Add API to support key remappings on native side

For adding support for modifier key remapping, we need to add
native support save key remappings and send appropriate android
key codes using KeyCharacterMap.

Test: atest KeyboardLayoutChangeTest
Bug: 252812993
Change-Id: Ib3efa866c6e6408dd11e97dfaf49feb92f48bc18

14 files changed, 198 insertions, 70 deletions

diff --git a/include/input/KeyCharacterMap.h b/include/input/KeyCharacterMap.h
index dc928b806f..867a08955c 100644
--- a/include/input/KeyCharacterMap.h
+++ b/include/input/KeyCharacterMap.h
@@ -125,14 +125,21 @@ public:
     bool getEvents(int32_t deviceId, const char16_t* chars, size_t numChars,
             Vector<KeyEvent>& outEvents) const;
 
+    /* Maps an Android key code to another Android key code. This mapping is applied after scanCode
+     * and usageCodes are mapped to corresponding Android Keycode */
+    void addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode);
+
     /* Maps a scan code and usage code to a key code, in case this key map overrides
      * the mapping in some way. */
     status_t mapKey(int32_t scanCode, int32_t usageCode, int32_t* outKeyCode) const;
 
-    /* Tries to find a replacement key code for a given key code and meta state
-     * in character map. */
-    void tryRemapKey(int32_t scanCode, int32_t metaState,
-            int32_t* outKeyCode, int32_t* outMetaState) const;
+    /* Returns keycode after applying Android key code remapping defined in mKeyRemapping */
+    int32_t applyKeyRemapping(int32_t fromKeyCode) const;
+
+    /* Returns the <keyCode, metaState> pair after applying key behavior defined in the kcm file,
+     * that tries to find a replacement key code based on current meta state */
+    std::pair<int32_t /*keyCode*/, int32_t /*metaState*/> applyKeyBehavior(int32_t keyCode,
+                                                                           int32_t metaState) const;
 
 #ifdef __linux__
     /* Reads a key map from a parcel. */
@@ -227,8 +234,9 @@ private:
     std::string mLoadFileName;
     bool mLayoutOverlayApplied;
 
-    KeyedVector<int32_t, int32_t> mKeysByScanCode;
-    KeyedVector<int32_t, int32_t> mKeysByUsageCode;
+    std::map<int32_t /* fromAndroidKeyCode */, int32_t /* toAndroidKeyCode */> mKeyRemapping;
+    std::map<int32_t /* fromScanCode */, int32_t /* toAndroidKeyCode */> mKeysByScanCode;
+    std::map<int32_t /* fromHidUsageCode */, int32_t /* toAndroidKeyCode */> mKeysByUsageCode;
 
     KeyCharacterMap(const std::string& filename);
 
diff --git a/libs/input/KeyCharacterMap.cpp b/libs/input/KeyCharacterMap.cpp
index 422e6e09eb..fa5c41f657 100644
--- a/libs/input/KeyCharacterMap.cpp
+++ b/libs/input/KeyCharacterMap.cpp
@@ -43,7 +43,6 @@
 // Enables debug output for mapping.
 #define DEBUG_MAPPING 0
 
-
 namespace android {
 
 static const char* WHITESPACE = " \t\r";
@@ -93,6 +92,7 @@ KeyCharacterMap::KeyCharacterMap(const KeyCharacterMap& other)
       : mType(other.mType),
         mLoadFileName(other.mLoadFileName),
         mLayoutOverlayApplied(other.mLayoutOverlayApplied),
+        mKeyRemapping(other.mKeyRemapping),
         mKeysByScanCode(other.mKeysByScanCode),
         mKeysByUsageCode(other.mKeysByUsageCode) {
     for (size_t i = 0; i < other.mKeys.size(); i++) {
@@ -114,7 +114,7 @@ bool KeyCharacterMap::operator==(const KeyCharacterMap& other) const {
     if (mLayoutOverlayApplied != other.mLayoutOverlayApplied) {
         return false;
     }
-    if (mKeys.size() != other.mKeys.size() ||
+    if (mKeys.size() != other.mKeys.size() || mKeyRemapping.size() != other.mKeyRemapping.size() ||
         mKeysByScanCode.size() != other.mKeysByScanCode.size() ||
         mKeysByUsageCode.size() != other.mKeysByUsageCode.size()) {
         return false;
@@ -131,22 +131,9 @@ bool KeyCharacterMap::operator==(const KeyCharacterMap& other) const {
         }
     }
 
-    for (size_t i = 0; i < mKeysByScanCode.size(); i++) {
-        if (mKeysByScanCode.keyAt(i) != other.mKeysByScanCode.keyAt(i)) {
-            return false;
-        }
-        if (mKeysByScanCode.valueAt(i) != other.mKeysByScanCode.valueAt(i)) {
-            return false;
-        }
-    }
-
-    for (size_t i = 0; i < mKeysByUsageCode.size(); i++) {
-        if (mKeysByUsageCode.keyAt(i) != other.mKeysByUsageCode.keyAt(i)) {
-            return false;
-        }
-        if (mKeysByUsageCode.valueAt(i) != other.mKeysByUsageCode.valueAt(i)) {
-            return false;
-        }
+    if (mKeyRemapping != other.mKeyRemapping || mKeysByScanCode != other.mKeysByScanCode ||
+        mKeysByUsageCode != other.mKeysByUsageCode) {
+        return false;
     }
 
     return true;
@@ -258,14 +245,12 @@ void KeyCharacterMap::combine(const KeyCharacterMap& overlay) {
         }
     }
 
-    for (size_t i = 0; i < overlay.mKeysByScanCode.size(); i++) {
-        mKeysByScanCode.replaceValueFor(overlay.mKeysByScanCode.keyAt(i),
-                                        overlay.mKeysByScanCode.valueAt(i));
+    for (auto const& it : overlay.mKeysByScanCode) {
+        mKeysByScanCode.insert_or_assign(it.first, it.second);
     }
 
-    for (size_t i = 0; i < overlay.mKeysByUsageCode.size(); i++) {
-        mKeysByUsageCode.replaceValueFor(overlay.mKeysByUsageCode.keyAt(i),
-                                         overlay.mKeysByUsageCode.valueAt(i));
+    for (auto const& it : overlay.mKeysByUsageCode) {
+        mKeysByUsageCode.insert_or_assign(it.first, it.second);
     }
     mLayoutOverlayApplied = true;
 }
@@ -400,11 +385,26 @@ bool KeyCharacterMap::getEvents(int32_t deviceId, const char16_t* chars, size_t
     return true;
 }
 
+void KeyCharacterMap::addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode) {
+    if (fromKeyCode == toKeyCode) {
+        mKeyRemapping.erase(fromKeyCode);
+#if DEBUG_MAPPING
+        ALOGD("addKeyRemapping: Cleared remapping forKeyCode=%d ~ Result Successful.", fromKeyCode);
+#endif
+        return;
+    }
+    mKeyRemapping.insert_or_assign(fromKeyCode, toKeyCode);
+#if DEBUG_MAPPING
+    ALOGD("addKeyRemapping: fromKeyCode=%d, toKeyCode=%d ~ Result Successful.", fromKeyCode,
+          toKeyCode);
+#endif
+}
+
 status_t KeyCharacterMap::mapKey(int32_t scanCode, int32_t usageCode, int32_t* outKeyCode) const {
     if (usageCode) {
-        ssize_t index = mKeysByUsageCode.indexOfKey(usageCode);
-        if (index >= 0) {
-            *outKeyCode = mKeysByUsageCode.valueAt(index);
+        const auto it = mKeysByUsageCode.find(usageCode);
+        if (it != mKeysByUsageCode.end()) {
+            *outKeyCode = it->second;
 #if DEBUG_MAPPING
             ALOGD("mapKey: scanCode=%d, usageCode=0x%08x ~ Result keyCode=%d.",
                     scanCode, usageCode, *outKeyCode);
@@ -413,9 +413,9 @@ status_t KeyCharacterMap::mapKey(int32_t scanCode, int32_t usageCode, int32_t* o
         }
     }
     if (scanCode) {
-        ssize_t index = mKeysByScanCode.indexOfKey(scanCode);
-        if (index >= 0) {
-            *outKeyCode = mKeysByScanCode.valueAt(index);
+        const auto it = mKeysByScanCode.find(scanCode);
+        if (it != mKeysByScanCode.end()) {
+            *outKeyCode = it->second;
 #if DEBUG_MAPPING
             ALOGD("mapKey: scanCode=%d, usageCode=0x%08x ~ Result keyCode=%d.",
                     scanCode, usageCode, *outKeyCode);
@@ -431,45 +431,59 @@ status_t KeyCharacterMap::mapKey(int32_t scanCode, int32_t usageCode, int32_t* o
     return NAME_NOT_FOUND;
 }
 
-void KeyCharacterMap::tryRemapKey(int32_t keyCode, int32_t metaState,
-                                  int32_t *outKeyCode, int32_t *outMetaState) const {
-    *outKeyCode = keyCode;
-    *outMetaState = metaState;
+int32_t KeyCharacterMap::applyKeyRemapping(int32_t fromKeyCode) const {
+    int32_t toKeyCode = fromKeyCode;
 
-    const Behavior* behavior = getKeyBehavior(keyCode, metaState);
+    const auto it = mKeyRemapping.find(fromKeyCode);
+    if (it != mKeyRemapping.end()) {
+        toKeyCode = it->second;
+    }
+#if DEBUG_MAPPING
+    ALOGD("applyKeyRemapping: keyCode=%d ~ replacement keyCode=%d.", fromKeyCode, toKeyCode);
+#endif
+    return toKeyCode;
+}
+
+std::pair<int32_t, int32_t> KeyCharacterMap::applyKeyBehavior(int32_t fromKeyCode,
+                                                              int32_t fromMetaState) const {
+    int32_t toKeyCode = fromKeyCode;
+    int32_t toMetaState = fromMetaState;
+
+    const Behavior* behavior = getKeyBehavior(fromKeyCode, fromMetaState);
     if (behavior != nullptr) {
         if (behavior->replacementKeyCode) {
-            *outKeyCode = behavior->replacementKeyCode;
-            int32_t newMetaState = metaState & ~behavior->metaState;
+            toKeyCode = behavior->replacementKeyCode;
+            toMetaState = fromMetaState & ~behavior->metaState;
             // Reset dependent meta states.
             if (behavior->metaState & AMETA_ALT_ON) {
-                newMetaState &= ~(AMETA_ALT_LEFT_ON | AMETA_ALT_RIGHT_ON);
+                toMetaState &= ~(AMETA_ALT_LEFT_ON | AMETA_ALT_RIGHT_ON);
             }
             if (behavior->metaState & (AMETA_ALT_LEFT_ON | AMETA_ALT_RIGHT_ON)) {
-                newMetaState &= ~AMETA_ALT_ON;
+                toMetaState &= ~AMETA_ALT_ON;
             }
             if (behavior->metaState & AMETA_CTRL_ON) {
-                newMetaState &= ~(AMETA_CTRL_LEFT_ON | AMETA_CTRL_RIGHT_ON);
+                toMetaState &= ~(AMETA_CTRL_LEFT_ON | AMETA_CTRL_RIGHT_ON);
             }
             if (behavior->metaState & (AMETA_CTRL_LEFT_ON | AMETA_CTRL_RIGHT_ON)) {
-                newMetaState &= ~AMETA_CTRL_ON;
+                toMetaState &= ~AMETA_CTRL_ON;
             }
             if (behavior->metaState & AMETA_SHIFT_ON) {
-                newMetaState &= ~(AMETA_SHIFT_LEFT_ON | AMETA_SHIFT_RIGHT_ON);
+                toMetaState &= ~(AMETA_SHIFT_LEFT_ON | AMETA_SHIFT_RIGHT_ON);
             }
             if (behavior->metaState & (AMETA_SHIFT_LEFT_ON | AMETA_SHIFT_RIGHT_ON)) {
-                newMetaState &= ~AMETA_SHIFT_ON;
+                toMetaState &= ~AMETA_SHIFT_ON;
             }
             // ... and put universal bits back if needed
-            *outMetaState = normalizeMetaState(newMetaState);
+            toMetaState = normalizeMetaState(toMetaState);
         }
     }
 
 #if DEBUG_MAPPING
-    ALOGD("tryRemapKey: keyCode=%d, metaState=0x%08x ~ "
-            "replacement keyCode=%d, replacement metaState=0x%08x.",
-            keyCode, metaState, *outKeyCode, *outMetaState);
+    ALOGD("applyKeyBehavior: keyCode=%d, metaState=0x%08x ~ "
+          "replacement keyCode=%d, replacement metaState=0x%08x.",
+          fromKeyCode, fromMetaState, toKeyCode, toMetaState);
 #endif
+    return std::make_pair(toKeyCode, toMetaState);
 }
 
 bool KeyCharacterMap::getKey(int32_t keyCode, const Key** outKey) const {
@@ -720,6 +734,18 @@ std::shared_ptr<KeyCharacterMap> KeyCharacterMap::readFromParcel(Parcel* parcel)
             return nullptr;
         }
     }
+    size_t numKeyRemapping = parcel->readInt32();
+    if (parcel->errorCheck()) {
+        return nullptr;
+    }
+    for (size_t i = 0; i < numKeyRemapping; i++) {
+        int32_t key = parcel->readInt32();
+        int32_t value = parcel->readInt32();
+        map->mKeyRemapping.insert_or_assign(key, value);
+        if (parcel->errorCheck()) {
+            return nullptr;
+        }
+    }
     size_t numKeysByScanCode = parcel->readInt32();
     if (parcel->errorCheck()) {
         return nullptr;
@@ -727,7 +753,7 @@ std::shared_ptr<KeyCharacterMap> KeyCharacterMap::readFromParcel(Parcel* parcel)
     for (size_t i = 0; i < numKeysByScanCode; i++) {
         int32_t key = parcel->readInt32();
         int32_t value = parcel->readInt32();
-        map->mKeysByScanCode.add(key, value);
+        map->mKeysByScanCode.insert_or_assign(key, value);
         if (parcel->errorCheck()) {
             return nullptr;
         }
@@ -739,7 +765,7 @@ std::shared_ptr<KeyCharacterMap> KeyCharacterMap::readFromParcel(Parcel* parcel)
     for (size_t i = 0; i < numKeysByUsageCode; i++) {
         int32_t key = parcel->readInt32();
         int32_t value = parcel->readInt32();
-        map->mKeysByUsageCode.add(key, value);
+        map->mKeysByUsageCode.insert_or_assign(key, value);
         if (parcel->errorCheck()) {
             return nullptr;
         }
@@ -773,17 +799,23 @@ void KeyCharacterMap::writeToParcel(Parcel* parcel) const {
         }
         parcel->writeInt32(0);
     }
+    size_t numKeyRemapping = mKeyRemapping.size();
+    parcel->writeInt32(numKeyRemapping);
+    for (auto const& [fromAndroidKeyCode, toAndroidKeyCode] : mKeyRemapping) {
+        parcel->writeInt32(fromAndroidKeyCode);
+        parcel->writeInt32(toAndroidKeyCode);
+    }
     size_t numKeysByScanCode = mKeysByScanCode.size();
     parcel->writeInt32(numKeysByScanCode);
-    for (size_t i = 0; i < numKeysByScanCode; i++) {
-        parcel->writeInt32(mKeysByScanCode.keyAt(i));
-        parcel->writeInt32(mKeysByScanCode.valueAt(i));
+    for (auto const& [fromScanCode, toAndroidKeyCode] : mKeysByScanCode) {
+        parcel->writeInt32(fromScanCode);
+        parcel->writeInt32(toAndroidKeyCode);
     }
     size_t numKeysByUsageCode = mKeysByUsageCode.size();
     parcel->writeInt32(numKeysByUsageCode);
-    for (size_t i = 0; i < numKeysByUsageCode; i++) {
-        parcel->writeInt32(mKeysByUsageCode.keyAt(i));
-        parcel->writeInt32(mKeysByUsageCode.valueAt(i));
+    for (auto const& [fromUsageCode, toAndroidKeyCode] : mKeysByUsageCode) {
+        parcel->writeInt32(fromUsageCode);
+        parcel->writeInt32(toAndroidKeyCode);
     }
 }
 #endif // __linux__
@@ -950,9 +982,9 @@ status_t KeyCharacterMap::Parser::parseMapKey() {
                 mapUsage ? "usage" : "scan code", codeToken.string());
         return BAD_VALUE;
     }
-    KeyedVector<int32_t, int32_t>& map =
-            mapUsage ? mMap->mKeysByUsageCode : mMap->mKeysByScanCode;
-    if (map.indexOfKey(code) >= 0) {
+    std::map<int32_t, int32_t>& map = mapUsage ? mMap->mKeysByUsageCode : mMap->mKeysByScanCode;
+    const auto it = map.find(code);
+    if (it != map.end()) {
         ALOGE("%s: Duplicate entry for key %s '%s'.", mTokenizer->getLocation().string(),
                 mapUsage ? "usage" : "scan code", codeToken.string());
         return BAD_VALUE;
@@ -971,7 +1003,7 @@ status_t KeyCharacterMap::Parser::parseMapKey() {
     ALOGD("Parsed map key %s: code=%d, keyCode=%d.",
             mapUsage ? "usage" : "scan code", code, keyCode);
 #endif
-    map.add(code, keyCode);
+    map.insert_or_assign(code, keyCode);
     return NO_ERROR;
 }
 
diff --git a/services/inputflinger/include/InputReaderBase.h b/services/inputflinger/include/InputReaderBase.h
index 6d6cefb0c0..b8a6dade34 100644
--- a/services/inputflinger/include/InputReaderBase.h
+++ b/services/inputflinger/include/InputReaderBase.h
@@ -88,6 +88,9 @@ public:
     virtual int32_t getSwitchState(int32_t deviceId, uint32_t sourceMask,
             int32_t sw) = 0;
 
+    virtual void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode,
+                                 int32_t toKeyCode) const = 0;
+
     virtual int32_t getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const = 0;
 
     /* Toggle Caps Lock */
diff --git a/services/inputflinger/reader/EventHub.cpp b/services/inputflinger/reader/EventHub.cpp
index f2ea90c291..e26bc8c6dc 100644
--- a/services/inputflinger/reader/EventHub.cpp
+++ b/services/inputflinger/reader/EventHub.cpp
@@ -952,15 +952,19 @@ int32_t EventHub::getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKey
             device->getKeyCharacterMap()->mapKey(scanCodes[0], 0 /*usageCode*/, &outKeyCode);
     switch (mapKeyRes) {
         case OK:
-            return outKeyCode;
+            break;
         case NAME_NOT_FOUND:
             // key character map doesn't re-map this scanCode, hence the keyCode remains the same
-            return locationKeyCode;
+            outKeyCode = locationKeyCode;
+            break;
         default:
             ALOGW("Failed to get key code for key location: Key character map returned error %s",
                   statusToString(mapKeyRes).c_str());
-            return AKEYCODE_UNKNOWN;
+            outKeyCode = AKEYCODE_UNKNOWN;
+            break;
     }
+    // Remap if there is a Key remapping added to the KCM and return the remapped key
+    return device->getKeyCharacterMap()->applyKeyRemapping(outKeyCode);
 }
 
 int32_t EventHub::getSwitchState(int32_t deviceId, int32_t sw) const {
@@ -1023,6 +1027,18 @@ bool EventHub::markSupportedKeyCodes(int32_t deviceId, const std::vector<int32_t
     return false;
 }
 
+void EventHub::addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const {
+    std::scoped_lock _l(mLock);
+    Device* device = getDeviceLocked(deviceId);
+    if (device == nullptr) {
+        return;
+    }
+    const std::shared_ptr<KeyCharacterMap> kcm = device->getKeyCharacterMap();
+    if (kcm) {
+        kcm->addKeyRemapping(fromKeyCode, toKeyCode);
+    }
+}
+
 status_t EventHub::mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode, int32_t metaState,
                           int32_t* outKeycode, int32_t* outMetaState, uint32_t* outFlags) const {
     std::scoped_lock _l(mLock);
@@ -1048,7 +1064,13 @@ status_t EventHub::mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode,
 
         if (status == NO_ERROR) {
             if (kcm) {
-                kcm->tryRemapKey(*outKeycode, metaState, outKeycode, outMetaState);
+                // Remap keys based on user-defined key remappings and key behavior defined in the
+                // corresponding kcm file
+                *outKeycode = kcm->applyKeyRemapping(*outKeycode);
+
+                // Remap keys based on Key behavior defined in KCM file
+                std::tie(*outKeycode, *outMetaState) =
+                        kcm->applyKeyBehavior(*outKeycode, metaState);
             } else {
                 *outMetaState = metaState;
             }
diff --git a/services/inputflinger/reader/InputDevice.cpp b/services/inputflinger/reader/InputDevice.cpp
index 150a8aac0d..e9a94b3a42 100644
--- a/services/inputflinger/reader/InputDevice.cpp
+++ b/services/inputflinger/reader/InputDevice.cpp
@@ -624,6 +624,12 @@ void InputDevice::updateMetaState(int32_t keyCode) {
     });
 }
 
+void InputDevice::addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode) {
+    for_each_subdevice([fromKeyCode, toKeyCode](auto& context) {
+        context.addKeyRemapping(fromKeyCode, toKeyCode);
+    });
+}
+
 void InputDevice::bumpGeneration() {
     mGeneration = mContext->bumpGeneration();
 }
diff --git a/services/inputflinger/reader/InputReader.cpp b/services/inputflinger/reader/InputReader.cpp
index f04a6469ea..57f679c022 100644
--- a/services/inputflinger/reader/InputReader.cpp
+++ b/services/inputflinger/reader/InputReader.cpp
@@ -650,6 +650,15 @@ bool InputReader::markSupportedKeyCodesLocked(int32_t deviceId, uint32_t sourceM
     return result;
 }
 
+void InputReader::addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const {
+    std::scoped_lock _l(mLock);
+
+    InputDevice* device = findInputDeviceLocked(deviceId);
+    if (device != nullptr) {
+        device->addKeyRemapping(fromKeyCode, toKeyCode);
+    }
+}
+
 int32_t InputReader::getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const {
     std::scoped_lock _l(mLock);
 
diff --git a/services/inputflinger/reader/include/EventHub.h b/services/inputflinger/reader/include/EventHub.h
index 42ca482a68..8a844b2088 100644
--- a/services/inputflinger/reader/include/EventHub.h
+++ b/services/inputflinger/reader/include/EventHub.h
@@ -262,6 +262,9 @@ public:
 
     virtual bool hasMscEvent(int32_t deviceId, int mscEvent) const = 0;
 
+    virtual void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode,
+                                 int32_t toKeyCode) const = 0;
+
     virtual status_t mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode,
                             int32_t metaState, int32_t* outKeycode, int32_t* outMetaState,
                             uint32_t* outFlags) const = 0;
@@ -460,6 +463,9 @@ public:
 
     bool hasMscEvent(int32_t deviceId, int mscEvent) const override final;
 
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode,
+                         int32_t toKeyCode) const override final;
+
     status_t mapKey(int32_t deviceId, int32_t scanCode, int32_t usageCode, int32_t metaState,
                     int32_t* outKeycode, int32_t* outMetaState,
                     uint32_t* outFlags) const override final;
diff --git a/services/inputflinger/reader/include/InputDevice.h b/services/inputflinger/reader/include/InputDevice.h
index 439123bf1d..6fa21e5362 100644
--- a/services/inputflinger/reader/include/InputDevice.h
+++ b/services/inputflinger/reader/include/InputDevice.h
@@ -114,6 +114,8 @@ public:
     int32_t getMetaState();
     void updateMetaState(int32_t keyCode);
 
+    void addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode);
+
     void bumpGeneration();
 
     [[nodiscard]] NotifyDeviceResetArgs notifyReset(nsecs_t when);
@@ -278,6 +280,10 @@ public:
 
     inline bool hasMscEvent(int mscEvent) const { return mEventHub->hasMscEvent(mId, mscEvent); }
 
+    inline void addKeyRemapping(int32_t fromKeyCode, int32_t toKeyCode) const {
+        mEventHub->addKeyRemapping(mId, fromKeyCode, toKeyCode);
+    }
+
     inline status_t mapKey(int32_t scanCode, int32_t usageCode, int32_t metaState,
                            int32_t* outKeycode, int32_t* outMetaState, uint32_t* outFlags) const {
         return mEventHub->mapKey(mId, scanCode, usageCode, metaState, outKeycode, outMetaState,
diff --git a/services/inputflinger/reader/include/InputReader.h b/services/inputflinger/reader/include/InputReader.h
index 4f2503ad5c..e9c989a224 100644
--- a/services/inputflinger/reader/include/InputReader.h
+++ b/services/inputflinger/reader/include/InputReader.h
@@ -68,6 +68,8 @@ public:
     int32_t getKeyCodeState(int32_t deviceId, uint32_t sourceMask, int32_t keyCode) override;
     int32_t getSwitchState(int32_t deviceId, uint32_t sourceMask, int32_t sw) override;
 
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const override;
+
     int32_t getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const override;
 
     void toggleCapsLockState(int32_t deviceId) override;
diff --git a/services/inputflinger/tests/FakeEventHub.cpp b/services/inputflinger/tests/FakeEventHub.cpp
index f6cf1cc304..289a7809cc 100644
--- a/services/inputflinger/tests/FakeEventHub.cpp
+++ b/services/inputflinger/tests/FakeEventHub.cpp
@@ -154,6 +154,11 @@ void FakeEventHub::addKeyCodeMapping(int32_t deviceId, int32_t fromKeyCode, int3
     getDevice(deviceId)->keyCodeMapping.insert_or_assign(fromKeyCode, toKeyCode);
 }
 
+void FakeEventHub::addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const {
+    Device* device = getDevice(deviceId);
+    device->keyRemapping.insert_or_assign(fromKeyCode, toKeyCode);
+}
+
 void FakeEventHub::addLed(int32_t deviceId, int32_t led, bool initialState) {
     getDevice(deviceId)->leds.add(led, initialState);
 }
@@ -299,7 +304,8 @@ status_t FakeEventHub::mapKey(int32_t deviceId, int32_t scanCode, int32_t usageC
         const KeyInfo* key = getKey(device, scanCode, usageCode);
         if (key) {
             if (outKeycode) {
-                *outKeycode = key->keyCode;
+                auto it = device->keyRemapping.find(key->keyCode);
+                *outKeycode = it != device->keyRemapping.end() ? it->second : key->keyCode;
             }
             if (outFlags) {
                 *outFlags = key->flags;
diff --git a/services/inputflinger/tests/FakeEventHub.h b/services/inputflinger/tests/FakeEventHub.h
index 21cb2f1963..fb3c8596c7 100644
--- a/services/inputflinger/tests/FakeEventHub.h
+++ b/services/inputflinger/tests/FakeEventHub.h
@@ -59,6 +59,7 @@ class FakeEventHub : public EventHubInterface {
         KeyedVector<int32_t, int32_t> absoluteAxisValue;
         KeyedVector<int32_t, KeyInfo> keysByScanCode;
         KeyedVector<int32_t, KeyInfo> keysByUsageCode;
+        std::unordered_map<int32_t, int32_t> keyRemapping;
         KeyedVector<int32_t, bool> leds;
         // fake mapping which would normally come from keyCharacterMap
         std::unordered_map<int32_t, int32_t> keyCodeMapping;
@@ -132,6 +133,7 @@ public:
     void addKey(int32_t deviceId, int32_t scanCode, int32_t usageCode, int32_t keyCode,
                 uint32_t flags);
     void addKeyCodeMapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode);
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const;
     void addVirtualKeyDefinition(int32_t deviceId, const VirtualKeyDefinition& definition);
 
     void addSensorAxis(int32_t deviceId, int32_t absCode, InputDeviceSensorType sensorType,
diff --git a/services/inputflinger/tests/InputReader_test.cpp b/services/inputflinger/tests/InputReader_test.cpp
index eef56902c7..4cc48f6fc3 100644
--- a/services/inputflinger/tests/InputReader_test.cpp
+++ b/services/inputflinger/tests/InputReader_test.cpp
@@ -2912,6 +2912,27 @@ TEST_F(KeyboardInputMapperTest, Process_SimpleKeyPress) {
     ASSERT_EQ(ARBITRARY_TIME, args.downTime);
 }
 
+TEST_F(KeyboardInputMapperTest, Process_KeyRemapping) {
+    mFakeEventHub->addKey(EVENTHUB_ID, KEY_A, 0, AKEYCODE_A, 0);
+    mFakeEventHub->addKey(EVENTHUB_ID, KEY_B, 0, AKEYCODE_B, 0);
+    mFakeEventHub->addKeyRemapping(EVENTHUB_ID, AKEYCODE_A, AKEYCODE_B);
+
+    KeyboardInputMapper& mapper =
+            addMapperAndConfigure<KeyboardInputMapper>(AINPUT_SOURCE_KEYBOARD,
+                                                       AINPUT_KEYBOARD_TYPE_ALPHABETIC);
+
+    // Key down by scan code.
+    process(mapper, ARBITRARY_TIME, READ_TIME, EV_KEY, KEY_A, 1);
+    NotifyKeyArgs args;
+    ASSERT_NO_FATAL_FAILURE(mFakeListener->assertNotifyKeyWasCalled(&args));
+    ASSERT_EQ(AKEYCODE_B, args.keyCode);
+
+    // Key up by scan code.
+    process(mapper, ARBITRARY_TIME + 1, READ_TIME, EV_KEY, KEY_A, 0);
+    ASSERT_NO_FATAL_FAILURE(mFakeListener->assertNotifyKeyWasCalled(&args));
+    ASSERT_EQ(AKEYCODE_B, args.keyCode);
+}
+
 /**
  * Ensure that the readTime is set to the time when the EV_KEY is received.
  */
diff --git a/services/inputflinger/tests/fuzzers/InputReaderFuzzer.cpp b/services/inputflinger/tests/fuzzers/InputReaderFuzzer.cpp
index 2eed9977be..057c15d6b8 100644
--- a/services/inputflinger/tests/fuzzers/InputReaderFuzzer.cpp
+++ b/services/inputflinger/tests/fuzzers/InputReaderFuzzer.cpp
@@ -153,6 +153,10 @@ public:
         return reader->getLightPlayerId(deviceId, lightId);
     }
 
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const {
+        reader->addKeyRemapping(deviceId, fromKeyCode, toKeyCode);
+    }
+
     int32_t getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const {
         return reader->getKeyCodeForKeyLocation(deviceId, locationKeyCode);
     }
diff --git a/services/inputflinger/tests/fuzzers/MapperHelpers.h b/services/inputflinger/tests/fuzzers/MapperHelpers.h
index 445ed182fe..cd852d668c 100644
--- a/services/inputflinger/tests/fuzzers/MapperHelpers.h
+++ b/services/inputflinger/tests/fuzzers/MapperHelpers.h
@@ -211,6 +211,7 @@ public:
     int32_t getSwitchState(int32_t deviceId, int32_t sw) const override {
         return mFdp->ConsumeIntegral<int32_t>();
     }
+    void addKeyRemapping(int32_t deviceId, int32_t fromKeyCode, int32_t toKeyCode) const override {}
     int32_t getKeyCodeForKeyLocation(int32_t deviceId, int32_t locationKeyCode) const override {
         return mFdp->ConsumeIntegral<int32_t>();
     }