自定义View关于画圆弧的一些笔记

public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    paint = new Paint();
    paint.setAntiAlias(true);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    paint.setColor(Color.BLACK);
    paint.setStyle(Paint.Style.STROKE);
    canvas.drawCircle(300,300,150,paint);
    canvas.drawCircle(300,300,130,paint);

    paint.setStrokeWidth(20);
    RectF oval=new RectF(160,160,440,440);
    canvas.drawArc(oval,0,90,false,paint);
}

1.首先这个300,300是圆的圆心,但是到了模拟器上并不一定会显示出300dp的长,涉及到屏幕适配等等.

2.这里的画圆弧Rectf 的 160 , 160   是通过  圆心X轴300-半径150 +  (150-130)/2=160

  440 , 440  是通过圆心Y轴300+(150+130)/2=440;

接来下是关于画一个动态的

1.View

public class MyView extends View {

    private Paint paint;
    private float progress;
    private int countProgress;

    public MyView(Context context) {
        this(context,null);
    }

    public MyView(Context context, AttributeSet attrs) {
        this(context, attrs,0);
    }

    public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint = new Paint();
        paint.setAntiAlias(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        paint.setStrokeWidth(0);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);
        canvas.drawCircle(300,300,150,paint);
        canvas.drawCircle(300,300,130,paint);
        paint.setTextSize(30);

        canvas.drawText(countProgress+"%",280,300,paint);

        paint.setStrokeWidth(20);
        RectF oval=new RectF(160,160,440,440);
        canvas.drawArc(oval,270,progress,false,paint);
    }

    public void setProgress(float progress) {
        this.progress = progress;
        countProgress= (int) (progress*100/360);
        invalidate();
    }

    public float getProgress() {
        return progress;
    }
}

2.MainXML

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.bawei.day1010.MainActivity">

    <com.bawei.day1010.MyView
        android:id="@+id/myview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/butStart"
        android:text="开始绘制圆弧"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginLeft="50dp"
        android:layout_marginStart="50dp"
        android:layout_marginBottom="132dp"/>
RelativeLayout>

3.MainActivity

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            mMyview.setProgress(mMyview.getProgress() + 1);
        }
    };
    private MyView mMyview;
    /**
     * 开始绘制圆弧
     */
    private Button mButStart;

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


    private void initView() {
        mMyview = (MyView) findViewById(R.id.myview);
        mButStart = (Button) findViewById(R.id.butStart);
        mButStart.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.butStart:
                new Thread() {
                    @Override
                    public void run() {
                        for (int i = 0; i <= 360; i++) {
                            //360°  30s  那么 1s12°  即  1°  1/12S
                            SystemClock.sleep(1000 / 12);
                            handler.sendEmptyMessage(0);
                        }
                    }
                }.start();
                break;
        }
    }
}

4.shape

xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
shape>

方法2:

new AsyncTask() {
    @Override
    protected String doInBackground(String... params) {

        for (int i = 0; i <= 360; i++) {
            SystemClock.sleep(100 / 12);
            publishProgress(i);
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... values) {
        if (mMyview.getProgress() >= 360) {
            mMyview.setProgress(360);
        }
        mMyview.setProgress(values[0]);
    }
}.execute();