Merge pull request #5200 from nyalldawson/drop_handler

[FEATURE][processing] Allow dropping model files onto QGIS window to execute them

python/gui/gui_auto.sip

@@ -1,7 +1,6 @@
 // Include auto-generated SIP files
 %Include qgsattributeeditorcontext.sip
 %Include qgsattributeforminterface.sip
-%Include qgscustomdrophandler.sip
 %Include qgsdetaileditemdata.sip
 %Include qgsexpressionbuilderdialog.sip
 %Include qgsgeometryrubberband.sip
@@ -91,6 +90,7 @@
 %Include qgsconfigureshortcutsdialog.sip
 %Include qgscredentialdialog.sip
 %Include qgscurveeditorwidget.sip
+%Include qgscustomdrophandler.sip
 %Include qgsdetaileditemdelegate.sip
 %Include qgsdetaileditemwidget.sip
 %Include qgsdial.sip

python/gui/qgscustomdrophandler.sip

@@ -8,12 +8,30 @@
 
 
 
-class QgsCustomDropHandler
+class QgsCustomDropHandler : QObject
 {
 %Docstring
  Abstract base class that may be implemented to handle new types of data to be dropped in QGIS.
- Implementations will be used when a QgsMimeDataUtils.Uri has layerType equal to "custom",
- and the providerKey is equal to key() returned by the implementation.
+
+ Implementations have three approaches they can use to handle drops.
+
+ 1. The simplest approach is to implement handeFileDrop() when they need to handle
+ dropped files (i.e. with mime type "text/uri-list").
+
+ 2. Reimplement handleCustomUriDrop() when they want to handle dropped custom
+ QgsMimeDataUtils.Uri entries, for instance handling dropping custom entries
+ from the browser tree (with mime type "application/x-vnd.qgis.qgis.uri"). In
+ this case the implementation's customUriProviderKey() must match the uri
+ entry's providerKey.
+
+ 3. Reimplement handleMimeData() to directly handle dropped QMimeData.
+ Subclasses should take care when overriding this method. When a drop event
+ occurs, Qt will lock the source application of the drag for the duration
+ of the drop event handling via handleMimeData() (e.g. dragging files from
+ explorer to QGIS will lock the explorer window until the drop handling has
+ been complete). Accordingly handleMimeData() implementations must return
+ quickly and defer any intensive or slow processing.
+
 .. versionadded:: 3.0
 %End
 
@@ -23,15 +41,55 @@ class QgsCustomDropHandler
   public:
     virtual ~QgsCustomDropHandler();
 
-    virtual QString key() const = 0;
+    virtual QString customUriProviderKey() const;
 %Docstring
-Type of custom URI recognized by the handler
+ Type of custom URI recognized by the handler. This must match
+ the URI entry's providerKey in order for handleCustomUriDrop()
+ to be called.
+
+.. seealso:: handleCustomUriDrop()
  :rtype: str
 %End
 
-    virtual void handleDrop( const QgsMimeDataUtils::Uri &uri ) const = 0;
+    virtual void handleCustomUriDrop( const QgsMimeDataUtils::Uri &uri ) const;
 %Docstring
-Method called from QGIS after a drop event with custom URI known by the handler
+ Called from QGIS after a drop event with custom URI known by the handler.
+
+ In order for handleCustomUriDrop() to be called, subclasses must
+ also implement customUriProviderKey() to indicate the providerKey
+ value which the handler accepts.
+
+.. seealso:: customUriProviderKey()
+%End
+
+    virtual void handleMimeData( const QMimeData *data );
+%Docstring
+ Called when the specified mime ``data`` has been dropped onto QGIS.
+
+ The base class implementation does nothing.
+
+ Subclasses should take care when overriding this method. When a drop event
+ occurs, Qt will lock the source application of the drag for the duration
+ of the drop event handling (e.g. dragging files from explorer to QGIS will
+ lock the explorer window until the drop handling has been complete).
+
+ Accordingly, only implementations must be lightweight and return ASAP.
+ (For instance by copying the relevant parts of ``data`` and then handling
+ the data after a short timeout).
+%End
+
+    virtual bool handleFileDrop( const QString &file );
+%Docstring
+ Called when the specified ``file`` has been dropped onto QGIS. If true
+ is returned, then the handler has accepted this file and it should not
+ be further processed (e.g. by other QgsCustomDropHandlers).
+
+ The base class implementation does nothing.
+
+ This method is not called directly while drop handling is occurring,
+ so the limitations described in handleMimeData() about returning
+ quickly do not apply.
+ :rtype: bool
 %End
 };
 

python/plugins/processing/ProcessingPlugin.py

@@ -32,13 +32,16 @@
 import sys
 
 from qgis.core import (QgsApplication,
-                       QgsProcessingUtils)
-from qgis.gui import QgsOptionsWidgetFactory
+                       QgsProcessingUtils,
+                       QgsProcessingModelAlgorithm)
+from qgis.gui import (QgsOptionsWidgetFactory,
+                      QgsCustomDropHandler)
 from qgis.PyQt.QtCore import Qt, QCoreApplication, QDir
 from qgis.PyQt.QtWidgets import QMenu, QAction
 from qgis.PyQt.QtGui import QIcon
 
 from processing.core.Processing import Processing
+from processing.gui.AlgorithmDialog import AlgorithmDialog
 from processing.gui.ProcessingToolbox import ProcessingToolbox
 from processing.gui.HistoryDialog import HistoryDialog
 from processing.gui.ConfigDialog import ConfigOptionsPage
@@ -66,13 +69,32 @@ def createWidget(self, parent):
         return ConfigOptionsPage(parent)
 
 
+class ProcessingDropHandler(QgsCustomDropHandler):
+
+    def handleFileDrop(self, file):
+        if not file.lower().endswith('.model3'):
+            return False
+
+        alg = QgsProcessingModelAlgorithm()
+        if not alg.fromFile(file):
+            return False
+
+        alg.setProvider(QgsApplication.processingRegistry().providerById('model'))
+        dlg = AlgorithmDialog(alg)
+        dlg.setAttribute(Qt.WA_DeleteOnClose)
+        dlg.show()
+        return True
+
+
 class ProcessingPlugin(object):
 
     def __init__(self, iface):
         self.iface = iface
         self.options_factory = ProcessingOptionsFactory()
         self.options_factory.setTitle(self.tr('Processing'))
         iface.registerOptionsWidgetFactory(self.options_factory)
+        self.drop_handler = ProcessingDropHandler()
+        iface.registerCustomDropHandler(self.drop_handler)
         self.locator_filter = AlgorithmLocatorFilter()
         iface.registerLocatorFilter(self.locator_filter)
         Processing.initialize()
@@ -159,6 +181,7 @@ def unload(self):
 
         self.iface.unregisterOptionsWidgetFactory(self.options_factory)
         self.iface.deregisterLocatorFilter(self.locator_filter)
+        self.iface.unregisterCustomDropHandler(self.drop_handler)
 
         removeMenus()
         Processing.deinitialize()

src/app/qgisapp.cpp

@@ -1333,6 +1333,14 @@ void QgisApp::dropEvent( QDropEvent *event )
   timer->setSingleShot( true );
   timer->setInterval( 50 );
 
+  // first, allow custom handlers to directly operate on the mime data
+  const QList<QPointer<QgsCustomDropHandler >> handlers = mCustomDropHandlers;
+  for ( QgsCustomDropHandler *handler : handlers )
+  {
+    if ( handler )
+      handler->handleMimeData( event->mimeData() );
+  }
+
   // get the file list
   QList<QUrl>::iterator i;
   QList<QUrl>urls = event->mimeData()->urls();
@@ -1392,40 +1400,49 @@ void QgisApp::dropEvent( QDropEvent *event )
       files << fileName;
     }
   }
-  timer->setProperty( "files", files );
 
   QgsMimeDataUtils::UriList lst;
   if ( QgsMimeDataUtils::isUriList( event->mimeData() ) )
   {
     lst = QgsMimeDataUtils::decodeUriList( event->mimeData() );
   }
-  timer->setProperty( "uris", QVariant::fromValue( lst ) );
 
-  connect( timer, &QTimer::timeout, this, &QgisApp::dropEventTimeout );
+  connect( timer, &QTimer::timeout, this, [this, timer, files, lst]
+  {
+    freezeCanvases();
 
-  event->acceptProposedAction();
-  timer->start();
-}
+    for ( const QString &file : qgsAsConst( files ) )
+    {
+      bool handled = false;
 
-void QgisApp::dropEventTimeout()
-{
-  freezeCanvases();
-  QStringList files = sender()->property( "files" ).toStringList();
-  sender()->deleteLater();
+      // give custom drop handlers first priority at handling the file
+      const QList<QPointer<QgsCustomDropHandler >>handlers = mCustomDropHandlers;
+      for ( QgsCustomDropHandler *handler : handlers )
+      {
+        if ( handler && handler->handleFileDrop( file ) )
+        {
+          handled = true;
+          break;
+        }
+      }
 
-  Q_FOREACH ( const QString &file, files )
-  {
-    openFile( file );
-  }
+      if ( !handled )
+        openFile( file );
+    }
 
-  QgsMimeDataUtils::UriList lst = sender()->property( "uris" ).value<QgsMimeDataUtils::UriList>();
-  if ( !lst.isEmpty() )
-  {
-    handleDropUriList( lst );
-  }
+    if ( !lst.isEmpty() )
+    {
+      handleDropUriList( lst );
+    }
 
-  freezeCanvases( false );
-  refreshMapCanvas();
+    freezeCanvases( false );
+    refreshMapCanvas();
+
+    timer->deleteLater();
+  } );
+
+  event->acceptProposedAction();
+  timer->start();
 }
 
 void QgisApp::annotationCreated( QgsAnnotation *annotation )
@@ -1474,9 +1491,9 @@ void QgisApp::handleDropUriList( const QgsMimeDataUtils::UriList &lst )
     {
       Q_FOREACH ( QgsCustomDropHandler *handler, mCustomDropHandlers )
       {
-        if ( handler->key() == u.providerKey )
+        if ( handler && handler->customUriProviderKey() == u.providerKey )
         {
-          handler->handleDrop( u );
+          handler->handleCustomUriDrop( u );
           break;
         }
       }

src/app/qgisapp.h

@@ -1511,9 +1511,6 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     //! Set the layer for the map style dock. Doesn't show the style dock
     void setMapStyleDockLayer( QgsMapLayer *layer );
 
-    //! Handles processing of dropped mimedata
-    void dropEventTimeout();
-
     void annotationCreated( QgsAnnotation *annotation );
 
     void updateCrsStatusBar();
@@ -2056,7 +2053,7 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     QList<QgsMapLayerConfigWidgetFactory *> mMapLayerPanelFactories;
     QList<QPointer<QgsOptionsWidgetFactory>> mOptionsWidgetFactories;
 
-    QList<QgsCustomDropHandler *> mCustomDropHandlers;
+    QList<QPointer<QgsCustomDropHandler>> mCustomDropHandlers;
 
     QDateTime mProjectLastModified;
 

src/gui/CMakeLists.txt

@@ -385,6 +385,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgsconfigureshortcutsdialog.h
   qgscredentialdialog.h
   qgscurveeditorwidget.h
+  qgscustomdrophandler.h
   qgsdatumtransformdialog.h
   qgsdetaileditemdelegate.h
   qgsdetaileditemwidget.h
@@ -684,7 +685,6 @@ SET(QGIS_GUI_HDRS
   qgsattributeforminterface.h
   qgsattributeformlegacyinterface.h
   qgscursors.h
-  qgscustomdrophandler.h
   qgsdetaileditemdata.h
   qgsexpressionbuilderdialog.h
   qgsgeometryrubberband.h

src/gui/qgscustomdrophandler.cpp

@@ -14,3 +14,24 @@
  ***************************************************************************/
 
 #include "qgscustomdrophandler.h"
+
+QString QgsCustomDropHandler::customUriProviderKey() const
+{
+  return QString();
+}
+
+void QgsCustomDropHandler::handleCustomUriDrop( const QgsMimeDataUtils::Uri &uri ) const
+{
+  Q_UNUSED( uri );
+}
+
+void QgsCustomDropHandler::handleMimeData( const QMimeData *data )
+{
+  Q_UNUSED( data );
+}
+
+bool QgsCustomDropHandler::handleFileDrop( const QString &file )
+{
+  Q_UNUSED( file );
+  return false;
+}