1CLASS:: GridLines 2summary:: given a spec and the actual data's min and max values, calculates the ideal spacing and labelling of grid lines for plotting 3categories:: GUI>Accessories 4related:: Reference/plot, Classes/Plotter, Classes/DrawGrid 5 6DESCRIPTION:: 7GridLines is a strategy object that implements a general strategy for finding a suitable min max range for graphing and suitable intervals for grid lines and labelling. 8 9The object that does the actual drawing on a view is DrawGrid. 10 11A GridLines object uses a ControlSpec to define the minimum and maximum possible values. Given a data set's actual minimum and maximum values, the GridLines object can choose a logical range for graphing that encompasses the data that will be plotted. 12 13Future development work will add subclasses of GridLines that can bind more tightly with the data they are representing. For instance a FreqGridLines (not yet implemented) could apply stronger lines to octave divisions. A DegreeGridLines could be used to draw pitch degree gridlines behind a frequency plot. 14 15Spec has a .grid variable that points to its preferred GridLines object that should be used for graphing. 16 17code:: 18\freq.asSpec.grid 19:: 20 21This default implementation does not know anything about the data is displaying: 22 23code:: 24DrawGrid.test( nil, \midinote.asSpec.grid ); 25:: 26 27A MidinoteGrid could be written that labels these correctly, shows octaves and individual notes depending on the current zoom. 28 29Note that the GridLines does not know which axis it is to be used on and could also be used in polar plots or in 3D rendering. 30 31CLASSMETHODS:: 32 33METHOD:: new 34 35argument:: spec 36The ControlSpec that defines the mininum and maximum values, warn and step. 37 38returns:: a GridLines 39 40 41INSTANCEMETHODS:: 42 43METHOD:: spec 44get/set the spec 45 46returns:: a ControlSpec 47 48METHOD:: asGrid 49return self. nil.asGrid would return a BlankGridLines which is a subclass of GridLines. So when plotting if you specify a grid of nil then you will get no lines at all. 50 51returns:: self 52 53METHOD:: niceNum 54Based on: http://books.google.de/books?id=fvA7zLEFWZgC&pg=PA61&lpg=PA61 55This rounds a value to a logical nice number. It is mostly used to support internal calculation, though it may be useful for other applications. 56 57argument:: val 58The value. 59 60argument:: round 61Boolean. Rounding uses a specific algorithm. This is not simple rounding to an integer value. 62 63returns:: the nice number 64 65METHOD:: ideals 66for internal use 67 68argument:: min 69(describe argument here) 70 71argument:: max 72(describe argument here) 73 74argument:: ntick 75(describe argument here) 76 77returns:: (returnvalue) 78 79METHOD:: looseRange 80Returns the logical minimum and maximum that will contain the data. 81 82argument:: min 83minimum value 84 85argument:: max 86maximum value. 87 88argument:: ntick 89the number of lines you would like (which usually varies by how much screen space you have and what you consider cluttered) 90 91returns:: [ideal min, ideal max] 92 93METHOD:: getParams 94Specifically for use by DrawGrid. This returns a dictionary filled with: 95'lines': an array of values where lines should be drawn 96'labels': [value, formatted label] for each line 97 98argument:: valueMin 99minimum value of the data to be plotted 100 101argument:: valueMax 102maximum value of the data to be plotted 103 104argument:: pixelMin 105If numTicks is nil: used to guess the ideal numTicks based on the graph size. 106 107argument:: pixelMax 108If numTicks is nil: used to guess the ideal numTicks based on the graph size. 109 110argument:: numTicks 111Explicit number of ticks you would like to see on the graph. 112 113returns:: A dictionary 114 115METHOD:: formatLabel 116Round the value and append the spec's units 117 118argument:: val 119The value 120 121argument:: numDecimalPlaces 122Number of decimal places 123 124returns:: a string 125 126 127