Merge pull request #35382 from 3nids/dnd-across-qgis-instances

[FEATURE] allow to drag'n'drop layer across several QGIS instances
qgis · May 6, 2020 · 37efb4d · 37efb4d
2 parents b1873a4 + c6ee633
commit 37efb4d
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Showing 7 changed files with 121 additions and 31 deletions.
diff --git a/python/core/auto_generated/layertree/qgslayertreemodel.sip.in b/python/core/auto_generated/layertree/qgslayertreemodel.sip.in
@@ -319,6 +319,15 @@ displays.
 ``standardSize`` should be set to a standard icon size, e.g. 16, 24, 48, etc.
 
 .. versionadded:: 3.6
+%End
+
+  signals:
+
+    void messageEmitted( const QString &message, Qgis::MessageLevel level = Qgis::Info, int duration = 5 );
+%Docstring
+Emits a message than can be displayed to the user in a GUI class
+
+.. versionadded:: 3.14
 %End
 
   protected slots:

diff --git a/python/gui/auto_generated/layertree/qgslayertreeview.sip.in b/python/gui/auto_generated/layertree/qgslayertreeview.sip.in
@@ -9,6 +9,7 @@
 
 
 
+
 class QgsLayerTreeView : QTreeView
 {
 %Docstring
@@ -211,6 +212,13 @@ Set width of contextual menu mark, at right of layer node items.
 .. seealso:: :py:func:`layerMarkWidth`
 
 .. versionadded:: 3.8
+%End
+
+    void setMessageBar( QgsMessageBar *messageBar );
+%Docstring
+Set the message bar to display messages from the layer tree
+
+.. versionadded:: 3.14
 %End
 
   signals:

diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
@@ -1687,6 +1687,7 @@ QgisApp::QgisApp()
   mUndoWidget = new QgsUndoWidget( nullptr, mMapCanvas );
   mUserInputDockWidget = new QgsUserInputWidget( this );
   mInfoBar = new QgsMessageBar( centralWidget() );
+  mLayerTreeView->setMessageBar( mInfoBar );
   mAdvancedDigitizingDockWidget = new QgsAdvancedDigitizingDockWidget( mMapCanvas, this );
   mPanelMenu = new QMenu( this );
   mProgressBar = new QProgressBar( this );
@@ -4590,6 +4591,8 @@ void QgisApp::initLayerTreeView()
   model->setAutoCollapseLegendNodes( 10 );
 
   mLayerTreeView->setModel( model );
+  mLayerTreeView->setMessageBar( mInfoBar );
+
   mLayerTreeView->setMenuProvider( new QgsAppLayerTreeViewMenuProvider( mLayerTreeView, mMapCanvas ) );
   new QgsLayerTreeViewFilterIndicatorProvider( mLayerTreeView );  // gets parented to the layer view
   new QgsLayerTreeViewEmbeddedIndicatorProvider( mLayerTreeView );  // gets parented to the layer view

diff --git a/src/core/layertree/qgslayertreemodel.cpp b/src/core/layertree/qgslayertreemodel.cpp
@@ -13,17 +13,16 @@
  *                                                                         *
  ***************************************************************************/
 
+#include <QMimeData>
+#include <QTextStream>
+
 #include "qgslayertreemodel.h"
 
 #include "qgslayertree.h"
 #include "qgslayertreeutils.h"
 #include "qgslayertreemodellegendnode.h"
 #include "qgsproject.h"
 #include "qgsapplication.h"
-
-#include <QMimeData>
-#include <QTextStream>
-
 #include "qgsdataitem.h"
 #include "qgsmaphittest.h"
 #include "qgsmaplayer.h"
@@ -34,6 +33,8 @@
 #include "qgsrenderer.h"
 #include "qgssymbollayerutils.h"
 #include "qgsvectorlayer.h"
+#include "qgslayerdefinition.h"
+
 
 QgsLayerTreeModel::QgsLayerTreeModel( QgsLayerTree *rootNode, QObject *parent )
   : QAbstractItemModel( parent )
@@ -1052,15 +1053,25 @@ QMimeData *QgsLayerTreeModel::mimeData( const QModelIndexList &indexes ) const
 
   QMimeData *mimeData = new QMimeData();
 
-  QDomDocument doc;
-  QDomElement rootElem = doc.createElement( QStringLiteral( "layer_tree_model_data" ) );
+  QDomDocument layerTreeDoc;
+  QDomElement rootLayerTreeElem = layerTreeDoc.createElement( QStringLiteral( "layer_tree_model_data" ) );
+
   for ( QgsLayerTreeNode *node : qgis::as_const( nodesFinal ) )
-    node->writeXml( rootElem, QgsReadWriteContext() );
-  doc.appendChild( rootElem );
-  QString txt = doc.toString();
+  {
+    node->writeXml( rootLayerTreeElem, QgsReadWriteContext() );
+  }
+  layerTreeDoc.appendChild( rootLayerTreeElem );
 
-  mimeData->setData( QStringLiteral( "application/qgis.layertreemodeldata" ), txt.toUtf8() );
+  QString errorMessage;
+  QgsReadWriteContext readWriteContext;
+  QDomDocument layerDefinitionsDoc( QStringLiteral( "qgis-layer-definition" ) );
+  QgsLayerDefinition::exportLayerDefinition( layerDefinitionsDoc, nodesFinal, errorMessage, QgsReadWriteContext() );
 
+  QString txt = layerDefinitionsDoc.toString();
+
+  mimeData->setData( QStringLiteral( "application/qgis.layertreemodeldata" ), layerTreeDoc.toString().toUtf8() );
+  mimeData->setData( QStringLiteral( "application/qgis.application.pid" ), QString::number( QCoreApplication::applicationPid() ).toUtf8() );
+  mimeData->setData( QStringLiteral( "application/qgis.layertree.layerdefinitions" ), txt.toUtf8() );
   mimeData->setData( QStringLiteral( "application/x-vnd.qgis.qgis.uri" ), QgsMimeDataUtils::layerTreeNodesToUriList( nodesFinal ) );
 
   return mimeData;
@@ -1081,36 +1092,54 @@ bool QgsLayerTreeModel::dropMimeData( const QMimeData *data, Qt::DropAction acti
   if ( !QgsLayerTree::isGroup( nodeParent ) )
     return false;
 
-  QByteArray encodedData = data->data( QStringLiteral( "application/qgis.layertreemodeldata" ) );
+  if ( parent.isValid() && row == -1 )
+    row = 0; // if dropped directly onto group item, insert at first position
 
-  QDomDocument doc;
-  if ( !doc.setContent( QString::fromUtf8( encodedData ) ) )
-    return false;
+  // if we are coming from another QGIS instance, we need to add the layers too
+  bool ok = false;
+  // the application pid is only provided from QGIS 3.14, so do not check to OK before defaulting to moving in the legend
+  int qgisPid = data->data( QStringLiteral( "application/qgis.application.pid" ) ).toInt( &ok );
 
-  QDomElement rootElem = doc.documentElement();
-  if ( rootElem.tagName() != QLatin1String( "layer_tree_model_data" ) )
-    return false;
+  if ( ok && qgisPid != QString::number( QCoreApplication::applicationPid() ) )
+  {
+    QByteArray encodedLayerDefinitionData = data->data( QStringLiteral( "application/qgis.layertree.layerdefinitions" ) );
+    QDomDocument layerDefinitionDoc;
+    if ( !layerDefinitionDoc.setContent( QString::fromUtf8( encodedLayerDefinitionData ) ) )
+      return false;
+    QgsReadWriteContext context;
+    QString errorMessage;
+    QgsLayerDefinition::loadLayerDefinition( layerDefinitionDoc, QgsProject::instance(), QgsLayerTree::toGroup( nodeParent ), errorMessage, context );
+    emit messageEmitted( tr( "New layers added from another QGIS instance" ) );
+  }
+  else
+  {
+    QByteArray encodedLayerTreeData = data->data( QStringLiteral( "application/qgis.layertreemodeldata" ) );
 
-  QList<QgsLayerTreeNode *> nodes;
+    QDomDocument layerTreeDoc;
+    if ( !layerTreeDoc.setContent( QString::fromUtf8( encodedLayerTreeData ) ) )
+      return false;
 
-  QDomElement elem = rootElem.firstChildElement();
-  while ( !elem.isNull() )
-  {
-    QgsLayerTreeNode *node = QgsLayerTreeNode::readXml( elem, QgsProject::instance() );
-    if ( node )
-      nodes << node;
+    QDomElement rootLayerTreeElem = layerTreeDoc.documentElement();
+    if ( rootLayerTreeElem.tagName() != QLatin1String( "layer_tree_model_data" ) )
+      return false;
 
-    elem = elem.nextSiblingElement();
-  }
+    QList<QgsLayerTreeNode *> nodes;
 
-  if ( nodes.isEmpty() )
-    return false;
+    QDomElement elem = rootLayerTreeElem.firstChildElement();
+    while ( !elem.isNull() )
+    {
+      QgsLayerTreeNode *node = QgsLayerTreeNode::readXml( elem, QgsProject::instance() );
+      if ( node )
+        nodes << node;
 
-  if ( parent.isValid() && row == -1 )
-    row = 0; // if dropped directly onto group item, insert at first position
+      elem = elem.nextSiblingElement();
+    }
 
-  QgsLayerTree::toGroup( nodeParent )->insertChildNodes( row, nodes );
+    if ( nodes.isEmpty() )
+      return false;
 
+    QgsLayerTree::toGroup( nodeParent )->insertChildNodes( row, nodes );
+  }
   return true;
 }
 

diff --git a/src/core/layertree/qgslayertreemodel.h b/src/core/layertree/qgslayertreemodel.h
@@ -286,6 +286,14 @@ class CORE_EXPORT QgsLayerTreeModel : public QAbstractItemModel
      */
     static int scaleIconSize( int standardSize );
 
+  signals:
+
+    /**
+     * Emits a message than can be displayed to the user in a GUI class
+     * \since QGIS 3.14
+     */
+    void messageEmitted( const QString &message, Qgis::MessageLevel level = Qgis::Info, int duration = 5 );
+
   protected slots:
     void nodeWillAddChildren( QgsLayerTreeNode *node, int indexFrom, int indexTo );
     void nodeAddedChildren( QgsLayerTreeNode *node, int indexFrom, int indexTo );

diff --git a/src/gui/layertree/qgslayertreeview.cpp b/src/gui/layertree/qgslayertreeview.cpp
@@ -22,6 +22,8 @@
 #include "qgslayertreeutils.h"
 #include "qgslayertreeviewdefaultactions.h"
 #include "qgsmaplayer.h"
+#include "qgsmessagebar.h"
+
 #include "qgsgui.h"
 
 #include <QMenu>
@@ -77,6 +79,12 @@ void QgsLayerTreeView::setModel( QAbstractItemModel *model )
   connect( model, &QAbstractItemModel::rowsInserted, this, &QgsLayerTreeView::modelRowsInserted );
   connect( model, &QAbstractItemModel::rowsRemoved, this, &QgsLayerTreeView::modelRowsRemoved );
 
+  if ( mMessageBar )
+    connect( layerTreeModel(), &QgsLayerTreeModel::messageEmitted,
+             [ = ]( const QString & message, Qgis::MessageLevel level = Qgis::Info, int duration = 5 )
+  {mMessageBar->pushMessage( message, level, duration );}
+         );
+
   QTreeView::setModel( model );
 
   connect( layerTreeModel()->rootGroup(), &QgsLayerTreeNode::expandedChanged, this, &QgsLayerTreeView::onExpandedChanged );
@@ -490,6 +498,20 @@ void QgsLayerTreeView::collapseAllNodes()
   collapseAll();
 }
 
+void QgsLayerTreeView::setMessageBar( QgsMessageBar *messageBar )
+{
+  if ( mMessageBar == messageBar )
+    return;
+
+  mMessageBar = messageBar;
+
+  if ( mMessageBar )
+    connect( layerTreeModel(), &QgsLayerTreeModel::messageEmitted,
+             [ = ]( const QString & message, Qgis::MessageLevel level = Qgis::Info, int duration = 5 )
+  {mMessageBar->pushMessage( message, level, duration );}
+         );
+}
+
 void QgsLayerTreeView::mouseReleaseEvent( QMouseEvent *event )
 {
   // we need to keep last mouse position in order to know whether to emit an indicator's clicked() signal

diff --git a/src/gui/layertree/qgslayertreeview.h b/src/gui/layertree/qgslayertreeview.h
@@ -29,6 +29,8 @@ class QgsLayerTreeViewDefaultActions;
 class QgsLayerTreeViewIndicator;
 class QgsLayerTreeViewMenuProvider;
 class QgsMapLayer;
+class QgsMessageBar;
+
 
 /**
  * \ingroup gui
@@ -206,6 +208,12 @@ class GUI_EXPORT QgsLayerTreeView : public QTreeView
      */
     void setLayerMarkWidth( int width ) { mLayerMarkWidth = width; }
 
+    /**
+     * Set the message bar to display messages from the layer tree
+     * \since QGIS 3.14
+     */
+    void setMessageBar( QgsMessageBar *messageBar );
+
   signals:
     //! Emitted when a current layer is changed
     void currentLayerChanged( QgsMapLayer *layer );
@@ -253,6 +261,9 @@ class GUI_EXPORT QgsLayerTreeView : public QTreeView
     //! Width of contextual menu mark for layer nodes
     int mLayerMarkWidth;
 
+  private:
+    QgsMessageBar *mMessageBar = nullptr;
+
     // friend so it can access viewOptions() method and mLastReleaseMousePos without making them public
     friend class QgsLayerTreeViewItemDelegate;
 };