安卓绘制指南针
时间: 2023-08-23 09:18:09 浏览: 54
在Android中,您可以使用传感器API(例如方向传感器)来获取设备的朝向,然后使用Canvas API来绘制指南针。下面是一个简单的示例代码,演示如何绘制一个简单的指南针:
```
public class CompassView extends View implements SensorEventListener {
private Paint paint;
private float[] orientationValues = new float[3];
public CompassView(Context context) {
super(context);
init();
}
public CompassView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setStyle(Paint.Style.FILL_AND_STROKE);
paint.setStrokeWidth(2);
paint.setTextSize(30);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
// 获取屏幕宽高
int width = getWidth();
int height = getHeight();
// 计算指南针中心点坐标
float centerX = width / 2;
float centerY = height / 2;
// 绘制指南针外圆
paint.setColor(Color.BLACK);
canvas.drawCircle(centerX, centerY, width / 3, paint);
// 绘制指南针刻度
paint.setColor(Color.WHITE);
for (int i = 0; i < 360; i += 15) {
canvas.drawLine(centerX, centerY - width / 3, centerX, centerY - width / 3 + 30, paint);
canvas.rotate(15, centerX, centerY);
}
// 绘制指南针文字
paint.setColor(Color.WHITE);
paint.setTextAlign(Paint.Align.CENTER);
canvas.drawText("N", centerX, centerY - width / 3 + 60, paint);
canvas.drawText("E", centerX + width / 3 - 60, centerY, paint);
canvas.drawText("S", centerX, centerY + width / 3 - 30, paint);
canvas.drawText("W", centerX - width / 3 + 60, centerY, paint);
// 绘制指南针指针
paint.setColor(Color.RED);
canvas.save();
canvas.rotate(-orientationValues[0], centerX, centerY);
canvas.drawLine(centerX, centerY, centerX, centerY - width / 3 + 60, paint);
canvas.restore();
}
@Override
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_ORIENTATION) {
orientationValues = event.values;
invalidate();
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// do nothing
}
}
```
这段代码创建了一个CompassView类,它继承自View并实现了SensorEventListener接口。在onDraw()方法中,它使用Canvas API绘制了指南针的外圆、刻度、文字和指针。在onSensorChanged()方法中,它获取方向传感器的值,并在指南针上旋转指针以反映设备的朝向。
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