我设计了一个简单的指南针应用程序，第一步，我用一个单一的视图（指南针视图）编写了这个应用程序，它工作得很好。我创建了一个自定义指南针视图的新实例，并使用了 setcontent(mView)。
现在我正在尝试使用布局，但我无法让它工作！每次我尝试时，应用程序都会崩溃。
这是代码：
自定义视图：
public class CustomDrawableView extends View {
public float azimut;
Paint paint = new Paint();
public CustomDrawableView(Context context) {
super(context);
paint.setStyle(Style.STROKE);
paint.setStrokeWidth(2);
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);
azimut=0;
};
public CustomDrawableView(Context context, float Azimut) {
super(context);
paint.setStyle(Style.STROKE);
paint.setStrokeWidth(2);
paint.setColor(Color.WHITE);
paint.setAntiAlias(true);
azimut=Azimut;
};
protected void onDraw(Canvas canvas) {
Bitmap bMap = BitmapFactory.decodeResource(getResources(),R.drawable.compassarrowbitmap);
int width = getWidth();
int height = getHeight();
int centerx = width/2;
int centery = height/2;
int imHeight=200;
int imWidth=200;
Bitmap arrow = Bitmap.createScaledBitmap(bMap,imHeight , imWidth, false);
canvas.save(Canvas.MATRIX_SAVE_FLAG); //Saving the canvas and later restoring it so only this image will be rotated.
canvas.rotate(-azimut*360/(2*3.14159f), centerx, centery);
canvas.drawBitmap(arrow, centerx-imWidth/2, centery-imHeight/2, null);
canvas.restore();
}
}
xml文件：
<?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"
>
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<org.example.compassTest.CustomDrawableView
android:id="@+id/compassview"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</FrameLayout>
</LinearLayout>
主要活动：
public class MainActivity extends Activity implements SensorEventListener {
Float azimut=(float) 0; // View to draw a compass
CustomDrawableView mCompassView;
private SensorManager mSensorManager;
Sensor accelerometer;
Sensor magnetometer;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.mCompassView = (CustomDrawableView) findViewById(R.id.compassview);
mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
magnetometer = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
}
protected void onResume() {
super.onResume();
mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_UI);
mSensorManager.registerListener(this, magnetometer, SensorManager.SENSOR_DELAY_UI);
}
protected void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
public void onAccuracyChanged(Sensor sensor, int accuracy) { }
float[] mGravity;
float[] mGeomagnetic;
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
mGravity = event.values;
if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
mGeomagnetic = event.values;
if (mGravity != null && mGeomagnetic != null) {
float R[] = new float[9];
float I[] = new float[9];
boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mGeomagnetic);
if (success) {
float orientation[] = new float[3];
SensorManager.getOrientation(R, orientation);
azimut = orientation[0]; // orientation contains: azimut, pitch and roll
}
}
this.mCompassView.azimut=azimut;
this.mCompassView.invalidate();
}
}
* *日志：
01-07 04:40:54.957: W/dalvikvm(18101): threadid=1: thread exiting with uncaught exception (group=0x40c431f8)
01-07 04:40:54.957: E/AndroidRuntime(18101): FATAL EXCEPTION: main
**01-07 04:40:54.957: E/AndroidRuntime(18101): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.compasstest/org.example.compasstest.MainActivity}: android.view.InflateException: Binary XML file line #11: Error inflating class org.example.compassTest.CustomDrawableView****
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1968)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1993)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread.access$600(ActivityThread.java:127)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1159)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.os.Handler.dispatchMessage(Handler.java:99)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.os.Looper.loop(Looper.java:137)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread.main(ActivityThread.java:4507)
01-07 04:40:54.957: E/AndroidRuntime(18101): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 04:40:54.957: E/AndroidRuntime(18101): at java.lang.reflect.Method.invoke(Method.java:511)
01-07 04:40:54.957: E/AndroidRuntime(18101): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790)
01-07 04:40:54.957: E/AndroidRuntime(18101): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
01-07 04:40:54.957: E/AndroidRuntime(18101): at dalvik.system.NativeStart.main(Native Method)
01-07 04:40:54.957: E/AndroidRuntime(18101): Caused by: android.view.InflateException: Binary XML file line #11: Error inflating class org.example.compassTest.CustomDrawableView
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:691)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.rInflate(LayoutInflater.java:739)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.rInflate(LayoutInflater.java:742)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.inflate(LayoutInflater.java:489)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.inflate(LayoutInflater.java:396)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.inflate(LayoutInflater.java:352)
01-07 04:40:54.957: E/AndroidRuntime(18101): at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:271)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.Activity.setContentView(Activity.java:1835)
01-07 04:40:54.957: E/AndroidRuntime(18101): at org.example.compasstest.MainActivity.onCreate(MainActivity.java:28)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.Activity.performCreate(Activity.java:4465)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1932)
01-07 04:40:54.957: E/AndroidRuntime(18101): ... 11 more
01-07 04:40:54.957: E/AndroidRuntime(18101): Caused by: java.lang.ClassNotFoundException: org.example.compassTest.CustomDrawableView
01-07 04:40:54.957: E/AndroidRuntime(18101): at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
01-07 04:40:54.957: E/AndroidRuntime(18101): at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
01-07 04:40:54.957: E/AndroidRuntime(18101): at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.createView(LayoutInflater.java:552)
01-07 04:40:54.957: E/AndroidRuntime(18101): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:680)
01-07 04:40:54.957: E/AndroidRuntime(18101): ... 22 more