diff --git a/services/inputflinger/PreferStylusOverTouchBlocker.h b/services/inputflinger/PreferStylusOverTouchBlocker.h
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+++ b/services/inputflinger/PreferStylusOverTouchBlocker.h
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2022 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 <ftl/static_vector.h>
+#include <optional>
+#include "InputListener.h"
+
+namespace android {
+
+/**
+ * When stylus is down, we ignore all touch.
+ * TODO(b/210159205): delete this when simultaneous stylus and touch is supported
+ */
+class PreferStylusOverTouchBlocker {
+public:
+    /**
+     * Process the provided event and emit up to 2 events in response.
+     * In the majority of cases, the returned result will just be the provided args (array with
+     * only 1 element), unmodified.
+     *
+     * If the gesture should be blocked, the returned result may be:
+     *
+     * a) An empty array, if the current event should just be ignored completely
+     * b) An array of 2 elements, containing an event with ACTION_CANCEL and the current event.
+     *
+     * bool is set to 'true'.
+     * NotifyMotionArgs potentially contains an event that should be used to cancel the existing
+     * gesture.
+     *
+     * If the event should not be blocked, bool contains 'false'.
+     */
+    ftl::StaticVector<NotifyMotionArgs, 2> processMotion(const NotifyMotionArgs& args);
+    std::string dump();
+
+private:
+    bool mIsTouchDown = false;
+    bool mIsStylusDown = false;
+    // Provide some default values for the stored MotionEvent to allow printint the event before
+    // any real event is received.
+    NotifyMotionArgs mLastTouchEvent{0 /*id*/,
+                                     0 /*eventTime*/,
+                                     0 /*readTime*/,
+                                     0 /*deviceId*/,
+                                     AINPUT_SOURCE_TOUCHSCREEN,
+                                     0 /*displayId*/,
+                                     0 /*policyFlags*/,
+                                     0 /*action*/,
+                                     0 /*actionButton*/,
+                                     0 /*flags*/,
+                                     0 /*metaState*/,
+                                     0 /*buttonState*/,
+                                     MotionClassification::NONE,
+                                     AMOTION_EVENT_EDGE_FLAG_NONE,
+                                     0 /*pointerCount*/,
+                                     nullptr /*properties*/,
+                                     nullptr /*coords*/,
+                                     0. /*xPrecision*/,
+                                     0. /*yPrecision*/,
+                                     AMOTION_EVENT_INVALID_CURSOR_POSITION,
+                                     AMOTION_EVENT_INVALID_CURSOR_POSITION,
+                                     0 /*downTime*/,
+                                     {}};
+    bool mCurrentTouchIsCanceled = false;
+};
+
+} // namespace android
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