摘要:本文将带你了解Android应用开发之安卓开发(二)人脸识别相册FaceMap,希望本文对大家学Android有所帮助。
本文将带你了解Android应用开发之安卓开发(二)人脸识别相册FaceMap,希望本文对大家学Android有所帮助。
算法部分
当时深度学习还没有很火,所以用的是经典的PCA方法,降维之后直接作为特征。人脸检测部分用的也是Opencv的Haar特征人脸检测。现在来看性能比较差了。这里就不介绍算法了,感兴趣的可以看看我的其他博文。
系统架构
本次系统架构分成2部分,一是算法;二是界面和业务逻辑。算法部分由于是C++写的,所以需要用Java的JNI接口封装一下。界面方面采用瀑布流界面,三栏极简风格。
业务逻辑是:
1.用户打开相册,自动读取系统照片;
2.用户点击某一张图像,若此照片此前未检测,则检测人脸并提取特征;若此照片此前已经检测,则显示人脸位置。
3.用户点击人脸,手工标注。
4.在第三栏,按照人脸识别实现自动分类。
这个逻辑的缺点是一开始需要用户手动标记,现在看来大概可以用聚类算法代替。
算法的JNI封装
因为我已经不做开发了,所以现在并不知道JNI怎么写了,已经不会写了。还是贴贴代码吧:
package cn.edu.zju.srtp.facemap.algorithm;
import java.io.File;
import java.util.Vector;
import org.opencv.core.Mat;
import android.content.Context;
import android.util.Log;
public class NativeFaceRecognizer {
public static final int LBPH_FACERECOGNIZER =1;
public static final int FISHER_FACERECOGNIZER =2;
public static final int EIGEN_FACERECOGNIZER =3;
private final static String TAG ="NativeFaceRecognizer";
public final static String LBPH_FILENAME ="lbph_model.xml";
public final static String FISHER_FILENAME ="fisher_model.xml";
public final static String EIGEN_FILENAME ="eigen_model.xml";
/**Note which faceRecognizer has been created
*
*/
private int mState =1;
/**The pointer to faceRecognizer with the initial value -1(important)
*
*/
private long mNativeObj =-1;
private Context mContext;
static{
Log.d(TAG, "NativeFaceRecognizer static initial block enter");
System.loadLibrary("opencv_java");
System.loadLibrary("face_rec");
Log.d(TAG, "NativeFaceRecognizer static initial block exit");
}
public NativeFaceRecognizer(Context context,int state) {
mContext=context;
mState=state;
createFaceRecognizer();
load();
}
/**Destroy the model first and create a FisherFaceRecognizer model.
*
*/
public void createFisherFaceRecognizer(){
destroy();
mState=FISHER_FACERECOGNIZER;
mNativeObj=nativeCreateFisherFaceRecognizer();
}
/**Destroy the model first and create a LBPHFaceRecognizer model.
*
*/
public void createLBPHFaceRecognizer(){
destroy();
mState=LBPH_FACERECOGNIZER;
mNativeObj=nativeCreateLBPHFaceRecognizer();
}
/**Destroy the model first and create a EigenFaceRecognizer model.
*
*/
public void createEigenFaceRecognizer(){
destroy();
mState=EIGEN_FACERECOGNIZER;
mNativeObj=nativeCreateEigenFaceRecognizer();
}
/**Train the model.The input image should be grayscale.
* The number of input images and labels should be equal.
* @param images
* @param labels_vec
*/
public void train(Vector<Mat>images,Vector<Integer>labels_vec){
if(mNativeObj==-1){
Log.d(TAG,"Error:No faceRecognizer for training");
return;
}
if(images.size()!=labels_vec.size()){
Log.d(TAG, "The number of input images and labels are not eaual!");
return;
}
//get the array of Mat address
long imagesAddr[]=new long[images.size()];
int i=0;
int[]labels=new int[labels_vec.size()];
for(Mat image:images){
if(image.width()!=image.height()||image.channels()!=1||image.width()<=0){
Log.d(TAG, "The intput images for training is illegal!" +
"image.width="+image.width()+" image.height="+image.height()
+"image.channels="+image.channels());
return;
}
imagesAddr[i]=image.getNativeObjAddr();
labels[i]=labels_vec.elementAt(i).intValue();
i++;
}
nativeTrain(mNativeObj,imagesAddr,labels);
}
public int predict(Mat image){
if(mNativeObj==-1){
Log.d(TAG,"Error:No faceRecognizer for predict.");
return -1;
}
return nativePredict(mNativeObj,image.getNativeObjAddr());
}
/**Only LBPHfaceRecognizer can be updated.
*
* @param images
* @param labels_vec
*/
public void update(Vector<Mat>images,Vector<Integer>labels_vec){
if(mState!=LBPH_FACERECOGNIZER){
Log.d(TAG,"Error:This kind of model"+" cannot be updated.");
return;
}
if(mNativeObj==-1){
Log.d(TAG,"Error:No faceRecognizer for model update.");
createLBPHFaceRecognizer();
}
//get the array of Mat address
long imagesAddr[]=new long[images.size()];
int i=0;
int[]labels=new int[labels_vec.size()];
for(Mat image:images){
if(image.width()!=image.height()||image.channels()!=1||image.width()<=0){
Log.d(TAG, "The intput images for training is illegal!" +
"image.width="+image.width()+" image.height="+image.height()
+"image.channels="+image.channels());
return;
}
imagesAddr[i]=image.getNativeObjAddr();
labels[i]=labels_vec.elementAt(i).intValue();
i++;
}
nativeUpdate(mNativeObj, imagesAddr, labels);
return;
}
/**Save the model to file.
*
*/
public void save(){
if(mNativeObj==-1){
Log.d(TAG,"Error:No faceRecognizer to save");
return;
}
String path=mContext.getFilesDir()+"/"+getFileName();
nativeSave(mNativeObj, path);
}
public void load(){
if(mNativeObj==-1){
Log.d(TAG,"Error:No faceRecognizer to load");
return;
}
String path=mContext.getFilesDir()+"/"+getFileName();
File f=new File(path);
if(f.exists()){
try{
nativeLoad(mNativeObj, path);
}catch(Exception e){
Log.d(TAG,"load file Alert:model doesn't exists.");
}
}
}
public void destroy(){
if(mNativeObj!=-1){
nativeDestroyObject(mNativeObj);
mNativeObj=-1;
}
else{
Log.d(TAG,"Cannot delete an illegal pointer");
}
}
/**
*Clear the model file.
*/
public Boolean clear(){
String fileName=getFileName();
File f=new File(mContext.getFilesDir()+"/"+fileName);
if(f.exists()){
return mContext.deleteFile(fileName);
}
return false;
}
private String getFileName(){
String fileName=new String();
if(mState==LBPH_FACERECOGNIZER){
fileName=LBPH_FILENAME;
}else if(mState==FISHER_FACERECOGNIZER){
fileName=FISHER_FILENAME;
}else if(mState==EIGEN_FACERECOGNIZER){
fileName=EIGEN_FILENAME;
}else{
return null;
}
return fileName;
}
private void createFaceRecognizer(){
if(mState==LBPH_FACERECOGNIZER){
createLBPHFaceRecognizer();
}else if(mState==FISHER_FACERECOGNIZER){
createFisherFaceRecognizer();
}else if(mState==EIGEN_FACERECOGNIZER){
createEigenFaceRecognizer();
}
}
public int getState(){
return mState;
}
private static native long nativeCreateFisherFaceRecognizer();
private static native long nativeCreateLBPHFaceRecognizer();
private static native long nativeCreateEigenFaceRecognizer();
private static native void nativeTrain(long thiz,long[]images,int[]labels);
private static native void nativeUpdate(long thiz,long[]images,int[]labels);
private static native int nativePredict(long thiz,long image);
private static native void nativeSave(long thiz,String fileName);
private static native void nativeLoad(long thiz,String fileName);
private static native void nativeDestroyObject(long thiz);
}
依稀记得当时写这个碰到了一些问题。主要的问题是,我在C++里写的类,需要动态分配,然后把它的指针保存在Java里。每次Java把这个指针再传给C++。这种方式是以Java为主的编程方式。不知道还有没有其他更好的写法。
图像缩放
当时为了实现图像缩放,在图书馆写了一上午。主要觉得挺好玩的。年少。
package cn.edu.zju.srtp.facemap.album;
import java.util.ArrayList;
import java.util.Calendar;
import org.opencv.core.Rect;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.text.format.Time;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import cn.edu.zju.srtp.facemap.R;
import cn.edu.zju.srtp.facemap.algorithm.Face;
import cn.edu.zju.srtp.facemap.algorithm.FaceRecManagerSingleInstance;
public class ZoomImageView extends View{
private static final String TAG ="ZoomImageView";
/**
* 初始化状态常量
*/
public static final int STATUS_INIT = 1;
/**
* 图片放大状态常量
*/
public static final int STATUS_ZOOM_OUT = 2;
/**
* 图片缩小状态常量
*/
public static final int STATUS_ZOOM_IN = 3;
/**
* 图片拖动状态常量
*/
public static final int STATUS_MOVE = 4;
/**
* 用于对图片进行移动和缩放变换的矩阵
*/
private Matrix matrix = new Matrix();
/**
* 待展示的Bitmap对象
*/
private Bitmap sourceBitmap;
/**
*图片边框
*/
private Bitmap borderBitmap;
/**
* 记录当前操作的状态,可选值为STATUS_INIT、STATUS_ZOOM_OUT、STATUS_ZOOM_IN和STATUS_MOVE
*/
private int currentStatus;
private ArrayList<Face> mFaces=new ArrayList<Face>();
private int mInSampleSize =1;
private Paint mPaint=new Paint();
private Bitmap mBackground;
private Time mTime =new Time();
private long mStartTime;
private Face mFaceClicked;
/**
* ZoomImageView控件的宽度
*/
private int width;
/**
* ZoomImageView控件的高度
*/
private int height;
/**
* 记录两指同时放在屏幕上时,中心点的横坐标值
*/
private float centerPointX;
/**
* 记录两指同时放在屏幕上时,中心点的纵坐标值
*/
private float centerPointY;
/**
* 记录当前图片的宽度,图片被缩放时,这个值会一起变动
*/
private float currentBitmapWidth;
/**
* 记录当前图片的高度,图片被缩放时,这个值会一起变动
*/
private float currentBitmapHeight;
/**
* 记录上次手指移动时的横坐标
*/
private float lastXMove = -1;
/**
* 记录上次手指移动时的纵坐标
*/
private float lastYMove = -1;
/**
* 记录手指在横坐标方向上的移动距离
*/
private float movedDistanceX;
/**
* 记录手指在纵坐标方向上的移动距离
*/
private float movedDistanceY;
/**
* 记录图片在矩阵上的横向偏移值
*/
private float totalTranslateX;
/**
* 记录图片在矩阵上的纵向偏移值
*/
private float totalTranslateY;
/**
* 记录图片在矩阵上的总缩放比例
*/
private float totalRatio;
/**
* 记录手指移动的距离所造成的缩放比例
*/
private float scaledRatio;
/**
* 记录图片初始化时的缩放比例
*/
private float initRatio;
/**
* 记录上次两指之间的距离
*/
private double lastFingerDis;
/**
* ZoomImageView构造函数,将当前操作状态设为STATUS_INIT。
*
* @param context
* @param attrs
*/
public ZoomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
currentStatus = STATUS_INIT;
mPaint.setColor(Color.WHITE);
mPaint.setStrokeWidth(2);
mPaint.setStyle(Paint.Style.STROKE);
borderBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.picture_frame_default);
}
/**
* 将待展示的图片设置进来。
*
* @param bitmap
* 待展示的Bitmap对象
*/
public void setImageBitmap(Bitmap bitmap) {
sourceBitmap = bitmap;
invalidate();
}
public void setInSampleSize(int inSampleSize){
mInSampleSize=inSampleSize;
}
public void setFaces(ArrayList<Face>faces){
mFaces=(ArrayList<Face>) faces.clone();
invalidate();
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (changed) {
// 分别获取到ZoomImageView的宽度和高度
width = getWidth();
height = getHeight();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if(totalRatio>initRatio){
getParent().requestDisallowInterceptTouchEvent(true);
}else{
getParent().requestDisallowInterceptTouchEvent(false);
}
switch (event.getActionMasked()) {
case MotionEvent.ACTION_POINTER_DOWN:
if (event.getPointerCount() == 2) {
// 当有两个手指按在屏幕上时,计算两指之间的距离
lastFingerDis = distanceBetweenFingers(event);
}
break;
case MotionEvent.ACTION_DOWN:
// mTime.setToNow();
mStartTime=Calendar.getInstance().getTimeInMillis();
case MotionEvent.ACTION_MOVE:
if (event.getPointerCount() == 1) {
// 只有单指按在屏幕上移动时,为拖动状态
float xMove = event.getX();
float yMove = event.getY();
if (lastXMove == -1 && lastYMove == -1) {
lastXMove = xMove;
lastYMove = yMove;
}
currentStatus = STATUS_MOVE;
movedDistanceX = xMove - lastXMove;
movedDistanceY = yMove - lastYMove;
// 进行边界检查,不允许将图片拖出边界
if (totalTranslateX + movedDistanceX > 0) {
movedDistanceX = 0;
} else if (width - (totalTranslateX + movedDistanceX) > currentBitmapWidth) {
movedDistanceX = 0;
}
if (totalTranslateY + movedDistanceY > 0) {
movedDistanceY = 0;
} else if (height - (totalTranslateY + movedDistanceY) > currentBitmapHeight) {
movedDistanceY = 0;
}
// 调用onDraw()方法绘制图片
invalidate();
lastXMove = xMove;
lastYMove = yMove;
}else if(event.getPointerCount() == 2){
// 有两个手指按在屏幕上移动时,为缩放状态
centerPointBetweenFingers(event);
double fingerDis = distanceBetweenFingers(event);
if (fingerDis > lastFingerDis) {
currentStatus = STATUS_ZOOM_OUT;
} else {
currentStatus = STATUS_ZOOM_IN;
}
// 进行缩放倍数检查,最大只允许将图片放大4倍,最小可以缩小到初始化比例
if ((currentStatus == STATUS_ZOOM_OUT && totalRatio < 4 * initRatio)
|| (currentStatus == STATUS_ZOOM_IN && totalRatio > initRatio)) {
scaledRatio = (float) (fingerDis / lastFingerDis);
totalRatio = totalRatio * scaledRatio;
if (totalRatio > 4 * initRatio) {
totalRatio = 4 * initRatio;
} else if (totalRatio < initRatio) {
totalRatio = initRatio;
}
// 调用onDraw()方法绘制图片
invalidate();
lastFingerDis = fingerDis;
}
}
break;
case MotionEvent.ACTION_POINTER_UP:
if (event.getPointerCount() == 2) {
// 手指离开屏幕时将临时值还原
lastXMove = -1;
lastYMove = -1;
}
break;
case MotionEvent.ACTION_UP:
// 手指离开屏幕时将临时值还原
lastXMove = -1;
lastYMove = -1;
//Time t=new Time();
//t.setToNow();
long t=Calendar.getInstance().getTimeInMillis();
if(t-mStartTime>=100){
break;
}
float fX=event.getX();
float fY=event.getY();
mFaceClicked=null;
for(Face f:mFaces){
Rect faceRect=f.getFaceRect();
float left=faceRect.x*totalRatio/mInSampleSize+totalTranslateX;
float top=faceRect.y*totalRatio/mInSampleSize+totalTranslateY;
float right=(faceRect.x+faceRect.width)*totalRatio/mInSampleSize+totalTranslateX;
float bottom=(faceRect.y+faceRect.height)*totalRatio/mInSampleSize+totalTranslateY;
if(fX>=left&&fX<=right&&
fY>=top&&fY<=bottom){
mFaceClicked=f;
}
}
final Face face=mFaceClicked;
if(face==null)
break;
invalidate();
if(face.getPeopleName()==null){
final EditText mText = new EditText(
getContext());
AlertDialog.Builder builder = new AlertDialog.Builder(
getContext());
builder.setTitle("请输入名字")
.setIcon(
android.R.drawable.ic_dialog_info)
.setView(mText)
.setPositiveButton(
"确定",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
FaceRecManagerSingleInstance.getInstance(getContext()).update(
face.getFaceId(),
mText.getText()
.toString());
invalidate();
}
})
.setNegativeButton("取消", null).show();
}else{
AlertDialog.Builder builder = new AlertDialog.Builder(
getContext());
builder.setMessage("这是 " + face.getPeopleName() + " 吗?")
.setIcon(
android.R.drawable.ic_dialog_info)
.setPositiveButton(
"是",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
FaceRecManagerSingleInstance.getInstance(getContext()).update(
face.getFaceId(),
face.getPeopleName());
invalidate();
}
})
.setNegativeButton(
"不是",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
final EditText mText = new EditText(
getContext());
AlertDialog.Builder builder = new AlertDialog.Builder(
getContext());
builder.setTitle(
"请输入名字")
.setIcon(android.R.drawable.ic_dialog_info)
.setView(mText)
.setPositiveButton(
"确定",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
FaceRecManagerSingleInstance.getInstance(getContext())
.update(face.getFaceId(),mText.getText().toString());
invalidate();
}
})
.setNegativeButton("取消",null)
.show();
}
}).show();
}
break;
default:
break;
}
return true;
}
public Bitmap getSrcBitmap(){
return sourceBitmap;
}
private void drawFaces(Canvas canvas){
Log.d(TAG,"drawFaces");
for(Face face:mFaces){
Rect faceRect=face.getFaceRect();
float left=faceRect.x*totalRatio/mInSampleSize+totalTranslateX;
float top=faceRect.y*totalRatio/mInSampleSize+totalTranslateY;
float right=(faceRect.x+faceRect.width)*totalRatio/mInSampleSize+totalTranslateX;
float bottom=(faceRect.y+faceRect.height)*totalRatio/mInSampleSize+totalTranslateY;
if(!face.getVerified()){
mPaint.setColor(Color.GREEN);
}
if(face.equals(mFaceClicked)){
mPaint.setColor(Color.YELLOW);
mFaceClicked=null;
}
canvas.drawRect(left,top,right,bottom, mPaint);
if(face.getPeopleName()!=null){
mPaint.setTextSize((float) ((right-left)*0.15));
mPaint.setStrokeWidth(0);
canvas.drawText(face.getPeopleName(),left ,top-4, mPaint);
mPaint.setStrokeWidth(2);
}
mPaint.setColor(Color.WHITE);
}
}
/**
* 根据currentStatus的值来决定对图片进行什么样的绘制操作。
*/
@Override
protected void onDraw(Canvas canvas) {
try{
super.onDraw(canvas);
switch (currentStatus) {
case STATUS_ZOOM_OUT:
case STATUS_ZOOM_IN:
zoom(canvas);
break;
case STATUS_MOVE:
move(canvas);
break;
case STATUS_INIT:
initBitmap(canvas);
default:
canvas.drawBitmap(sourceBitmap, matrix, null);
drawFaces(canvas);
break;
}
}catch(Exception e){
Log.e(TAG,"Error in onDraw:",e);
}
}
/**
* 对图片进行缩放处理。
*
* @param canvas
*/
private void zoom(Canvas canvas) {
matrix.reset();
// 将图片按总缩放比例进行缩放
matrix.postScale(totalRatio, totalRatio);
float scaledWidth = sourceBitmap.getWidth() * totalRatio;
float scaledHeight = sourceBitmap.getHeight() * totalRatio;
float translateX = 0f;
float translateY = 0f;
// 如果当前图片宽度小于屏幕宽度,则按屏幕中心的横坐标进行水平缩放。
//否则按两指的中心点的横坐标进行水平缩放
if (currentBitmapWidth < width) {
translateX = (width - scaledWidth) / 2f;
} else {
translateX = totalTranslateX * scaledRatio + centerPointX * (1 - scaledRatio);
// 进行边界检查,保证图片缩放后在水平方向上不会偏移出屏幕
if (translateX > 0) {
translateX = 0;
} else if (width - translateX > scaledWidth) {
translateX = width - scaledWidth;
}
}
// 如果当前图片高度小于屏幕高度,则按屏幕中心的纵
//坐标进行垂直缩放。否则按两指的中心点的纵坐标进行垂直缩放
if (currentBitmapHeight < height) {
translateY = (height - scaledHeight) / 2f;
}else{
translateY = totalTranslateY * scaledRatio + centerPointY * (1 - scaledRatio);
// 进行边界检查,保证图片缩放后在垂直方向上不会偏移出屏幕
if (translateY > 0) {
translateY = 0;
} else if (height - translateY > scaledHeight) {
translateY = height - scaledHeight;
}
}
// 缩放后对图片进行偏移,以保证缩放后中心点位置不变
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
currentBitmapWidth = scaledWidth;
currentBitmapHeight = scaledHeight;
canvas.drawBitmap(sourceBitmap, matrix, null);
drawFaces(canvas);
}
/**
* 对图片进行平移处理
*
* @param canvas
*/
private void move(Canvas canvas) {
matrix.reset();
// 根据手指移动的距离计算出总偏移值
float translateX = totalTranslateX + movedDistanceX;
float translateY = totalTranslateY + movedDistanceY;
// 先按照已有的缩放比例对图片进行缩放
matrix.postScale(totalRatio, totalRatio);
// 再根据移动距离进行偏移
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
canvas.drawBitmap(sourceBitmap, matrix, null);
drawFaces(canvas);
}
/**
* 对图片进行初始化操作,包括让图片居中,以及当图片大于屏幕宽高时对图片进行压缩。
*
* @param canvas
*/
private void initBitmap(Canvas canvas) {
if (sourceBitmap != null) {
matrix.reset();
int bitmapWidth = sourceBitmap.getWidth();
int bitmapHeight = sourceBitmap.getHeight();
if (bitmapWidth > width || bitmapHeight > height) {
if (bitmapWidth - width > bitmapHeight - height) {
// 当图片宽度大于屏幕宽度时,将图片等比例压缩,使它可以完全显示出来
float ratio = width / (bitmapWidth * 1.0f);
matrix.postScale(ratio, ratio);
float translateY = (height - (bitmapHeight * ratio)) / 2f;
// 在纵坐标方向上进行偏移,以保证图片居中显示
matrix.postTranslate(0, translateY);
totalTranslateY = translateY;
totalRatio = initRatio = ratio;
}else {
// 当图片高度大于屏幕高度时,将图片等比例压缩,使它可以完全显示出来
float ratio = height / (bitmapHeight * 1.0f);
matrix.postScale(ratio, ratio);
float translateX = (width - (bitmapWidth * ratio)) / 2f;
// 在横坐标方向上进行偏移,以保证图片居中显示
matrix.postTranslate(translateX, 0);
totalTranslateX = translateX;
totalRatio = initRatio = ratio;
}
currentBitmapWidth = bitmapWidth * initRatio;
currentBitmapHeight = bitmapHeight * initRatio;
}else{
// 当图片的宽高都小于屏幕宽高时,直接让图片居中显示
float translateX = (width - sourceBitmap.getWidth()) / 2f;
float translateY = (height - sourceBitmap.getHeight()) / 2f;
matrix.postTranslate(translateX, translateY);
totalTranslateX = translateX;
totalTranslateY = translateY;
totalRatio = initRatio = 1f;
currentBitmapWidth = bitmapWidth;
currentBitmapHeight = bitmapHeight;
}
canvas.drawBitmap(sourceBitmap, matrix, null);
drawFaces(canvas);
}
}
/**
* 计算两个手指之间的距离。
*
* @param event
* @return 两个手指之间的距离
*/
private double distanceBetweenFingers(MotionEvent event) {
float disX = Math.abs(event.getX(0) - event.getX(1));
float disY = Math.abs(event.getY(0) - event.getY(1));
return Math.sqrt(disX * disX + disY * disY);
}
/**
* 计算两个手指之间中心点的坐标。
*
* @param event
*/
private void centerPointBetweenFingers(MotionEvent event) {
float xPoint0 = event.getX(0);
float yPoint0 = event.getY(0);
float xPoint1 = event.getX(1);
float yPoint1 = event.getY(1);
centerPointX = (xPoint0 + xPoint1) / 2;
centerPointY = (yPoint0 + yPoint1) / 2;
}
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