Android SurfaceView: textsize changing in Paint is not smooth

Question

I have a problem with drawing text on canvas of SurfaceView. I need to draw text each frame with different size. To change text size i use:

    mTextPaint.setTextSize(mTextSize);

mTextSize is calculating correctly and has float values, but it looks like text scaling is happening by steps and it is not smooth (looks like symbols are changing size, for example, from 9 to 10 like this 9 -> 9.25 -> 9.5 ->9.75 -> 10). I used flags on paint but it didn't help.

    TextPaint mTextPaint = new TextPaint(TextPaint.ANTI_ALIAS_FLAG | TextPaint.SUBPIXEL_TEXT_FLAG | TextPaint.FAKE_BOLD_TEXT_FLAG | TextPaint.LINEAR_TEXT_FLAG);
    mTextPaint.setTextAlign(Paint.Align.CENTER);

Do font symbols have some predefined sizes or problem is in something other?