127 lines
3.6 KiB
Text
127 lines
3.6 KiB
Text
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CLASS:: GridLines
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summary:: given a spec and the actual data's min and max values, calculates the ideal spacing and labelling of grid lines for plotting
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categories:: GUI>Accessories
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related:: Reference/plot, Classes/Plotter, Classes/DrawGrid
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DESCRIPTION::
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GridLines 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.
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The object that does the actual drawing on a view is DrawGrid.
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A 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.
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Future 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.
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Spec has a .grid variable that points to its preferred GridLines object that should be used for graphing.
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code::
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\freq.asSpec.grid
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::
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This default implementation does not know anything about the data is displaying:
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code::
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DrawGrid.test( nil, \midinote.asSpec.grid );
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::
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A MidinoteGrid could be written that labels these correctly, shows octaves and individual notes depending on the current zoom.
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Note 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.
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CLASSMETHODS::
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METHOD:: new
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argument:: spec
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The ControlSpec that defines the mininum and maximum values, warn and step.
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returns:: a GridLines
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INSTANCEMETHODS::
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METHOD:: spec
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get/set the spec
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returns:: a ControlSpec
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METHOD:: asGrid
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return 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.
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returns:: self
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METHOD:: niceNum
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Based on: http://books.google.de/books?id=fvA7zLEFWZgC&pg=PA61&lpg=PA61
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This rounds a value to a logical nice number. It is mostly used to support internal calculation, though it may be useful for other applications.
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argument:: val
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The value.
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argument:: round
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Boolean. Rounding uses a specific algorithm. This is not simple rounding to an integer value.
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returns:: the nice number
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METHOD:: ideals
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for internal use
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argument:: min
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(describe argument here)
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argument:: max
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(describe argument here)
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argument:: ntick
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(describe argument here)
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returns:: (returnvalue)
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METHOD:: looseRange
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Returns the logical minimum and maximum that will contain the data.
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argument:: min
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minimum value
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argument:: max
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maximum value.
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argument:: ntick
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the number of lines you would like (which usually varies by how much screen space you have and what you consider cluttered)
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returns:: [ideal min, ideal max]
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METHOD:: getParams
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Specifically for use by DrawGrid. This returns a dictionary filled with:
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'lines': an array of values where lines should be drawn
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'labels': [value, formatted label] for each line
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argument:: valueMin
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minimum value of the data to be plotted
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argument:: valueMax
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maximum value of the data to be plotted
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argument:: pixelMin
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If numTicks is nil: used to guess the ideal numTicks based on the graph size.
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argument:: pixelMax
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If numTicks is nil: used to guess the ideal numTicks based on the graph size.
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argument:: numTicks
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Explicit number of ticks you would like to see on the graph.
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returns:: A dictionary
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METHOD:: formatLabel
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Round the value and append the spec's units
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argument:: val
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The value
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argument:: numDecimalPlaces
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Number of decimal places
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returns:: a string
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