[Chromoting] Add InputMonitor and InputState

remoting/android/java/src/org/chromium/chromoting/InputState.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chromoting;
+
+/**
+ * A state machine to indicate user input actions. It stores the start action (tap or long tap),
+ * finger count, detected action, etc. This class is not thread-safe.

[Lambros, 2016/07/14 18:58:07]

You can remove the thread-safety comment if you like.
The default assumption is thread-unsafe. And code that deals with UI and input
can be assumed to run on the main UI thread.

[Hzj_jie, 2016/07/14 23:18:06]

Done.

+ */
+public class InputState {
+    /**
+     * A settable {@link InputState}.
+     */
+    public static final class Settable extends InputState {
+        public void setFingerCount(int fingerCount) {
+            mFingerCount = fingerCount;
+            if (mFingerCount == 0) {
+                mStartAction = StartAction.UNDEFINED;
+                mDetectedAction = DetectedAction.UNDEFINED;
+            }
+        }
+
+        public void setStartAction(StartAction startAction) {
+            Preconditions.isTrue(startAction != StartAction.UNDEFINED);
+            mStartAction = startAction;
+        }
+
+        public void setDetectedAction(DetectedAction detectedAction) {
+            Preconditions.isTrue(detectedAction != DetectedAction.UNDEFINED);
+            mDetectedAction = detectedAction;
+        }
+    }
+
+    public enum StartAction {
+        UNDEFINED,
+        // The action started from a long press. Note, a tap won't need to impact InputState.
+        LONG_PRESS,
+    }
+
+    public enum DetectedAction {
+        UNDEFINED,
+        SCROLL,
+        SCROLL_FLING,
+        // AFTER_SCROLL_FLING is a fake action to indicate the state after a scroll fling has been
+        // performed.
+        AFTER_SCROLL_FLING,
+        FLING,
+        SCALE,
+        SWIPE,
+        MOVE,
+        SCROLL_EDGE,
+    }
+
+    protected int mFingerCount;
+    protected StartAction mStartAction;
+    protected DetectedAction mDetectedAction;
+
+    public InputState() {
+        mStartAction = StartAction.UNDEFINED;
+        mFingerCount = 0;
+        mDetectedAction = DetectedAction.UNDEFINED;
+    }
+
+    public int getFingerCount() {
+        return mFingerCount;
+    }
+
+    public StartAction getStartAction() {
+        return mStartAction;
+    }
+
+    public DetectedAction getDetectedAction() {
+        return mDetectedAction;
+    }
+
+    public boolean suppressCursorMovement() {

[Lambros, 2016/07/14 18:58:07]

Name this as a boolean-noun instead of a verb? Perhaps:
getSuppressCursorMovement() or
shouldSuppressCursorMovement() or
suppressesCursorMovement()

[Hzj_jie, 2016/07/14 23:18:06]

Done.

+        return mDetectedAction == DetectedAction.SWIPE
+                || mDetectedAction == DetectedAction.SCROLL_FLING
+                || mDetectedAction == DetectedAction.SCROLL_EDGE;
+    }
+
+    public boolean suppressFling() {

[Lambros, 2016/07/14 18:58:07]

Same here.

[Hzj_jie, 2016/07/14 23:18:06]

Done.

+        return mDetectedAction == DetectedAction.SWIPE
+                || mStartAction == StartAction.LONG_PRESS;
+    }
+
+    public boolean scrollFling() {

[Lambros, 2016/07/14 18:58:07]

isScrollFling()

[Hzj_jie, 2016/07/14 23:18:06]

Done.

+        return mDetectedAction == DetectedAction.SCROLL_FLING;
+    }
+
+    public boolean swipeCompleted() {
+        return mDetectedAction == DetectedAction.SWIPE;
+    }
+
+    public boolean isDragging() {
+        return mStartAction == StartAction.LONG_PRESS;
+    }
+}