手势状态控制图片的缩放和移动(双击放大,俩指滑动图片缩放)

            



         手势状态控制图片的缩放和移动(双击放大,俩指滑动图片缩放)

MainActivity:

package com.example.pointerstouchevent;

        import android.support.v7.app.AppCompatActivity;
        import android.os.Bundle;
        import android.util.Log;
        import android.view.GestureDetector;
        import android.view.MotionEvent;

public class MainActivity extends AppCompatActivity implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener {
    private CystomImage image;
    private GestureDetector gestureDetector;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        //将自定义View控件找出来
        image= (CystomImage) findViewById(R.id.image);
        //手势探测器实现手势的监听
        gestureDetector=new GestureDetector(this,this);
        //手指在屏幕上双击的手势监听
        gestureDetector.setOnDoubleTapListener(this);
    }

    //Activity检测手势的方法
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        //通过event获取屏幕上手指个数
        int pointerCount = event.getPointerCount();

        switch(pointerCount){
            case 1://移动图片
                image.move(event);
                break;
            case 2://缩放图片
                image.scale(event);

                break;
            default:
                break;
        }
        //return super.onTouchEvent(event);
        return  gestureDetector.onTouchEvent(event);
    }
    
    
    
    
    //+++++++++++++++++++++++这六个方法就是手势监听方法++++++++++++++++++++++++++++++++++++++++++++
    @Override
    public boolean onDown(MotionEvent e) {
        Log.e("flag", "--------------------->onDown:手指按下 ");
        return false;
    }

    @Override
    public void onShowPress(MotionEvent e) {
        Log.e("flag", "--------------------->onShowPress: 手指按下,长按之前");

    }

    @Override
    public boolean onSingleTapUp(MotionEvent e) {
        Log.e("flag", "--------------------->onSingleTapUp: 单击抬起事件");
        return false;
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
        Log.e("flag", "--------------------->onScroll: 手指在屏幕上滑动");
        return false;
    }

    @Override
    public void onLongPress(MotionEvent e) {
        Log.e("flag", "--------------------->onLongPress: 长按");

    }

    @Override
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        Log.e("flag", "--------------------->onFling: 手指离开屏幕的惯性滑动");

        //这一块是实现让图片向左移动缩小,向右移动放大
        float e1X = e1.getX();
        float e2X = e2.getX();
        if(e1X-e2X>10){//向左移动
            //缩小图片
            image.scaleImage(0);

        }else if(e1X-e2X<-10){
            //放大
            image.scaleImage(1);
        }

        return false;
    }
    
    
    
//+++++++++++++++下面三个方法是手势双击屏幕的监听+++++++++++++++++++++++++++++++++++++++++++++

    @Override
    public boolean onSingleTapConfirmed(MotionEvent e) {
        Log.e("flag", "--------------------->onSingleTapConfirmed: 单击确定事件,俩次单击的事件间隔有点长");

        return false;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {
        Log.e("flag", "--------------------->onDoubleTap: 双击事件");
        //这里调用scaleImage()方法来实现双击图片的缩放
        image.scaleImage(1);//放大图片

        return false;
    }

    @Override
    public boolean onDoubleTapEvent(MotionEvent e) {
        Log.e("flag", "--------------------->onDoubleTapEvent: 双击发生之间的事件(双击的时候移动了,滑动了等等..)");
        return false;
    }
}

自定义View中:

package com.example.pointerstouchevent;

import android.content.Context;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView;

/**
 * Created by SuBang on 2017/4/26.
 */

public class CystomImage extends ImageView {
    private float last_x = 0;
    private float last_y = 0;
    private float scaleSize = 0.1f;//缩放的比例
    private float last_gap = 0;//俩点之间的 距离

    public CystomImage(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    //1.实现手指滑动图片移动
    public void move(MotionEvent event) {
        //当前的坐标
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                 last_x = event.getX();
                 last_y = event.getY();
                 break;
            case MotionEvent.ACTION_MOVE:
                float current_x = event.getX();
                float currnt_y = event.getY();
                float abs_x = Math.abs(current_x - last_x);
                float abs_y = Math.abs(currnt_y - last_y);
                if (abs_x > 10 && abs_x < 40 || abs_y > 10 && abs_y < 40) {
                    moveImage(current_x - last_x, currnt_y - last_y);
                }
                last_x = current_x;
                last_y = currnt_y;

                break;
            default:
                break;
        }
    }

    private void moveImage(float x, float y) {
        int offsetX = (int) x;
        int offsetY = (int) y;
        this.setFrame(
                getLeft() + offsetX,
                getTop() + offsetY,
                getRight() + offsetX,
                getBottom() + offsetY);


    }



    //2.实现俩个指头滑动让图片缩放
    public void scale(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_MOVE:
                //一个手指的坐标
                float x = event.getX(0);
                float y = event.getY(0);
                //另一个手指的坐标
                float x1 = event.getX(1);
                float y1 = event.getY(1);

                //勾股定理算出俩个手指之间的距离
                float current_gap = (float) Math.sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1));
                if (current_gap - last_gap > 10) {
                    //图片放大
                    scaleImage(1);
                } else if (current_gap - last_gap < -10) {
                    //图片缩小
                    scaleImage(0);
                }
                last_gap = current_gap;
                break;
            default:
                break;
        }
    }
   //3.双击让图片放大缩小
    public void scaleImage(int flag) {
        int scaleSize_x = (int) (scaleSize * getWidth());
        int scaleSize_y = (int) (scaleSize * getHeight());
        switch (flag) {
            case 0://缩小

                if (getWidth() > 50 + scaleSize_x * 2) {//变小
                    this.setFrame(
                            getLeft() + scaleSize_x,
                            getTop() + scaleSize_y,
                            getRight() - scaleSize_x,
                            getBottom() - scaleSize_y);
                }
                break;
            case 1://变大
                if (getWidth() < getContext().getResources().getDisplayMetrics().widthPixels * 3) {
                    this.setFrame(
                            getLeft() - scaleSize_x,
                            getTop() - scaleSize_y,
                            getRight() + scaleSize_x,
                            getBottom() + scaleSize_y);
                }
                break;
            default:
                break;
        }
    }
}

布局activity_main中:

<?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="com.example.pointerstouchevent.MainActivity">

    <com.example.pointerstouchevent.CystomImage
        android:id="@+id/image"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:src="@mipmap/ic_launcher"
        />


</RelativeLayout>

每天进步一点点!