question: private void drawThreshold ( Canvas canvas , float left , float top , float right , float bottom ) { if ( left == right || top == bottom ) canvas . drawLine ( left , top , right , bottom , style . thresholdPaint ) ; else canvas . drawRect ( left , top , right , bottom , style . thresholdPaint ) ; }
target:  Draw a threshold line or band on the labels or values axis. If same values or same label index have been given then a line will be drawn rather than a band.