Android 使用opencv实现抠图

1.openCv配置

从https://github.com/opencv/opencv/releases/tag/3.3.0下载对应的android版本

a.  import module 选择

b.还要配置so文件来调取opencv的接口，在main文件夹下创建jniLibs文件夹，如下图：

把下载的native目录下libs文件下的所有文件拷入jniLibs文件下

c.别忘了把module里的build.gradle修改成和你一样的gradle配置

d.配置manifiest

在application标签前添加

在application标签后添加

e.在Activity中实现opencv的初始化

private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
            case LoaderCallbackInterface.SUCCESS:
            {
                Log.i(TAG, "OpenCV loaded successfully");
            } break;
            default:
            {
                super.onManagerConnected(status);
            } break;
        }
    }
};

@Override
public void onResume()
{
    super.onResume();
    if (!OpenCVLoader.initDebug()) {
        Log.d("OpenCV", "Internal OpenCV library not found. Using OpenCV Manager for initialization");
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
    } else {
        Log.d("OpenCV", "OpenCV library found inside package. Using it!");
        mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
    }
}

到此为此，opencv配置完成，进入正题，首先先看下效果：

    

其实实现抠图的效果也就是调用opencv提供的grabcut函数，函数方法如下： 

   private Bitmap cupBitmap(Bitmap bitmap,int x,int y,int width,int height){
        Mat img = new Mat();
//缩小图片尺寸
       // Bitmap bm = Bitmap.createScaledBitmap(bitmap,bitmap.getWidth(),bitmap.getHeight(),true);
//bitmap->mat
        Utils.bitmapToMat(bitmap, img);
//转成CV_8UC3格式
        Imgproc.cvtColor(img, img, Imgproc.COLOR_RGBA2RGB);
//设置抠图范围的左上角和右下角
        Rect rect = new Rect(x,y,width,height);
//生成遮板
        Mat firstMask = new Mat();
        Mat bgModel = new Mat();
        Mat fgModel = new Mat();
        Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(Imgproc.GC_PR_FGD));
	//这是实现抠图的重点，难点在于rect的区域，为了选取抠图区域，我借鉴了某大神的自定义裁剪View，返回坐标和宽高
        Imgproc.grabCut(img, firstMask, rect, bgModel, fgModel,5, Imgproc.GC_INIT_WITH_RECT);
        Core.compare(firstMask, source, firstMask, Core.CMP_EQ);

//抠图
        Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));
        img.copyTo(foreground, firstMask);

//mat->bitmap
        Bitmap bitmap1 = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(foreground,bitmap1);
        return bitmap1;
    }

废话不多说，奉上干粮：

import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.RectF;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;


import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.android.Utils;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.imgproc.Imgproc;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    static final int REQUEST_OPEN_IMAGE = 1;
    private static final String TAG ="xxx";
    MyCropView cropView;
    String mCurrentPhotoPath;
    boolean targetChose = false;
    ProgressDialog dlg;
    private Button select;
    private Button cut;
    private Button modify;
    private Button saveImage;
    private Bitmap originalBitmap;
    private ImageView choiceView;
    private boolean hasCut =false;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        cropView = (MyCropView) findViewById(R.id.myCropView);
        select = (Button) findViewById(R.id.btn_gray_process);
        cut = (Button) findViewById(R.id.btn_cut_process);
        modify = (Button) findViewById(R.id.btn_modify_process);
        saveImage = (Button) findViewById(R.id.btn_save_process);
        choiceView = (ImageView) findViewById(R.id.croppedImageView);
        select.setOnClickListener(this);
        cut.setOnClickListener(this);
        saveImage.setOnClickListener(this);
        modify.setOnClickListener(this);
        dlg = new ProgressDialog(this);
    }

    private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    Log.i(TAG, "OpenCV loaded successfully");
                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
        }
    };

    @Override
    public void onResume()
    {
        super.onResume();
        if (!OpenCVLoader.initDebug()) {
            Log.d("OpenCV", "Internal OpenCV library not found. Using OpenCV Manager for initialization");
            OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
        } else {
            Log.d("OpenCV", "OpenCV library found inside package. Using it!");
            mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
        }
    }
    //从图库中选择图片	
    public void setPic(){
        originalBitmap = BitmapFactory.decodeFile(mCurrentPhotoPath);
        cropView.setBmpPath(mCurrentPhotoPath);
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        switch (requestCode) {
            case REQUEST_OPEN_IMAGE:
                if (resultCode == RESULT_OK) {
                    Uri imgUri = data.getData();
                    String[] filePathColumn = { MediaStore.Images.Media.DATA };

                    Cursor cursor = getContentResolver().query(imgUri, filePathColumn,
                            null, null, null);
                    cursor.moveToFirst();

                    int colIndex = cursor.getColumnIndex(filePathColumn[0]);
                    mCurrentPhotoPath = cursor.getString(colIndex);
                    cursor.close();
                    setPic();
                }
                break;
        }
    }

   //选择剪切区域	
    private void selectImageCut(){
        targetChose = true;
        try{
            Bitmap cropBitmap = cropView.getCroppedImage();
            choiceView.setImageBitmap(cropBitmap);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.btn_gray_process:
                Intent getPictureIntent = new Intent(Intent.ACTION_GET_CONTENT);
                getPictureIntent.setType("image/*");
                Intent pickPictureIntent = new Intent(Intent.ACTION_PICK,
                        MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
                Intent chooserIntent = Intent.createChooser(getPictureIntent, "Select Image");
                chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, new Intent[] {
                        pickPictureIntent
                });
                startActivityForResult(chooserIntent, REQUEST_OPEN_IMAGE);
                break;
            case R.id.btn_cut_process:
		//抠图是耗时的过程，子线程中运行，并dialog提示
                if (targetChose){
                    dlg.show();
                    dlg.setMessage("正在抠图...");
                    final RectF croppedBitmapData = cropView.getCroppedBitmapData();
                    final int croppedBitmapWidth = cropView.getCroppedBitmapWidth();
                    final int croppedBitmapHeight = cropView.getCroppedBitmapHeight();
                    new Thread(new Runnable() {
                        @Override
                        public void run() {
                            final Bitmap bitmap = cupBitmap(originalBitmap, (int) croppedBitmapData.left, (int) croppedBitmapData.top, croppedBitmapWidth, croppedBitmapHeight);
                            runOnUiThread(new Runnable() {
                                @Override
                                public void run() {
                                    dlg.dismiss();
                                    hasCut = true;
                                    choiceView.setImageBitmap(bitmap);
                                }
                            });
                        }
                    }).start();

                }
                break;
            case R.id.btn_modify_process:
                selectImageCut();
                break;
            case R.id.btn_save_process:
                if (hasCut){
                    String s = saveImageToGalleryString(this, ((BitmapDrawable) (choiceView).getDrawable()).getBitmap());
                    Toast.makeText(this, "保存在"+s, Toast.LENGTH_SHORT).show();
                }else {
                    Toast.makeText(this, "请先扣图", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }

    private Bitmap cupBitmap(Bitmap bitmap,int x,int y,int width,int height){
        Mat img = new Mat();
//缩小图片尺寸
       // Bitmap bm = Bitmap.createScaledBitmap(bitmap,bitmap.getWidth(),bitmap.getHeight(),true);
//bitmap->mat
        Utils.bitmapToMat(bitmap, img);
//转成CV_8UC3格式
        Imgproc.cvtColor(img, img, Imgproc.COLOR_RGBA2RGB);
//设置抠图范围的左上角和右下角
        Rect rect = new Rect(x,y,width,height);
//生成遮板
        Mat firstMask = new Mat();
        Mat bgModel = new Mat();
        Mat fgModel = new Mat();
        Mat source = new Mat(1, 1, CvType.CV_8U, new Scalar(Imgproc.GC_PR_FGD));
        Imgproc.grabCut(img, firstMask, rect, bgModel, fgModel,5, Imgproc.GC_INIT_WITH_RECT);
        Core.compare(firstMask, source, firstMask, Core.CMP_EQ);

//抠图
        Mat foreground = new Mat(img.size(), CvType.CV_8UC3, new Scalar(255, 255, 255));
        img.copyTo(foreground, firstMask);

//mat->bitmap
        Bitmap bitmap1 = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(foreground,bitmap1);
        return bitmap1;
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        if (dlg != null) {
            dlg.dismiss();
        }
    }
	//保存在系统图库	
        public static String saveImageToGalleryString(Context context, Bitmap bmp) {
            // 首先保存图片
            String storePath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "dearxy";
            File appDir = new File(storePath);
            if (!appDir.exists()) {
                appDir.mkdir();
            }
            String fileName = System.currentTimeMillis() + ".png";
            File file = new File(appDir, fileName);
            try {
                FileOutputStream fos = new FileOutputStream(file);
                //通过io流的方式来压缩保存图片
                bmp.compress(Bitmap.CompressFormat.PNG, 100, fos);
                fos.flush();
                fos.close();

                //把文件插入到系统图库
                //MediaStore.Images.Media.insertImage(context.getContentResolver(), file.getAbsolutePath(), fileName, null);

                //保存图片后发送广播通知更新数据库
                Uri uri = Uri.fromFile(file);
                context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
                return file.getPath();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

    }

2.xml布局（布局很丑，请忽视）：

3.自定义的裁剪View

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PointF;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;


public class MyCropView extends View {

    // Private Constants ///////////////////////////////////////////////////////
    private static final float BMP_LEFT = 0f;
    private static final float BMP_TOP = 20f;

    private static final float DEFAULT_BORDER_RECT_WIDTH = 200f;
    private static final float DEFAULT_BORDER_RECT_HEIGHT = 200f;

    private static final int POS_TOP_LEFT = 0;
    private static final int POS_TOP_RIGHT = 1;
    private static final int POS_BOTTOM_LEFT = 2;
    private static final int POS_BOTTOM_RIGHT = 3;
    private static final int POS_TOP = 4;
    private static final int POS_BOTTOM = 5;
    private static final int POS_LEFT = 6;
    private static final int POS_RIGHT = 7;
    private static final int POS_CENTER = 8;

    // this constant would be best to use event number
    private static final float BORDER_LINE_WIDTH = 6f;
    private static final float BORDER_CORNER_LENGTH = 30f;
    private static final float TOUCH_FIELD = 10f;

    // Member Variables ////////////////////////////////////////////////////////
    private String mBmpPath;
    private Bitmap mBmpToCrop;
    private RectF mBmpBound;
    private Paint mBmpPaint;

    private Paint mBorderPaint;// 裁剪区边框
    private Paint mGuidelinePaint;
    private Paint mCornerPaint;
    private Paint mBgPaint;

    private RectF mDefaultBorderBound;
    private RectF mBorderBound;

    private PointF mLastPoint = new PointF();

    private float mBorderWidth;
    private float mBorderHeight;

    private int touchPos;

    // Constructors ////////////////////////////////////////////////////////////
    public MyCropView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        init(context);
    }

    public MyCropView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    // View Methods ////////////////////////////////////////////////////////////
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        // TODO Auto-generated method stub
        // super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        // super.onDraw(canvas);
        if (mBmpPath != null) {
            canvas.drawBitmap(mBmpToCrop, null, mBmpBound, mBmpPaint);
            canvas.drawRect(mBorderBound.left, mBorderBound.top, mBorderBound.right, mBorderBound.bottom, mBorderPaint);
            drawGuidlines(canvas);
            drawBackground(canvas);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        // TODO Auto-generated method stub
        // super.onTouchEvent(event);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                setLastPosition(event);
                getParent().requestDisallowInterceptTouchEvent(true);
                // onActionDown(event.getX(), event.getY());
                touchPos = detectTouchPosition(event.getX(), event.getY());
                break;
            case MotionEvent.ACTION_MOVE:
                onActionMove(event.getX(), event.getY());
                setLastPosition(event);
                break;
            case MotionEvent.ACTION_UP:
                break;
        }

        return true;
    }

    // Public Methods //////////////////////////////////////////////////////////
    public String getBmpPath() {
        return mBmpPath;
    }

    public void setBmpPath(String picPath) {
        this.mBmpPath = picPath;
        setBmp();
    }
    public RectF getCroppedBitmapData(){
        return mBorderBound;
    }
    public int getCroppedBitmapWidth(){
        return (int) mBorderWidth;
    }
    public int getCroppedBitmapHeight(){
        return (int) mBorderHeight;
    }
    public Bitmap getCroppedImage() {
        // 先不考虑图片被压缩的情况 就当作现在的图片就是1：1的
        Bitmap bitmap = null;
        try {
           bitmap = Bitmap.createBitmap(mBmpToCrop, (int) mBorderBound.left, (int) mBorderBound.top, (int) mBorderWidth,
                    (int) mBorderHeight);
        }catch (Exception e){
            Toast.makeText(getContext(), "图片格式无法剪切", Toast.LENGTH_SHORT).show();
            e.printStackTrace();
        }
        return bitmap;
    }

    // Private Methods /////////////////////////////////////////////////////////
    private void init(Context context) {

        mBmpPaint = new Paint();
        // 以下是抗锯齿
        mBmpPaint.setAntiAlias(true);// 防止边缘的锯齿
        mBmpPaint.setFilterBitmap(true);// 对位图进行滤波处理

        mBorderPaint = new Paint();
        mBorderPaint.setStyle(Style.STROKE);
        mBorderPaint.setColor(Color.parseColor("#AAFFFFFF"));
        mBorderPaint.setStrokeWidth(BORDER_LINE_WIDTH);

        mGuidelinePaint = new Paint();
        mGuidelinePaint.setColor(Color.parseColor("#AAFFFFFF"));
        mGuidelinePaint.setStrokeWidth(1f);

        mCornerPaint = new Paint();

        mBgPaint = new Paint();
        mBgPaint.setColor(Color.parseColor("#B0000000"));
        mBgPaint.setAlpha(150);

    }

    private void setBmp() {

        mBmpToCrop = BitmapFactory.decodeFile(mBmpPath);

        mBmpBound = new RectF();
        mBmpBound.left = BMP_LEFT;
        mBmpBound.top = BMP_TOP;
        mBmpBound.right = mBmpBound.left + mBmpToCrop.getWidth();
        mBmpBound.bottom = mBmpBound.top + mBmpToCrop.getHeight();

        // 使裁剪框一开始出现在图片的中心位置
        mDefaultBorderBound = new RectF();
        mDefaultBorderBound.left = (mBmpBound.left + mBmpBound.right - DEFAULT_BORDER_RECT_WIDTH) / 2;
        mDefaultBorderBound.top = (mBmpBound.top + mBmpBound.bottom - DEFAULT_BORDER_RECT_HEIGHT) / 2;
        mDefaultBorderBound.right = mDefaultBorderBound.left + DEFAULT_BORDER_RECT_WIDTH;
        mDefaultBorderBound.bottom = mDefaultBorderBound.top + DEFAULT_BORDER_RECT_HEIGHT;

        mBorderBound = new RectF();
        mBorderBound.left = mDefaultBorderBound.left;
        mBorderBound.top = mDefaultBorderBound.top;
        mBorderBound.right = mDefaultBorderBound.right;
        mBorderBound.bottom = mDefaultBorderBound.bottom;

        getBorderEdgeLength();
        invalidate();
    }

    private void drawBackground(Canvas canvas) {

        /*-
          -------------------------------------
          |                top                |
          -------------------------------------
          |      |                    |       |<——————————mBmpBound
          |      |                    |       |
          | left |                    | right |
          |      |                    |       |
          |      |                  <─┼───────┼────mBorderBound
          -------------------------------------
          |              bottom               |
          -------------------------------------
         */

        // Draw "top", "bottom", "left", then "right" quadrants.
        // because the border line width is larger than 1f, in order to draw a complete border rect ,
        // i have to change zhe rect coordinate to draw
        float delta = BORDER_LINE_WIDTH / 2;
        float left = mBorderBound.left - delta;
        float top = mBorderBound.top - delta;
        float right = mBorderBound.right + delta;
        float bottom = mBorderBound.bottom + delta;

        // -------------------------------------------------------------------------------移动到上下两端会多出来阴影
        canvas.drawRect(mBmpBound.left, mBmpBound.top, mBmpBound.right, top, mBgPaint);
        canvas.drawRect(mBmpBound.left, bottom, mBmpBound.right, mBmpBound.bottom, mBgPaint);
        canvas.drawRect(mBmpBound.left, top, left, bottom, mBgPaint);
        canvas.drawRect(right, top, mBmpBound.right, bottom, mBgPaint);
    }

    // 画裁剪区域中间的参考线
    private void drawGuidlines(Canvas canvas) {
        // Draw vertical guidelines.
        final float oneThirdCropWidth = mBorderBound.width() / 3;

        final float x1 = mBorderBound.left + oneThirdCropWidth;
        canvas.drawLine(x1, mBorderBound.top, x1, mBorderBound.bottom, mGuidelinePaint);
        final float x2 = mBorderBound.right - oneThirdCropWidth;
        canvas.drawLine(x2, mBorderBound.top, x2, mBorderBound.bottom, mGuidelinePaint);

        // Draw horizontal guidelines.
        final float oneThirdCropHeight = mBorderBound.height() / 3;

        final float y1 = mBorderBound.top + oneThirdCropHeight;
        canvas.drawLine(mBorderBound.left, y1, mBorderBound.right, y1, mGuidelinePaint);
        final float y2 = mBorderBound.bottom - oneThirdCropHeight;
        canvas.drawLine(mBorderBound.left, y2, mBorderBound.right, y2, mGuidelinePaint);
    }

    private void onActionDown(float x, float y) {

    }

    private void onActionMove(float x, float y) {
        float deltaX = x - mLastPoint.x;
        float deltaY = y - mLastPoint.y;
        // 这里先不考虑裁剪框放最大的情况
        switch (touchPos) {
            case POS_CENTER:
                mBorderBound.left += deltaX;
                // fix border position
                if (mBorderBound.left < mBmpBound.left)
                    mBorderBound.left = mBmpBound.left;
                if (mBorderBound.left > mBmpBound.right - mBorderWidth)
                    mBorderBound.left = mBmpBound.right - mBorderWidth;

                mBorderBound.top += deltaY;
                if (mBorderBound.top < mBmpBound.top)
                    mBorderBound.top = mBmpBound.top;

                if (mBorderBound.top > mBmpBound.bottom - mBorderHeight)
                    mBorderBound.top = mBmpBound.bottom - mBorderHeight;

                mBorderBound.right = mBorderBound.left + mBorderWidth;
                mBorderBound.bottom = mBorderBound.top + mBorderHeight;

                break;

            case POS_TOP:
                resetTop(deltaY);
                break;
            case POS_BOTTOM:
                resetBottom(deltaY);
                break;
            case POS_LEFT:
                resetLeft(deltaX);
                break;
            case POS_RIGHT:
                resetRight(deltaX);
                break;
            case POS_TOP_LEFT:
                resetTop(deltaY);
                resetLeft(deltaX);
                break;
            case POS_TOP_RIGHT:
                resetTop(deltaY);
                resetRight(deltaX);
                break;
            case POS_BOTTOM_LEFT:
                resetBottom(deltaY);
                resetLeft(deltaX);
                break;
            case POS_BOTTOM_RIGHT:
                resetBottom(deltaY);
                resetRight(deltaX);
                break;
            default:

                break;
        }
        invalidate();
    }

    private void onActionUp(float x, float y) {

    }

    private int detectTouchPosition(float x, float y) {
        if (x > mBorderBound.left + TOUCH_FIELD && x < mBorderBound.right - TOUCH_FIELD
                && y > mBorderBound.top + TOUCH_FIELD && y < mBorderBound.bottom - TOUCH_FIELD)
            return POS_CENTER;

        if (x > mBorderBound.left + BORDER_CORNER_LENGTH && x < mBorderBound.right - BORDER_CORNER_LENGTH) {
            if (y > mBorderBound.top - TOUCH_FIELD && y < mBorderBound.top + TOUCH_FIELD)
                return POS_TOP;
            if (y > mBorderBound.bottom - TOUCH_FIELD && y < mBorderBound.bottom + TOUCH_FIELD)
                return POS_BOTTOM;
        }

        if (y > mBorderBound.top + BORDER_CORNER_LENGTH && y < mBorderBound.bottom - BORDER_CORNER_LENGTH) {
            if (x > mBorderBound.left - TOUCH_FIELD && x < mBorderBound.left + TOUCH_FIELD)
                return POS_LEFT;
            if (x > mBorderBound.right - TOUCH_FIELD && x < mBorderBound.right + TOUCH_FIELD)
                return POS_RIGHT;
        }

        // 前面的逻辑已经排除掉了几种情况 所以后面的 ┏ ┓ ┗ ┛ 边角就按照所占区域的方形来判断就可以了
        if (x > mBorderBound.left - TOUCH_FIELD && x < mBorderBound.left + BORDER_CORNER_LENGTH) {
            if (y > mBorderBound.top - TOUCH_FIELD && y < mBorderBound.top + BORDER_CORNER_LENGTH)
                return POS_TOP_LEFT;
            if (y > mBorderBound.bottom - BORDER_CORNER_LENGTH && y < mBorderBound.bottom + TOUCH_FIELD)
                return POS_BOTTOM_LEFT;
        }

        if (x > mBorderBound.right - BORDER_CORNER_LENGTH && x < mBorderBound.right + TOUCH_FIELD) {
            if (y > mBorderBound.top - TOUCH_FIELD && y < mBorderBound.top + BORDER_CORNER_LENGTH)
                return POS_TOP_RIGHT;
            if (y > mBorderBound.bottom - BORDER_CORNER_LENGTH && y < mBorderBound.bottom + TOUCH_FIELD)
                return POS_BOTTOM_RIGHT;
        }

        return -1;
    }

    private void setLastPosition(MotionEvent event) {
        mLastPoint.x = event.getX();
        mLastPoint.y = event.getY();
    }

    private void getBorderEdgeLength() {
        mBorderWidth = mBorderBound.width();
        mBorderHeight = mBorderBound.height();
    }

    private void getBorderEdgeWidth() {
        mBorderWidth = mBorderBound.width();
    }

    private void getBorderEdgeHeight() {
        mBorderHeight = mBorderBound.height();
    }

    private void resetLeft(float delta) {
        mBorderBound.left += delta;

        getBorderEdgeWidth();
        fixBorderLeft();
    }

    private void resetTop(float delta) {
        mBorderBound.top += delta;
        getBorderEdgeHeight();
        fixBorderTop();
    }

    private void resetRight(float delta) {
        mBorderBound.right += delta;

        getBorderEdgeWidth();
        fixBorderRight();

    }

    private void resetBottom(float delta) {
        mBorderBound.bottom += delta;

        getBorderEdgeHeight();
        fixBorderBottom();
    }

    private void fixBorderLeft() {
        // fix left
        if (mBorderBound.left < mBmpBound.left)
            mBorderBound.left = mBmpBound.left;
        if (mBorderWidth < 2 * BORDER_CORNER_LENGTH)
            mBorderBound.left = mBorderBound.right - 2 * BORDER_CORNER_LENGTH;
    }

    private void fixBorderTop() {
        // fix top
        if (mBorderBound.top < mBmpBound.top)
            mBorderBound.top = mBmpBound.top;
        if (mBorderHeight < 2 * BORDER_CORNER_LENGTH)
            mBorderBound.top = mBorderBound.bottom - 2 * BORDER_CORNER_LENGTH;
    }

    private void fixBorderRight() {
        // fix right
        if (mBorderBound.right > mBmpBound.right)
            mBorderBound.right = mBmpBound.right;
        if (mBorderWidth < 2 * BORDER_CORNER_LENGTH)
            mBorderBound.right = mBorderBound.left + 2 * BORDER_CORNER_LENGTH;
    }

    private void fixBorderBottom() {
        // fix bottom
        if (mBorderBound.bottom > mBmpBound.bottom)
            mBorderBound.bottom = mBmpBound.bottom;
        if (mBorderHeight < 2 * BORDER_CORNER_LENGTH)
            mBorderBound.bottom = mBorderBound.top + 2 * BORDER_CORNER_LENGTH;
    }
}

end...............好了，就这些了，快去试试把！