From d6d7df73241ba78a1e41a7ad1c358164e2358867 Mon Sep 17 00:00:00 2001
From: Arpit Singh <arpitks@google.com>
Date: Fri, 7 Mar 2025 11:14:03 +0000
Subject: [CD Cursor] Add DisplayTopologyValidator

Add a DisplayTopologyValidator to verify assumptions made in the
PointerChoreographer and InputDispatcher, some sanity checks on the
topology graph to flag issues realted to topology for debugging.

The validator will be used in the InputManager to validated and discard
invalid topology updates.

Test: atest inputflinger_tests
Bug: 401219231
Flag: com.android.input.flags.enable_display_topology_validation

Change-Id: I624bc32b73144cc047f317ef889f7f07cc1c3dfc
---
 libs/input/DisplayTopologyGraph.cpp | 105 ++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 libs/input/DisplayTopologyGraph.cpp

(limited to 'libs/input/DisplayTopologyGraph.cpp')

diff --git a/libs/input/DisplayTopologyGraph.cpp b/libs/input/DisplayTopologyGraph.cpp
new file mode 100644
index 0000000000..7ad9f163b8
--- /dev/null
+++ b/libs/input/DisplayTopologyGraph.cpp
@@ -0,0 +1,105 @@
+/*
+ * 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
-- 
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