考虑到android java中的距离和Angular ，我试图从起点到终点画一条直线。我使用的公式是：

lineX = (float) (lastX + (30 * cos(orientationDegree)));
lineY = (float) (lastY + (30 * sin(orientationDegree)));

ondraw公司：

protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        drawRotateImage(canvas);

        for (Line l : listLine) {
            canvas.drawLine(l.StartX, l.StartY, l.EndX, l.EndY, paint);
        }
   }

   private void stepDetector () {
        l = new Line();
        l.setStartX(lastX);
        l.setStartY(lastY);
        l.setOrientationDegree(orientationDegree);
        lineX = (float) (lastX + (30 * cos(orientationDegree)));
        lineY = (float) (lastY + (30 * sin(orientationDegree)));
        l.setEndX(lineX);
        l.setEndY(lineY);
        listLine.add(l);
        System.out.println ("" + l.toString());
        invalidate();
        lastX = lineX;
        lastY = lineY;
    }

每行将保存在一个数组中 onDraw 是为了划清界限。然而，它似乎并不准确。方向是朝着任何不符合预期的方向。如果用户以特定Angular 笔直行走，则应画一条直线，而不是以不同Angular 。这似乎是由于android的坐标系统。你能告诉我如何使它准确吗？
谢谢。