"Volume by Price" is a horizontal histogram that overlays a price chart. The histogram bars stretch from left to right starting at the left side of the chart. The length of each bar is determined by the cumulative total of all volume bars for the periods during which the closing price fell within the vertical range of the histogram bar. Example
In the chart below, each volume-by-price bar covers a vertical range of 5 points. The longest bar covers the range from 27.5 to 32.5. The length of that bar was determined by adding up all of the volume bars on the days during which the price closed anywhere between 27.5 and 32.5.
Volume by Price can be selected as the "Volume By Price" overlay in SharpCharts. It takes no parameters.