[qgsquick] New map to screen class to tie QML items to the map canvas

src/quickgui/CMakeLists.txt

@@ -5,6 +5,7 @@ set(QGIS_QUICK_GUI_MOC_HDRS
   qgsquickelevationprofilecanvas.h
   qgsquickmapcanvasmap.h
   qgsquickmapsettings.h
+  qgsquickmaptoscreen.h
   qgsquickmaptransform.h
   qgsquickutils.h
 )
@@ -14,6 +15,7 @@ set(QGIS_QUICK_GUI_SRC
   qgsquickelevationprofilecanvas.cpp
   qgsquickmapcanvasmap.cpp
   qgsquickmapsettings.cpp
+  qgsquickmaptoscreen.cpp
   qgsquickmaptransform.cpp
   qgsquickutils.cpp
 )

src/quickgui/qgsquickmaptoscreen.cpp

@@ -0,0 +1,117 @@
+/***************************************************************************
+  qgsquickmaptoscreen.cpp
+  ----------------------------------------------------
+  Date                 : 22.08.2018
+  Copyright            : (C) 2018 by Denis Rouzaud
+  Email                : denis (at) opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   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 "qgsquickmaptoscreen.h"
+#include "qgspoint.h"
+
+QgsQuickMapToScreen::QgsQuickMapToScreen( QObject *parent )
+  : QObject( parent )
+{
+}
+
+void QgsQuickMapToScreen::setMapSettings( QgsQuickMapSettings *mapSettings )
+{
+  if ( mMapSettings == mapSettings )
+    return;
+
+  if ( mMapSettings )
+  {
+    disconnect( mMapSettings, &QgsQuickMapSettings::extentChanged, this, &QgsQuickMapToScreen::transformPoint );
+    disconnect( mMapSettings, &QgsQuickMapSettings::rotationChanged, this, &QgsQuickMapToScreen::transformPoint );
+    disconnect( mMapSettings, &QgsQuickMapSettings::outputSizeChanged, this, &QgsQuickMapToScreen::transformPoint );
+  }
+
+  mMapSettings = mapSettings;
+
+  connect( mMapSettings, &QgsQuickMapSettings::extentChanged, this, &QgsQuickMapToScreen::transformPoint );
+  connect( mMapSettings, &QgsQuickMapSettings::rotationChanged, this, &QgsQuickMapToScreen::transformPoint );
+  connect( mMapSettings, &QgsQuickMapSettings::outputSizeChanged, this, &QgsQuickMapToScreen::transformPoint );
+
+  transformPoint();
+  transformDistance();
+
+  emit mapSettingsChanged();
+}
+
+QgsQuickMapSettings *QgsQuickMapToScreen::mapSettings() const
+{
+  return mMapSettings;
+}
+
+void QgsQuickMapToScreen::setMapPoint( const QgsPoint &point )
+{
+  if ( mMapPoint == point )
+    return;
+
+  mMapPoint = point;
+  emit mapPointChanged();
+  transformPoint();
+}
+
+QgsPoint QgsQuickMapToScreen::mapPoint() const
+{
+  return mMapPoint;
+}
+
+QPointF QgsQuickMapToScreen::screenPoint() const
+{
+  return mScreenPoint;
+}
+
+void QgsQuickMapToScreen::transformPoint()
+{
+  if ( !mMapSettings )
+  {
+    mScreenPoint = QPointF();
+  }
+  else
+  {
+    mScreenPoint = mMapSettings->coordinateToScreen( mMapPoint );
+  }
+  emit screenPointChanged();
+}
+
+void QgsQuickMapToScreen::setMapDistance( const double distance )
+{
+  if ( mMapDistance == distance )
+    return;
+
+  mMapDistance = distance;
+  emit mapDistanceChanged();
+  transformDistance();
+}
+
+double QgsQuickMapToScreen::mapDistance() const
+{
+  return mMapDistance;
+}
+
+double QgsQuickMapToScreen::screenDistance() const
+{
+  return mScreenDistance;
+}
+
+void QgsQuickMapToScreen::transformDistance()
+{
+  if ( !mMapSettings || qgsDoubleNear( mMapDistance, 0.0 ) || qgsDoubleNear( mMapSettings->mapUnitsPerPoint(), 0.0 ) )
+  {
+    mScreenDistance = 0.0;
+  }
+  else
+  {
+    mScreenDistance = mMapDistance / mMapSettings->mapUnitsPerPoint();
+  }
+  emit screenDistanceChanged();
+}

src/quickgui/qgsquickmaptoscreen.h

@@ -0,0 +1,101 @@
+/***************************************************************************
+  qgsquickmaptoscreen.h
+  ----------------------------------------------------
+  Date                 : 22.08.2018
+  Copyright            : (C) 2018 by Denis Rouzaud
+  Email                : denis (at) opengis.ch
+ ***************************************************************************
+ *                                                                         *
+ *   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 QGSQUICKMAPTOSCREEN_H
+#define QGSQUICKMAPTOSCREEN_H
+
+#include "qgsquickmapsettings.h"
+
+#include <QObject>
+#include <QPointF>
+#include <qgspoint.h>
+
+/**
+ * \ingroup quick
+ *
+ * @brief The QgsQuickMapToScreen class transform map points to screen coordinates as
+ * well as distances from map to screen units. Screen points and/or distances will be
+ * automatically updated on map extent changes.
+ *
+ * \since QGIS 3.32
+ */
+class QUICK_EXPORT QgsQuickMapToScreen : public QObject
+{
+    Q_OBJECT
+
+    //! Map settings used to define the map canvas CRS and detect any extent change
+    Q_PROPERTY( QgsQuickMapSettings *mapSettings READ mapSettings WRITE setMapSettings NOTIFY mapSettingsChanged )
+
+    //! Point in map coordinates
+    Q_PROPERTY( QgsPoint mapPoint READ mapPoint WRITE setMapPoint NOTIFY mapPointChanged )
+    //! Point in screen coordinates (read-only)
+    Q_PROPERTY( QPointF screenPoint READ screenPoint NOTIFY screenPointChanged )
+
+    //! Distance in map unit
+    Q_PROPERTY( double mapDistance READ mapDistance WRITE setMapDistance NOTIFY mapDistanceChanged )
+    //! Distance in screen coordinates (read-only)
+    Q_PROPERTY( double screenDistance READ screenDistance NOTIFY screenDistanceChanged )
+
+  public:
+
+    explicit QgsQuickMapToScreen( QObject *parent = nullptr );
+
+    //! \copydoc mapSettings
+    void setMapSettings( QgsQuickMapSettings *mapSettings );
+    //! \copydoc mapSettings
+    QgsQuickMapSettings *mapSettings() const;
+
+    //! \copydoc mapPoint
+    void setMapPoint( const QgsPoint &point );
+    //! \copydoc mapPoint
+    QgsPoint mapPoint() const;
+
+    //! \copydoc mapDistance
+    void setMapDistance( const double distance );
+    //! \copydoc mapDistance
+    double mapDistance() const;
+
+    //! \copydoc screenPoint
+    QPointF screenPoint() const;
+
+    //! \copydoc screenDistance
+    double screenDistance() const;
+
+  signals:
+
+    //! \copydoc mapSettings
+    void mapSettingsChanged();
+    //! \copydoc mapPoint
+    void mapPointChanged();
+    //! \copydoc mapDistance
+    void mapDistanceChanged();
+    //! \copydoc screenPoint
+    void screenPointChanged();
+    //! \copydoc screenDistance
+    void screenDistanceChanged();
+
+  private slots:
+    void transformPoint();
+    void transformDistance();
+
+  private:
+    QgsQuickMapSettings *mMapSettings = nullptr;
+    QgsPoint mMapPoint = QgsPoint();
+    double mMapDistance = 0.0;
+    QPointF mScreenPoint = QPointF();
+    double mScreenDistance = 0.0;
+};
+
+#endif // QGSQUICKMAPTOSCREEN_H

tests/src/quickgui/testqgsquickmapsettings.cpp

@@ -15,12 +15,14 @@
 #include <QObject>
 #include <QApplication>
 
+#include "qgis.h"
 #include "qgsapplication.h"
 #include "qgstest.h"
-#include "qgis.h"
+#include "qgspoint.h"
 #include "qgsunittypes.h"
 
 #include "qgsquickmapsettings.h"
+#include "qgsquickmaptoscreen.h"
 
 class TestQgsQuickMapSettings: public QObject
 {
@@ -30,6 +32,7 @@ class TestQgsQuickMapSettings: public QObject
     void cleanup() {} // will be called after every testfunction.
 
     void test_project_existency();
+    void test_map_to_screen();
 };
 
 void TestQgsQuickMapSettings::test_project_existency()
@@ -39,5 +42,20 @@ void TestQgsQuickMapSettings::test_project_existency()
   delete settings;
 }
 
+void TestQgsQuickMapSettings::test_map_to_screen()
+{
+  QgsQuickMapSettings *settings = new QgsQuickMapSettings();
+  settings->setOutputSize( QSize( 10, 10 ) );
+  settings->setExtent( QgsRectangle( 0, 0, 10, 10 ) );
+
+  QgsPoint point( 5, 5 );
+
+  QgsQuickMapToScreen *mapToScreen = new QgsQuickMapToScreen();
+  mapToScreen->setMapSettings( settings );
+  mapToScreen->setMapPoint( point );
+
+  QCOMPARE( mapToScreen->screenPoint(), QPointF( 5, 5 ) );
+}
+
 QGSTEST_MAIN( TestQgsQuickMapSettings )
 #include "testqgsquickmapsettings.moc"