Show nice friendly warnings to users when

- A coordinate transform cannot be created, e.g. due to not making sense (transforming earth coords to mars coords) - A coordinate transform cannot be created due to a missing grid file (along with links to download the grid if available) - A coordinate transform was created, BUT a better one is possible, it just is missing some prerequisite on the user's system (again, with links to download if available) Sponsored by ICSM
qgis · Jun 3, 2019 · 3e89df8 · 3e89df8
1 parent a8b5583
commit 3e89df8
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diff --git a/src/app/CMakeLists.txt b/src/app/CMakeLists.txt
@@ -13,6 +13,7 @@ SET(QGIS_APP_SRCS
   qgsalignrasterdialog.cpp
   qgsappauthrequesthandler.cpp
   qgsappbrowserproviders.cpp
+  qgsappcoordinateoperationhandlers.cpp
   qgsapplayertreeviewmenuprovider.cpp
   qgsappwindowmanager.cpp
   qgsaddattrdialog.cpp
@@ -255,6 +256,7 @@ SET (QGIS_APP_MOC_HDRS
   qgsaddattrdialog.h
   qgsalignrasterdialog.h
   qgsappbrowserproviders.h
+  qgsappcoordinateoperationhandlers.h
   qgsappscreenshots.h
   qgsjoindialog.h
   qgsaddtaborgroup.h

diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
@@ -335,6 +335,7 @@ Q_GUI_EXPORT extern int qt_defaultDpiX();
 #include "qgsdatasourcemanagerdialog.h"
 #include "qgsappwindowmanager.h"
 #include "qgsvaliditycheckregistry.h"
+#include "qgsappcoordinateoperationhandlers.h"
 
 #include "qgsuserprofilemanager.h"
 #include "qgsuserprofile.h"
@@ -1407,6 +1408,8 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
     QgsGui::instance()->nativePlatformInterface()->setApplicationBadgeCount( count );
   } );
 
+  ( void )new QgsAppMissingGridHandler( this );
+
   // supposedly all actions have been added, now register them to the shortcut manager
   QgsGui::shortcutsManager()->registerAllChildren( this );
   QgsGui::shortcutsManager()->registerAllChildren( mSnappingWidget );

diff --git a/src/app/qgsappcoordinateoperationhandlers.cpp b/src/app/qgsappcoordinateoperationhandlers.cpp
@@ -0,0 +1,203 @@
+/***************************************************************************
+    qgsappcoordinateoperationhandlers.cpp
+    -------------------------
+    begin                : May 2019
+    copyright            : (C) 2019 by 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 "qgsappcoordinateoperationhandlers.h"
+#include "qgscoordinatetransform.h"
+#include "qgisapp.h"
+#include "qgsmessagebar.h"
+#include "qgsmessagebaritem.h"
+#include "qgsmessageoutput.h"
+
+//
+// QgsAppMissingRequiredGridHandler
+//
+QgsAppMissingGridHandler::QgsAppMissingGridHandler( QObject *parent )
+  : QObject( parent )
+{
+  QgsCoordinateTransform::setCustomMissingRequiredGridHandler( [ = ]( const QgsCoordinateReferenceSystem & sourceCrs,
+      const QgsCoordinateReferenceSystem & destinationCrs,
+      const QgsDatumTransform::GridDetails & grid )
+  {
+    emit missingRequiredGrid( sourceCrs, destinationCrs, grid );
+  } );
+
+  QgsCoordinateTransform::setCustomMissingPreferredGridHandler( [ = ]( const QgsCoordinateReferenceSystem & sourceCrs,
+      const QgsCoordinateReferenceSystem & destinationCrs,
+      const QgsDatumTransform::TransformDetails & preferredOperation,
+      const QgsDatumTransform::TransformDetails & availableOperation )
+  {
+    emit missingPreferredGrid( sourceCrs, destinationCrs, preferredOperation, availableOperation );
+  } );
+
+  QgsCoordinateTransform::setCustomCoordinateOperationCreationErrorHandler( [ = ]( const QgsCoordinateReferenceSystem & sourceCrs,
+      const QgsCoordinateReferenceSystem & destinationCrs,
+      const QString & error )
+  {
+    emit coordinateOperationCreationError( sourceCrs, destinationCrs, error );
+  } );
+
+  connect( this, &QgsAppMissingGridHandler::missingRequiredGrid, this, &QgsAppMissingGridHandler::onMissingRequiredGrid, Qt::QueuedConnection );
+  connect( this, &QgsAppMissingGridHandler::missingPreferredGrid, this, &QgsAppMissingGridHandler::onMissingPreferredGrid, Qt::QueuedConnection );
+  connect( this, &QgsAppMissingGridHandler::coordinateOperationCreationError, this, &QgsAppMissingGridHandler::onCoordinateOperationCreationError, Qt::QueuedConnection );
+
+}
+
+QString displayIdentifierForCrs( const QgsCoordinateReferenceSystem &crs, bool shortString = false )
+{
+  if ( !crs.authid().isEmpty() )
+  {
+    if ( !shortString && !crs.description().isEmpty() )
+      return QStringLiteral( "%1 [%2]" ).arg( crs.authid(), crs.description() );
+    return crs.authid();
+  }
+  else if ( !crs.description().isEmpty() )
+    return crs.description();
+  else if ( !crs.toProj4().isEmpty() )
+    return crs.toProj4();
+  else
+    return crs.toWkt();
+}
+
+void QgsAppMissingGridHandler::onMissingRequiredGrid( const QgsCoordinateReferenceSystem &sourceCrs, const QgsCoordinateReferenceSystem &destinationCrs, const QgsDatumTransform::GridDetails &grid )
+{
+  if ( !shouldWarnAboutPair( sourceCrs, destinationCrs ) )
+    return;
+
+  const QString shortMessage = tr( "No transform available between %1 and %2" ).arg( displayIdentifierForCrs( sourceCrs, true ),
+                               displayIdentifierForCrs( destinationCrs, true ) );
+
+  QString downloadMessage;
+  if ( !grid.url.isEmpty() )
+  {
+    if ( !grid.packageName.isEmpty() )
+    {
+      downloadMessage = tr( "This grid is part of the “<i>%1</i>” package, available for download from <a href=\"%2\">%2</a>." ).arg( grid.packageName, grid.url );
+    }
+    else
+    {
+      downloadMessage = tr( "This grid is available for download from <a href=\"%1\">%1</a>." ).arg( grid.url );
+    }
+  }
+
+  const QString longMessage = tr( "<p>No transform is available between <i>%1</i> and <i>%2</i>.</p>"
+                                  "<p>This transformation requires the grid file “%3”, which is not available for use on the system.%4</p>" ).arg( displayIdentifierForCrs( sourceCrs ),
+                                      displayIdentifierForCrs( destinationCrs ),
+                                      grid.shortName,
+                                      downloadMessage.isEmpty() ? QString() : " " + downloadMessage );
+
+  QgsMessageBar *bar = QgisApp::instance()->messageBar();
+  QgsMessageBarItem *widget = bar->createMessage( QString(), shortMessage );
+  QPushButton *detailsButton = new QPushButton( tr( "Details" ) );
+  connect( detailsButton, &QPushButton::clicked, this, [longMessage]
+  {
+    // dlg has deleted on close
+    QgsMessageOutput * dlg( QgsMessageOutput::createMessageOutput() );
+    dlg->setTitle( tr( "No Transformations Available" ) );
+    dlg->setMessage( longMessage, QgsMessageOutput::MessageHtml );
+    dlg->showMessage();
+  } );
+
+  widget->layout()->addWidget( detailsButton );
+  bar->pushWidget( widget, Qgis::Critical, 0 );
+}
+
+void QgsAppMissingGridHandler::onMissingPreferredGrid( const QgsCoordinateReferenceSystem &sourceCrs, const QgsCoordinateReferenceSystem &destinationCrs, const QgsDatumTransform::TransformDetails &preferredOperation, const QgsDatumTransform::TransformDetails &availableOperation )
+{
+  if ( !shouldWarnAboutPair( sourceCrs, destinationCrs ) )
+    return;
+
+  const QString shortMessage = tr( "Cannot use preferred transform between %1 and %2" ).arg( displayIdentifierForCrs( sourceCrs, true ),
+                               displayIdentifierForCrs( destinationCrs, true ) );
+
+  QString gridMessage;
+  for ( const QgsDatumTransform::GridDetails &grid : preferredOperation.grids )
+  {
+    if ( !grid.isAvailable )
+    {
+      QString m = tr( "This transformation requires the grid file “%1”, which is not available for use on the system." ).arg( grid.shortName );
+      if ( !grid.url.isEmpty() )
+      {
+        if ( !grid.packageName.isEmpty() )
+        {
+          m += ' ' +  tr( "This grid is part of the <i>%1</i> package, available for download from <a href=\"%2\">%2</a>." ).arg( grid.packageName, grid.url );
+        }
+        else
+        {
+          m += ' ' + tr( "This grid is available for download from <a href=\"%1\">%1</a>." ).arg( grid.url );
+        }
+      }
+      gridMessage += QStringLiteral( "<li>%1</li>" ).arg( m );
+    }
+  }
+  if ( !gridMessage.isEmpty() )
+  {
+    gridMessage = "<ul>" + gridMessage + "</ul>";
+  }
+
+  const QString longMessage = tr( "<p>The preferred transform between <i>%1</i> and <i>%2</i> is not available for use on the system.</p>" ).arg( displayIdentifierForCrs( sourceCrs ),
+                              displayIdentifierForCrs( destinationCrs ) )
+                              + gridMessage +
+                              tr( "<p>Current transform “<i>%1</i>” has an accuracy of %2 meters, while the preferred transformation “<i>%3</i>” has accuracy %4 meters.</p>" ).arg( availableOperation.name )
+                              .arg( availableOperation.accuracy ).arg( preferredOperation.name ).arg( preferredOperation.accuracy );
+
+  QgsMessageBar *bar = QgisApp::instance()->messageBar();
+  QgsMessageBarItem *widget = bar->createMessage( QString(), shortMessage );
+  QPushButton *detailsButton = new QPushButton( tr( "Details" ) );
+  connect( detailsButton, &QPushButton::clicked, this, [longMessage]
+  {
+    // dlg has deleted on close
+    QgsMessageOutput * dlg( QgsMessageOutput::createMessageOutput() );
+    dlg->setTitle( tr( "Preferred Transformation Not Available" ) );
+    dlg->setMessage( longMessage, QgsMessageOutput::MessageHtml );
+    dlg->showMessage();
+  } );
+
+  widget->layout()->addWidget( detailsButton );
+  bar->pushWidget( widget, Qgis::Warning, 0 );
+}
+
+void QgsAppMissingGridHandler::onCoordinateOperationCreationError( const QgsCoordinateReferenceSystem &sourceCrs, const QgsCoordinateReferenceSystem &destinationCrs, const QString &error )
+{
+  if ( !shouldWarnAboutPair( sourceCrs, destinationCrs ) )
+    return;
+
+  const QString shortMessage = tr( "No transform available between %1 and %2" ).arg( displayIdentifierForCrs( sourceCrs, true ), displayIdentifierForCrs( destinationCrs, true ) );
+  const QString longMessage = tr( "<p>No transform is available between <i>%1</i> and <i>%2</i>.</p><p>%3</p>" ).arg( displayIdentifierForCrs( sourceCrs ), displayIdentifierForCrs( destinationCrs ), error );
+
+  QgsMessageBar *bar = QgisApp::instance()->messageBar();
+  QgsMessageBarItem *widget = bar->createMessage( QString(), shortMessage );
+  QPushButton *detailsButton = new QPushButton( tr( "Details" ) );
+  connect( detailsButton, &QPushButton::clicked, this, [longMessage]
+  {
+    // dlg has deleted on close
+    QgsMessageOutput * dlg( QgsMessageOutput::createMessageOutput() );
+    dlg->setTitle( tr( "No Transformations Available" ) );
+    dlg->setMessage( longMessage, QgsMessageOutput::MessageHtml );
+    dlg->showMessage();
+  } );
+
+  widget->layout()->addWidget( detailsButton );
+  bar->pushWidget( widget, Qgis::Critical, 0 );
+}
+
+bool QgsAppMissingGridHandler::shouldWarnAboutPair( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest )
+{
+  if ( mAlreadyWarnedPairs.contains( qMakePair( source, dest ) ) || mAlreadyWarnedPairs.contains( qMakePair( dest, source ) ) )
+  {
+    return false;
+  }
+
+  mAlreadyWarnedPairs.append( qMakePair( source, dest ) );
+  return true;
+}
diff --git a/src/app/qgsappcoordinateoperationhandlers.h b/src/app/qgsappcoordinateoperationhandlers.h
@@ -0,0 +1,70 @@
+/***************************************************************************
+    qgsappcoordinateoperationhandlers.h
+    -------------------------
+    begin                : May 2019
+    copyright            : (C) 2019 by 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 QGSAPPCOORDINATEOPERATIONHANDLERS_H
+#define QGSAPPCOORDINATEOPERATIONHANDLERS_H
+
+#include <QObject>
+#include "qgscoordinatereferencesystem.h"
+#include "qgsdatumtransform.h"
+
+/**
+ * Alerts users when a transform grids are required (or desired) for an operation between two
+ * CRSes, yet they are not available on the current system.
+ */
+class QgsAppMissingGridHandler : public QObject
+{
+    Q_OBJECT
+  public:
+
+    QgsAppMissingGridHandler( QObject *parent );
+
+  signals:
+
+    void missingRequiredGrid( const QgsCoordinateReferenceSystem &sourceCrs,
+                              const QgsCoordinateReferenceSystem &destinationCrs,
+                              const QgsDatumTransform::GridDetails &grid );
+
+    void missingPreferredGrid( const QgsCoordinateReferenceSystem &sourceCrs,
+                               const QgsCoordinateReferenceSystem &destinationCrs,
+                               const QgsDatumTransform::TransformDetails &preferredOperation,
+                               const QgsDatumTransform::TransformDetails &availableOperation );
+
+    void coordinateOperationCreationError( const QgsCoordinateReferenceSystem &sourceCrs,
+                                           const QgsCoordinateReferenceSystem &destinationCrs,
+                                           const QString &error );
+
+  private slots:
+
+    void onMissingRequiredGrid( const QgsCoordinateReferenceSystem &sourceCrs,
+                                const QgsCoordinateReferenceSystem &destinationCrs,
+                                const QgsDatumTransform::GridDetails &grid );
+
+    void onMissingPreferredGrid( const QgsCoordinateReferenceSystem &sourceCrs,
+                                 const QgsCoordinateReferenceSystem &destinationCrs,
+                                 const QgsDatumTransform::TransformDetails &preferredOperation,
+                                 const QgsDatumTransform::TransformDetails &availableOperation );
+
+    void onCoordinateOperationCreationError( const QgsCoordinateReferenceSystem &sourceCrs,
+        const QgsCoordinateReferenceSystem &destinationCrs,
+        const QString &error );
+  private:
+
+    bool shouldWarnAboutPair( const QgsCoordinateReferenceSystem &source, const QgsCoordinateReferenceSystem &dest );
+
+    QList< QPair< QgsCoordinateReferenceSystem, QgsCoordinateReferenceSystem > > mAlreadyWarnedPairs;
+
+};
+
+#endif // QGSAPPCOORDINATEOPERATIONHANDLERS_H
diff --git a/src/core/qgsapplication.cpp b/src/core/qgsapplication.cpp
@@ -216,6 +216,8 @@ void QgsApplication::init( QString profileFolder )
   qRegisterMetaType<QgsNetworkRequestParameters>( "QgsNetworkRequestParameters" );
   qRegisterMetaType<QgsNetworkReplyContent>( "QgsNetworkReplyContent" );
   qRegisterMetaType<QgsGeometry>( "QgsGeometry" );
+  qRegisterMetaType<QgsDatumTransform::GridDetails>( "QgsDatumTransform::GridDetails" );
+  qRegisterMetaType<QgsDatumTransform::TransformDetails>( "QgsDatumTransform::TransformDetails" );
 
   ( void ) resolvePkgPath();