Increase major version due to the API change

The API should be backward compatible but the overzoom extension should rather
be promoted with a major version number change.

.appveyor.yml

@@ -1,4 +1,4 @@
-version: 2.6.{build}
+version: 3.0.{build}
 
 configuration:
   - Release

README.md

@@ -23,19 +23,34 @@ QPixmap::loadFromData() functions. The zoom number is passed as ASCII string
 to the functions:
 ```cpp
 QPixmap pm;
-pm.loadFromData(tileData, QByteArray::number(zoom));
+pm.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,
 so when used like in the following example:
 ```cpp
+QImage img;
 QImageReader reader(file, QByteArray::number(zoom));
 reader.setScaledSize(QSize(1024, 1024));
-reader.read(&image);
+reader.read(&img);
 ```
 you will get 1024x1024px tiles with a pixel ratio of 2 (= HiDPI tiles).
 
-For a sample code see the [pbf2png](https://github.com/tumic0/pbf2png)
-conversion utility.
+### Overzoom
+Since version 3 of the plugin tile overzoom is supported. If you set *format*
+to `$zoom;$overzoom`:
+```cpp
+QPixmap pm;
+QByteArray fmt(QByteArray::number(zoom) + ';' + QByteArray::number(overzoom));
+pm.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
+tile size.
 
 ## Styles
 The map style is loaded from the

pbfplugin.pro

@@ -2,7 +2,7 @@ TARGET  = pbf
 TEMPLATE = lib
 CONFIG += plugin
 QT += gui
-VERSION = 2.6
+VERSION = 3.0
 
 PROTOS = protobuf/vector_tile.proto
 include(protobuf/vector_tile.pri)

src/pbfhandler.cpp

@@ -79,16 +79,19 @@ bool PBFHandler::read(QImage *image)
 		return false;
 	}
 
-	bool ok;
-	int zoom = format().toInt(&ok);
+	QList<QByteArray> list(format().split(';'));
+	int zoom = list.size() ? list.first().toInt() : 0;
+	int overzoom = (list.size() > 1) ? list.at(1).toInt() : 0;
+
+	QSize scaledSize(_scaledSize.isValid()
+	  ? _scaledSize : QSize(TILE_SIZE, TILE_SIZE));
+	QSize size(scaledSize.width()<<overzoom,
+	  scaledSize.height()<<overzoom);
+	QPointF scale((qreal)scaledSize.width() / TILE_SIZE,
+	  (qreal)scaledSize.height() / TILE_SIZE);
 
-	QSize size = _scaledSize.isValid()
-	  ? _scaledSize : QSize(TILE_SIZE, TILE_SIZE);
-	QPointF scale = _scaledSize.isValid()
-	  ? QPointF((qreal)_scaledSize.width() / TILE_SIZE,
-		(qreal)_scaledSize.height() / TILE_SIZE) : QPointF(1.0, 1.0);
 	*image = QImage(size, QImage::Format_ARGB32_Premultiplied);
-	Tile tile(image, ok ? zoom : -1, scale);
+	Tile tile(image, zoom, scale);
 
 	_style->render(data, tile);
 

style/style.json

@@ -2265,7 +2265,6 @@
       "source": "openmaptiles",
       "source-layer": "building",
       "minzoom": 13,
-      "maxzoom": 14,
       "layout": {
         "visibility": "visible"
       },