自定义view画太极图

效果图：

布局：

<!--包名要对应--><com.example.day03_custom_view.view.Taiji_view    android:layout_width="match_parent"    android:layout_height="match_parent" />

java代码：

public class Taiji_view extends View{    private static final String TAG = "Taiji_view";    private int padding = 8;    //画笔工具    private Paint mPaint;    //圆心坐标    private float currentX = 0;    private float currentY = 0;    //大圆半径    private float radiusBig = 100;    //中圆半径    private float radiusCenter = radiusBig / 2;    //小圆半径    private float radiusSmall = radiusCenter / 3;    public Taiji_view(Context context) {        this(context,null);    }    public Taiji_view(Context context, @Nullable AttributeSet attrs) {        this(context, attrs,0);    }    public Taiji_view(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        mPaint = new Paint();        mPaint.setAntiAlias(true);        setAnimation();    }    /**     * 设置缩放动画     */    private void setAnimation() {        ScaleAnimation scaleAnimation2 = new ScaleAnimation(0.7f, 1.0f, 0.7f, 1.0f, ScaleAnimation.RELATIVE_TO_PARENT, 0.5f, ScaleAnimation.RELATIVE_TO_PARENT, 0.5f);        scaleAnimation2.setDuration(500);// 设置持续时间        scaleAnimation2.setRepeatCount(99999);// 设置重复次数        scaleAnimation2.setFillAfter(true);// 保持动画结束时的状态        startAnimation(scaleAnimation2);    }    @Override    protected void onDraw(Canvas canvas) {        super.onDraw(canvas);        drawBg(canvas);        drawLeftHalfCirle(canvas);        drawTBCirle(canvas);    }    /**     * 画上下两个圆--中圆和小圆     *     * @param canvas     */    private void drawTBCirle(Canvas canvas) {        //画上面的白中圆        mPaint.setColor(Color.WHITE);        canvas.drawCircle(currentX, currentY - radiusBig / 2, radiusCenter, mPaint);        //画上面的黑小圆        mPaint.setColor(Color.BLACK);        canvas.drawCircle(currentX, currentY - radiusBig / 2, radiusSmall, mPaint);        //画下面的黑中圆        mPaint.setColor(Color.BLACK);        canvas.drawCircle(currentX, currentY + radiusBig / 2, radiusCenter, mPaint);        //画下面的白小圆        mPaint.setColor(Color.WHITE);        canvas.drawCircle(currentX, currentY + radiusBig / 2, radiusSmall, mPaint);    }    /**     * 画左边半圆     *     * @param canvas     */    private void drawLeftHalfCirle(Canvas canvas) {        mPaint.setColor(Color.WHITE);        canvas.drawArc(new RectF(currentX - radiusBig, currentY - radiusBig, currentX + radiusBig, currentY + radiusBig), 90, 180, true, mPaint);//90度开始画180度    }    /**     * 画黑色的背景底板     *     * @param canvas     */    private void drawBg(Canvas canvas) {        mPaint.setColor(Color.BLACK);        canvas.drawCircle(currentX, currentY, radiusBig + padding, mPaint);    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        super.onMeasure(widthMeasureSpec, heightMeasureSpec);        currentX = MeasureSpec.getSize(widthMeasureSpec) / 2;        currentY = MeasureSpec.getSize(heightMeasureSpec) / 2;        setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);    }    @Override    public boolean onTouchEvent(MotionEvent event) {        currentX = event.getX();        currentY = event.getY();        invalidate();        return true;    }}