Editing QTMapWidget

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This page is intended to collect thoughts about a Qt map widget.

== Why a QTMapWidget? ==

Maemo/Meego devices are mobile GPS based devices. A demand for mapping services is thus very obvious. The current situation in [[Open development/Maemo roadmap/Fremantle|Maemo 5]] shows that leaving this task to the individual developers has several disadvantages for the developer as well for the end user.

=== Disadvantages of current Maemo5 situation ===

In Maemo5 there is no generic map widget. Thus various developers came up with their own solutions. Some of these were based on existing widgets (e.g. osm-gps-map), are ports of previous maemo4 projects (mappero) or are completely new solutions written from scratch. Few of these share the same map widget.

* Every developer had to implement his own solution
* Map tiles are stored/cached in different locations on the device
** Waste of bandwidth (one widget cannot re-use data cached by another one and needs to re-download it)
*** Some map servers have limited bandwidth [http://wiki.openstreetmap.org/wiki/Tile_usage_policy], one unified map widget may allow easier caching at one proxy server of all applications that use it.
** Waste of flash space as the same data is stored separately by different map widgets
* No central place for map cache maintenance
** No way to globally add new map sources
** No way to flush the map tile cache
** No way to prefetch map tiles for offline usage
* Individual look and feel for widgets addressing the same problem
* No interoperability (e.g. one app cannot display the track that was captured while another one was running) 
* Some widgets don't work behind network proxies
* None of the existing widgets is really developer friendly

== Wishlist ==

If you are a developer and are interested in using such a widget. What would be the things you really want to have? What do you explicitly don't want to see in such a widget?

* Support for various map sources
** Classic tile based sources (openstreetmap [http://www.openstreetmap.org], google [http://maps.google.com], yahoo [http://maps.yahoo.com], virtual earth [http://www.bing.com/maps/])
*** Simple/dynamic method to add more sources (also user specific ones like [[Maemo-mapper topomaps]])
** WMS data [http://www.ogc-services.net/]
** Vector data
*** OSM vector data ("planet file" [http://wiki.openstreetmap.org/wiki/Planet.osm])
*** Map data stored by OVI maps [http://maps.ovi.com/]
* Plugin concept for map sources
* Built-in location support, options:
** GPSD: GPS position
** Liblocation: position (GPS, network), compass and gyro
** QT mobility location: position (GPS, network), compass and gyro
** Ability to provide location to main application
* Overlays
** Static overlays (don't move nor zoom with the map)
*** Current position in textual representation
*** Map center ("cross hair")
*** Scale (metric as well as imperial)
*** Zoom buttons
*** Map source selection
** Dynamic overlays (move and zoom with the map)
*** Waypoints incl. icons
*** Tracks incl. a dynamic one built from GPS data
*** Location indicator (position, direction and precision)
* Separate maintenance tool
** Limit/monitor tile cache size
** Clean tile cache
** Preload tiles for offline usage
** Refresh tiles
** Perhaps as a control panel plugin

== Related resources ==

Qt mobility location [http://labs.trolltech.com/page/Projects/QtMobility]

== Existing widgets ==

We are not the first ones to work with maps under Qt. What projects exist? Can they be re-used? What are their advantages and disadvantages?

=== QMapControl [http://www.medieninf.de/qmapcontrol/] ===

Pros:
* Lightweight
* Runs out of the box on Maemo5
* Supports WMS

Cons:
* Not actively maintained atm
* Lacks basic functionality (GPS integration, live track capture, ...)
* Has some rendering problems under Maemo (track display)
* Google maps integration broken

=== Marble [http://edu.kde.org/marble/] ===

Pros:
* Very active big developer community. Some core developers are involved with the Maemo / MeeGo project already. There are currently 3 GSoC developers working exclusively on Marble. 
* Support for Maemo 5 and MeeGo. Early Maemo 5 packages available.
* Lightweight for what it does (100000LOC).
* Used in KDE as a generic map widget already.
* Supports OpenStreetMap, Google Maps, Yahoo, Custom Server Layouts. Basic WMS support.
* Online Routing support (via e.g. ORS).
* Support for position providers as plugins (gpsd, GeoClue, liblocation).
* Support for KML, GPS (support for OSM in the works).
* Different projections (sphere, Mercator, Equirectangular).
* Qt-Style API throughout the Marble Library.

Cons: 
* Performance improvements for Maemo 5 necessary. However these are in the works.
* While the overall quality of the code is pretty good there is still some legacy code in a few places.
* I am very concerned regarding battery usage with this 3d approach as it puts a huge load (currently 100%) on the CPU even at low refresh rates

== Count me in! ==

We need some people who would like to contribute. Please state here if you want to contribute some of your time.

Widget coding:
* Till Harbaum

I have an application i'd like to use such a widget in:
* Till Harbaum (tool to visualize contact positions and to track friends)

UI-Design, Mockups:

[[Category:Development]]
[[Category:Qt]]

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Editing QTMapWidget

@@ Line 96: / Line 96: @@
 * Performance improvements for Maemo 5 necessary. However these are in the works.
 * While the overall quality of the code is pretty good there is still some legacy code in a few places.
-* I am very concerned regarding battery usage with this 3d approach as it puts a huge load (currently 100%) on the CPU even at low refresh rates --[[User:harbaum|harbaum]] 18:40, 12 June 2010 (UTC)
+* I am very concerned regarding battery usage with this 3d approach as it puts a huge load (currently 100%) on the CPU even at low refresh rates
 == Count me in! ==