android – 垂直轴的旋转角度

我希望能够通过沿着屏幕拖动/触摸来增加图像1中蓝色区域的大小(角度).现在这些是我现在能以某种方式做的事情.我面临的真正问题是：

我使用以下代码绘制蓝色区域：

@H_8_11@mStart = -90; int degree = (int)((theta + Math.PI) * 180 / Math.PI); mSweep = degree; RectF mOvals = new RectF(c.x - outerRadius + circleThickness,c.y - outerRadius + circleThickness,c.x + outerRadius - circleThickness,c.y + outerRadius - circleThickness ); mArcSetLevel = new Path(); if(mArcSetLevel != null ) { canvas.drawArc(mOvals,mStart,mSweep,true,arcPaint); }

将起点设置为-90使其提前90度开始.为了跟踪触摸的角度,我使用这个公式,但这是出错的地方：

int py = (int)event.getY() - c.y;
int px = (int)event.getX() - c.x;

theta = (float) ((float)  Math.atan2(py,pX) - (Math.PI / 2)); // - Math.PI / 2 to correct -90 start

当我进一步超过270度时,蓝色区域会被重置,并以更小的角度从北向西拉伸(因为-90的’假’开始,如第三张图所示).我的数学技能根本不足以让我能够解决这个问题,虽然我能想到为什么会发生这种情况我似乎无法找到解决方案.

我做的整个视图的(非常混乱的)代码如下：

private Canvas canvas;  

//Canvas width and height
privatE int h = -1;
privatE int w = -1;

//circle properties
private Paint paint;
private Paint arcPaint;
private Path circle;
private Point c;
privatE int outerRadius;
privatE int circleThickness = 20;

//point click in wheel
private float theta = 0;

private float mStart;
private float mSweep;
private Paint mBgPaints   = new Paint();
private Path mArcSetLevel;

int padding = 10;

OnMeterWheelchangelistener onMeterWheelchangelistener = null;

public MeterWheel(Context context){
    super(context);
    initCircleSeekBar();
}

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

private void initCircleSeekBar() {

    canvas = new Canvas();
    circle = new Path();
    paint = new Paint();
    arcPaint = new Paint();
    c = new Point();

    mBgPaints.setAntiAlias(true);
    mBgPaints.setStyle(Paint.Style.FILL);
    mBgPaints.setColor(0x88FF0000);
    mBgPaints.setstrokeWidth(0.5f);

    mArcSetLevel = new Path();

    this.draw(canvas);
}


@Override
protected void onSizeChanged(int width,int height,int oldw,int oldh) {
    // TODO Auto-generated method stub
    super.onSizeChanged(width,height,oldw,oldh);

    w = width;
    h = height;
    Log.i("POWERWHEEL",String.valueOf(w) + "   " + String.valueOf(h));
    c.set(w/2,h/2);
    drawCircle();
}

private void drawCircle() {
    outerRadius = Math.min(h,w)/2;
    circleThickness = (int) (outerRadius*0.15);

    circle.addArc(new RectF(c.x - outerRadius + circleThickness/2,c.y - outerRadius + circleThickness/2,c.x + outerRadius - circleThickness/2,c.y + outerRadius - circleThickness/2 ),360);
    circle.moveTo(c.x,c.y);
    //paint.setShader(new SweepGradient(w/2,h/2,colourarry,null));
    paint.setColor(Color.GRAY);
    paint.setStyle(Style.stroke);
    paint.setstrokeWidth(circleThickness);
    paint.setAntiAlias(true);

    arcPaint.setColor(Color.bLUE);
    arcPaint.setStyle(Style.FILL);
    arcPaint.setstrokeWidth(circleThickness);
    arcPaint.setAntiAlias(true);
}


@SuppressLint("DrawAlLOCATIOn")
@Override
protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    super.onDraw(canvas);

    if(circle != null){
    //draw circle
        canvas.drawPath(circle,paint);

        mStart = -90;

        int degree = (int)((theta + Math.PI) * 180 / Math.PI);
        Log.d("POWERWHEEL","" + degreE);
        mSweep = degree;

        RectF mOvals = new RectF(c.x - outerRadius + circleThickness,c.y + outerRadius - circleThickness );

        mArcSetLevel = new Path();

        if(mArcSetLevel != null ) {
            canvas.drawArc(mOvals,arcPaint);
        }
    }

}


@Override
public Boolean onTouchEvent(MotionEvent event) {

    if (!isEnabled()) {
        return false;
    }

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            setPressed(true);
            onStartTrackingTouch(event);
            trackTouchEvent(event);
            break;

        case MotionEvent.ACTION_MOVE:
            trackTouchEvent(event);
            break;

        case MotionEvent.ACTION_UP:
            trackTouchEvent(event);
            onStopTrackingTouch();
            setPressed(false);
            invalidate();
            break;

        case MotionEvent.ACTION_CANCEL:
            onStopTrackingTouch();
            setPressed(false);
            invalidate();
            break;
    }

    return true;
}

@Override
protected void onMeasure(int widthMeasureSpec,int heightMeasureSpeC) {

    int width = MeasureSpec.getSize(widthMeasureSpec);
    int height = MeasureSpec.getSize(heightMeasureSpec);

    setMeasuredDimension(width,height);
}

private void onStartTrackingTouch(MotionEvent event) {

}

private void onStopTrackingTouch() {

}

private void trackTouchEvent(MotionEvent event) {

    int py = (int)event.getY() - c.y;
    int px = (int)event.getX() - c.x;

    theta = (float) ((float)  Math.atan2(py,pX) - (Math.PI / 2));
    Log.d("POWERWHEEL","theta: " + theta);

    this.invalidate();
}



public void setSize(int x,int y){
    h = y;
    w = x;
}

public void setCirleThickness(int t){
    circleThickness = t;
}


public void setOnMeterWheelchangelistener (OnMeterWheelchangelistener listener) {
    onMeterWheelchangelistener = listener;
}

public interface OnMeterWheelchangelistener{
    public void onStartTrackingTouch (MeterWheel colourWheel);
    public void onStopTrackingTouch (MeterWheel colourWheel);
}

提前一百万！