android实现拖拽裁剪功能

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.RelativeLayout;
 
import eebochina.com.testsomething.R;
 
public class DragTakePhoto extends AppCompatActivity implements View.OnTouchListener {
    ImageView takePhoto;
    ImageView takeImage;
    Button mButton;
    static final String tag = "takePhoto";
    RelativeLayout.LayoutParams mLayoutParams;
    int left, top, bottom, right;
    int x, y;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_drag_take_photo);
 
        takePhoto = (ImageView) findViewById(R.id.take_layout);
        takeImage = (ImageView) findViewById(R.id.take_image);
        mButton = (Button) findViewById(R.id.take_crop);
        takePhoto.setOnTouchListener(this);
        takePhoto.post(new Runnable() {
            @Override
            public void run() {
                Log.d(tag, "" + takePhoto.getX() + "  ," + takePhoto.getY() + " :" + takePhoto.getPivotX() + " " + takePhoto.getPivotY());
            }
        });
        mLayoutParams = (RelativeLayout.LayoutParams) takePhoto.getLayoutParams();
        final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.take);
        mButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                float wd = (bitmap.getWidth() * 10000 / takeImage.getWidth()) / 10000f;
                float hd = (bitmap.getHeight() * 10000 / takeImage.getHeight()) / 10000f;
                Bitmap bitmap1 = Bitmap.createBitmap(bitmap, (int) (takePhoto.getX() * wd), (int) (takePhoto.getY() * hd), (int) (takePhoto.getWidth() * wd), (int) (takePhoto.getHeight() * hd));
                takePhoto.setImageBitmap(bitmap1);
            }
        });
 
 
    }
 
    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) takeImage.getLayoutParams();
        left = layoutParams.leftMargin;
        top = layoutParams.topMargin;
        right = takeImage.getWidth() - left - takePhoto.getWidth();
        bottom = takeImage.getHeight() - top - takePhoto.getHeight();
    }
 
    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        switch (motionEvent.getAction()) {
            case MotionEvent.ACTION_DOWN:
                x = (int) motionEvent.getRawX() - mLayoutParams.leftMargin;
                y = (int) motionEvent.getRawY() - mLayoutParams.topMargin;
                break;
            case MotionEvent.ACTION_MOVE:
                int movex = (int) (motionEvent.getRawX() - x);
                int movey = (int) (motionEvent.getRawY() - y);
                Log.d(tag, "x:" + movex + "  y:" + movey);
                if (movex < left) movex = left;
                if (movey < top) movey = top;
                if (movex > right) movex = right;
                if (movey > bottom) movey = bottom;
                mLayoutParams.leftMargin = movex;
                mLayoutParams.topMargin = movey;
                takePhoto.setLayoutParams(mLayoutParams);
                break;
        }
        takePhoto.invalidate();
        return true;
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="eebochina.com.testsomething.dragTake.DragTakePhoto">
 
    <ImageView
        android:id="@+id/take_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@mipmap/take"
        android:layout_marginBottom="50dp"
        />
 
    <ImageView
        android:id="@+id/take_layout"
        android:layout_width="200dp"
        android:layout_height="40dp"
        android:layout_marginRight="10dp"
        android:layout_marginLeft="10dp"
        android:background="@android:color/holo_blue_dark"
        />
 
    <Button
        android:id="@+id/take_crop"
        android:layout_width="200dp"
        android:layout_height="40dp"
        android:background="@android:color/holo_blue_dark"
        android:text="裁剪"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        />
</RelativeLayout>