?

?

準備一張名為arrow的指北針圖片，一張名為background的背景圖片。

?

?

在main.xml中：

?

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

??? xmlns:android="http://schemas.android.com/apk/res/android"

? android:orientation="vertical"

? android:layout_width="fill_parent"

? android:layout_height="fill_parent"

? android:background="@drawable/background">

? <com.li.sensor.ArrowView

? ??? android:layout_width="fill_parent"

???? android:layout_height="wrap_content"? />

</LinearLayout>

?

?

?

?

?

在ArrowView.java中：

?

package com.li.sensor;

?

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.util.AttributeSet;

import android.view.View;

?

public class ArrowView extends View implements SensorEventListener {

? private Bitmap comp = null;

? private float[] allValue;

?

? public ArrowView(Context context, AttributeSet attrs) {

???? super(context, attrs);

//?? super.setBackgroundColor(Color.WHITE); // 底色為白色

???? this.comp = BitmapFactory.decodeResource(super.getResources(),

???????? R.drawable.arrow);

???? SensorManager manager = (SensorManager) context

???????? .getSystemService(Context.SENSOR_SERVICE); // 現(xiàn)在只是找到了一個傳感器，但是沒有定義類型

???? manager.registerListener(this,

???????? manager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),

???????? SensorManager.SENSOR_DELAY_GAME); // 創(chuàng)建了一個適合于游戲操作的磁場傳感器

? }

?

? public void onAccuracyChanged(Sensor sensor, int accuracy) {

?

? }

?

? public void onSensorChanged(SensorEvent event) { // 傳感器方位改變

???? if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) { // 現(xiàn)在是方位傳感器

?????? float value[] = event.values; // 取得所有的偏離數(shù)據(jù)

?????? ArrowView.this.allValue = value; // 取得三個軸的值

?????? super.postInvalidate(); // 主線程的現(xiàn)實需要重繪

???? }

? }

?

? @Override

? protected void onDraw(Canvas canvas) {

???? super.onDraw(canvas);

???? Paint p = new Paint(); // 根據(jù)傳感器的數(shù)值來改變球的速度

???? if (this.allValue != null) { // 已經(jīng)取得了數(shù)據(jù)

?????? float x = this.allValue[0] ;

?????? float y = this.allValue[1] ;

?????? canvas.restore(); // 重置繪圖對象

?????? // 設(shè)置以屏幕中心點作為旋轉(zhuǎn)中心

?????? canvas.translate(super.getWidth() / 2, super.getHeight() / 2) ;

?????? // 判斷y軸是否為0的旋轉(zhuǎn)角度

?????? if (y == 0 && x > 0) {

???????? canvas.rotate(90) ;? // 旋轉(zhuǎn)角度為90度

?????? } else if (y == 0 && x < 0) {

???????? canvas.rotate(270) ; // 旋轉(zhuǎn)角度為270度

?????? } else { // 根據(jù)x和y的值計算旋轉(zhuǎn)角度，而這個角度就是依靠tan()值來計算

???????? if(y >= 0) {

??????????? canvas.rotate((float) Math.tanh(x / y) * 90);

???????? } else {

??????????? canvas.rotate(180 + (float) Math.tanh(x / y) * 90);

???????? }

?????? }

???? }

???? canvas.drawBitmap(this.comp, -this.comp.getWidth() / 2,

???????? -this.comp.getHeight() / 2, p);

? }

?

}

?

?

?

?

?

?

?

在BallView.java中：

?

package com.li.sensor;

?

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Point;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.util.AttributeSet;

import android.view.View;

?

public class BallView extends View implements SensorEventListener {

? private Bitmap ball = null;

? private float[] allValue;

? private Point point = new Point();

? private int xSpeed = 0;

? private int ySpeed = 0;

?

? public BallView(Context context, AttributeSet attrs) {

???? super(context, attrs);

???? super.setBackgroundColor(Color.WHITE); // 底色為白色

???? this.ball = BitmapFactory.decodeResource(super.getResources(),

???????? R.drawable.ball);

???? SensorManager manager = (SensorManager) context

???????? .getSystemService(Context.SENSOR_SERVICE); // 現(xiàn)在只是找到了一個傳感器，但是沒有定義類型

???? manager.registerListener(this,

???????? manager.getDefaultSensor(Sensor.TYPE_ORIENTATION),

???????? SensorManager.SENSOR_DELAY_GAME); // 創(chuàng)建了一個適合于游戲操作的方位傳感器

? }

?

? public void onAccuracyChanged(Sensor sensor, int accuracy) {

?

? }

?

? public void onSensorChanged(SensorEvent event) { // 傳感器方位改變

???? if (event.sensor.getType() == Sensor.TYPE_ORIENTATION) { // 現(xiàn)在是方位傳感器

?????? float value[] = event.values; // 取得所有的偏離數(shù)據(jù)

?????? BallView.this.allValue = value; // 取得三個軸的值

?????? super.postInvalidate(); // 主線程的現(xiàn)實需要重繪

???? }

? }

?

? @Override

? protected void onDraw(Canvas canvas) {

???? super.onDraw(canvas);

???? Paint p = new Paint(); // 根據(jù)傳感器的數(shù)值來改變球的速度

???? if (this.allValue != null) { // 已經(jīng)取得了數(shù)據(jù)

?????? this.xSpeed = (int) -this.allValue[2]; // 計算X軸速度

?????? this.ySpeed = (int) -this.allValue[1];

???? }

???? this.point.x += this.xSpeed;

???? this.point.y += this.ySpeed;

???? if (this.point.x < 0) {

?????? this.point.x = 0;

???? }

???? if (this.point.y < 0) {

?????? this.point.y = 0;

???? }

???? if (point.x > super.getWidth() - this.ball.getWidth()) { // X軸已經(jīng)顯示過了

?????? this.point.x = super.getWidth() - this.ball.getWidth();

???? }

???? if (point.y > super.getHeight() - this.ball.getHeight()) {

?????? this.point.y = super.getHeight() - this.ball.getWidth(); // 設(shè)置Y 軸的邊界

???? }

???? canvas.drawBitmap(this.ball, this.point.x, this.point.y, p);

? }

?

}

?

?

?

?

?

?

?

在MySensorDemo.java中：

?

package com.li.sensor;

?

import android.app.Activity;

import android.os.Bundle;

?

public class MySensorDemo extends Activity {

???

??? @Override

??? public void onCreate(Bundle savedInstanceState) {

??????? super.onCreate(savedInstanceState);

??????? setContentView(R.layout.main);

??? }

}

?

?

?

?

?

修改AndroidManifest.xml，設(shè)置為豎屏。

?

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

??? package="com.li.sensor"

??? android:versionCode="1"

??? android:versionName="1.0" >

?

??? <uses-sdk

??????? android:minSdkVersion="8"

??????? android:targetSdkVersion="15" />

?

??? <application

??????? android:icon="@drawable/ic_launcher"

??????? android:label="@string/app_name"

??????? android:theme="@style/AppTheme" >

??????? <activity

??????????? android:name=".MySensorDemo"

??????????? android:label="@string/title_activity_my_sensor_demo"

??????????? android:screenOrientation="portrait">

??????????? <intent-filter>

??????????????? <action android:name="android.intent.action.MAIN" />

?

??????????????? <category android:name="android.intent.category.LAUNCHER" />

??????????? </intent-filter>

??????? </activity>

??? </application>

?

</manifest>

?

總結(jié)

以上是生活随笔為你收集整理的磁场传感器（指北针）的全部內(nèi)容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網(wǎng)站內(nèi)容還不錯，歡迎將生活随笔推薦給好友。