Move logic to calculate combined extent of a set of map layers

to new QgsMapLayerUtils class
qgis · May 21, 2021 · dc50988 · dc50988
1 parent 700390a
commit dc50988
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Showing 8 changed files with 254 additions and 60 deletions.
diff --git a/python/core/auto_generated/qgsmaplayerutils.sip.in b/python/core/auto_generated/qgsmaplayerutils.sip.in
@@ -0,0 +1,42 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/qgsmaplayerutils.h                                          *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsMapLayerUtils
+{
+%Docstring(signature="appended")
+Contains utility functions for working with map layers.
+
+.. versionadded:: 3.20
+%End
+
+%TypeHeaderCode
+#include "qgsmaplayerutils.h"
+%End
+  public:
+
+    static QgsRectangle combinedExtent( const QList<QgsMapLayer *> &layers, const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &transformContext );
+%Docstring
+Returns the combined extent of a list of ``layers``.
+
+The ``crs`` argument specifies the desired coordinate reference system for the combined extent.
+%End
+
+};
+
+
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/qgsmaplayerutils.h                                          *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
diff --git a/python/core/core_auto.sip b/python/core/core_auto.sip
@@ -104,6 +104,7 @@
 %Include auto_generated/qgsmaplayerstylemanager.sip
 %Include auto_generated/qgsmaplayerelevationproperties.sip
 %Include auto_generated/qgsmaplayertemporalproperties.sip
+%Include auto_generated/qgsmaplayerutils.sip
 %Include auto_generated/qgsmapsettings.sip
 %Include auto_generated/qgsmapsettingsutils.sip
 %Include auto_generated/qgsmapthemecollection.sip

diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
@@ -367,6 +367,7 @@ set(QGIS_CORE_SRCS
   qgsmaplayerstyle.cpp
   qgsmaplayerstylemanager.cpp
   qgsmaplayertemporalproperties.cpp
+  qgsmaplayerutils.cpp
   qgsmapsettings.cpp
   qgsmapsettingsutils.cpp
   qgsmaptopixel.cpp
@@ -984,6 +985,7 @@ set(QGIS_CORE_HDRS
   qgsmaplayerstylemanager.h
   qgsmaplayerelevationproperties.h
   qgsmaplayertemporalproperties.h
+  qgsmaplayerutils.h
   qgsmapsettings.h
   qgsmapsettingsutils.h
   qgsmapthemecollection.h

diff --git a/src/core/project/qgsprojectviewsettings.cpp b/src/core/project/qgsprojectviewsettings.cpp
@@ -17,6 +17,7 @@
 #include "qgis.h"
 #include "qgsproject.h"
 #include "qgslogger.h"
+#include "qgsmaplayerutils.h"
 #include <QDomElement>
 
 QgsProjectViewSettings::QgsProjectViewSettings( QgsProject *project )
@@ -80,66 +81,8 @@ QgsReferencedRectangle QgsProjectViewSettings::fullExtent() const
   }
   else
   {
-    // reset the map canvas extent since the extent may now be smaller
-    // We can't use a constructor since QgsRectangle normalizes the rectangle upon construction
-    QgsRectangle fullExtent;
-    fullExtent.setMinimal();
-
-    // iterate through the map layers and test each layers extent
-    // against the current min and max values
-    const QMap<QString, QgsMapLayer *> layers = mProject->mapLayers( true );
-    QgsDebugMsgLevel( QStringLiteral( "Layer count: %1" ).arg( layers.count() ), 5 );
-    for ( auto it = layers.constBegin(); it != layers.constEnd(); ++it )
-    {
-      QgsDebugMsgLevel( "Updating extent using " + it.value()->name(), 5 );
-      QgsDebugMsgLevel( "Input extent: " + it.value()->extent().toString(), 5 );
-
-      if ( it.value()->extent().isNull() )
-        continue;
-
-      // Layer extents are stored in the coordinate system (CS) of the
-      // layer. The extent must be projected to the canvas CS
-      QgsCoordinateTransform ct( it.value()->crs(), mProject->crs(), mProject->transformContext() );
-      ct.setBallparkTransformsAreAppropriate( true );
-      try
-      {
-        const QgsRectangle extent = ct.transformBoundingBox( it.value()->extent() );
-
-        QgsDebugMsgLevel( "Output extent: " + extent.toString(), 5 );
-        fullExtent.combineExtentWith( extent );
-      }
-      catch ( QgsCsException & )
-      {
-        QgsDebugMsg( QStringLiteral( "Could not reproject layer extent" ) );
-      }
-    }
-
-    if ( fullExtent.width() == 0.0 || fullExtent.height() == 0.0 )
-    {
-      // If all of the features are at the one point, buffer the
-      // rectangle a bit. If they are all at zero, do something a bit
-      // more crude.
-
-      if ( fullExtent.xMinimum() == 0.0 && fullExtent.xMaximum() == 0.0 &&
-           fullExtent.yMinimum() == 0.0 && fullExtent.yMaximum() == 0.0 )
-      {
-        fullExtent.set( -1.0, -1.0, 1.0, 1.0 );
-      }
-      else
-      {
-        const double padFactor = 1e-8;
-        double widthPad = fullExtent.xMinimum() * padFactor;
-        double heightPad = fullExtent.yMinimum() * padFactor;
-        double xmin = fullExtent.xMinimum() - widthPad;
-        double xmax = fullExtent.xMaximum() + widthPad;
-        double ymin = fullExtent.yMinimum() - heightPad;
-        double ymax = fullExtent.yMaximum() + heightPad;
-        fullExtent.set( xmin, ymin, xmax, ymax );
-      }
-    }
-
-    QgsDebugMsgLevel( "Full extent: " + fullExtent.toString(), 5 );
-    return QgsReferencedRectangle( fullExtent, mProject->crs() );
+    const QList< QgsMapLayer * > layers = mProject->mapLayers( true ).values();
+    return QgsReferencedRectangle( QgsMapLayerUtils::combinedExtent( layers, mProject->crs(), mProject->transformContext() ), mProject->crs() );
   }
 }
 

diff --git a/src/core/qgsmaplayerutils.cpp b/src/core/qgsmaplayerutils.cpp
@@ -0,0 +1,86 @@
+/***************************************************************************
+                             qgsmaplayerutils.cpp
+                             -------------------
+    begin                : May 2021
+    copyright            : (C) 2021 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 "qgsmaplayerutils.h"
+#include "qgsrectangle.h"
+#include "qgscoordinatereferencesystem.h"
+#include "qgscoordinatetransformcontext.h"
+#include "qgsreferencedgeometry.h"
+#include "qgslogger.h"
+#include "qgsmaplayer.h"
+
+QgsRectangle QgsMapLayerUtils::combinedExtent( const QList<QgsMapLayer *> &layers, const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &transformContext )
+{
+  // We can't use a constructor since QgsRectangle normalizes the rectangle upon construction
+  QgsRectangle fullExtent;
+  fullExtent.setMinimal();
+
+  // iterate through the map layers and test each layers extent
+  // against the current min and max values
+  QgsDebugMsgLevel( QStringLiteral( "Layer count: %1" ).arg( layers.count() ), 5 );
+  for ( const QgsMapLayer *layer : layers )
+  {
+    QgsDebugMsgLevel( "Updating extent using " + layer->name(), 5 );
+    QgsDebugMsgLevel( "Input extent: " + layer->extent().toString(), 5 );
+
+    if ( layer->extent().isNull() )
+      continue;
+
+    // Layer extents are stored in the coordinate system (CS) of the
+    // layer. The extent must be projected to the canvas CS
+    QgsCoordinateTransform ct( layer->crs(), crs, transformContext );
+    ct.setBallparkTransformsAreAppropriate( true );
+    try
+    {
+      const QgsRectangle extent = ct.transformBoundingBox( layer->extent() );
+
+      QgsDebugMsgLevel( "Output extent: " + extent.toString(), 5 );
+      fullExtent.combineExtentWith( extent );
+    }
+    catch ( QgsCsException & )
+    {
+      QgsDebugMsg( QStringLiteral( "Could not reproject layer extent" ) );
+    }
+  }
+
+  if ( fullExtent.width() == 0.0 || fullExtent.height() == 0.0 )
+  {
+    // If all of the features are at the one point, buffer the
+    // rectangle a bit. If they are all at zero, do something a bit
+    // more crude.
+
+    if ( fullExtent.xMinimum() == 0.0 && fullExtent.xMaximum() == 0.0 &&
+         fullExtent.yMinimum() == 0.0 && fullExtent.yMaximum() == 0.0 )
+    {
+      fullExtent.set( -1.0, -1.0, 1.0, 1.0 );
+    }
+    else
+    {
+      const double padFactor = 1e-8;
+      double widthPad = fullExtent.xMinimum() * padFactor;
+      double heightPad = fullExtent.yMinimum() * padFactor;
+      double xmin = fullExtent.xMinimum() - widthPad;
+      double xmax = fullExtent.xMaximum() + widthPad;
+      double ymin = fullExtent.yMinimum() - heightPad;
+      double ymax = fullExtent.yMaximum() + heightPad;
+      fullExtent.set( xmin, ymin, xmax, ymax );
+    }
+  }
+
+  QgsDebugMsgLevel( "Full extent: " + fullExtent.toString(), 5 );
+  return fullExtent;
+}
diff --git a/src/core/qgsmaplayerutils.h b/src/core/qgsmaplayerutils.h
@@ -0,0 +1,50 @@
+/***************************************************************************
+                             qgsmaplayerutils.h
+                             -------------------
+    begin                : May 2021
+    copyright            : (C) 2021 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 QGSMAPLAYERUTILS_H
+#define QGSMAPLAYERUTILS_H
+
+#include "qgis_sip.h"
+#include "qgis_core.h"
+#include "qgis.h"
+
+class QgsMapLayer;
+class QgsRectangle;
+class QgsCoordinateReferenceSystem;
+class QgsCoordinateTransformContext;
+
+/**
+ * \ingroup core
+ * \brief Contains utility functions for working with map layers.
+ * \since QGIS 3.20
+*/
+class CORE_EXPORT QgsMapLayerUtils
+{
+
+  public:
+
+    /**
+     * Returns the combined extent of a list of \a layers.
+     *
+     * The \a crs argument specifies the desired coordinate reference system for the combined extent.
+     */
+    static QgsRectangle combinedExtent( const QList<QgsMapLayer *> &layers, const QgsCoordinateReferenceSystem &crs, const QgsCoordinateTransformContext &transformContext );
+
+};
+
+#endif // QGSMAPLAYERUTILS_H
+
+
diff --git a/tests/src/python/CMakeLists.txt b/tests/src/python/CMakeLists.txt
@@ -181,6 +181,7 @@ ADD_PYTHON_TEST(PyQgsMapLayerFactory test_qgsmaplayerfactory.py)
 ADD_PYTHON_TEST(PyQgsMapLayerModel test_qgsmaplayermodel.py)
 ADD_PYTHON_TEST(PyQgsMapLayerProxyModel test_qgsmaplayerproxymodel.py)
 ADD_PYTHON_TEST(PyQgsMapLayerStore test_qgsmaplayerstore.py)
+ADD_PYTHON_TEST(PyQgsMapLayerUtils test_qgsmaplayerutils.py)
 ADD_PYTHON_TEST(PyQgsMapRenderer test_qgsmaprenderer.py)
 ADD_PYTHON_TEST(PyQgsMapRendererCache test_qgsmaprenderercache.py)
 ADD_PYTHON_TEST(PyQgsMapThemeCollection test_qgsmapthemecollection.py)

diff --git a/tests/src/python/test_qgsmaplayerutils.py b/tests/src/python/test_qgsmaplayerutils.py
@@ -0,0 +1,69 @@
+# -*- coding: utf-8 -*-
+"""QGIS Unit tests for QgsMapLayerUtils.
+
+.. note:: 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.
+"""
+__author__ = 'Nyall Dawson'
+__date__ = '2021-05'
+__copyright__ = 'Copyright 2021, The QGIS Project'
+
+
+import qgis  # NOQA
+
+from qgis.testing import unittest
+from qgis.core import (
+    QgsMapLayerUtils,
+    QgsCoordinateReferenceSystem,
+    QgsCoordinateTransformContext,
+    QgsVectorLayer,
+    QgsRasterLayer,
+    QgsRectangle
+)
+from qgis.testing import start_app, unittest
+from utilities import unitTestDataPath
+
+start_app()
+
+
+class TestQgsMapLayerUtils(unittest.TestCase):
+
+    def testCombinedExtent(self):
+        extent = QgsMapLayerUtils.combinedExtent([], QgsCoordinateReferenceSystem(), QgsCoordinateTransformContext())
+        self.assertTrue(extent.isEmpty())
+
+        layer1 = QgsVectorLayer(unitTestDataPath() + '/points.shp', 'l1')
+        self.assertTrue(layer1.isValid())
+
+        # one layer
+        extent = QgsMapLayerUtils.combinedExtent([layer1], QgsCoordinateReferenceSystem(), QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(3), '-118.889,22.800 : -83.333,46.872')
+
+        extent = QgsMapLayerUtils.combinedExtent([layer1], QgsCoordinateReferenceSystem('EPSG:4326'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(3), '-118.889,22.800 : -83.333,46.872')
+        extent = QgsMapLayerUtils.combinedExtent([layer1], QgsCoordinateReferenceSystem('EPSG:3857'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(0), '-13234651,2607875 : -9276624,5921203')
+
+        # two layers
+        layer2 = QgsRasterLayer(unitTestDataPath() + '/landsat-f32-b1.tif', 'l2')
+        self.assertTrue(layer2.isValid())
+        extent = QgsMapLayerUtils.combinedExtent([layer1, layer2], QgsCoordinateReferenceSystem('EPSG:4326'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(3), '-118.889,22.800 : 18.046,46.872')
+        extent = QgsMapLayerUtils.combinedExtent([layer2, layer1], QgsCoordinateReferenceSystem('EPSG:4326'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(3), '-118.889,22.800 : 18.046,46.872')
+        extent = QgsMapLayerUtils.combinedExtent([layer1, layer2], QgsCoordinateReferenceSystem('EPSG:3857'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(0), '-13234651,2607875 : 2008833,5921203')
+        extent = QgsMapLayerUtils.combinedExtent([layer2, layer1], QgsCoordinateReferenceSystem('EPSG:3857'),
+                                                 QgsCoordinateTransformContext())
+        self.assertEqual(extent.toString(0), '-13234651,2607875 : 2008833,5921203')
+
+
+if __name__ == '__main__':
+    unittest.main()