[ImageGallery] Correctly set the selected index of the gallery model

The selected index was only being updated when the user clicked on an
image delegate in the gallery, but never when the `selectedViewId` was
changed from an external source, such as the Sequence Player or the 3D
Viewer.

`currentIndex` was correctly updated (meaning the navigation index of the
gallery was indeed correct, i.e. including the selected view) but
`selectedIndex` itself was never updated, so the highlight remained on the
previously selected image (even if it was out of the updated navigation
view).

Author: cbentejac

meshroom/ui/qml/ImageGallery/ImageGridView.qml

@@ -54,8 +54,11 @@ GridView {
     function updateCurrentIndexFromSelectionViewId() {
         if (!sortedModel) return
         var idx = sortedModel.find(_currentScene.selectedViewId, "viewId")
-        if (idx >= 0 && root.currentIndex !== idx) {
-            root.currentIndex = idx
+        if (idx >= 0) {
+            if (root.currentIndex !== idx) {
+                root.currentIndex = idx
+            }
+            sortedModel.selectedIndex = idx
         }
     }
 

meshroom/ui/qml/ImageGallery/ImageListView.qml

@@ -55,8 +55,11 @@ ListView {
     function updateCurrentIndexFromSelectionViewId() {
         if (!sortedModel) return
         var idx = sortedModel.find(_currentScene.selectedViewId, "viewId")
-        if (idx >= 0 && root.currentIndex !== idx) {
-            root.currentIndex = idx
+        if (idx >= 0) {
+            if (root.currentIndex !== idx) {
+                root.currentIndex = idx
+            }
+            sortedModel.selectedIndex = idx
         }
     }