[ui] drag&drop: common behavior for graph editor and image gallery

In Image Gallery :
- drop 1 .mg open the scene
- drop images either create new camera or augment the reconstruction

In Graph Editor :
- drop 1 .mg open the scene
- drop images create new camera at position of mouse

meshroom/ui/qml/GraphEditor/GraphEditor.qml

@@ -29,6 +29,9 @@ Item {
     signal computeRequest(var node)
     signal submitRequest(var node)
 
+    // Files have been dropped
+    signal filesDropped(var drop, var mousePosition)
+
     // trigger initial fit() after initialization
     // (ensure GraphEditor has its final size)
     Component.onCompleted: firstFitTimer.start()
@@ -705,6 +708,20 @@ Item {
         Item {
             id: boxSelectDraggable
         }
+
+        DropArea {
+            id: dropArea
+            anchors.fill: parent
+            keys: ["text/uri-list"]
+            onDropped: {
+                // retrieve mouse position and convert coordinate system
+                // from pixel values to graph reference system
+                var mousePosition = mapToItem(draggable, drag.x, drag.y)
+                // send the list of files,
+                // to create the corresponding nodes or open another scene
+                filesDropped(drop, mousePosition)
+            }
+        }
     }
 
     // Toolbar

meshroom/ui/qml/ImageGallery/ImageGallery.qml

@@ -28,6 +28,9 @@ Panel {
     property int defaultCellSize: 160
     property bool readOnly: false
 
+    property bool isMeshroomScene : false
+    property int nbFilesDropped: 0
+
     signal removeImageRequest(var attribute)
     signal allViewpointsCleared()
     signal filesDropped(var drop, var augmentSfm)
@@ -438,7 +441,16 @@ Panel {
                 anchors.fill: parent
                 enabled: !m.readOnly && !intrinsicsFilterButton.checked
                 keys: ["text/uri-list"]
-                // TODO: onEntered: call specific method to filter files based on extension
+                onEntered: {
+                    isMeshroomScene = false
+                    nbFilesDropped = drag.urls.length
+                    if (nbFilesDropped == 1){
+                        var url = drag.urls[0]
+                        if (url.endsWith(".mg")){
+                            isMeshroomScene = true
+                        }
+                    }
+                }
                 onDropped: {
                     var augmentSfm = augmentArea.hovered
                     root.filesDropped(drop, augmentSfm)
@@ -463,7 +475,17 @@ Panel {
                         Layout.fillHeight: true
                         horizontalAlignment: Text.AlignHCenter
                         verticalAlignment: Text.AlignVCenter
-                        text: "Add Images"
+                        text: {
+                            if (isMeshroomScene) {
+                                if(nbFilesDropped == 1) {
+                                    return "Load Project"
+                                } else {
+                                    return "Only one project"
+                                }
+                            }else if (!isMeshroomScene){
+                                return "Add Images"
+                            }
+                        }
                         font.bold: true
                         background: Rectangle {
                             color: parent.hovered ? parent.palette.highlight : parent.palette.window
@@ -483,7 +505,15 @@ Panel {
                         text: "Augment Reconstruction"
                         font.bold: true
                         wrapMode: Text.WrapAtWordBoundaryOrAnywhere
-                        visible: m.viewpoints ? m.viewpoints.count > 0 : false
+                        visible: {
+                            if(isMeshroomScene)
+                                return false
+                            if(m.viewpoints){
+                                return m.viewpoints.count > 0
+                            }else{
+                                return false
+                            }
+                        }
                         background: Rectangle {
                             color: parent.hovered ? palette.highlight : palette.window
                             opacity: 0.8

meshroom/ui/qml/WorkspaceView.qml

@@ -80,7 +80,9 @@ Item {
                 cameraInitIndex: reconstruction ? reconstruction.cameraInitIndex : -1
                 onRemoveImageRequest: reconstruction.removeAttribute(attribute)
                 onAllViewpointsCleared: { reconstruction.removeAllImages(); reconstruction.selectedViewId = "-1" }
-                onFilesDropped: reconstruction.handleFilesDrop(drop, augmentSfm ? null : cameraInit)
+                onFilesDropped: {
+                    reconstruction.handleFilesUrl(drop.urls, augmentSfm ? null : cameraInit)
+                }
             }
             LiveSfmView {
                 visible: settings_UILayout.showLiveReconstruction

meshroom/ui/qml/main.qml

@@ -1186,6 +1186,9 @@ ApplicationWindow {
                         _reconstruction.forceNodesStatusUpdate();
                         computeManager.submit(node)
                     }
+                    onFilesDropped: {
+                        _reconstruction.handleFilesUrl(drop.urls, null, mousePosition)
+                    }
                 }
 
                 TaskManager {

meshroom/ui/reconstruction.py

@@ -6,7 +6,7 @@ from collections.abc import Iterable
 from multiprocessing.pool import ThreadPool
 from threading import Thread
 
-from PySide2.QtCore import QObject, Slot, Property, Signal, QUrl, QSizeF
+from PySide2.QtCore import QObject, Slot, Property, Signal, QUrl, QSizeF, QPoint
 from PySide2.QtGui import QMatrix4x4, QMatrix3x3, QQuaternion, QVector3D, QVector2D
 
 import meshroom.core
@@ -716,14 +716,24 @@ class Reconstruction(UIGraph):
         """ Get all view Ids involved in the reconstruction. """
         return [vp.viewId.value for node in self._cameraInits for vp in node.viewpoints.value]
 
-    @Slot(QObject, Node)
-    def handleFilesDrop(self, drop, cameraInit):
+    @Slot('QList<QUrl>')
+    @Slot('QList<QUrl>', Node)
+    @Slot('QList<QUrl>', Node, 'QPoint')
+    def handleFilesUrl(self, urls, cameraInit=None, position=None):
         """ Handle drop events aiming to add images to the Reconstruction.
-        Fetching urls from dropEvent is generally expensive in QML/JS (bug ?).
         This method allows to reduce process time by doing it on Python side.
         """
-        filesByType = self.getFilesByTypeFromDrop(drop)
+        filesByType = self.getFilesByTypeFromDrop(urls)
         if filesByType.images:
+            if cameraInit is None:
+                boundingBox = self.layout.boundingBox()
+                if not position:
+                    p = Position(boundingBox[0], boundingBox[1] + boundingBox[3])
+                elif isinstance(position, QPoint):
+                    p = Position(position.x(), position.y())
+                else:
+                    p = position
+                cameraInit = self.addNewNode("CameraInit", position=p)
             self._workerThreads.apply_async(func=self.importImagesSync, args=(filesByType.images, cameraInit,))
         if filesByType.videos:
             boundingBox = self.layout.boundingBox()
@@ -773,6 +783,14 @@ class Reconstruction(UIGraph):
 
         if not filesByType.images and not filesByType.videos and not filesByType.panoramaInfo:
             if filesByType.other:
+                singleMgFile = False
+                if len(filesByType.other) == 1:
+                    url = filesByType.other[0]
+                    ext = os.path.splitext(url)[1]
+                    if ext == '.mg':
+                        self.loadUrl(url)
+                        singleMgFile = True
+                if not singleMgFile:
                     extensions = set([os.path.splitext(url)[1] for url in filesByType.other])
                     self.error.emit(
                         Message(
@@ -783,16 +801,15 @@ class Reconstruction(UIGraph):
                     )
 
     @staticmethod
-    def getFilesByTypeFromDrop(drop):
+    def getFilesByTypeFromDrop(urls):
         """
 
         Args:
-            drop:
+            urls: list of filepaths
 
         Returns:
             <images, otherFiles> List of recognized images and list of other files
         """
-        urls = drop.property("urls")
         # Build the list of images paths
         filesByType = multiview.FilesByType()
         for url in urls: