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Unify the code samples to use QImage

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Martin Tůma 2023-12-11 11:40:18 +01:00 committed by GitHub
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@ -18,19 +18,19 @@ to fit the styles and available data (OpenMapTiles, Mapbox tiles).
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
parameter of the QImage constructor or the *QImage::loadFromData()* or
*QPixmap::loadFromData()* functions. The zoom number is passed as ASCII string
to the functions:
```cpp
QPixmap pm;
pm.loadFromData(data, QByteArray::number(zoom));
QImage img;
img.loadFromData(data, QByteArray::number(zoom));
```
For a complete code sample see the [pbf2png](https://github.com/tumic0/pbf2png)
conversion utility.
### HiDPI
The plugin supports vector scaling using QImageReader's setScaledSize() method,
The plugin supports vector scaling using QImageReader's *setScaledSize()* method,
so when used like in the following example:
```cpp
QImage img;
@ -44,9 +44,9 @@ you will get 1024x1024px tiles with a pixel ratio of 2 (= HiDPI tiles).
Since version 3 of the plugin tile overzoom is supported. If you set *format*
to `$zoom;$overzoom`:
```cpp
QPixmap pm;
QImage img;
QByteArray fmt(QByteArray::number(zoom) + ';' + QByteArray::number(overzoom));
pm.loadFromData(data, fmt);
img.loadFromData(data, fmt);
```
you will get (512<<overzoom)x(512<<overzoom)px tiles with a pixel ratio of 1.
When overzoom is combined with setScaledSize(), the base size is the overzoomed