New map canvas item QgsGpsBearingItem, for showing a bearing line ori…

…ginating from the GPS location
qgis · Dec 10, 2019 · 9356cd8 · 9356cd8
1 parent 12e0b0e
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diff --git a/src/app/CMakeLists.txt b/src/app/CMakeLists.txt
@@ -232,6 +232,7 @@ SET(QGIS_APP_SRCS
   locator/qgsinbuiltlocatorfilters.cpp
   locator/qgslocatoroptionswidget.cpp
 
+  gps/qgsgpsbearingitem.cpp
   gps/qgsgpsinformationwidget.cpp
   gps/qgsgpsmarker.cpp
 

diff --git a/src/app/gps/qgsgpsbearingitem.cpp b/src/app/gps/qgsgpsbearingitem.cpp
@@ -0,0 +1,80 @@
+/***************************************************************************
+    qgsgpsbearingitem.cpp
+    ---------------------
+    begin                : December 2019
+    copyright            : (C) 2019 Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+
+ ***************************************************************************
+ *                                                                         *
+ *   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 <QPainter>
+#include <QObject>
+
+#include "qgsgpsbearingitem.h"
+#include "qgscoordinatetransform.h"
+#include "qgsmapcanvas.h"
+#include "qgsexception.h"
+#include "qgsproject.h"
+#include "qgsmessagelog.h"
+#include "qgssymbol.h"
+
+
+QgsGpsBearingItem::QgsGpsBearingItem( QgsMapCanvas *mapCanvas )
+  : QgsMapCanvasLineSymbolItem( mapCanvas )
+{
+  mSymbol->setColor( QColor( 255, 0, 0 ) );
+  mWgs84CRS = QgsCoordinateReferenceSystem::fromOgcWmsCrs( QStringLiteral( "EPSG:4326" ) );
+
+  connect( mMapCanvas, &QgsMapCanvas::rotationChanged, this, &QgsGpsBearingItem::updateLine );
+  connect( mMapCanvas, &QgsMapCanvas::extentsChanged, this, &QgsGpsBearingItem::updateLine );
+}
+
+void QgsGpsBearingItem::setGpsPosition( const QgsPointXY &point )
+{
+  //transform to map crs
+  if ( mMapCanvas )
+  {
+    QgsCoordinateTransform t( mWgs84CRS, mMapCanvas->mapSettings().destinationCrs(), QgsProject::instance() );
+    try
+    {
+      mCenter = t.transform( point );
+    }
+    catch ( QgsCsException &e ) //silently ignore transformation exceptions
+    {
+      QgsMessageLog::logMessage( QObject::tr( "Error transforming the map center point: %1" ).arg( e.what() ), QStringLiteral( "GPS" ), Qgis::Warning );
+      return;
+    }
+  }
+  else
+  {
+    mCenter = point;
+  }
+  updateLine();
+}
+
+void QgsGpsBearingItem::setGpsBearing( double bearing )
+{
+  mBearing = bearing;
+  updateLine();
+}
+
+void QgsGpsBearingItem::updatePosition()
+{
+  setGpsPosition( mCenter );
+}
+
+void QgsGpsBearingItem::updateLine()
+{
+  QLineF bearingLine;
+  bearingLine.setP1( toCanvasCoordinates( mCenter ) );
+  bearingLine.setLength( 5 * std::max( mMapCanvas->width(), mMapCanvas->height() ) );
+  bearingLine.setAngle( 90 - mBearing  - mMapCanvas->rotation() );
+  setLine( bearingLine );
+}
diff --git a/src/app/gps/qgsgpsbearingitem.h b/src/app/gps/qgsgpsbearingitem.h
@@ -0,0 +1,55 @@
+/***************************************************************************
+    qgsgpsbearingitem.h
+    -------------------
+    begin                : December 2019
+    copyright            : (C) 2019 Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************
+ *                                                                         *
+ *   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.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSGPSBEARINGITEM_H
+#define QGSGPSBEARINGITEM_H
+
+#include "qgspointmarkeritem.h"
+#include "qgscoordinatereferencesystem.h"
+#include "qgspointxy.h"
+
+class QPainter;
+class QgsLineSymbol;
+
+/**
+ * \ingroup app
+ * A canvas item for showing the bearing of the GPS device
+ */
+class QgsGpsBearingItem : public QObject, QgsMapCanvasLineSymbolItem
+{
+    Q_OBJECT
+
+  public:
+    explicit QgsGpsBearingItem( QgsMapCanvas *mapCanvas );
+
+    void setGpsPosition( const QgsPointXY &point );
+    void setGpsBearing( double bearing );
+
+    void updatePosition() override;
+
+  protected:
+
+    //! coordinates of the point in the center
+    QgsPointXY mCenter;
+
+  private:
+    void updateLine();
+
+    QgsCoordinateReferenceSystem mWgs84CRS;
+    double mBearing = 0;
+
+};
+
+#endif // QGSGPSBEARINGITEM_H