[SLD] Align the feeders' names horizontally (#747)

* Separate yShift computation for feeder nodes to align the labels' name
* Update unit tests
* Fix graph label position

Signed-off-by: BOUTIER Charly <charly.boutier@rte-france.com>
Co-authored-by: Florian Dupuy <florian.dupuy@rte-france.com>

Author: EstherDarkish

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/svg/AbstractLabelProvider.java

@@ -54,7 +54,7 @@ public List<NodeLabel> getNodeLabels(Node node, Direction direction) {
         if (node instanceof BusNode) {
             getLabelOrNameOrId(node).ifPresent(label -> nodeLabels.add(new NodeLabel(label, getBusLabelPosition(), null)));
         } else if (node instanceof FeederNode || svgParameters.isDisplayEquipmentNodesLabel() && node instanceof EquipmentNode) {
-            getLabelOrNameOrId(node).ifPresent(label -> nodeLabels.add(new NodeLabel(label, getLabelPosition(node, direction), null)));
+            getLabelOrNameOrId(node).ifPresent(label -> nodeLabels.add(new NodeLabel(label, getFeederLabelPosition(node, direction), null)));
         } else if (svgParameters.isDisplayConnectivityNodesId() && node instanceof ConnectivityNode) {
             nodeLabels.add(new NodeLabel(node.getId(), getLabelPosition(node, direction), null));
         }
@@ -100,22 +100,58 @@ protected LabelPosition getBusDecoratorPosition() {
         return new LabelPosition("BUS_DECORATOR", 35, -10, true, 0);
     }
 
+    protected LabelPosition getFeederLabelPosition(Node node, Direction direction) {
+        return new LabelPosition(getLabelPositionName(direction), getLabelXShift(),
+                getFeederLabelYShift(node, direction), svgParameters.isLabelCentered(), getLabelAngle(direction));
+    }
+
     protected LabelPosition getLabelPosition(Node node, Direction direction) {
-        double yShift = -LABEL_OFFSET;
-        String positionName = "";
-        double angle = 0;
-        if (direction != UNDEFINED) {
-            yShift = direction == TOP
-                    ? -LABEL_OFFSET
-                    : ((int) (componentLibrary.getSize(node.getComponentType()).getHeight()) + LABEL_OFFSET);
-            positionName = direction == TOP ? "N" : "S";
-            if (svgParameters.isLabelDiagonal()) {
-                angle = direction == TOP ? -svgParameters.getAngleLabelShift() : svgParameters.getAngleLabelShift();
-            }
+        return new LabelPosition(getLabelPositionName(direction), getLabelXShift(),
+                getLabelYShift(node, direction), svgParameters.isLabelCentered(), getLabelAngle(direction));
+    }
+
+    private double getLabelXShift() {
+        return svgParameters.isLabelCentered() ? 0 : -LABEL_OFFSET;
+    }
+
+    private double getLabelYShift(Node node, Direction direction) {
+        return direction != TOP
+                ? componentLibrary.getSize(node.getComponentType()).getHeight() + LABEL_OFFSET
+                : -LABEL_OFFSET;
+    }
+
+    private double getFeederLabelYShift(Node node, Direction direction) {
+        if (direction == UNDEFINED) {
+            return -LABEL_OFFSET;
         }
 
-        return new LabelPosition(positionName + "_LABEL",
-                svgParameters.isLabelCentered() ? 0 : -LABEL_OFFSET, yShift, svgParameters.isLabelCentered(), (int) angle);
+        // The FeederNode position is at the top-left position of the corresponding component.
+        // We first shift to half the component height to be back at the center of the component, knowing that
+        // all the FeederNode centers are on the same horizontal line.
+        double shiftToFeederComponentCenter = componentLibrary.getSize(node.getComponentType()).getHeight() / 2;
+
+        // Then we add a shift of half the max component height to be just above/just below all feeder components.
+        double shiftToFeederOut = (direction == TOP ? -1 : 1) * layoutParameters.getMaxComponentHeight() / 2;
+
+        // And finally we add an offset to be slightly above a component whose height is equal to the max height
+        double margin = (direction == TOP ? -1 : 1) * LABEL_OFFSET;
+
+        return shiftToFeederComponentCenter + shiftToFeederOut + margin;
+    }
+
+    private int getLabelAngle(Direction direction) {
+        if (!svgParameters.isLabelDiagonal()) {
+            return 0;
+        }
+        return (int) Math.round((direction == TOP ? -1 : 1) * svgParameters.getAngleLabelShift());
+    }
+
+    private String getLabelPositionName(Direction direction) {
+        return switch (direction) {
+            case TOP -> "N_LABEL";
+            case BOTTOM -> "S_LABEL";
+            default -> "LABEL";
+        };
     }
 
     protected LabelPosition getInternal2WTDecoratorPosition(Orientation orientation) {

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/svg/CustomLabelProvider.java

@@ -150,7 +150,7 @@ public List<NodeLabel> getNodeLabels(Node node, Direction direction) {
                     addNodeLabels(l, nodeLabels, getBusLabelPosition(), getAdditionalBusLabelPosition()));
         } else if (node instanceof FeederNode || svgParameters.isDisplayEquipmentNodesLabel() && node instanceof EquipmentNode) {
             getEquipmentLabel(node).ifPresent(l ->
-                    addNodeLabels(l, nodeLabels, getLabelPosition(node, direction), getAdditionalLabelPosition(node, direction)));
+                    addNodeLabels(l, nodeLabels, getFeederLabelPosition(node, direction), getAdditionalLabelPosition(node, direction)));
         } else if (svgParameters.isDisplayConnectivityNodesId() && node instanceof ConnectivityNode) {
             nodeLabels.add(new NodeLabel(node.getId(), getLabelPosition(node, direction), null));
         }

single-line-diagram/single-line-diagram-core/src/main/java/com/powsybl/sld/svg/DefaultSVGWriter.java

@@ -531,7 +531,7 @@ protected void drawGraphLabel(Element root, VoltageLevelGraph graph, GraphMetada
         Element gLabel = root.getOwnerDocument().createElement(GROUP);
         gLabel.setAttribute("id", idLabelVoltageLevel);
 
-        double yPos = graph.getY() - 20.;
+        double yPos = graph.getY() - 24.;
 
         String graphName = svgParameters.isUseName() ? graph.getVoltageLevelInfos().getName() : graph.getVoltageLevelInfos().getId();
         Element label = createLabelElement(graphName, graph.getX(), yPos, 0, gLabel);