android - 如何在android中制作自定义罗盘 View

Question

我正在使用一个简单的指南针应用程序。我需要使用传感器 Activity 设置指南针 View ，因为我选择了一个指南针 View 类。但它只是为指南针 View 画了一个圆和一条线。我需要通过用我自己的可绘制图像替换这个圆圈和线条来自定义此 View ，请有人帮我解决这个问题。

我的 View 类

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class MyCompassView extends View {

  private Paint paint;
  private float position = 0;

  public MyCompassView(Context context) {
    super(context);
    init();
  }

  private void init() {
    paint = new Paint();
    paint.setAntiAlias(true);
    paint.setStrokeWidth(2);
    paint.setTextSize(25);
    paint.setStyle(Paint.Style.STROKE);
    paint.setColor(Color.WHITE);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    int xPoint = getMeasuredWidth() / 2;
    int yPoint = getMeasuredHeight() / 2;

    float radius = (float) (Math.max(xPoint, yPoint) * 0.6);
    canvas.drawCircle(xPoint, yPoint, radius, paint);
    canvas.drawRect(0, 0, getMeasuredWidth(), getMeasuredHeight(), paint);

    // 3.143 is a good approximation for the circle
    canvas.drawLine(xPoint,
        yPoint,
        (float) (xPoint + radius
            * Math.sin((double) (-position) / 180 * 3.143)),
        (float) (yPoint - radius
            * Math.cos((double) (-position) / 180 * 3.143)), paint);

    canvas.drawText(String.valueOf(position), xPoint, yPoint, paint);
  }

  public void updateData(float position) {
    this.position = position;
    invalidate();
  }

} 

Answer 1

以上代码已被弃用。更新代码可用here

XML 布局 activty_main

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#fff" >
    <TextView
        android:id="@+id/tvHeading"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="40dp"
        android:layout_marginTop="20dp"
        android:text="Heading: 0.0" />
    <ImageView
        android:id="@+id/imageViewCompass"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/tvHeading"
        android:layout_centerHorizontal="true"
        android:src="@drawable/img_compass" />
</RelativeLayout>

主 Activity

public class MainActivity extends Activity implements SensorEventListener {

    // define the display assembly compass picture
    private ImageView image;

    // record the compass picture angle turned
    private float currentDegree = 0f;

    // device sensor manager
    private SensorManager mSensorManager;

    TextView tvHeading;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 
        image = (ImageView) findViewById(R.id.main_iv);

        // TextView that will tell the user what degree is he heading
        tvHeading = (TextView) findViewById(R.id.tvHeading);

        // initialize your android device sensor capabilities
        mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
    }

    @Override
    protected void onResume() {
        super.onResume();

        // for the system's orientation sensor registered listeners
        mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
                SensorManager.SENSOR_DELAY_GAME);
    }

    @Override
    protected void onPause() {
        super.onPause();

        // to stop the listener and save battery
        mSensorManager.unregisterListener(this);
    }

    @Override
    public void onSensorChanged(SensorEvent event) {

        // get the angle around the z-axis rotated
        float degree = Math.round(event.values[0]);

        tvHeading.setText("Heading: " + Float.toString(degree) + " degrees");

        // create a rotation animation (reverse turn degree degrees)
        RotateAnimation ra = new RotateAnimation(
                currentDegree, 
                -degree,
                Animation.RELATIVE_TO_SELF, 0.5f, 
                Animation.RELATIVE_TO_SELF,
                0.5f);

        // how long the animation will take place
        ra.setDuration(210);

        // set the animation after the end of the reservation status
        ra.setFillAfter(true);

        // Start the animation
        image.startAnimation(ra);
        currentDegree = -degree;

    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // not in use
    }
}