Minimal test IME with Stylus HW support

Minimal IME with Handwriting support that can draw ink trail and commit
random text after each session.

Test: Manually
      1. m -j HandwritingIme
      2. adb install out/../HandwritingIme.apk
      3. Simulate stylus with  I7723be718354872509a9e85beda10acdbe25dd48
      4. and enable the property in #3 with
         adb shell setprop <property> true
      5. Open any app with editor and swipe on EditText.
      6. HW ink window with ink will appear.
Bug: 217957587

Change-Id: I53808ec261bd4364797b93d57cf6a8ddfd615390

tests/HandwritingIme/Android.bp

+// 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.
+
+package {
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "frameworks_base_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    default_applicable_licenses: ["frameworks_base_license"],
+}
+
+android_test {
+    name: "HandwritingIme",
+    srcs: ["src/**/*.java"],
+    resource_dirs: ["res"],
+    certificate: "platform",
+    platform_apis: true,
+    static_libs: [
+        "androidx.core_core",
+        "androidx.appcompat_appcompat",
+        "com.google.android.material_material",
+    ],
+}

tests/HandwritingIme/AndroidManifest.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (018C) 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
+  -->
+
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.google.android.test.handwritingime">
+
+    <application android:label="Handwriting IME">
+        <service android:name=".HandwritingIme"
+                 android:process=":HandwritingIme"
+                 android:label="Handwriting IME"
+                 android:permission="android.permission.BIND_INPUT_METHOD"
+                 android:exported="true">
+            <intent-filter>
+                <action android:name="android.view.InputMethod"/>
+            </intent-filter>
+            <meta-data android:name="android.view.im"
+                       android:resource="@xml/ime"/>
+        </service>
+
+    </application>
+</manifest>

tests/HandwritingIme/res/xml/ime.xml

+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ 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.
+  -->
+
+<!-- Configuration info for an input method -->
+<input-method xmlns:android="http://schemas.android.com/apk/res/android"
+              android:supportsStylusHandwriting="true"/>
\ No newline at end of file

tests/HandwritingIme/src/com/google/android/test/handwritingime/HandwritingIme.java

+/*
+ * 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.
+ */
+package com.google.android.test.handwritingime;
+
+import android.annotation.Nullable;
+import android.inputmethodservice.InputMethodService;
+import android.util.Log;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.Window;
+import android.widget.FrameLayout;
+import android.widget.Toast;
+
+import java.util.Random;
+
+public class HandwritingIme extends InputMethodService {
+
+    public static final int HEIGHT_DP = 100;
+
+    private Window mInkWindow;
+    private InkView mInk;
+
+    static final String TAG = "HandwritingIme";
+
+    interface HandwritingFinisher {
+        void finish();
+    }
+
+    interface StylusListener {
+        void onStylusEvent(MotionEvent me);
+    }
+
+    final class StylusConsumer implements StylusListener {
+        @Override
+        public void onStylusEvent(MotionEvent me) {
+            HandwritingIme.this.onStylusEvent(me);
+        }
+    }
+
+    final class HandwritingFinisherImpl implements HandwritingFinisher {
+
+        HandwritingFinisherImpl() {}
+
+        @Override
+        public void finish() {
+            finishStylusHandwriting();
+            Log.d(TAG, "HandwritingIme called finishStylusHandwriting() ");
+        }
+    }
+
+    private void onStylusEvent(@Nullable MotionEvent event) {
+        // TODO Hookup recognizer here
+        if (event.getAction() == MotionEvent.ACTION_UP) {
+            sendKeyChar((char) (56 + new Random().nextInt(66)));
+        }
+    }
+
+    @Override
+    public View onCreateInputView() {
+        Log.d(TAG, "onCreateInputView");
+        final ViewGroup view = new FrameLayout(this);
+        final View inner = new View(this);
+        final float density = getResources().getDisplayMetrics().density;
+        final int height = (int) (HEIGHT_DP * density);
+        view.setPadding(0, 0, 0, 0);
+        view.addView(inner, new FrameLayout.LayoutParams(
+                FrameLayout.LayoutParams.MATCH_PARENT, height));
+        inner.setBackgroundColor(0xff0110fe); // blue
+
+        return view;
+    }
+
+    public void onPrepareStylusHandwriting() {
+        Log.d(TAG, "onPrepareStylusHandwriting ");
+        if (mInk == null) {
+            mInk = new InkView(this, new HandwritingFinisherImpl(), new StylusConsumer());
+        }
+    }
+
+    @Override
+    public boolean onStartStylusHandwriting() {
+        Log.d(TAG, "onStartStylusHandwriting ");
+        Toast.makeText(this, "START HW", Toast.LENGTH_SHORT).show();
+        mInkWindow = getStylusHandwritingWindow();
+        mInkWindow.setContentView(mInk, mInk.getLayoutParams());
+        return true;
+    }
+
+    @Override
+    public void onFinishStylusHandwriting() {
+        Log.d(TAG, "onFinishStylusHandwriting ");
+        Toast.makeText(this, "Finish HW", Toast.LENGTH_SHORT).show();
+        // Free-up
+        ((ViewGroup) mInk.getParent()).removeView(mInk);
+        mInk = null;
+    }
+}

tests/HandwritingIme/src/com/google/android/test/handwritingime/InkView.java

+/*
+ * 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.
+ */
+
+package com.google.android.test.handwritingime;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Insets;
+import android.graphics.Paint;
+import android.graphics.Path;
+import android.view.MotionEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.WindowInsets;
+import android.view.WindowManager;
+import android.view.WindowMetrics;
+
+class InkView extends View {
+    private static final long FINISH_TIMEOUT = 2500;
+    private final HandwritingIme.HandwritingFinisher mHwCanceller;
+    private final HandwritingIme.StylusConsumer mConsumer;
+    private Paint mPaint;
+    private Path  mPath;
+    private float mX, mY;
+    private static final float STYLUS_MOVE_TOLERANCE = 1;
+    private Runnable mFinishRunnable;
+
+    InkView(Context context, HandwritingIme.HandwritingFinisher hwController,
+            HandwritingIme.StylusConsumer consumer) {
+        super(context);
+        mHwCanceller = hwController;
+        mConsumer = consumer;
+
+        mPaint = new Paint();
+        mPaint.setAntiAlias(true);
+        mPaint.setDither(true);
+        mPaint.setColor(Color.GREEN);
+        mPaint.setStyle(Paint.Style.STROKE);
+        mPaint.setStrokeJoin(Paint.Join.ROUND);
+        mPaint.setStrokeCap(Paint.Cap.ROUND);
+        mPaint.setStrokeWidth(14);
+
+        mPath = new Path();
+
+        WindowManager wm = context.getSystemService(WindowManager.class);
+        WindowMetrics metrics =  wm.getCurrentWindowMetrics();
+        Insets insets = metrics.getWindowInsets()
+                .getInsetsIgnoringVisibility(WindowInsets.Type.systemBars());
+        setLayoutParams(new ViewGroup.LayoutParams(
+                metrics.getBounds().width() - insets.left - insets.right,
+                metrics.getBounds().height() - insets.top - insets.bottom));
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+
+        canvas.drawPath(mPath, mPaint);
+        canvas.drawARGB(20, 255, 50, 50);
+    }
+
+    private void stylusStart(float x, float y) {
+        mPath.moveTo(x, y);
+        mX = x;
+        mY = y;
+    }
+
+    private void stylusMove(float x, float y) {
+        float dx = Math.abs(x - mX);
+        float dy = Math.abs(y - mY);
+        if (mPath.isEmpty()) {
+            stylusStart(x, y);
+        }
+        if (dx >= STYLUS_MOVE_TOLERANCE || dy >= STYLUS_MOVE_TOLERANCE) {
+            mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
+            mX = x;
+            mY = y;
+        }
+    }
+
+    private void stylusFinish() {
+        mPath.lineTo(mX, mY);
+        // TODO: support offscreen? e.g. mCanvas.drawPath(mPath, mPaint);
+        mPath.reset();
+        mX = 0;
+        mY = 0;
+
+    }
+
+
+    @Override
+    public boolean onTouchEvent(MotionEvent event) {
+        if (event.getToolType(0) == MotionEvent.TOOL_TYPE_STYLUS) {
+            mConsumer.onStylusEvent(event);
+            android.util.Log.w(HandwritingIme.TAG, "INK touch onStylusEvent " + event);
+            float x = event.getX();
+            float y = event.getY();
+            switch (event.getAction()) {
+                case MotionEvent.ACTION_DOWN:
+                    cancelTimer();
+                    stylusStart(x, y);
+                    invalidate();
+                    break;
+                case MotionEvent.ACTION_MOVE:
+                    stylusMove(x, y);
+                    invalidate();
+                    break;
+
+                case MotionEvent.ACTION_UP:
+                    scheduleTimer();
+                    break;
+
+            }
+            return true;
+        }
+        return false;
+    }
+
+    private void cancelTimer() {
+        if (mFinishRunnable != null) {
+            if (getHandler() != null) {
+                getHandler().removeCallbacks(mFinishRunnable);
+            }
+            mFinishRunnable = null;
+        }
+        if (getHandler() != null) {
+            getHandler().removeCallbacksAndMessages(null);
+        }
+    }
+
+    private void scheduleTimer() {
+        cancelTimer();
+        if (getHandler() != null) {
+            postDelayed(getFinishRunnable(), FINISH_TIMEOUT);
+        }
+    }
+
+    private Runnable getFinishRunnable() {
+        mFinishRunnable = () -> {
+            android.util.Log.e(HandwritingIme.TAG, "Hw view timer finishHandwriting ");
+            mHwCanceller.finish();
+            stylusFinish();
+            mPath.reset();
+            invalidate();
+        };
+
+        return mFinishRunnable;
+    }
+
+}