1 files changed, 194 insertions, 0 deletions
diff --git a/libs/ui/include/ui/DisplayId.h b/libs/ui/include/ui/DisplayId.h
new file mode 100644
index 0000000000..f196ab901a
--- /dev/null
+++ b/libs/ui/include/ui/DisplayId.h
@@ -0,0 +1,194 @@
+/*
+ * Copyright 2020 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 <optional>
+#include <string>
+
+namespace android {
+
+// ID of a physical or a virtual display. This class acts as a type safe wrapper around uint64_t.
+// The encoding of the ID is type-specific for bits 0 to 61.
+struct DisplayId {
+    // Flag indicating that the display is virtual.
+    static constexpr uint64_t FLAG_VIRTUAL = 1ULL << 63;
+
+    // Flag indicating that the ID is stable across reboots.
+    static constexpr uint64_t FLAG_STABLE = 1ULL << 62;
+
+    // TODO(b/162612135) Remove default constructor
+    DisplayId() = default;
+    constexpr DisplayId(const DisplayId&) = default;
+    DisplayId& operator=(const DisplayId&) = default;
+
+    uint64_t value;
+
+protected:
+    explicit constexpr DisplayId(uint64_t id) : value(id) {}
+};
+
+static_assert(sizeof(DisplayId) == sizeof(uint64_t));
+
+inline bool operator==(DisplayId lhs, DisplayId rhs) {
+    return lhs.value == rhs.value;
+}
+
+inline bool operator!=(DisplayId lhs, DisplayId rhs) {
+    return !(lhs == rhs);
+}
+
+inline std::string to_string(DisplayId displayId) {
+    return std::to_string(displayId.value);
+}
+
+// DisplayId of a physical display, such as the internal display or externally connected display.
+struct PhysicalDisplayId : DisplayId {
+    static constexpr std::optional<PhysicalDisplayId> tryCast(DisplayId id) {
+        if (id.value & FLAG_VIRTUAL) {
+            return std::nullopt;
+        }
+        return {PhysicalDisplayId(id)};
+    }
+
+    // Returns a stable ID based on EDID information.
+    static constexpr PhysicalDisplayId fromEdid(uint8_t port, uint16_t manufacturerId,
+                                                uint32_t modelHash) {
+        return PhysicalDisplayId(FLAG_STABLE, port, manufacturerId, modelHash);
+    }
+
+    // Returns an unstable ID. If EDID is available using "fromEdid" is preferred.
+    static constexpr PhysicalDisplayId fromPort(uint8_t port) {
+        constexpr uint16_t kManufacturerId = 0;
+        constexpr uint32_t kModelHash = 0;
+        return PhysicalDisplayId(0, port, kManufacturerId, kModelHash);
+    }
+
+    // TODO(b/162612135) Remove default constructor
+    PhysicalDisplayId() = default;
+    // TODO(b/162612135) Remove constructor
+    explicit constexpr PhysicalDisplayId(uint64_t id) : DisplayId(id) {}
+
+    constexpr uint16_t getManufacturerId() const { return static_cast<uint16_t>(value >> 40); }
+
+    constexpr uint8_t getPort() const { return static_cast<uint8_t>(value); }
+
+private:
+    constexpr PhysicalDisplayId(uint64_t flags, uint8_t port, uint16_t manufacturerId,
+                                uint32_t modelHash)
+          : DisplayId(flags | (static_cast<uint64_t>(manufacturerId) << 40) |
+                      (static_cast<uint64_t>(modelHash) << 8) | port) {}
+
+    explicit constexpr PhysicalDisplayId(DisplayId other) : DisplayId(other) {}
+};
+
+static_assert(sizeof(PhysicalDisplayId) == sizeof(uint64_t));
+
+struct VirtualDisplayId : DisplayId {
+    using BaseId = uint32_t;
+    // Flag indicating that this virtual display is backed by the GPU.
+    static constexpr uint64_t FLAG_GPU = 1ULL << 61;
+
+    static constexpr std::optional<VirtualDisplayId> tryCast(DisplayId id) {
+        if (id.value & FLAG_VIRTUAL) {
+            return {VirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+protected:
+    constexpr VirtualDisplayId(uint64_t flags, BaseId baseId)
+          : DisplayId(DisplayId::FLAG_VIRTUAL | flags | baseId) {}
+
+    explicit constexpr VirtualDisplayId(DisplayId other) : DisplayId(other) {}
+};
+
+struct HalVirtualDisplayId : VirtualDisplayId {
+    explicit constexpr HalVirtualDisplayId(BaseId baseId) : VirtualDisplayId(0, baseId) {}
+
+    static constexpr std::optional<HalVirtualDisplayId> tryCast(DisplayId id) {
+        if ((id.value & FLAG_VIRTUAL) && !(id.value & VirtualDisplayId::FLAG_GPU)) {
+            return {HalVirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+private:
+    explicit constexpr HalVirtualDisplayId(DisplayId other) : VirtualDisplayId(other) {}
+};
+
+struct GpuVirtualDisplayId : VirtualDisplayId {
+    explicit constexpr GpuVirtualDisplayId(BaseId baseId)
+          : VirtualDisplayId(VirtualDisplayId::FLAG_GPU, baseId) {}
+
+    static constexpr std::optional<GpuVirtualDisplayId> tryCast(DisplayId id) {
+        if ((id.value & FLAG_VIRTUAL) && (id.value & VirtualDisplayId::FLAG_GPU)) {
+            return {GpuVirtualDisplayId(id)};
+        }
+        return std::nullopt;
+    }
+
+private:
+    explicit constexpr GpuVirtualDisplayId(DisplayId other) : VirtualDisplayId(other) {}
+};
+
+// HalDisplayId is the ID of a display which is managed by HWC.
+// PhysicalDisplayId and HalVirtualDisplayId are implicitly convertible to HalDisplayId.
+struct HalDisplayId : DisplayId {
+    constexpr HalDisplayId(HalVirtualDisplayId other) : DisplayId(other) {}
+    constexpr HalDisplayId(PhysicalDisplayId other) : DisplayId(other) {}
+
+    static constexpr std::optional<HalDisplayId> tryCast(DisplayId id) {
+        if (GpuVirtualDisplayId::tryCast(id)) {
+            return std::nullopt;
+        }
+        return {HalDisplayId(id)};
+    }
+
+private:
+    explicit constexpr HalDisplayId(DisplayId other) : DisplayId(other) {}
+};
+
+static_assert(sizeof(VirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(HalVirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(GpuVirtualDisplayId) == sizeof(uint64_t));
+static_assert(sizeof(HalDisplayId) == sizeof(uint64_t));
+
+} // namespace android
+
+namespace std {
+
+template <>
+struct hash<android::DisplayId> {
+    size_t operator()(android::DisplayId displayId) const {
+        return hash<uint64_t>()(displayId.value);
+    }
+};
+
+template <>
+struct hash<android::PhysicalDisplayId> : hash<android::DisplayId> {};
+
+template <>
+struct hash<android::HalVirtualDisplayId> : hash<android::DisplayId> {};
+
+template <>
+struct hash<android::GpuVirtualDisplayId> : hash<android::DisplayId> {};
+
+template <>
+struct hash<android::HalDisplayId> : hash<android::DisplayId> {};
+
+} // namespace std