question: private synchronized void initialiseBaseLayer ( Point maxTileDimensions ) { scale = Math . min ( 2F , Math . min ( getWidth ( ) / ( float ) sWidth ( ) , getHeight ( ) / ( float ) sHeight ( ) ) ) ; defaultScale = scale ; fitToBounds ( true ) ; fullImageSampleSize = calculateInSampleSize ( ) ; if ( fullImageSampleSize > 1 ) { fullImageSampleSize /= 2 ; } initialiseTileMap ( maxTileDimensions ) ; List < Tile > baseGrid = tileMap . get ( fullImageSampleSize ) ; for ( Tile baseTile : baseGrid ) { BitmapTileTask task = new BitmapTileTask ( this , decoder , decoderLock , baseTile , this . failListener ) ; task . execute ( ) ; } }
target:  Called on first draw when the view has dimensions. Calculates the initial sample size and starts async loading of the base layer image - the whole source subsampled as necessary.