canvas - Incorrect colors while drawing lines on android -

i try draw 10 lines using overrided method ondraw , code:

public void ondraw(canvas canvas){      super.ondraw(canvas);     canvas.drawcolor(color.black);     paint paint = new paint();     paint.setcolor(color.blue);     for(int i=0;i<10;i++){         canvas.drawline(0,100*i,canvas.getwidth(),100*i,paint);     }  } 

in result lines different opacity. don't know reason of these transormations. use genymotion emu android 5.1 , api 22