viewer: click to select an ROI, with live move and a hand cursor

Clicking a box/circle on the image now selects it (syncing the side-panel
combobox) and grabs it for moving, with a closed-hand cursor during the
drag. The move recomputes ROI statistics live rather than only on release,
throttled to at most one in-flight recompute so the worker is not flooded.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

viewer/image_viewer/JFJochDiffractionImage.cpp

@@ -466,35 +466,39 @@ void JFJochDiffractionImage::setSelectedROI(QString name) {
 }
 
 bool JFJochDiffractionImage::roiEditPress(const QPointF &scenePos) {
-    if (!image || selected_roi_.isEmpty())
+    if (!image)
         return false;
 
     const auto &rois = image->Dataset().experiment.ROI().GetROIDefinition();
-    const std::string sel = selected_roi_.toStdString();
 
-    for (const auto &b : rois.boxes)
-        if (b.GetName() == sel) {
-            const QRectF r(QPointF(b.GetXMin(), b.GetYMin()), QPointF(b.GetXMax(), b.GetYMax()));
-            if (!r.contains(scenePos))
-                return false;
+    // Pick the first box/circle under the cursor, so an ROI can be grabbed by clicking it.
+    for (const auto &b : rois.boxes) {
+        const QRectF r(QPointF(b.GetXMin(), b.GetYMin()), QPointF(b.GetXMax(), b.GetYMax()));
+        if (r.contains(scenePos)) {
             roi_edit_ = RoiEdit::MoveBox;
-            edit_name_ = selected_roi_;
+            edit_name_ = QString::fromStdString(b.GetName());
             edit_box_ = r;
             move_last_ = scenePos;
+            selected_roi_ = edit_name_;
+            emit roiSelected(edit_name_);
+            setCursor(Qt::ClosedHandCursor);
             return true;
         }
-    for (const auto &c : rois.circles)
-        if (c.GetName() == sel) {
-            const QPointF center(c.GetX(), c.GetY());
-            if (QLineF(center, scenePos).length() > c.GetRadius_pxl())
-                return false;
+    }
+    for (const auto &c : rois.circles) {
+        const QPointF center(c.GetX(), c.GetY());
+        if (QLineF(center, scenePos).length() <= c.GetRadius_pxl()) {
             roi_edit_ = RoiEdit::MoveCircle;
-            edit_name_ = selected_roi_;
+            edit_name_ = QString::fromStdString(c.GetName());
             edit_center_ = center;
             edit_radius_ = c.GetRadius_pxl();
             move_last_ = scenePos;
+            selected_roi_ = edit_name_;
+            emit roiSelected(edit_name_);
+            setCursor(Qt::ClosedHandCursor);
             return true;
         }
+    }
     return false;   // azimuthal editing is not yet supported
 }
 
@@ -506,15 +510,28 @@ void JFJochDiffractionImage::roiEditMove(const QPointF &scenePos) {
     else if (roi_edit_ == RoiEdit::MoveCircle)
         edit_center_ += delta;
     updateOverlay();
+
+    // Live recompute, but keep at most one in flight (cleared in loadImage) so the
+    // worker is not flooded with edits faster than it can recompute them.
+    if (!live_pending_) {
+        live_pending_ = true;
+        emit roiGeometryEdited(BuildEditedROIDefinition());
+    }
 }
 
 void JFJochDiffractionImage::roiEditRelease() {
-    if (roi_edit_ == RoiEdit::None || !image) {
-        roi_edit_ = RoiEdit::None;
+    if (roi_edit_ == RoiEdit::None)
         return;
-    }
+    const ROIDefinition rois = BuildEditedROIDefinition();
+    roi_edit_ = RoiEdit::None;
+    setCursor(Qt::ArrowCursor);
+    emit roiGeometryEdited(rois);   // final, exact position
+}
 
-    ROIDefinition rois = image->Dataset().experiment.ROI().GetROIDefinition();
+ROIDefinition JFJochDiffractionImage::BuildEditedROIDefinition() const {
+    ROIDefinition rois;
+    if (image)
+        rois = image->Dataset().experiment.ROI().GetROIDefinition();
     const std::string sel = edit_name_.toStdString();
     if (roi_edit_ == RoiEdit::MoveBox) {
         for (auto &b : rois.boxes)
@@ -530,8 +547,7 @@ void JFJochDiffractionImage::roiEditRelease() {
                 break;
             }
     }
-    roi_edit_ = RoiEdit::None;
-    emit roiGeometryEdited(rois);
+    return rois;
 }
 
 
@@ -556,6 +572,7 @@ void JFJochDiffractionImage::setHDRMode(bool input) {
 }
 
 void JFJochDiffractionImage::loadImage(std::shared_ptr<const JFJochReaderImage> in_image) {
+    live_pending_ = false;   // a live ROI edit (if any) has now been recomputed
     if (in_image) {
         image = in_image;
         UpdateForeground();