Changes between Initial Version and Version 1 of MapGuideRfc132

Timestamp:

03/19/13 06:38:22 (12 years ago)

Author:

jng

Comment:

--

MapGuideRfc132

@@ +1 @@
+
+= !MapGuide RFC 132 - Fusion OpenLayers upgrade =
+
+This page contains a change request (RFC) for the !MapGuide Open Source project.
+More !MapGuide RFCs can be found on the [wiki:MapGuideRfcs RFCs] page.
+
+== Status ==
+
+||RFC Template Version||(1.0)||
+||Submission Date||19 Mar 2013||
+||Last Modified||19 Mar 2013||
+||Author||Jackie Ng||
+||RFC Status||draft||
+||Implementation Status||completed||
+||Proposed Milestone||2.6||
+||Assigned PSC guide(s)||(when determined)||
+||'''Voting History'''||(vote date)||
+||+1||||
+||+0||||
+||-0||||
+||-1||||
+||no vote|| ||
+
+== Overview ==
+
+This RFC proposes to upgrade the OpenLayers in Fusion to the latest stable release (2.12)
+
+== Motivation ==
+
+Fusion is using a somewhat old version of OpenLayers.
+
+Upgrading to the latest stable release of OpenLayers (2.12) offers a bunch of useful new features that Fusion can take advantage of:
+
+ * Touch input support, allowing for our Fusion templates to be somewhat serviceable on an Android/iOS phone or tablet device, as swipe and pinch zoom functionality can be leveraged automatically for map panning, zooming and navigation.
+ * Tile Queues, for improved tile loading.
+ * New CacheRead and CacheWrite controls for limited client-side caching of tile images.
+ * Client Zoom, allowing for map tile images to be stretched client-side to fit the current view of the map. This one feature alone presents some new scenarios that previously were not possible, such as the ability to have a Map Definition with dynamic and tiled layers acting as a fully dynamic map that can be zoomed to any arbitrary scale without finite scale restrictions (as tiles will be stretched client-side by OpenLayers). Tiles from commerical layers like OpenStreetMap can also be stretched client-side in such a manner.
+
+== Proposed Solution ==
+
+Upgrade Fusion's internal copy of OpenLayers to 2.12
+
+To improve our audit trail of customizations to OpenLayers and to make future OpenLayers upgrades easier, Fusion-specific modifications to OpenLayers are kept under lib/OpenLayers/ext. Whenever a new built OpenLayers.js needs to be checked in, the files and folders under lib/OpenLayers/ext can be copied into a standard OpenLayers distribution (overwriting any existing files) to be built with our fusion.cfg build configuration file.
+
+Currently, we are keeping OpenLayers.Util and our implementation of OpenLayers.Layer.MapGuide under this directory.
+
+The client-zoom feature is controlled by the existing FractionalZoom extension property of the Map widget. 
+
+Under client-zoom the following behaviour occurs (under these examples, OSM is interchangeable with any other grid-based tiled layer):
+ * MapGuide dynamic layers + OSM (fractionalZoom = true): Map is fully dynamic and OSM tiles are stretched accordingly
+ * MapGuide dynamic layers + OSM (fractionalZoom = false): Scales "snap" to OSM scales and are stretched accordingly when going below the smallest supported OSM scale.
+
+The client-zoom feature has no effect if the map has no tiled layers.
+
+The client-zoom technique does not work in conjunction with Google/Bing layers. See implications
+
+This implementation work has already been completed on the [http://trac.osgeo.org/fusion/browser/sandbox/ol212 ol212 sandbox branch of Fusion]. Upon adoption of this RFC, the changes will be merged back into Fusion trunk that's automatically linked by our MapGuide Oem tree.
+
+== Implications ==
+
+The following components in OpenLayers 2.12 are deprecated and we should look at replacing such instances in our core/widget code before another future OpenLayers upgrade:
+
+ * OpenLayers.Class.isPrototype
+ * OpenLayers.Class.create
+ * OpenLayers.Class.inherit
+ * OpenLayers.Util.clearArray
+ * OpenLayers.Util.setOpacity
+ * OpenLayers.Util.safeStopPropagation
+ * OpenLayers.Util.getArgs
+ * OpenLayers.nullHandler
+ * OpenLayers.loadURL
+ * OpenLayers.parseXMLString
+ * OpenLayers.Ajax.* (all methods)
+ * OpenLayers.Element.hide
+ * OpenLayers.Element.show
+ * OpenLayers.Element.getDimensions
+ * OpenLayers.Tile.prototype.getBoundsFromBaseLayer
+ * OpenLayers.Control.MouseDefaults
+ * OpenLayers.Control.MouseToolbar
+ * OpenLayers.Layer.Grid.prototype.getGridBounds
+ * OpenLayers.Format.XML.prototype.concatChildValues
+ * OpenLayers.Layer.WMS.Post
+ * OpenLayers.Layer.WMS.Untiled
+ * OpenLayers.Layer.MapServer.Untiled
+ * OpenLayers.Tile.WFS
+ * OpenLayers.Feature.WFS
+ * OpenLayers.Layer.WFS
+ * OpenLayers.Layer.VirtualEarth
+ * OpenLayers.Protocol.SQL
+ * OpenLayers.Protocol.SQL.Gears
+ * OpenLayers.Layer.Yahoo
+ * OpenLayers.Layer.GML
+ * OpenLayers.Geometry.Rectangle
+ * OpenLayers.Renderer.NG
+ * OpenLayers.Renderer.SVG2
+
+OpenLayers 2.12 along with the current JxLib presents an issue on Firefox 18+, this is due to the version of MooTools used by JxLib causing "too much recursion" errors under Firefox 18+. As part of this RFC, the MooTools used by JxLib will be upgraded to 1.2.6
+
+The OpenLayers client-zoom feature cannot be used with Google and Bing layers as:
+
+ a) These layers aren't Grid-based. Client zoom only works with layers inheriting from OpenLayers.Layer.Grid
+
+ b) Client-side stretching of such tiles constitutes content modification of their tiles and violates the terms of use.
+
+If we're viewing a map with Google + Bing + OSM and set the FractionalZoom property of the Map widget to true, switching to a Google or Bing layer will disable client-zoom while that layer is active.
+
+Such limitations should be ideally communicated to the user in the tools/editors department.
+
+== Test Plan ==
+
+Test and verify our changes on our current suite of supported browsers
+
+== Funding / Resources ==
+
+Community