c3d632f 100644
--- a/libs/gui/SurfaceComposerClient.cpp
+++ b/libs/gui/SurfaceComposerClient.cpp
@@ -1087,7 +1087,7 @@
 }
 
 SurfaceComposerClient::Transaction& SurfaceComposerClient::Transaction::setLayerStack(
-        const sp<SurfaceControl>& sc, uint32_t layerStack) {
+        const sp<SurfaceControl>& sc, ui::LayerStack layerStack) {
     layer_state_t* s = getLayerState(sc);
     if (!s) {
         mStatus = BAD_INDEX;
@@ -1751,7 +1751,7 @@
 }
 
 void SurfaceComposerClient::Transaction::setDisplayLayerStack(const sp<IBinder>& token,
-        uint32_t layerStack) {
+                                                              ui::LayerStack layerStack) {
     DisplayState& s(getDisplayState(token));
     s.layerStack = layerStack;
     s.what |= DisplayState::eLayerStackChanged;
diff --git a/libs/gui/include/gui/LayerState.h b/libs/gui/include/gui/LayerState.h
index b27d9cf..427f2a5 100644
--- a/libs/gui/include/gui/LayerState.h
+++ b/libs/gui/include/gui/LayerState.h
@@ -35,6 +35,7 @@
 #include <math/vec3.h>
 #include <ui/BlurRegion.h>
 #include <ui/GraphicTypes.h>
+#include <ui/LayerStack.h>
 #include <ui/Rect.h>
 #include <ui/Region.h>
 #include <ui/Rotation.h>
@@ -143,7 +144,7 @@
     int32_t z;
     uint32_t w;
     uint32_t h;
-    uint32_t layerStack;
+    ui::LayerStack layerStack = ui::DEFAULT_LAYER_STACK;
     float alpha;
     uint32_t flags;
     uint32_t mask;
@@ -262,11 +263,12 @@
     DisplayState();
     void merge(const DisplayState& other);
 
-    uint32_t what;
+    uint32_t what = 0;
+    uint32_t flags = 0;
     sp<IBinder> token;
     sp<IGraphicBufferProducer> surface;
-    uint32_t layerStack;
-    uint32_t flags;
+
+    ui::LayerStack layerStack = ui::DEFAULT_LAYER_STACK;
 
     // These states define how layers are projected onto the physical display.
     //
@@ -280,10 +282,11 @@
     // will be additionally rotated by 90 degrees around the origin clockwise and translated by (W,
     // 0).
     ui::Rotation orientation = ui::ROTATION_0;
-    Rect layerStackSpaceRect;
-    Rect orientedDisplaySpaceRect;
+    Rect layerStackSpaceRect = Rect::EMPTY_RECT;
+    Rect orientedDisplaySpaceRect = Rect::EMPTY_RECT;
 
-    uint32_t width, height;
+    uint32_t width = 0;
+    uint32_t height = 0;
 
     status_t write(Parcel& output) const;
     status_t read(const Parcel& input);
diff --git a/libs/gui/include/gui/SurfaceComposerClient.h b/libs/gui/include/gui/SurfaceComposerClient.h
index 869cef6..ec68ca9 100644
--- a/libs/gui/include/gui/SurfaceComposerClient.h
+++ b/libs/gui/include/gui/SurfaceComposerClient.h
@@ -456,7 +456,7 @@
                                              int backgroundBlurRadius);
         Transaction& setBlurRegions(const sp<SurfaceControl>& sc,
                                     const std::vector<BlurRegion>& regions);
-        Transaction& setLayerStack(const sp<SurfaceControl>& sc, uint32_t layerStack);
+        Transaction& setLayerStack(const sp<SurfaceControl>&, ui::LayerStack);
         Transaction& setMetadata(const sp<SurfaceControl>& sc, uint32_t key, const Parcel& p);
 
         /// Reparents the current layer to the new parent handle. The new parent must not be null.
@@ -566,7 +566,7 @@
         status_t setDisplaySurface(const sp<IBinder>& token,
                 const sp<IGraphicBufferProducer>& bufferProducer);
 
-        void setDisplayLayerStack(const sp<IBinder>& token, uint32_t layerStack);
+        void setDisplayLayerStack(const sp<IBinder>& token, ui::LayerStack);
 
         void setDisplayFlags(const sp<IBinder>& token, uint32_t flags);
 
diff --git a/libs/gui/tests/BLASTBufferQueue_test.cpp b/libs/gui/tests/BLASTBufferQueue_test.cpp
index 9082d27..26d902d 100644
--- a/libs/gui/tests/BLASTBufferQueue_test.cpp
+++ b/libs/gui/tests/BLASTBufferQueue_test.cpp
@@ -128,7 +128,7 @@
         mDisplayToken = mClient->getInternalDisplayToken();
         ASSERT_NE(nullptr, mDisplayToken.get());
         Transaction t;
-        t.setDisplayLayerStack(mDisplayToken, 0);
+        t.setDisplayLayerStack(mDisplayToken, ui::DEFAULT_LAYER_STACK);
         t.apply();
         t.clear();
 
@@ -142,7 +142,7 @@
                                                  mDisplayHeight, PIXEL_FORMAT_RGBA_8888,
                                                  ISurfaceComposerClient::eFXSurfaceBufferState,
                                                  /*parent*/ nullptr);
-        t.setLayerStack(mSurfaceControl, 0)
+        t.setLayerStack(mSurfaceControl, ui::DEFAULT_LAYER_STACK)
                 .setLayer(mSurfaceControl, std::numeric_limits<int32_t>::max())
                 .show(mSurfaceControl)
                 .setDataspace(mSurfaceControl, ui::Dataspace::V0_SRGB)
@@ -490,7 +490,7 @@
                                      ISurfaceComposerClient::eFXSurfaceEffect);
     ASSERT_NE(nullptr, bg.get());
     Transaction t;
-    t.setLayerStack(bg, 0)
+    t.setLayerStack(bg, ui::DEFAULT_LAYER_STACK)
             .setCrop(bg, Rect(0, 0, mDisplayWidth, mDisplayHeight))
             .setColor(bg, half3{0, 0, 0})
             .setLayer(bg, 0)
@@ -545,7 +545,7 @@
                                      ISurfaceComposerClient::eFXSurfaceEffect);
     ASSERT_NE(nullptr, bg.get());
     Transaction t;
-    t.setLayerStack(bg, 0)
+    t.setLayerStack(bg, ui::DEFAULT_LAYER_STACK)
             .setCrop(bg, Rect(0, 0, mDisplayWidth, mDisplayHeight))
             .setColor(bg, half3{0, 0, 0})
             .setLayer(bg, 0)
@@ -612,7 +612,7 @@
                                      ISurfaceComposerClient::eFXSurfaceEffect);
     ASSERT_NE(nullptr, bg.get());
     Transaction t;
-    t.setLayerStack(bg, 0)
+    t.setLayerStack(bg, ui::DEFAULT_LAYER_STACK)
             .setCrop(bg, Rect(0, 0, mDisplayWidth, mDisplayHeight))
             .setColor(bg, half3{0, 0, 0})
             .setLayer(bg, 0)
@@ -733,7 +733,7 @@
                                    ISurfaceComposerClient::eFXSurfaceBufferState);
     ASSERT_NE(nullptr, bgSurface.get());
     Transaction t;
-    t.setLayerStack(bgSurface, 0)
+    t.setLayerStack(bgSurface, ui::DEFAULT_LAYER_STACK)
             .show(bgSurface)
             .setDataspace(bgSurface, ui::Dataspace::V0_SRGB)
             .setLayer(bgSurface, std::numeric_limits<int32_t>::max() - 1)
diff --git a/libs/ui/include/ui/DisplayState.h b/libs/ui/include/ui/DisplayState.h
index 70a0d50..98ee356 100644
--- a/libs/ui/include/ui/DisplayState.h
+++ b/libs/ui/include/ui/DisplayState.h
@@ -16,21 +16,18 @@
 
 #pragma once
 
+#include <ui/LayerStack.h>
 #include <ui/Rotation.h>
 #include <ui/Size.h>
 
-#include <cstdint>
 #include <type_traits>
 
 namespace android::ui {
 
-using LayerStack = uint32_t;
-constexpr LayerStack NO_LAYER_STACK = static_cast<LayerStack>(-1);
-
 // Transactional state of physical or virtual display. Note that libgui defines
 // android::DisplayState as a superset of android::ui::DisplayState.
 struct DisplayState {
-    LayerStack layerStack = NO_LAYER_STACK;
+    LayerStack layerStack;
     Rotation orientation = ROTATION_0;
     Size layerStackSpaceRect;
 };
diff --git a/libs/ui/include/ui/LayerStack.h b/libs/ui/include/ui/LayerStack.h
new file mode 100644
index 0000000..d6ffeb7
--- /dev/null
+++ b/libs/ui/include/ui/LayerStack.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <cstdint>
+
+#include <ftl/cast.h>
+#include <ftl/string.h>
+#include <log/log.h>
+
+namespace android::ui {
+
+// A LayerStack identifies a Z-ordered group of layers. A layer can only be associated to a single
+// LayerStack, but a LayerStack can be associated to multiple displays, mirroring the same content.
+struct LayerStack {
+    uint32_t id = UINT32_MAX;
+
+    template <typename T>
+    static constexpr LayerStack fromValue(T v) {
+        if (ftl::cast_safety<uint32_t>(v) == ftl::CastSafety::kSafe) {
+            return {static_cast<uint32_t>(v)};
+        }
+
+        ALOGW("Invalid layer stack %s", ftl::to_string(v).c_str());
+        return {};
+    }
+};
+
+constexpr LayerStack INVALID_LAYER_STACK;
+constexpr LayerStack DEFAULT_LAYER_STACK{0u};
+
+inline bool operator==(LayerStack lhs, LayerStack rhs) {
+    return lhs.id == rhs.id;
+}
+
+inline bool operator!=(LayerStack lhs, LayerStack rhs) {
+    return !(lhs == rhs);
+}
+
+inline bool operator>(LayerStack lhs, LayerStack rhs) {
+    return lhs.id > rhs.id;
+}
+
+// A LayerFilter determines if a layer is included for output to a display.
+struct LayerFilter {
+    LayerStack layerStack;
+
+    // True if the layer is only output to internal displays, i.e. excluded from screenshots, screen
+    // recordings, and mirroring to virtual or external displays. Used for display cutout overlays.
+    bool toInternalDisplay = false;
+
+    // Returns true if the input filter can be output to this filter.
+    bool includes(LayerFilter other) const {
+        // The layer stacks must match.
+        if (other.layerStack == INVALID_LAYER_STACK || other.layerStack != layerStack) {
+            return false;
+        }
+
+        // The output must be to an internal display if the input filter has that constraint.
+        return !other.toInternalDisplay || toInternalDisplay;
+    }
+};
+
+} // namespace android::ui