Calendar Layout Algorithm

This algorithm will calculate top, width, height, and width for each event in a list of events so that they can be drawn on a canvas such that none of them overlap.

Algorithm

The most complex bit in the algorithm is CalLayout.mkIntersectionsForest, which, given a list of calendar events produces a Data.Tree.Forest.

Given a list of events, and an initial event (such that it intersects all events), mkIntersectionsForest will convert them to a forest such that every parent overlaps the children. This will produce a similar forest (by excluding the initial element):

> putStr $ drawForest $ map (fmap show) forest
"P&P Leg Training"
|
`- "Gym Tour"

"12 days of Christmas workout"

"12 days of Christmas workout"
|
`- "12 days of Christmas workout"

Otherwise, the tree really looks like:

> putStr $ drawTree $ fmap show (Node initial forest)
"root"
|
+- "P&P Leg Training"
|  |
|  `- "Gym Tour"
|
+- "12 days of Christmas workout"
|
`- "12 days of Christmas workout"
   |
   `- "12 days of Christmas workout"

Now that we have this structure, we need to calculate the depth and maxDepth of each node. CalLayout.populateDepths does exactly that. Viewed as a forest, it looks something like:

("P&P Leg Training", 1, 1)
|
`- ("Gym Tour", 1, 0)

("12 days of Christmas workout", 0, 0)

("12 days of Christmas workout", 1, 1)
|
`- ("12 days of Christmas workout", 1, 0)

Once we have this data, calculations are straight-forward:

top    = start e
left   = width * depth
width  = 100 / (1 + maxDepth)
height = end e - start e

As we can see, all this calculation is just for figuring out left and width, whereas top and height were easy.

Prerequisites

Make sure you have stack installed.

Running

1. Run stack init
2. Run stack run

For playground, you can use stack repl.

Example:

$ stack run
("P&P Leg Training",Dimension {top = 600.0, left = 50.0, width = 50.0, height = 60.0})
("Gym Tour",Dimension {top = 600.0, left = 0.0, width = 50.0, height = 15.0})
("12 days of Christmas workout",Dimension {top = 720.0, left = 0.0, width = 100.0, height = 120.0})
("12 days of Christmas workout",Dimension {top = 840.0, left = 50.0, width = 50.0, height = 360.0})
("12 days of Christmas workout",Dimension {top = 1020.0, left = 0.0, width = 50.0, height = 120.0})

Copyright 2019, Boro Sitnikovski. All rights reserved.