进阶篇－安卓系统：2.多点触控的交互处理

1.android 触摸事件侦听

安卓的用户交互方式包括两种，一种是点击交互，一种是触摸交互。点击交互就是手指按下抬起一个动作组。而触摸交互分为按下（down），移动（move），抬起（up）。

触摸事件侦听代码：输出触摸事件的三个动作：

我们用一个framlayout布局进行操作

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;public class MainActivity extends AppCompatActivity {private FrameLayout container;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);container = (FrameLayout) findViewById(R.id.container);container.setOnTouchListener(new View.OnTouchListener() {@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()){case MotionEvent.ACTION_DOWN:System.out.println("action:down");break;case MotionEvent.ACTION_MOVE:System.out.println("action:move");break;case MotionEvent.ACTION_UP:System.out.println("action:up");break;}return true;   //remember to change this return to ture
            }});}
}

注意：记得把onTouch方法的返回值改成true。

运行结果：

07-13 14:35:19.883 11720-11720/bhu.com.myapplication I/System.out: action:down
07-13 14:35:19.924 11720-11720/bhu.com.myapplication I/System.out: action:move
07-13 14:35:19.954 11720-11720/bhu.com.myapplication I/System.out: action:move
07-13 14:35:19.964 11720-11720/bhu.com.myapplication I/System.out: action:move
07-13 14:35:19.984 11720-11720/bhu.com.myapplication I/System.out: action:move
07-13 14:35:19.984 11720-11720/bhu.com.myapplication I/System.out: action:up

2.获取触摸的当前坐标

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;public class MainActivity extends AppCompatActivity {private FrameLayout container;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);container = (FrameLayout) findViewById(R.id.container);container.setOnTouchListener(new View.OnTouchListener() {@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()){case MotionEvent.ACTION_DOWN:System.out.println("action:down");break;case MotionEvent.ACTION_MOVE:System.out.println(String.format("(%f,%f)",motionEvent.getX(),motionEvent.getY()));break;case MotionEvent.ACTION_UP:System.out.println("action:up");break;}return true;   //remember to change this return to ture
            }});}
}

输出结果：

07-13 14:39:50.442 11720-11720/bhu.com.myapplication I/System.out: (366.251312,682.000000)
07-13 14:39:50.452 11720-11720/bhu.com.myapplication I/System.out: (367.076874,682.000000)
07-13 14:39:50.472 11720-11720/bhu.com.myapplication I/System.out: (367.000000,680.500000)
07-13 14:39:50.482 11720-11720/bhu.com.myapplication I/System.out: (368.067780,681.000000)
07-13 14:39:50.512 11720-11720/bhu.com.myapplication I/System.out: (369.000000,681.000000)
07-13 14:39:50.532 11720-11720/bhu.com.myapplication I/System.out: (370.142609,681.000000)
07-13 14:39:50.542 11720-11720/bhu.com.myapplication I/System.out: (371.500000,681.000000)
07-13 14:39:50.582 11720-11720/bhu.com.myapplication I/System.out: (373.497681,681.000000)
07-13 14:39:50.592 11720-11720/bhu.com.myapplication I/System.out: (374.960114,681.000000)
07-13 14:39:50.612 11720-11720/bhu.com.myapplication I/System.out: (376.413116,681.000000)

3.实现拖动控件

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ImageView;public class MainActivity extends AppCompatActivity {private FrameLayout container;private ImageView imv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);container = (FrameLayout) findViewById(R.id.container);imv = (ImageView) findViewById(R.id.imv);container.setOnTouchListener(new View.OnTouchListener() {@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()){case MotionEvent.ACTION_DOWN:System.out.println("action:down");break;case MotionEvent.ACTION_MOVE://System.out.println(String.format("(%f,%f)",motionEvent.getX(),motionEvent.getY()));FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) imv.getLayoutParams();lp.leftMargin = (int) motionEvent.getX();lp.topMargin = (int) motionEvent.getY();imv.setLayoutParams(lp);break;case MotionEvent.ACTION_UP:System.out.println("action:up");break;}return true;   //remember to change this return to ture
            }});}
}

运行结果：

该图片无法显示！

4.获取多个触控点的坐标

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ImageView;public class MainActivity extends AppCompatActivity {private FrameLayout container;private ImageView imv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);container = (FrameLayout) findViewById(R.id.container);imv = (ImageView) findViewById(R.id.imv);container.setOnTouchListener(new View.OnTouchListener() {@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()){case MotionEvent.ACTION_DOWN:System.out.println("action:down");break;case MotionEvent.ACTION_MOVE://System.out.println(String.format("(%f,%f)",motionEvent.getX(),motionEvent.getY()));System.out.println("pointers count:"+motionEvent.getPointerCount());  //get the number of pointers
System.out.println(String.format("point1:(%f,%f)  point2:(%f,%f)",motionEvent.getX(0),motionEvent.getY(0),motionEvent.getX(1),motionEvent.getY(1)));//when you put just one finger on the screen,there will be a exception,because there is not a getX(1).break;case MotionEvent.ACTION_UP:System.out.println("action:up");break;}return true;   //remember to change this return to ture
            }});}

输出结果：

07-13 14:54:52.855 5804-5804/bhu.com.myapplication I/System.out: point1:(245.296295,718.407410)  point2:(456.000000,389.000000)
07-13 14:54:52.865 5804-5804/bhu.com.myapplication I/System.out: pointers count:2
07-13 14:54:52.865 5804-5804/bhu.com.myapplication I/System.out: point1:(244.000000,721.000000)  point2:(455.000000,392.000000)
07-13 14:54:52.885 5804-5804/bhu.com.myapplication I/System.out: pointers count:2
07-13 14:54:52.885 5804-5804/bhu.com.myapplication I/System.out: point1:(242.387100,722.612915)  point2:(454.000000,394.000000)
07-13 14:54:52.895 5804-5804/bhu.com.myapplication I/System.out: pointers count:2
07-13 14:54:52.905 5804-5804/bhu.com.myapplication I/System.out: point1:(242.000000,724.000000)  point2:(453.000000,396.000000)
07-13 14:54:52.915 5804-5804/bhu.com.myapplication I/System.out: pointers count:2
07-13 14:54:52.915 5804-5804/bhu.com.myapplication I/System.out: point1:(241.000000,724.000000)  point2:(452.000000,397.000000)
07-13 14:54:52.935 5804-5804/bhu.com.myapplication I/System.out: pointers count:2
07-13 14:54:52.935 5804-5804/bhu.com.myapplication I/System.out: point1:(241.000000,725.000000)  point2:(452.000000,397.000000)

5.根据手势动作实现图片的缩放（两点触控）<并且可以拖动>

import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.ImageView;import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.common.api.GoogleApiClient;public class MainActivity extends AppCompatActivity {private FrameLayout container;private ImageView imv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);container = (FrameLayout) findViewById(R.id.container);imv = (ImageView) findViewById(R.id.imv);container.setOnTouchListener(new View.OnTouchListener() {float cureentDistance;float lastDistance = -1; //the distance of two point can not be a minus,when the distance is -1 ,it means it's a initial value.
@Overridepublic boolean onTouch(View view, MotionEvent motionEvent) {switch (motionEvent.getAction()) {case MotionEvent.ACTION_DOWN:System.out.println("action:down");break;case MotionEvent.ACTION_MOVE:if (motionEvent.getPointerCount() >= 2) {//there must be two finger on the screenfloat offsetX = motionEvent.getX(0) - motionEvent.getX(1);float offsetY = motionEvent.getY(1) - motionEvent.getY(1);cureentDistance = (float) Math.sqrt(offsetX * offsetX + offsetY * offsetY);if (lastDistance < 0) {lastDistance = cureentDistance;} else {if (cureentDistance - lastDistance > 5) {System.out.println("Zoom in");FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) imv.getLayoutParams();lp.width = (int) (1.1f*imv.getWidth());lp.height = (int) (1.1f*imv.getHeight());imv.setLayoutParams(lp);lastDistance = cureentDistance;} else if (lastDistance - cureentDistance > 5) {System.out.println("Zoom out");FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) imv.getLayoutParams();lp.width = (int) (0.9f*imv.getWidth());lp.height = (int) (0.9f*imv.getHeight());imv.setLayoutParams(lp);lastDistance = cureentDistance;}}}else{FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) imv.getLayoutParams();lp.leftMargin = (int) (motionEvent.getX()-(imv.getWidth()/2));lp.topMargin = (int) (motionEvent.getY()-(imv.getHeight()/2));imv.setLayoutParams(lp);}break;case MotionEvent.ACTION_UP:System.out.println("action:up");break;}return true;   //remember to change this return to ture
            }});}}