Create time-aware PointTrack

[ianmayo]

Introduction

This ticket describes an OpenLayers layer that shows a series of time-aware points, provisionally titled TimedPointTrack. A highlight over the points shows the position at a particular point in time. This layer will extend the functionality of the PointTrack layer, hopefully through inheritance.

Mandatory Requirements

1. The data-read functionality will be extended to load and store the time value from entries in a georss feed.
2. The layer will be aware of the times of it's earliest & latest entries (start/finish times), presenting them as properties
3. In addition to the vector-line and textual markers shown by the PointTrack layer, this layer will also show a 'current location' highlight. This will be a 10px*10px rectangle in the same colour as the point-track. The size & colour will be maintained by styles.
4. The layer will have an "interpolatePoints" yes/no option.
5. The layer will have an "permanentHighlight" yes/no option.
6. The layer will have a setTime function that receives a javascript Date value. On receipt of this function call the layer will move it's highlight according to the interpolate points flag. If the flag is no, the layer will place the highlight over the data point nearest in time to the supplied value, over the later point if exactly between two points. If the flag is yes, the layer will identify the data points either side of the time supplied, and interpolate a position using their time values. Support for this algorithm can be provided as necessary.
7. If the time supplied by setTime is outside the time period of the track, the permanentHighlight value will be examined. If no, the highlight will not be shown. If yes, the highlight will be placed at the start/end of the track as applicable.

Optional Requirements

1. A time-control will be created, consisting of a slider control with attached date-time label.
2. The example map will track start/finish times of point track layers as they are loaded, informing the time control of their start/finish times. The time control will span the union of their time period.
3. When the slider is moved it will examine the layers in the current map, firing a 'setTime' event to any TimedPointTrack layers. The label will update to show the current date value.
4. The time control will have a textual parameter that provides it's time-format string. The label will show the date-time using this format. A function to support this is available at  http://www.javascripttoolbox.com/lib/date/index.php

[pspencer]

I think it is excellent that Ian is offering to fund development of OpenLayers related stuff, but I have a concern about this particular feature being a part of the core OpenLayers library. It seems quite application-specific to me, and of limited value in a library.

I'd like to get the other developers' opinions on whether this functionality is too specific to include in OpenLayers directly or not.

That being said, we had talked about a home within OpenLayers for add-ons that were not quite suitable to go into the core library. I don't think that has happened yet, but I think this would be an ideal candidate for it.

[openlayers]

Perhaps it has been talked about before, but there is an aspect that might be worth getting into core even if there is a pear-like repository. It is the chronological awareness of core libraries, mainly Map, Layer and Feature classes. This, of course is a far bigger issue (especially considering support of the different data sources towards the time dimension) than just this class, but that would also be an aswer to it, and would make the Time control a perfectly natural fit.

[ahocevar]

I would not say that this has to go into the core library, but it is worth considering. At least, time ranges are part of the WMS specification, and GeoRSS items also have publication date properties.

[achipa]

Here is a sandbox implementation:

 http://dev.openlayers.org/sandbox/achipa/openlayers/examples/timed-point-track-markers.html  http://dev.openlayers.org/sandbox/achipa/openlayers/examples/time-select-control.html

these rely on the basic time-aware patch from #1395 and the square point renderer patch in #1398, so I'm attaching a patch here when they get resolved/accepted into trunk.

[achipa]

This seems to be a duplicate (or rather a more specific description) of #1074, will mark it as duplicate unless somebody says it isn't.

[euzuro]

Mass ticket move out of 2.7 in preparation for a release plan.

If you are actively working on this task, and think that you can help this ticket to get finished and closed by September 1, please move it back to 2.7.

[crschmidt]

Not touched since 2.7, moving forward.

[fredj]

Not touched since 2.7, bumping.

[fredj]

3 years without activity

[ahocevar]

See #2591 for an addin proposal.