Android基础新手教程——3.4 TouchListener PK OnTouchEvent + 多点触碰
标签（空格分隔）： Android基础新手教程
本节引言：
1.基于监听的TouchListener
代码演示样例：
实现效果图：
实现代码：
main.xml
<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"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MyActivity">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/imgtouch"
android:background="@drawable/touch"/>
</RelativeLayout> MainAcitivity.java
public class MyActivity extends ActionBarActivity {
private ImageView imgtouch;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
imgtouch = (ImageView)findViewById(R.id.imgtouch);
imgtouch.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
Toast.makeText(getApplicationContext(),"你通过监听器模式:OnTouchListener摸了伦家~",Toast.LENGTH_LONG).show();
return true;
}
});
}
} 代码解析：
OnTouchListener相关方法与属性:
2.基于回调的onTouchEvent( )方法
代码演示样例：
定义一个简单的view，绘制一个蓝色的小圆，能够尾随手指进行移动
实现代码：
MyView.java
public class MyView extends View{
public float X = 50;
public float Y = 50;
//创建画笔
Paint paint = new Paint();
public MyView(Context context,AttributeSet set)
{
super(context,set);
}
@Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
paint.setColor(Color.BLUE);
canvas.drawCircle(X,Y,30,paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
this.X = event.getX();
this.Y = event.getY();
//通知组件进行重绘
this.invalidate();
return true;
}
}main.xml:
<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=".MyActivity">
<example.jay.com.touch2.MyView
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</RelativeLayout> 实现效果图：
用手指触摸进行移动~
3.多点触碰
原理类的东西：
我们能够通过event.getX(int)或者event.getY(int)来获得不同触摸点的位置：
比方event.getX(0)能够获得第一个接触点的X坐标，event.getX(1)获得第二个接触点的X坐标这样…
另外。我们还能够在调用MotionEvent对象的getPointerCount()方法推断当前有多少个手指在触摸~
代码演示样例：
好吧，我们来写个最常见的单指拖动图片，双指缩放图片的演示样例吧：
实现效果图：
实现代码：
activity_main.xml：
<?xml version="1.0" encoding="utf-8"?
>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="@+id/img_test"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="matrix"
android:src="@drawable/pic1" />
</RelativeLayout>MainActivity.java
package com.jay.example.edittextdemo;
import android.app.Activity;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
public class MainActivity extends Activity implements OnTouchListener {
private ImageView img_test;
// 縮放控制
private Matrix matrix = new Matrix();
private Matrix savedMatrix = new Matrix();
// 不同状态的表示：
private static final int NONE = 0;
private static final int DRAG = 1;
private static final int ZOOM = 2;
private int mode = NONE;
// 定义第一个按下的点。两仅仅接触点的重点。以及出事的两指按下的距离：
private PointF startPoint = new PointF();
private PointF midPoint = new PointF();
private float oriDis = 1f;
/*
* (non-Javadoc)
*
* @see android.app.Activity#onCreate(android.os.Bundle)
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
img_test = (ImageView) this.findViewById(R.id.img_test);
img_test.setOnTouchListener(this);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
ImageView view = (ImageView) v;
switch (event.getAction() & MotionEvent.ACTION_MASK) {
// 单指
case MotionEvent.ACTION_DOWN:
matrix.set(view.getImageMatrix());
savedMatrix.set(matrix);
startPoint.set(event.getX(), event.getY());
mode = DRAG;
break;
// 双指
case MotionEvent.ACTION_POINTER_DOWN:
oriDis = distance(event);
if (oriDis > 10f) {
savedMatrix.set(matrix);
midPoint = middle(event);
mode = ZOOM;
}
break;
// 手指放开
case MotionEvent.ACTION_UP:
case MotionEvent.ACTION_POINTER_UP:
mode = NONE;
break;
// 单指滑动事件
case MotionEvent.ACTION_MOVE:
if (mode == DRAG) {
// 是一个手指拖动
matrix.set(savedMatrix);
matrix.postTranslate(event.getX() - startPoint.x, event.getY() - startPoint.y);
} else if (mode == ZOOM) {
// 两个手指滑动
float newDist = distance(event);
if (newDist > 10f) {
matrix.set(savedMatrix);
float scale = newDist / oriDis;
matrix.postScale(scale, scale, midPoint.x, midPoint.y);
}
}
break;
}
// 设置ImageView的Matrix
view.setImageMatrix(matrix);
return true;
}
// 计算两个触摸点之间的距离
private float distance(MotionEvent event) {
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return FloatMath.sqrt(x * x + y * y);
}
// 计算两个触摸点的中点
private PointF middle(MotionEvent event) {
float x = event.getX(0) + event.getX(1);
float y = event.getY(0) + event.getY(1);
return new PointF(x / 2, y / 2);
}
}
本节小结：
好的。关于TouchListener**和OnTouchEvent**以及多点触碰就到这里~