QtPBFImagePlugin/README.md

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# QtPBFImagePlugin
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Qt image plugin for displaying Mapbox vector tiles
## Description
QtPBFImagePlugin is a Qt image plugin that enables applications capable of
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displaying raster MBTiles maps to also display PBF vector tiles without
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(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
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is loaded from the
[$AppDataLocation](http://doc.qt.io/qt-5/qstandardpaths.html)/style/style.json
file on plugin load. A default fallback style (Klokantech-basic) for
OpenMapTiles is part of the plugin.
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## Usage
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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
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the zoom level is necessary. This is done by exploiting the optional *format*
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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;
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pm.loadFromData(tileData, QString::number(zoom).toLatin1());
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```
## Build
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### Requirements
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* Qt 5
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* Google Protocol Buffers (protobuf-lite)
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* Zlib
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### Build steps
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#### Linux
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```shell
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qmake pbfplugin.pro
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make
```
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#### Windows
```shell
qmake PROTOBUF=path/to/protobuf ZLIB=path/to/zlib pbfplugin.pro
make
```
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## 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.
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## Status
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A picture is worth a thousand words. Data and styles from https://openmaptiles.org.
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#### OSM-liberty
![osm-liberty 2](https://tumic0.github.io/QtPBFImagePlugin/images/osm-liberty-2.png)
![osm-liberty 5](https://tumic0.github.io/QtPBFImagePlugin/images/osm-liberty-5.png)
![osm-liberty 9](https://tumic0.github.io/QtPBFImagePlugin/images/osm-liberty-9.png)
![osm-liberty 11](https://tumic0.github.io/QtPBFImagePlugin/images/osm-liberty-11.png)
![osm-liberty 14](https://tumic0.github.io/QtPBFImagePlugin/images/osm-liberty-14.png)
#### Klokantech-basic
![klokantech-basic 2](https://tumic0.github.io/QtPBFImagePlugin/images/klokantech-basic-2.png)
![klokantech-basic 4](https://tumic0.github.io/QtPBFImagePlugin/images/klokantech-basic-4.png)
![klokantech-basic 9](https://tumic0.github.io/QtPBFImagePlugin/images/klokantech-basic-9.png)
![klokantech-basic 13](https://tumic0.github.io/QtPBFImagePlugin/images/klokantech-basic-13.png)
![klokantech-basic 14](https://tumic0.github.io/QtPBFImagePlugin/images/klokantech-basic-14.png)
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