[ui] Improve UX by adding an original source label when changing / updating layer data source

Author: nirvn

python/gui/auto_generated/qgsdatasourceselectdialog.sip.in

@@ -50,6 +50,19 @@ Constructs a QgsDataSourceSelectDialog, optionally filtering by layer type
     void setLayerTypeFilter( QgsMapLayerType layerType );
 %Docstring
 Sets layer type filter to ``layerType`` and activates the filtering
+%End
+
+    void setDescription( const QString description );
+%Docstring
+Sets a description label
+
+:param description: a description string
+
+.. note::
+
+   the description will be displayed at the bottom of the dialog
+
+.. versionadded:: 3.8
 %End
 
     QgsMimeDataUtils::Uri uri() const;

src/app/qgisapp.cpp

@@ -7164,6 +7164,7 @@ void QgisApp::changeDataSource( QgsMapLayer *layer )
   QgsMapLayerType layerType( layer->type() );
 
   QgsDataSourceSelectDialog dlg( mBrowserModel, true, layerType );
+  dlg.setDescription( tr( "Original source URI: %1" ).arg( layer->publicSource() ) );
 
   if ( dlg.exec() == QDialog::Accepted )
   {

src/gui/qgsdatasourceselectdialog.cpp

@@ -162,6 +162,30 @@ void QgsDataSourceSelectDialog::showFilterWidget( bool visible )
   }
 }
 
+void QgsDataSourceSelectDialog::setDescription( const QString description )
+{
+  if ( !description.isEmpty() )
+  {
+    if ( !mDescriptionLabel )
+    {
+      mDescriptionLabel = new QLabel();
+      mDescriptionLabel->setWordWrap( true );
+      mDescriptionLabel->setMargin( 4 );
+      verticalLayout->insertWidget( 1, mDescriptionLabel );
+    }
+    mDescriptionLabel->setText( description );
+  }
+  else
+  {
+    if ( mDescriptionLabel )
+    {
+      verticalLayout->removeWidget( mDescriptionLabel );
+      delete mDescriptionLabel;
+      mDescriptionLabel = nullptr;
+    }
+  }
+}
+
 void QgsDataSourceSelectDialog::setFilter()
 {
   QString filter = mLeFilter->text();

src/gui/qgsdatasourceselectdialog.h

@@ -16,7 +16,6 @@
 #ifndef QGSDATASOURCESELECTDIALOG_H
 #define QGSDATASOURCESELECTDIALOG_H
 
-#include <QObject>
 #include "ui_qgsdatasourceselectdialog.h"
 
 #include "qgis_gui.h"
@@ -25,6 +24,8 @@
 #include "qgsbrowsermodel.h"
 #include "qgsbrowserproxymodel.h"
 
+#include <QObject>
+#include <QLabel>
 
 /**
  * \ingroup gui
@@ -68,6 +69,14 @@ class GUI_EXPORT QgsDataSourceSelectDialog: public QDialog, private Ui::QgsDataS
      */
     void setLayerTypeFilter( QgsMapLayerType layerType );
 
+    /**
+     * Sets a description label
+     * \param description a description string
+     * \note the description will be displayed at the bottom of the dialog
+     * \since 3.8
+     */
+    void setDescription( const QString description );
+
     /**
      * Returns the (possibly invalid) uri of the selected data source
      */
@@ -98,6 +107,7 @@ class GUI_EXPORT QgsDataSourceSelectDialog: public QDialog, private Ui::QgsDataS
     std::unique_ptr<QgsBrowserModel> mBrowserModel;
     bool mOwnModel = true;
     QgsMimeDataUtils::Uri mUri;
+    QLabel *mDescriptionLabel = nullptr;
 
 };