Add a new visiblePolygon method to QgsMapSettings

Centralizes code to return a possible rotated map area boundaries.
Makes use of the new method from the grid decoration.

Adds new testcase for QgsMapSettings, including test for visibleExtent,
mapUnitsPerPixel and the new visiblePolygon method.

python/core/qgsmapsettings.sip

@@ -110,6 +110,9 @@ class QgsMapSettings
     bool hasValidSettings() const;
     //! Return the actual extent derived from requested extent that takes takes output image size into account
     QgsRectangle visibleExtent() const;
+    //! Return the visible area as a polygon (may be rotated)
+    //! @note added in 2.8
+    QPolygonF visiblePolygon() const;
     //! Return the distance in geographical coordinates that equals to one pixel in the map
     double mapUnitsPerPixel() const;
     //! Return the calculated scale of the map

src/app/qgsdecorationgrid.cpp

@@ -524,15 +524,7 @@ QPolygonF canvasPolygon()
 
   const QgsMapCanvas& mapCanvas = canvas();
   const QgsMapSettings& mapSettings = mapCanvas.mapSettings();
-  const QSize& sz = mapSettings.outputSize();
+  return mapSettings.visiblePolygon();
-  const QgsMapToPixel& m2p = mapSettings.mapToPixel();
-
-  poly << m2p.toMapCoordinatesF( 0,          0 ).toQPointF();
-  poly << m2p.toMapCoordinatesF( sz.width(), 0 ).toQPointF();
-  poly << m2p.toMapCoordinatesF( sz.width(), sz.height() ).toQPointF();
-  poly << m2p.toMapCoordinatesF( 0,          sz.height() ).toQPointF();
-
-  return poly;
 }
 
 bool clipByRect( QLineF& line, const QPolygonF& rect )

src/core/qgsmapsettings.cpp

@@ -311,6 +311,21 @@ QgsRectangle QgsMapSettings::visibleExtent() const
   return mVisibleExtent;
 }
 
+QPolygonF QgsMapSettings::visiblePolygon() const
+{
+  QPolygonF poly;
+
+  const QSize& sz = outputSize();
+  const QgsMapToPixel& m2p = mapToPixel();
+
+  poly << m2p.toMapCoordinatesF( 0,          0 ).toQPointF();
+  poly << m2p.toMapCoordinatesF( sz.width(), 0 ).toQPointF();
+  poly << m2p.toMapCoordinatesF( sz.width(), sz.height() ).toQPointF();
+  poly << m2p.toMapCoordinatesF( 0,          sz.height() ).toQPointF();
+
+  return poly;
+}
+
 double QgsMapSettings::mapUnitsPerPixel() const
 {
   return mMapUnitsPerPixel;

src/core/qgsmapsettings.h

@@ -156,6 +156,9 @@ class CORE_EXPORT QgsMapSettings
     bool hasValidSettings() const;
     //! Return the actual extent derived from requested extent that takes takes output image size into account
     QgsRectangle visibleExtent() const;
+    //! Return the visible area as a polygon (may be rotated)
+    //! @note added in 2.8
+    QPolygonF visiblePolygon() const;
     //! Return the distance in geographical coordinates that equals to one pixel in the map
     double mapUnitsPerPixel() const;
     //! Return the calculated scale of the map

tests/src/core/CMakeLists.txt

@@ -140,6 +140,7 @@ ADD_QGIS_TEST(invertedpolygontest testqgsinvertedpolygonrenderer.cpp )
 ADD_QGIS_TEST(colorschemeregistry testqgscolorschemeregistry.cpp)
 ADD_QGIS_TEST(colorscheme testqgscolorscheme.cpp)
 ADD_QGIS_TEST(maptopixeltest testqgsmaptopixel.cpp)
+ADD_QGIS_TEST(mapsettingstest testqgsmapsettings.cpp)
 ADD_QGIS_TEST(networkcontentfetcher testqgsnetworkcontentfetcher.cpp )
 ADD_QGIS_TEST(legendrenderertest testqgslegendrenderer.cpp )
 ADD_QGIS_TEST(vectorlayerjoinbuffer testqgsvectorlayerjoinbuffer.cpp )

tests/src/core/testqgsmapsettings.cpp

@@ -0,0 +1,141 @@
+/***************************************************************************
+     testqgsmapsettings.cpp
+     --------------------------------------
+    Date                 : Tue  6 Feb 2015
+    Copyright            : (C) 2014 by Sandro Santilli
+    Email                : strk@keybit.net
+ ***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+#include <QtTest/QtTest>
+#include <QObject>
+#include <QString>
+#include <QObject>
+//header for class being tested
+#include <qgsrectangle.h>
+#include <qgsmapsettings.h>
+#include <qgspoint.h>
+#include <math.h>
+#include "qgslogger.h"
+
+class TestQgsMapSettings: public QObject
+{
+    Q_OBJECT
+  private slots:
+    void visibleExtent();
+    void mapUnitsPerPixel();
+    void visiblePolygon();
+  private:
+    QString toString( const QPolygonF& p, int decimalPlaces = 2 ) const;
+};
+
+QString TestQgsMapSettings::toString( const QPolygonF& p, int dec ) const
+{
+  QString s;
+  const char *sep = "";
+  double r = pow( 10, dec );
+  for ( int i = 0; i < p.size(); ++i )
+  {
+    s += QString( "%1%2 %3" ).arg( sep )
+         .arg( int( p[i].x() * r ) / r )
+         .arg( int( p[i].y() * r ) / r );
+    sep = ",";
+  }
+
+  return s;
+}
+
+void TestQgsMapSettings::visibleExtent()
+{
+  QgsMapSettings ms;
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+  ms.setOutputSize( QSize( 100, 50 ) );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-50,0 : 150,100" ) );
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+  ms.setOutputSize( QSize( 100, 100 ) );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "0,0 : 100,100" ) );
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+  ms.setOutputSize( QSize( 50, 100 ) );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "0,-50 : 100,150" ) );
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+  ms.setOutputSize( QSize( 50, 100 ) );
+  ms.setRotation( 90 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-50,0 : 150,100" ) );
+  ms.setRotation( -90 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-50,0 : 150,100" ) );
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 50 ) );
+  ms.setOutputSize( QSize( 50, 100 ) );
+  ms.setRotation( 0 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "0,-75 : 100,125" ) );
+  ms.setRotation( 90 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-50,-25 : 150,75" ) );
+  ms.setRotation( -90 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-50,-25 : 150,75" ) );
+  ms.setRotation( 45 );
+  QCOMPARE( ms.visibleExtent().toString( 0 ), QString( "-56,-81 : 156,131" ) );
+}
+
+void TestQgsMapSettings::mapUnitsPerPixel()
+{
+  QgsMapSettings ms;
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+
+  ms.setOutputSize( QSize( 100, 50 ) );
+  QCOMPARE( ms.mapUnitsPerPixel(), 2.0 );
+
+  ms.setOutputSize( QSize( 100, 100 ) );
+  QCOMPARE( ms.mapUnitsPerPixel(), 1.0 );
+
+  ms.setOutputSize( QSize( 50, 100 ) );
+  QCOMPARE( ms.mapUnitsPerPixel(), 2.0 );
+
+  ms.setOutputSize( QSize( 5000, 1000 ) );
+  QCOMPARE( ms.mapUnitsPerPixel(), 0.1 );
+
+  ms.setOutputSize( QSize( 1000, 500 ) );
+  QCOMPARE( ms.mapUnitsPerPixel(), 0.2 );
+}
+
+void TestQgsMapSettings::visiblePolygon()
+{
+  QgsMapSettings ms;
+
+  ms.setExtent( QgsRectangle( 0, 0, 100, 100 ) );
+  ms.setOutputSize( QSize( 100, 50 ) );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "-50 100,150 100,150 0,-50 0" ) );
+
+  ms.setExtent( QgsRectangle( 0, -50, 100, 0 ) );
+  ms.setOutputSize( QSize( 100, 50 ) );
+  ms.setRotation( 90 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "25 -75,25 25,75 25,75 -75" ) );
+  ms.setRotation( -90 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "75 25,75 -75,25 -75,25 25" ) );
+  ms.setRotation( 30 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "-5.8 -28.34,80.8 21.65,105.8 -21.65,19.19 -71.65" ) );
+  ms.setRotation( -30 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "19.19 21.65,105.8 -28.34,80.8 -71.65,-5.8 -21.65" ) );
+  ms.setRotation( 45 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "-3.03 -42.67,67.67 28.03,103.03 -7.32,32.32 -78.03" ) );
+  ms.setRotation( -45 );
+  QCOMPARE( toString( ms.visiblePolygon() ),
+            QString( "32.32 28.03,103.03 -42.67,67.67 -78.03,-3.03 -7.32" ) );
+}
+
+QTEST_MAIN( TestQgsMapSettings )
+#include "testqgsmapsettings.moc"