Android自定义view画五星红旗

<com.example.day03_view_demo.StarFlagView
    android:layout_height="match_parent"
    android:layout_width="match_parent" />

、、

java代码：

public class StarFlagView extends SurfaceView implements SurfaceHolder.Callback ,Runnable{


    private final static int STAR_COLOR = 0xffffff00;
    private final static int BACK_COLOR = 0xffff0000;
    private SurfaceHolder mHolder;
    private boolean isStop = false;
    private Thread mThread;
    private Path mBigStarPath;
    private Path[] mSmallStarsPath;
    private Paint mStarPaint;
    private int mWidth, mHeight;
    private Paint mBackPaint;

    public StarFlagView(Context context) {
        super(context);
        init(null, 0);
    }

    public StarFlagView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(attrs, defStyle);
    }

    public StarFlagView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs, 0);
    }

    private void init(AttributeSet attrs, int defStyle) {

        mHolder = getHolder();
        mHolder.addCallback(this);
        setFocusable(true);
        setFocusableInTouchMode(true);
        setZOrderOnTop(true);
        mHolder.setFormat(PixelFormat.TRANSPARENT);// 设置背景透明

        mThread = new Thread(this);
    }

    public void run() {
        Canvas canvas = null;
        while (!isStop) {
            try {
                canvas = mHolder.lockCanvas();
                canvas.drawColor(Color.BLACK, PorterDuff.Mode.CLEAR);// 清除屏幕
                canvas.drawRect(0, 0, mWidth, mHeight, mBackPaint);
                canvas.drawPath(mBigStarPath, mStarPaint);
                for (int i = 0; i < mSmallStarsPath.length; i++) {
                    canvas.drawPath(mSmallStarsPath[i], mStarPaint);
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (canvas != null) {
                    mHolder.unlockCanvasAndPost(canvas);
                }
            }
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width,
                               int height) {
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // 大圆中心点
        int width = getWidth();
        int height = getHeight();

        if (width * 2 / 3 > height) {
            width = height / 2 * 3;
        } else {
            height = width / 3 * 2;
        }
        int cellWidth = width / 30;
        mWidth = width;
        mHeight = height;
        // 大五角星路径
        mBigStarPath = createStarPath(new PointF(width / 6, height / 4),
                width / 10, -90);
        // 小五角星路径
        mSmallStarsPath = new Path[4];
        mSmallStarsPath[0] = createStarPath(new PointF(cellWidth * 10,
                        cellWidth * 2), cellWidth,
                (float) (Math.atan2(3, -5) / Math.PI * 180));
        mSmallStarsPath[1] = createStarPath(new PointF(cellWidth * 12,
                        cellWidth * 4), cellWidth,
                (float) (Math.atan2(1, -7) / Math.PI * 180));
        mSmallStarsPath[2] = createStarPath(new PointF(cellWidth * 12,
                        cellWidth * 7), cellWidth,
                (float) (Math.atan2(-2, 7) / Math.PI * 180));
        mSmallStarsPath[3] = createStarPath(new PointF(cellWidth * 10,
                        cellWidth * 9), cellWidth,
                (float) (Math.atan2(-4, 5) / Math.PI * 180-90));
        mStarPaint = new Paint();
        mStarPaint.setColor(STAR_COLOR);
        mStarPaint.setStyle(Paint.Style.FILL);
        mStarPaint.setAntiAlias(true);// 抗锯齿
        mBackPaint = new Paint();
        mBackPaint.setColor(BACK_COLOR);
        mBackPaint.setStyle(Paint.Style.FILL);

        mThread.start();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        isStop = true;
    }

    private Path createStarPath(PointF centerPointF, float radius, float rotate) {
        final double arc = Math.PI / 5;
        final double rad = Math.sin(Math.PI / 10) / Math.sin(3 * Math.PI / 10);
        Path path = new Path();
        path.moveTo(1, 0);
        for (int idx = 0; idx < 5; idx++) {
            path.lineTo((float) (rad * Math.cos((1 + 2 * idx) * arc)),
                    (float) (rad * Math.sin((1 + 2 * idx) * arc)));
            path.lineTo((float) (Math.cos(2 * (idx + 1) * arc)),
                    (float) (Math.sin(2 * (idx + 1) * arc)));
        }
        path.close();
        Matrix matrix = new Matrix();
        matrix.postRotate(rotate);
        matrix.postScale(radius, radius);
        matrix.postTranslate(centerPointF.x, centerPointF.y);
        path.transform(matrix);
        return path;
    }

}