android canvas使用line画半圆

本文实例为大家分享了android canvas使用line画半圆具体代码，供大家参考，具体内容如下

LineView.java

public class LineView extends View {
private int progress = 0;
private int max = 100;
private int roundWidth = 50;
public LineView(Context context) {
super(context);
}

public LineView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public LineView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}

public void setProgress(int progress) {
this.progress = progress;
invalidate();
}

@Override
protected void onDraw(Canvas canvas) {

Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.RED);

paint.setStrokeWidth(roundWidth);
paint.setStyle(Paint.Style.STROKE);

canvas.drawCircle(getWidth() / 2, getHeight() / 2, 200, paint);

paint.setStyle(Paint.Style.FILL);
paint.setStrokeWidth(10);
paint.setColor(Color.BLUE);
int startX = 0, startY = 0, stopX = 0, stopY = 0;

startX=0;
stopX=500;
for (int i = 0; i <= progress; i++) {
startY = stopY = getHeight()/2+200-roundWidth/2 - i*(400-roundWidth)/max;
double v = Math.pow((200 - roundWidth / 2), 2) - (Math.pow((startY-getHeight()/2), 2));
startX = (int)(getWidth()/2-Math.sqrt(v));
stopX = (int)(getWidth()/2+Math.sqrt(v));
canvas.drawLine(startX, startY, stopX, stopY, paint);
}
}
}

MainActivity.java

public class MainActivity extends Activity {

private LineView lv;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
lv = (LineView)findViewById(R.id.lv);

lv.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
lv.setEnabled(false);

new Thread() {
@Override
public void run() {
for (int i = 0; i <= 100; i++) {

final int finalI = i;
runOnUiThread(new Runnable() {
@Override
public void run() {
lv.setProgress(finalI);
}
});
try {
sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

runOnUiThread(new Runnable() {
@Override
public void run() {
lv.setEnabled(true);
}
});
}
}.start();

}
});
}
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>

<com.xhly.sdv.lineview.view.LineView
android:id="@+id/lv"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_centerInParent="true"
/>

</RelativeLayout>

以上就是本文的全部内容，希望对大家的学习有所帮助

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