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);}@Overrideprotected 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<String, Integer, String>() {    @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();