Question

我正在练习一些自定义视图。我成功地将画布平移到居中并旋转一定距离的圆（就像风扇一样），效果很好。

但是现在我想像旋钮一样在210度到150度之间旋转该圆。我将尝试添加到

  if(theta == 210 || theta == 150)
       theta *= -1;

但是它不能正常工作...

public class RoundMovingView  extends View {

    private static final String TAG = "CustomDrawing";
    private float circleRadius = 50;
    private float radius = 300;
    double theta = 150.0;
    private Paint circlePaint;

    public RoundMovingView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        setFocusable(true);
        setFocusableInTouchMode(true);
        setupPaint();
    }

    private void setupPaint() {
        circlePaint = new Paint();
        circlePaint.setColor(Color.BLACK);
        circlePaint.setAntiAlias(true);
        circlePaint.setStrokeWidth(4);
        circlePaint.setStyle(Paint.Style.STROKE);
        circlePaint.setStrokeJoin(Paint.Join.ROUND);
        circlePaint.setStrokeCap(Paint.Cap.ROUND);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        ///super.onDraw(canvas);

        canvas.translate(getWidth()/2,getHeight()/2);

        //Center Circle
        circlePaint.setColor(Color.BLACK);

        float center_circle_X = (float) (radius * Math.cos(theta));
        float center_circle_Y = (float) (radius * Math.sin(theta));
        canvas.drawCircle(center_circle_X, center_circle_Y, circleRadius, circlePaint);
        canvas.drawLine(center_circle_X,center_circle_Y,0,0,circlePaint);

        theta += .05;

        if(theta == 210 || theta == 150)
            theta *= -1;

        invalidate();
        requestLayout();
    }
}

activity_splashy.xml

<?xml version="1.0" encoding="utf-8"?>
<c.customviewpracticing.RoundMovingView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/custom_relative_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    tools:context=".Splashy">

</c.customviewpracticing.RoundMovingView>

在210至150度之间移动摆锤

0 个答案: