6/n: Add camera preview to FaceEnrollEnrolling

Bug: 112005540

Test: manual
Change-Id: Ie4f810dffecdec9731e20d5756854d9c9f420f4b

src/com/android/settings/biometrics/face/FaceEnrollAnimationDrawable.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2018 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.android.settings.biometrics.face;
+
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.ColorFilter;
+import android.graphics.Paint;
+import android.graphics.PixelFormat;
+import android.graphics.PorterDuff;
+import android.graphics.PorterDuffXfermode;
+import android.graphics.Rect;
+import android.graphics.drawable.Drawable;
+
+/**
+ * A drawable containing the circle cutout.
+ */
+public class FaceEnrollAnimationDrawable extends Drawable {
+
+    private Rect mBounds;
+    private final Paint mSquarePaint;
+    private final Paint mCircleCutoutPaint;
+
+    public FaceEnrollAnimationDrawable() {
+        mSquarePaint = new Paint();
+        mSquarePaint.setColor(Color.WHITE);
+        mSquarePaint.setAntiAlias(true);
+
+        mCircleCutoutPaint = new Paint();
+        mCircleCutoutPaint.setColor(Color.TRANSPARENT);
+        mCircleCutoutPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
+        mCircleCutoutPaint.setAntiAlias(true);
+    }
+
+    @Override
+    protected void onBoundsChange(Rect bounds) {
+        mBounds = bounds;
+    }
+
+    @Override
+    public void draw(Canvas canvas) {
+        if (mBounds == null) {
+            return;
+        }
+        canvas.save();
+
+        // Draw a rectangle covering the whole view
+        canvas.drawRect(0, 0, mBounds.width(), mBounds.height(), mSquarePaint);
+
+        // Clear a circle in the middle for the camera preview
+        canvas.drawCircle(mBounds.exactCenterX(), mBounds.exactCenterY(),
+                mBounds.height() / 2, mCircleCutoutPaint);
+
+        canvas.restore();
+    }
+
+    @Override
+    public void setAlpha(int alpha) {
+
+    }
+
+    @Override
+    public void setColorFilter(ColorFilter colorFilter) {
+
+    }
+
+    @Override
+    public int getOpacity() {
+        return PixelFormat.TRANSLUCENT;
+    }
+}