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FaceTrackerFactory.java

/*
 * Copyright (C) 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.gms.samples.vision.face.multitracker;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;

import com.google.android.gms.vision.MultiProcessor;
import com.google.android.gms.vision.Tracker;
import com.google.android.gms.vision.face.Face;
import com.google.android.gms.samples.vision.face.multitracker.ui.camera.GraphicOverlay;

/**
 * Factory for creating a tracker and associated graphic to be associated with a new face.  The
 * multi-processor uses this factory to create face trackers as needed -- one for each individual.
 */
class FaceTrackerFactory implements MultiProcessor.Factory<Face> {
    private GraphicOverlay mGraphicOverlay;

FaceTrackerFactory(GraphicOverlay graphicOverlay) {
        mGraphicOverlay = graphicOverlay;
    }

@Override
    public Tracker<Face> create(Face face) {
        FaceGraphic graphic = new FaceGraphic(mGraphicOverlay);
        return new GraphicTracker<>(mGraphicOverlay, graphic);
    }
}

/**
 * Graphic instance for rendering face position, size, and ID within an associated graphic overlay
 * view.
 */
class FaceGraphic extends TrackedGraphic<Face> {
    private static final float FACE_POSITION_RADIUS = 10.0f;
    private static final float ID_TEXT_SIZE = 40.0f;
    private static final float ID_Y_OFFSET = 50.0f;
    private static final float ID_X_OFFSET = -50.0f;
    private static final float BOX_STROKE_WIDTH = 5.0f;

private static final int COLOR_CHOICES[] = {
        Color.MAGENTA,
        Color.RED,
        Color.YELLOW
    };
    private static int mCurrentColorIndex = 0;

private Paint mFacePositionPaint;
    private Paint mIdPaint;
    private Paint mBoxPaint;

private volatile Face mFace;

FaceGraphic(GraphicOverlay overlay) {
        super(overlay);

mCurrentColorIndex = (mCurrentColorIndex + 1) % COLOR_CHOICES.length;
        final int selectedColor = COLOR_CHOICES[mCurrentColorIndex];

mFacePositionPaint = new Paint();
        mFacePositionPaint.setColor(selectedColor);

mIdPaint = new Paint();
        mIdPaint.setColor(selectedColor);
        mIdPaint.setTextSize(ID_TEXT_SIZE);

mBoxPaint = new Paint();
        mBoxPaint.setColor(selectedColor);
        mBoxPaint.setStyle(Paint.Style.STROKE);
        mBoxPaint.setStrokeWidth(BOX_STROKE_WIDTH);
    }

/**
     * Updates the face instance from the detection of the most recent frame.  Invalidates the
     * relevant portions of the overlay to trigger a redraw.
     */
    void updateItem(Face face) {
        mFace = face;
        postInvalidate();
    }

/**
     * Draws the face annotations for position, size, and ID on the supplied canvas.
     */
    @Override
    public void draw(Canvas canvas) {
        Face face = mFace;
        if (face == null) {
            return;
        }

// Draws a circle at the position of the detected face, with the face's track id below.
        float cx = translateX(face.getPosition().x + face.getWidth() / 2);
        float cy = translateY(face.getPosition().y + face.getHeight() / 2);
        canvas.drawCircle(cx, cy, FACE_POSITION_RADIUS, mFacePositionPaint);
        canvas.drawText("id: " + getId(), cx + ID_X_OFFSET, cy + ID_Y_OFFSET, mIdPaint);

// Draws an oval around the face.
        float xOffset = scaleX(face.getWidth() / 2.0f);
        float yOffset = scaleY(face.getHeight() / 2.0f);
        float left = cx - xOffset;
        float top = cy - yOffset;
        float right = cx + xOffset;
        float bottom = cy + yOffset;
        canvas.drawOval(left, top, right, bottom, mBoxPaint);
    }
}