2018-10-29 00:07:56 +01:00
|
|
|
# QtPBFImagePlugin
|
2018-10-29 01:04:26 +01:00
|
|
|
Qt image plugin for displaying Mapbox vector tiles
|
|
|
|
|
|
|
|
|
|
## Description
|
|
|
|
|
QtPBFImagePlugin is a Qt image plugin that enables applications capable of
|
|
|
|
|
displaying raster MBTiles maps to also display vector (PBF) tiles without
|
|
|
|
|
(almost, see usage) any application modifications.
|
|
|
|
|
|
|
|
|
|
Standard Mapbox GL Styles are used for styling the maps. Most style features
|
|
|
|
|
used by [Maputnik](http://editor.openmaptiles.org) are supported. The style
|
|
|
|
|
is loaded from /usr/share/pbf/style.json or ~/.pbf/style.json if it exists.
|
|
|
|
|
|
|
|
|
|
## Usage
|
|
|
|
|
Due to a major design flaw in the Mapbox vector tiles specification (the zoom
|
|
|
|
|
is not part of the PBF data), the plugin can not be used "as is", but passing
|
|
|
|
|
the zoom level is necessary. This is done by exploiting the optional format
|
|
|
|
|
parameter of the QImage constructor or the QImage::fromData() or
|
|
|
|
|
QPixmap::loadFromData() functions. The zoom number is passed as ASCII string
|
|
|
|
|
to the functions:
|
|
|
|
|
```cpp
|
|
|
|
|
QPixmap pm;
|
|
|
|
|
pm.loadFromData(tileData(_zoom), QString::number(_zoom).toLatin1());
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## Build
|
|
|
|
|
Build requirements:
|
|
|
|
|
* QT 5.x
|
|
|
|
|
* Google Protocol Buffers (protobuf-lite)
|
|
|
|
|
|
|
|
|
|
Build steps:
|
|
|
|
|
```shell
|
2018-10-29 01:13:03 +01:00
|
|
|
qmake pbfplugin.pro
|
2018-10-29 01:04:26 +01:00
|
|
|
make
|
|
|
|
|
```
|
|
|
|
|
|
|
|
|
|
## Install
|
|
|
|
|
Copy the plugin to the system Qt image plugins path to make it work. You may
|
|
|
|
|
also set the QT_PLUGIN_PATH system variable before starting the application.
|
|
|
|
|
|
|
|
|
|
## Limitations
|
|
|
|
|
As the plugin only has isolated info about a single tile image, texts
|
|
|
|
|
overlapping to neighbour tiles can not be displayed or their overlapping can
|
|
|
|
|
not be avoided (the plugin uses the first approach). This is a principal
|
|
|
|
|
constraint that can't be evaded.
|
