Refactor code to reduce duplication.

BUG: 153886988
Test: make, install and run
Change-Id: I64294a3438e297fb8c6e90b078697b883dee8cb4

2 files changed, 103 insertions, 119 deletions

diff --git a/RotaryPlayground/src/com/android/car/rotaryplayground/DirectManipulationView.java b/RotaryPlayground/src/com/android/car/rotaryplayground/DirectManipulationView.java
index 6c37556..733de87 100644
--- a/RotaryPlayground/src/com/android/car/rotaryplayground/DirectManipulationView.java
+++ b/RotaryPlayground/src/com/android/car/rotaryplayground/DirectManipulationView.java
@@ -15,17 +15,20 @@
  */
 package com.android.car.rotaryplayground;
 
+import static java.lang.Math.min;
+
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Paint;
 import android.util.AttributeSet;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
 import android.view.View;
 
+import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
-import static java.lang.Math.min;
-
 /**
  * A {@link View} used to demonstrate direct manipulation mode.
  * <p>
@@ -95,7 +98,7 @@ public class DirectManipulationView extends View {
     }
 
     /** Changes the radius of the circle by {@code dr} then redraws it. */
-    void zoom(float dr) {
+    void resizeCircle(float dr) {
         mDeltaRadius += dr;
         invalidate();
     }
@@ -113,4 +116,95 @@ public class DirectManipulationView extends View {
         mPaint.setStrokeJoin(Paint.Join.ROUND);
         mPaint.setStrokeCap(Paint.Cap.ROUND);
     }
+
+    /**
+     * A {@link View.OnKeyListener} for handling Direct Manipulation rotary nudge behavior
+     * for a {@link DirectManipulationView}.
+     * <p>
+     * This handler expects that it is being used in Direct Manipulation mode, i.e. as a directional
+     * delegate through a {@link DirectManipulationHandler} which can invoke it at the
+     * appropriate times.
+     * <p>
+     * Moves the circle drawn in the {@link DirectManipulationView} in the relevant direction for
+     * following {@link KeyEvent}s:
+     * <ul>
+     *     <li>{@link KeyEvent#KEYCODE_DPAD_UP}
+     *     <li>{@link KeyEvent#KEYCODE_DPAD_DOWN}
+     *     <li>{@link KeyEvent#KEYCODE_DPAD_LEFT}
+     *     <li>{@link KeyEvent#KEYCODE_DPAD_RIGHT}
+     * </ul>
+     */
+    static class NudgeHandler implements View.OnKeyListener {
+
+        /** How many pixels do we want to move the {@link DirectManipulationView} per nudge. */
+        private static final float DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE = 10f;
+
+        @Override
+        public boolean onKey(View v, int keyCode, KeyEvent keyEvent) {
+            if (keyEvent.getAction() != KeyEvent.ACTION_UP) {
+                return true;
+            }
+
+            if (v instanceof DirectManipulationView) {
+                DirectManipulationView dmv = (DirectManipulationView) v;
+                handleNudgeEvent(dmv, keyCode);
+                return true;
+            }
+
+            throw new UnsupportedOperationException("NudgeHandler shouldn't be registered "
+                    + "as a listener on a view other than a DirectManipulationView.");
+        }
+
+        /** Moves the circle of the DirectManipulationView when the controller nudges. */
+        private void handleNudgeEvent(@NonNull DirectManipulationView dmv, int keyCode) {
+            switch (keyCode) {
+                case KeyEvent.KEYCODE_DPAD_UP:
+                    dmv.move(0f, -DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE);
+                    return;
+                case KeyEvent.KEYCODE_DPAD_DOWN:
+                    dmv.move(0f, DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE);
+                    return;
+                case KeyEvent.KEYCODE_DPAD_LEFT:
+                    dmv.move(-DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE, 0f);
+                    return;
+                case KeyEvent.KEYCODE_DPAD_RIGHT:
+                    dmv.move(DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE, 0f);
+                    return;
+                default:
+                    throw new IllegalArgumentException("Invalid keycode: " + keyCode);
+            }
+        }
+    }
+
+    /**
+     * A {@link View.OnGenericMotionListener} for handling Direct Manipulation rotation events for
+     * a {@link DirectManipulationView}. It does so by increasing or decreasing the radius of
+     * the circle drawn depending on the direction of rotation.
+     */
+    static class RotationHandler implements View.OnGenericMotionListener {
+
+        /**
+         * How many pixels do we want to change the radius of the circle in the
+         * {@link DirectManipulationView} for a rotation.
+         */
+        private static final float DIRECT_MANIPULATION_VIEW_PX_PER_ROTATION = 10f;
+
+        @Override
+        public boolean onGenericMotion(View v, MotionEvent event) {
+            if (v instanceof DirectManipulationView) {
+                handleRotateEvent(
+                        (DirectManipulationView) v,
+                        event.getAxisValue(MotionEvent.AXIS_SCROLL));
+                return true;
+            }
+
+            throw new UnsupportedOperationException("RotationHandler shouldn't be registered "
+                    + "as a listener on a view other than a DirectManipulationView.");
+        }
+
+        /** Resizes the circle of the DirectManipulationView when the controller rotates. */
+        private void handleRotateEvent(@NonNull DirectManipulationView dmv, float scroll) {
+            dmv.resizeCircle(DIRECT_MANIPULATION_VIEW_PX_PER_ROTATION * scroll);
+        }
+    }
 }
diff --git a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryDirectManipulationWidgets.java b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryDirectManipulationWidgets.java
index 79a384c..a4715c3 100644
--- a/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryDirectManipulationWidgets.java
+++ b/RotaryPlayground/src/com/android/car/rotaryplayground/RotaryDirectManipulationWidgets.java
@@ -51,12 +51,6 @@ public class RotaryDirectManipulationWidgets extends Fragment {
     // TODO(agathaman): refactor a common class that takes in a fragment xml id and inflates it, to
     //  share between this and RotaryCards.
 
-    /** How many pixels do we want to move the {@link DirectManipulationView} for nudge. */
-    private static final float DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE = 10f;
-
-    /** How many pixels do we want to zoom the {@link DirectManipulationView} for a rotation. */
-    private static final float DIRECT_MANIPULATION_VIEW_PX_PER_ROTATION = 10f;
-
     /** Background color of a view when it's in direct manipulation mode. */
     private static final int BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE = Color.BLUE;
 
@@ -71,7 +65,12 @@ public class RotaryDirectManipulationWidgets extends Fragment {
         View view = inflater.inflate(R.layout.rotary_direct_manipulation, container, false);
 
         DirectManipulationView dmv = view.findViewById(R.id.direct_manipulation_view);
-        initDirectManipulationMode(dmv, /* handleNudge= */ true, /* handleRotate= */ true);
+        registerDirectManipulationHandler(dmv,
+                new DirectManipulationHandler.Builder(mDirectManipulationMode)
+                        .setNudgeHandler(new DirectManipulationView.NudgeHandler())
+                        .setRotationHandler(new DirectManipulationView.RotationHandler())
+                        .build());
+
 
         TimePicker spinnerTimePicker = view.findViewById(R.id.spinner_time_picker);
         registerDirectManipulationHandler(spinnerTimePicker,
@@ -139,52 +138,6 @@ public class RotaryDirectManipulationWidgets extends Fragment {
         super.onPause();
     }
 
-    /**
-     * Initializes the given view so that it can enter/exit direct manipulation mode and interact
-     * with the rotary controller directly.
-     *
-     * @param dmv          the view to enable direct manipulation mode
-     * @param handleNudge  whether to handle controller nudge in direct manipulation mode
-     * @param handleRotate whether to handle controller rotate in direct manipulation mode
-     */
-    private void initDirectManipulationMode(
-            @NonNull View dmv, boolean handleNudge, boolean handleRotate) {
-        dmv.setOnKeyListener((view, keyCode, keyEvent) -> {
-            boolean isActionUp = keyEvent.getAction() == KeyEvent.ACTION_UP;
-            switch (keyCode) {
-                // Always consume KEYCODE_DPAD_CENTER and KEYCODE_BACK event.
-                case KeyEvent.KEYCODE_DPAD_CENTER:
-                    if (!mDirectManipulationMode.isActive() && isActionUp) {
-                        enableDirectManipulationMode(dmv, true);
-                    }
-                    return true;
-                case KeyEvent.KEYCODE_BACK:
-                    if (mDirectManipulationMode.isActive() && isActionUp) {
-                        enableDirectManipulationMode(dmv, false);
-                    }
-                    return true;
-                // Consume nudge event if the view handles controller nudge in direct manipulation
-                // mode.
-                case KeyEvent.KEYCODE_DPAD_UP:
-                case KeyEvent.KEYCODE_DPAD_DOWN:
-                case KeyEvent.KEYCODE_DPAD_LEFT:
-                case KeyEvent.KEYCODE_DPAD_RIGHT:
-                    return handleNudge ? handleNudgeEvent(keyEvent) : false;
-                // Don't consume other key events.
-                default:
-                    return false;
-            }
-        });
-
-        // Consume rotate event if the view handles controller rotate in direct manipulation mode.
-        if (handleRotate) {
-            dmv.setOnGenericMotionListener(((view, motionEvent) -> {
-                float scroll = motionEvent.getAxisValue(MotionEvent.AXIS_SCROLL);
-                return handleRotateEvent(scroll);
-            }));
-        }
-    }
-
     private void enableDirectManipulationMode(@NonNull View view, boolean enable) {
         view.setBackgroundColor(enable
                 ? BACKGROUND_COLOR_IN_DIRECT_MANIPULATION_MODE
@@ -195,69 +148,6 @@ public class RotaryDirectManipulationWidgets extends Fragment {
         mDirectManipulationMode.setStartingView(currentView);
     }
 
-    /** Handles controller nudge event. Returns whether the event was consumed. */
-    private boolean handleNudgeEvent(KeyEvent keyEvent) {
-        if (!mDirectManipulationMode.isActive()) {
-            return false;
-        }
-        if (keyEvent.getAction() != KeyEvent.ACTION_UP) {
-            return true;
-        }
-        int keyCode = keyEvent.getKeyCode();
-        if (mDirectManipulationMode.getStartingView() instanceof DirectManipulationView) {
-            DirectManipulationView dmv =
-                    (DirectManipulationView) mDirectManipulationMode.getStartingView();
-            handleNudgeEvent(dmv, keyCode);
-            return true;
-        }
-
-        // TODO: support other views.
-
-        return true;
-    }
-
-    /** Handles controller rotate event. Returns whether the event was consumed. */
-    private boolean handleRotateEvent(float scroll) {
-        if (!mDirectManipulationMode.isActive()) {
-            return false;
-        }
-        if (mDirectManipulationMode.getStartingView() instanceof DirectManipulationView) {
-            DirectManipulationView dmv =
-                    (DirectManipulationView) mDirectManipulationMode.getStartingView();
-            handleRotateEvent(dmv, scroll);
-            return true;
-        }
-
-        // TODO: support other views.
-
-        return true;
-    }
-
-    /** Moves the circle of the DirectManipulationView when the controller nudges. */
-    private void handleNudgeEvent(@NonNull DirectManipulationView dmv, int keyCode) {
-        switch (keyCode) {
-            case KeyEvent.KEYCODE_DPAD_UP:
-                dmv.move(0f, -DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE);
-                return;
-            case KeyEvent.KEYCODE_DPAD_DOWN:
-                dmv.move(0f, DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE);
-                return;
-            case KeyEvent.KEYCODE_DPAD_LEFT:
-                dmv.move(-DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE, 0f);
-                return;
-            case KeyEvent.KEYCODE_DPAD_RIGHT:
-                dmv.move(DIRECT_MANIPULATION_VIEW_PX_PER_NUDGE, 0f);
-                return;
-            default:
-                throw new IllegalArgumentException("Invalid keycode :" + keyCode);
-        }
-    }
-
-    /** Zooms the circle of the DirectManipulationView when the controller rotates. */
-    private void handleRotateEvent(@NonNull DirectManipulationView dmv, float scroll) {
-        dmv.zoom(DIRECT_MANIPULATION_VIEW_PX_PER_ROTATION * scroll);
-    }
-
     /**
      * Register the given {@link DirectManipulationHandler} as both the
      * {@link View.OnKeyListener} and {@link View.OnGenericMotionListener} for the given