1 files changed, 105 insertions, 0 deletions
diff --git a/libs/input/DisplayTopologyGraph.cpp b/libs/input/DisplayTopologyGraph.cpp
new file mode 100644
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+++ b/libs/input/DisplayTopologyGraph.cpp
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+/*
+ * Copyright 2025 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.
+ */
+
+#define LOG_TAG "DisplayTopologyValidator"
+
+#include <android-base/logging.h>
+#include <ftl/enum.h>
+#include <input/DisplayTopologyGraph.h>
+#include <ui/LogicalDisplayId.h>
+
+#include <algorithm>
+
+namespace android {
+
+namespace {
+DisplayTopologyPosition getOppositePosition(DisplayTopologyPosition position) {
+    switch (position) {
+        case DisplayTopologyPosition::LEFT:
+            return DisplayTopologyPosition::RIGHT;
+        case DisplayTopologyPosition::TOP:
+            return DisplayTopologyPosition::BOTTOM;
+        case DisplayTopologyPosition::RIGHT:
+            return DisplayTopologyPosition::LEFT;
+        case DisplayTopologyPosition::BOTTOM:
+            return DisplayTopologyPosition::TOP;
+    }
+}
+
+bool validatePrimaryDisplay(const android::DisplayTopologyGraph& displayTopologyGraph) {
+    return displayTopologyGraph.primaryDisplayId != ui::LogicalDisplayId::INVALID &&
+            displayTopologyGraph.graph.contains(displayTopologyGraph.primaryDisplayId);
+}
+
+bool validateTopologyGraph(const android::DisplayTopologyGraph& displayTopologyGraph) {
+    for (const auto& [sourceDisplay, adjacentDisplays] : displayTopologyGraph.graph) {
+        for (const DisplayTopologyAdjacentDisplay& adjacentDisplay : adjacentDisplays) {
+            const auto adjacentGraphIt = displayTopologyGraph.graph.find(adjacentDisplay.displayId);
+            if (adjacentGraphIt == displayTopologyGraph.graph.end()) {
+                LOG(ERROR) << "Missing adjacent display in topology graph: "
+                           << adjacentDisplay.displayId << " for source " << sourceDisplay;
+                return false;
+            }
+            const auto reverseEdgeIt =
+                    std::find_if(adjacentGraphIt->second.begin(), adjacentGraphIt->second.end(),
+                                 [sourceDisplay](const DisplayTopologyAdjacentDisplay&
+                                                         reverseAdjacentDisplay) {
+                                     return sourceDisplay == reverseAdjacentDisplay.displayId;
+                                 });
+            if (reverseEdgeIt == adjacentGraphIt->second.end()) {
+                LOG(ERROR) << "Missing reverse edge in topology graph for: " << sourceDisplay
+                           << " -> " << adjacentDisplay.displayId;
+                return false;
+            }
+            DisplayTopologyPosition expectedPosition =
+                    getOppositePosition(adjacentDisplay.position);
+            if (reverseEdgeIt->position != expectedPosition) {
+                LOG(ERROR) << "Unexpected reverse edge for: " << sourceDisplay << " -> "
+                           << adjacentDisplay.displayId
+                           << " expected position: " << ftl::enum_string(expectedPosition)
+                           << " actual " << ftl::enum_string(reverseEdgeIt->position);
+                return false;
+            }
+            if (reverseEdgeIt->offsetDp != -adjacentDisplay.offsetDp) {
+                LOG(ERROR) << "Unexpected reverse edge offset: " << sourceDisplay << " -> "
+                           << adjacentDisplay.displayId
+                           << " expected offset: " << -adjacentDisplay.offsetDp << " actual "
+                           << reverseEdgeIt->offsetDp;
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+bool validateDensities(const android::DisplayTopologyGraph& displayTopologyGraph) {
+    for (const auto& [sourceDisplay, adjacentDisplays] : displayTopologyGraph.graph) {
+        if (!displayTopologyGraph.displaysDensity.contains(sourceDisplay)) {
+            LOG(ERROR) << "Missing density value in topology graph for display: " << sourceDisplay;
+            return false;
+        }
+    }
+    return true;
+}
+
+} // namespace
+
+bool DisplayTopologyGraph::isValid() const {
+    return validatePrimaryDisplay(*this) && validateTopologyGraph(*this) &&
+            validateDensities(*this);
+}
+
+} // namespace android