Graphical display of data on display and/or remotely

[letsfindaway]

A nice feature would be to display the absolute humidity and window mode or other data graphically either on the TFT display or remotely on a browser. Most interesting is data from the same day or yesterday.

For local display we have to develop a user interaction scheme: how to switch to the graphical display and back, how to select the date. We will then read the corresponding CSV file and evaluate and display the data.

For remote display, the URL scheme needs to be defined. Similar the CSV files will be read and a SVG graphic is generated from that.

Both will work quite similar, so a common concept would be useful.

[letsfindaway]

This would also be the right time to extract writing the CSV data to the SD card and extracting information from there to a common class. Currently this is scattered over Anzeige and Wlan.

[letsfindaway]

Some more ideas on this feature and its implementation:

Features:

• daily and weekly graphs of absolute humidity in the two rooms and outside
• thin line while window is closed, thicker line when opened
  • thick line on TFT display is drawn by drawing the original line, then one with x of both ends incremented, then one with y on both ends incremented.
• x-axis with marks and labeling
  • daily diagram: ticks every hour, label every 3 hours
  • weekly diagram: ticks every 6 hours, label every 12 hours
• y-axis with horizontal lines and label
  • automatically scaled for the biggest value, rounded to the next higher integer
  • ticks every 1, labels every 1, 2 or 5 ticks, so that no more than 8 labels are necessary
• navigation to the next/previous day/week
• output to the TFT display or as SVG for the browser

Implementation notes:

• The diagram class uses an abstract class for drawing which can draw rectangles, lines, text and triangles with a link.
• there are two implementations of this class, one writing to the TFT display and one for SVG writing to a Print*
• links are mapped to hotspots for the touch screen or hypertext links for SVG.
• The CSV parser necessary to gather the data will write it to an optimized data structure using 2 bytes to represent the value and window mode. This will result in a maximum of 3 (lines) * 24 (hours) * 12 (values/hour) * 2 bytes = 1728 data bytes. Our Feather M0 can cope with this.