android - Path points don't move accordingly to scale factor -

i'm making makeup application. application can detect parts on face, such eyebrow , mouth, , draw them line, using path detection. user can change path moving points. have problem when i'm making pinch zooming, image , lines zoomed perfectly, can't move point after zooming. points seem stay @ same points when detected @ beginning.

this picture of example of app.

i use scale factor onscale method zoom canvas.

i have class of each part on face. have points , draw method draw line. don't know how calculate scale factor, zooming operation, , points of each line move points accordingly scale factor.

this draw method of main canvas.

    float pivotx, pivoty;     pivotx = width / 2;     pivoty = height / 2;      //draw , translate canvas     canvas.save();     canvas.translate(mposx, mposy);     canvas.scale(mscalefactor, mscalefactor, pivotx, pivoty);     canvas.drawbitmap(mybitmap, 0, 0, null);      //draw eyebrow     leftadjustbrow.draw(canvas);     rightadjustbrow.draw(canvas); 

and draw method of eyebrow

    public void draw(canvas canvas) {     (pointf point : points) {         canvas.drawpoint(point.x, point.y, paintpoint);     }     path path = new path();     path.moveto(points[0].x, points[0].y);     path.lineto(points[1].x, points[1].y);     path.moveto(points[1].x, points[1].y);     path.lineto(points[2].x, points[2].y);     path.moveto(points[2].x, points[2].y);     canvas.drawpath(path, paint);  }