检测人脸有很多用处, 可以提供更好的交互, 和一些有针对性的意见. 检测脸部关键信息, 也可以处理一些微表情的内容.
Google推出了官方的人脸检测功能, 很不幸依赖Google Service, 需要版本8.1以上. 国内手机基本不会默认配置. 下载地址, 此版本适配手机系统4.4+.
关注:
(1) 如何提取人脸(Face)位置.
(2) 如何提取脸部关键点(Landmark)位置.
(3) 如何在画布(Canvas)创建居中图片控件.
我讲解一下用法, 写了一个简单的显示控件, 注释详细.
本文源码的GitHub下载地址
效果
1. 配置项目
新建HelloWorld项目, 配置build.gradle.
compile 'com.google.android.gms:play-services-vision:8.1.0' // 包含人脸识别类
compile 'com.jakewharton:butterknife:7.0.1'
一般都会从最基础的HelloWorld开始, 方便学习和理解. ButterKnife必用.
2. 检测人脸控件
控件居中显示一张图片, 在图片上, 绘制人脸位置和关键点(Landmarks).
关键点包括: 眼睛, 鼻子, 嘴等属性. 存在遮挡, 根据不同人脸提取量不同.
通过FaceDetector检测Bitmap, 获取图片的所有脸部(face)信息.
根据位置(Position)画出脸的形状, 根据关键点(Landmarks)画出脸部特征.
同时可以获取各种特征的概率(Probability), 和脸部偏移.
/**
* 检测人脸的控件
* <p/>
* Created by wangchenlong on 15/12/15.
*/
public class FacesDisplayView extends View {
private static final String TAG = "DEBUG-WCL: " + FacesDisplayView.class.getSimpleName();
private Bitmap mBitmap; // 图片
private SparseArray<Face> mFaces; // 人脸数组
// 确保图片居中
private int mHorizonOffset; // 水平偏移
private int mVerticalOffset; // 竖直偏移
public FacesDisplayView(Context context) {
this(context, null);
}
public FacesDisplayView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public FacesDisplayView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
// 设置显示图片
@SuppressWarnings("unused")
public void setBitmap(Bitmap bitmap) {
mBitmap = bitmap;
FaceDetector detector = new FaceDetector.Builder(getContext())
.setTrackingEnabled(true)
.setLandmarkType(FaceDetector.ALL_LANDMARKS)
.setMode(FaceDetector.ACCURATE_MODE)
.build();
if (!detector.isOperational()) {
Log.e(TAG, "加载失败");
return;
} else {
Frame frame = new Frame.Builder().setBitmap(bitmap).build();
mFaces = detector.detect(frame);
detector.release();
}
logFaceData(); // 打印人脸数据
invalidate(); // 填充
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if ((mBitmap != null) && (mFaces != null)) {
double scale = drawBitmap(canvas);
drawFaceBox(canvas, scale);
drawFaceLandmarks(canvas, scale);
}
}
// 绘制图片, 返回缩放概率
private double drawBitmap(Canvas canvas) {
double viewWidth = canvas.getWidth(); // 显示宽度
double viewHeight = canvas.getHeight(); // 显示高度
double imageWidth = mBitmap.getWidth(); // 图片宽度
double imageHeight = mBitmap.getHeight(); // 图片高度
double wScale = viewWidth / imageWidth;
double hScale = viewHeight / imageHeight;
double scale;
Rect destBounds;
// 水平竖直缩放
if (wScale > hScale) {
mHorizonOffset = (int) ((viewWidth - imageWidth * hScale) / 2.0f);
destBounds = new Rect(mHorizonOffset, 0,
(int) (imageWidth * hScale) + mHorizonOffset, (int) (imageHeight * hScale));
scale = hScale;
} else {
mVerticalOffset = (int) ((viewHeight - imageHeight * wScale) / 2.0f);
destBounds = new Rect(0, mVerticalOffset,
(int) (imageWidth * wScale), (int) (imageHeight * wScale) + mVerticalOffset);
scale = wScale;
}
canvas.drawBitmap(mBitmap, null, destBounds, null); // 添加图片
return scale;
}
// 绘制脸部方形
private void drawFaceBox(Canvas canvas, double scale) {
// 画笔
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
float left;
float top;
float right;
float bottom;
// 绘制每张脸
for (int i = 0; i < mFaces.size(); i++) {
Face face = mFaces.valueAt(i);
left = (float) (face.getPosition().x * scale);
top = (float) (face.getPosition().y * scale);
right = (float) scale * (face.getPosition().x + face.getWidth());
bottom = (float) scale * (face.getPosition().y + face.getHeight());
canvas.drawRect(left + mHorizonOffset, top + mVerticalOffset,
right + mHorizonOffset, bottom + mVerticalOffset, paint);
}
}
// 绘制脸部关键部位
private void drawFaceLandmarks(Canvas canvas, double scale) {
Paint paint = new Paint();
paint.setColor(Color.YELLOW);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
for (int i = 0; i < mFaces.size(); i++) {
Face face = mFaces.valueAt(i);
for (Landmark landmark : face.getLandmarks()) {
int cx = (int) (landmark.getPosition().x * scale);
int cy = (int) (landmark.getPosition().y * scale);
canvas.drawCircle(cx + mHorizonOffset, cy + mVerticalOffset, 10, paint);
}
}
}
// 输出脸部数据
private void logFaceData() {
float smilingProbability;
float leftEyeOpenProbability;
float rightEyeOpenProbability;
float eulerY;
float eulerZ;
for (int i = 0; i < mFaces.size(); i++) {
Face face = mFaces.valueAt(i);
// 可能性
smilingProbability = face.getIsSmilingProbability();
leftEyeOpenProbability = face.getIsLeftEyeOpenProbability();
rightEyeOpenProbability = face.getIsRightEyeOpenProbability();
eulerY = face.getEulerY(); // 竖直轴偏移
eulerZ = face.getEulerZ(); // 前后偏移
Log.e(TAG, "脸数: " + i);
Log.e(TAG, "微笑概率: " + smilingProbability);
Log.e(TAG, "左眼睁开概率: " + leftEyeOpenProbability);
Log.e(TAG, "右眼睁开概率: " + rightEyeOpenProbability);
Log.e(TAG, "竖直轴偏移: " + eulerY);
Log.e(TAG, "前后偏移: " + eulerZ);
Log.e(TAG, "--------------------");
}
}
}
图像和特征是显示在画布上, 根据画布大小, 等比例缩放, 并居中显示.
3. 主页面
主界面通过一个简单的ViewPager连续显示图片.
@Bind(R.id.main_vp_container) ViewPager mVpContainer; // 连续
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ButterKnife.bind(this);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mVpContainer.setAdapter(new FacesViewPagerAdapter(getSupportFragmentManager()));
}
适配传递参数, 根据参数, 返回不同的图片页面.
/**
* 脸部适配器
* <p/>
* Created by wangchenlong on 15/12/15.
*/
public class FacesViewPagerAdapter extends FragmentPagerAdapter {
private static final int NUM = 9;
public FacesViewPagerAdapter(FragmentManager fm) {
super(fm);
}
@Override public Fragment getItem(int position) {
return ShowFaceFragment.newInstance(position);
}
@Override public int getCount() {
return NUM;
}
}
每页是个Fragment, 根据参数, 使用不同资源.
/**
* 显示人脸的界面
* <p/>
* Created by wangchenlong on 15/12/15.
*/
public class ShowFaceFragment extends Fragment {
private static final String ARG_SELECTION_NUM = "arg_selection_num";
@Bind(R.id.main_fdv_face_detector) FacesDisplayView mFdvFaceDetector;
@RawRes ArrayList<Integer> mPhotos; // 图片集合
public ShowFaceFragment() {
mPhotos = new ArrayList<>();
mPhotos.add(R.raw.total_large_poster);
mPhotos.add(R.raw.jessicajung_large_poster);
mPhotos.add(R.raw.seohyun_large_poster);
mPhotos.add(R.raw.sooyoung_large_poster);
mPhotos.add(R.raw.sunny_large_poster);
mPhotos.add(R.raw.taeyeon_large_poster);
mPhotos.add(R.raw.tiffany_large_poster);
mPhotos.add(R.raw.yoona_large_poster);
mPhotos.add(R.raw.yuri_large_poster);
}
public static ShowFaceFragment newInstance(int selectionNum) {
ShowFaceFragment simpleFragment = new ShowFaceFragment();
Bundle args = new Bundle();
args.putInt(ARG_SELECTION_NUM, selectionNum);
simpleFragment.setArguments(args);
return simpleFragment;
}
@Nullable @Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_show_face, container, false);
ButterKnife.bind(this, view);
return view;
}
@Override public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
@RawRes int image = mPhotos.get(getArguments().getInt(ARG_SELECTION_NUM));
InputStream stream = getResources().openRawResource(image);
Bitmap bitmap = BitmapFactory.decodeStream(stream);
mFdvFaceDetector.setBitmap(bitmap);
}
@Override public void onDestroyView() {
super.onDestroyView();
ButterKnife.unbind(this);
}
}
注意使用注释(Annotation), 判断资源类型, 如
@RawRes.
动画
有时间再完善一下这个小控件吧.
OK, Enjoy It.
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