知识点:
1、对矩阵:Matrix类熟悉,链接:https://blog.csdn.net/jdsjlzx/article/details/52741445
2、MotionEvent详解:https://blog.csdn.net/vansbelove/article/details/78416791
3、定位一个点使用:new PointF();
getX()、getY():获取点相对于左上角的相对坐标
4、顺序:创建矩阵锁定位置--->创建常量记录触点动作--->创建点--->计算点间距、两点中心的位置
重点:1、计算两点之间的距离计算
2、计算两点间中间点的位置
代码如下:
1、MainActivity.java源码:
1 package com.example.moremovetest; 2 3 import android.app.Activity; 4 import android.app.usage.UsageEvents.Event; 5 import android.graphics.Matrix; 6 import android.graphics.PointF; 7 import android.os.Bundle; 8 import android.view.MotionEvent; 9 import android.view.View; 10 import android.view.View.OnTouchListener; 11 import android.widget.ImageView; 12 13 public class MainActivity extends Activity implements OnTouchListener{ 14 private ImageView imageView; 15 16 private Matrix matrix1=new Matrix();//创建一个矩阵,移动前的矩阵、移动后的矩阵 17 private Matrix matrix2=new Matrix(); 18 19 private static final int NONE=0; //常量,没有触点,一个触点,两个触点,实际触点 20 private static final int DRAG=1; 21 private static final int ZOOM=2; 22 private int mode=NONE; 23 24 private PointF startPoint=new PointF();//第一个手指按下的点 25 private PointF midPoint=new PointF();//两个手指按下的点之间的中点 26 private float distance=1f;//最初两个手指按下的点之间的距离 27 28 @Override 29 protected void onCreate(Bundle savedInstanceState) { 30 super.onCreate(savedInstanceState); 31 setContentView(R.layout.activity_main); 32 imageView=(ImageView)findViewById(R.id.image); 33 imageView.setOnTouchListener(this); 34 } 35 36 @Override 37 public boolean onTouch(View arg0, MotionEvent arg1) { 38 ImageView view=(ImageView)arg0; //参数中传入的view转换为ImageView 39 40 //触摸设置: 41 switch (arg1.getAction() & MotionEvent.ACTION_MASK) { 42 case MotionEvent.ACTION_DOWN: //第一个手指按下 43 matrix1.set(view.getImageMatrix()); //将图片大小设置一个单位矩阵 44 matrix2.set(matrix1); //将矩阵matrix1保存 45 startPoint.set(arg1.getX(), arg1.getY()); //设置第一个触点的位置 46 mode=DRAG; 47 break; 48 case MotionEvent.ACTION_POINTER_DOWN: //第二个手指按下 49 distance=distance(arg1); //函数distance(MotionEvent event)用于计算两点间的距离 50 //防止一个手指上出现两个茧 51 if(distance>10f) { 52 matrix2.set(matrix1); 53 midPoint=middle(arg1); //计算两个触点的中间点的位置 54 mode=ZOOM; 55 } 56 break; 57 //手指松开: 58 case MotionEvent.ACTION_UP: 59 case MotionEvent.ACTION_POINTER_UP: 60 mode=NONE; 61 break; 62 //手指滑动事件: 63 case MotionEvent.ACTION_MOVE: 64 if(mode==DRAG) { 65 //一个手指滑动: 66 matrix1.set(matrix2); 67 //位置迁移 68 matrix1.postTranslate(arg1.getX()-startPoint.x, arg1.getY()-startPoint.y); 69 }else if(mode==ZOOM){ 70 //两个手指滑动 71 float newDistance=distance(arg1); 72 if(newDistance>10f) { 73 matrix1.set(matrix2); 74 float scale=newDistance/distance; 75 matrix1.postScale(scale, scale,midPoint.x, midPoint.y); 76 } 77 } 78 break; 79 default: 80 break; 81 } 82 //设置ImageView的矩阵(Matrix) 83 view.setImageMatrix(matrix1); 84 return true; 85 } 86 87 //计算两点间的距离: 88 private float distance(MotionEvent event) { 89 float x=event.getX(0)-event.getX(1); 90 float y=event.getY(0)-event.getY(1); 91 return (float)Math.sqrt(x*x+y*y); 92 } 93 94 //计算两点之间中间点的位置: 95 private PointF middle(MotionEvent event) { 96 float x=event.getX(0)-event.getX(1); 97 float y=event.getY(0)-event.getY(1); 98 return new PointF(x/2,y/2); 99 } 100 }
2、activity_main.xml:
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:paddingBottom="@dimen/activity_vertical_margin" 6 android:paddingLeft="@dimen/activity_horizontal_margin" 7 android:paddingRight="@dimen/activity_horizontal_margin" 8 android:paddingTop="@dimen/activity_vertical_margin" 9 tools:context="com.example.moremovetest.MainActivity" > 10 11 <ImageView 12 android:id="@+id/image" 13 android:layout_width="match_parent" 14 android:layout_height="match_parent" 15 android:src="@drawable/image" 16 android:scaleType="matrix" 17 /> 18 19 </LinearLayout>
3、AndroidManifest.xml:
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 package="com.example.moremovetest" 4 android:versionCode="1" 5 android:versionName="1.0" > 6 7 <uses-sdk 8 android:minSdkVersion="18" 9 android:targetSdkVersion="22" /> 10 11 <application 12 android:allowBackup="true" 13 android:icon="@drawable/ic_launcher" 14 android:label="@string/app_name" 15 android:theme="@style/AppTheme" > 16 <activity 17 android:name=".MainActivity" 18 android:label="@string/app_name" > 19 <intent-filter> 20 <action android:name="android.intent.action.MAIN" /> 21 22 <category android:name="android.intent.category.LAUNCHER" /> 23 </intent-filter> 24 </activity> 25 </application> 26 27 </manifest>