Odtnhj

I need to implement something like SeekBar. I created my class heir from View. In which I paint an oval on canvas. When touched, this oval goes up and down. I can not correctly calculate the position for the point (thumb).

enter image description here

here is my code, but it has already been redone many times and stopped working:

public class BalanceView extends View 
 private Paint ovalPaint;
 private Paint thumbPaint;
 private float ovalBottom = 0f;
 private Bitmap thumb;
 private RectF oval1;


 //params
 private int maxValue = 18;
 private float ovalPaintWidth = 2.0f;
 private float ovalHeight = 60f;
 //end params


 private float touchX = 0f;
 private float touchY = 0f;

 private float mUnreachedRadius;



 public BalanceView(Context context) 
 super(context);
 init(context, null);
 

 public BalanceView(Context context, @Nullable AttributeSet attrs) 
 super(context, attrs);
 init(context, attrs);
 

 public BalanceView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) 
 super(context, attrs, defStyleAttr);
 init(context, attrs);
 



 private void init(Context ctx, @Nullable AttributeSet attrs)
 if (attrs != null)

 

 if (ovalPaint == null)
 ovalPaint = new Paint();
 ovalPaint.setAntiAlias(true);
 ovalPaint.setStrokeWidth(ovalPaintWidth);
 ovalPaint.setStyle(Paint.Style.STROKE);
 Shader shader = new SweepGradient(10, 10, new intR.color.white, R.color.black, R.color.white, null);
 ovalPaint.setShader(shader);
 

 if (thumbPaint == null)
 thumbPaint = new Paint();
 

 thumb = BitmapFactory.decodeResource(getResources(), R.drawable.move_point);
 

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) 
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);

 //refershPosition();
 

 @Override
 protected void onDraw(Canvas canvas) 
 paintOval(ovalPaint, canvas);


 float cos = computeCos(touchX, touchY);
 float y = calcYLocationInWheel(cos);

 Log.d("balance", "cos: " + cos + " y: " + y + " touchX: " + touchX + " touchY: " + touchY + "mUnreachedRadius: " + mUnreachedRadius) ;
 canvas.drawBitmap(thumb, touchX, y, thumbPaint);

 super.onDraw(canvas);
 

 private void paintOval(Paint paint, @NonNull Canvas canvas)
 if (paint != null) 
 int right = getWidth() - 30;
 int left = (getWidth() - right) / 2;
 float top = ovalBottom - ovalHeight;

 oval1 = new RectF(left, top, right + left, ovalBottom);
 canvas.drawOval(oval1, paint);
 
 

 @Override
 public boolean dispatchTouchEvent(MotionEvent event) 
 if (event.getY() >= getTop() && event.getY() <= getBottom()) 
 touchY = event.getY();
 
 if (event.getX() <= oval1.right - thumb.getWidth() && event.getX() >= oval1.left) 
 touchX = event.getX();
 

 ovalBottom = touchY;
 invalidate();
 return super.dispatchTouchEvent(event);
 

 private float computeCos(float x, float y) 
 float width = x - oval1.width() / 2;
 float height = y - oval1.height() / 2;
 float slope = (float) Math.sqrt(width * width + height * height);
 return height / slope;
 

 private float calcYLocationInWheel(double cos) 
 return oval1.bottom * (float) cos;
 

I try so:

private float getY(float a, float b, float x)
 // return (float) (Math.pow(b, 2d) * ((Math.pow(a, 2d) - Math.pow(x, 2d)) / Math.pow(a, 2d)));
 return (float)
 ((Math.pow(b, 2d) / Math.pow(a, 2d)) * (Math.sqrt(b * b * (a * a - x * x))));
 

But the data is wrong.