Write container property into edges only in CONTAINER mode

Also, mention this in the docs.
eclipse-elk · Aug 29, 2024 · 2312415 · 2312415
1 parent 5d7cf1a
commit 2312415
Show file tree

Hide file tree

Showing 3 changed files with 29 additions and 39 deletions.
diff --git a/docs/content/documentation/tooldevelopers/graphdatastructure/coordinatesystem.md b/docs/content/documentation/tooldevelopers/graphdatastructure/coordinatesystem.md
@@ -49,12 +49,16 @@ There are four possible values:
 * `PARENT`: Coordinates are relative to the node in which the edge was defined in the given JSON.
 * `ROOT`: Coordinates are relative to the root node, i.e. global coordinates.
 
-The default value is `INHERIT`, except at the root node, where the default is `CONTAINER`.
+The default value is `INHERIT`, except at the root node, where the default is (for historical reasons) `CONTAINER`.
 Thus, the default behavior is as described at the top of this page.
 
-Edge containment is a tricky subject, and the definition of an edge's proper container is given at the end
-of the page on the
+The definition of an edge's proper container is given at the end of the page on the
 [_Graph Data Structure_]({{< relref "documentation/tooldevelopers/graphdatastructure.md" >}}).
-Since you are allowed to define an edge under any node whatsoever in the input JSON, the edge's *parent* node
-(the one it is defined under) may be different from the edge's *container*. Therefore, while `CONTAINER` is the
-default mode for historical reasons, users may find it easier to use `PARENT` or `ROOT`.
+It involves lowest common ancestors, and can be tricky to compute correctly.
+In particular, since you are allowed to define an edge under any node whatsoever in the input JSON, the edge's
+*parent* node (the one it is defined under) may be different from its container.
+
+If you elect to work in `CONTAINER` mode, ELK helps you by writing a `container` property into each edge after layout,
+giving the `id` of the edge's container node. This can then be used to interpret the coordinates.
+
+If you elect to work in `PARENT` or `ROOT` mode instead, then you do not need to know about edge containers at all.
diff --git a/plugins/org.eclipse.elk.graph.json/src/org/eclipse/elk/graph/json/JsonImporter.xtend b/plugins/org.eclipse.elk.graph.json/src/org/eclipse/elk/graph/json/JsonImporter.xtend
@@ -670,7 +670,9 @@ final class JsonImporter {
             }
         }
 
-        jsonObj.addJsonObj("container", edge.getContainingNode.identifier)
+        if (edge.originalParent.edgeCoordsMode === EdgeCoords.CONTAINER) {
+            jsonObj.addJsonObj("container", edge.getContainingNode.identifier)
+        }
     }
 
     private def dispatch transferLayoutInt2(ElkLabel label) {

diff --git a/.../org.eclipse.elk.graph.json.test/src/org/eclipse/elk/graph/json/test/EdgeCoordsTest.xtend b/.../org.eclipse.elk.graph.json.test/src/org/eclipse/elk/graph/json/test/EdgeCoordsTest.xtend
@@ -412,8 +412,7 @@ class EdgeCoordsTest {
              "incomingShape": "y",
              "outgoingShape": "z"
             }
-           ],
-           "container": "B"
+           ]
           },
           {
            "id": "e2",
@@ -464,8 +463,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "z"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e3",
@@ -489,8 +487,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "p"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e4",
@@ -514,8 +511,7 @@ class EdgeCoordsTest {
              "incomingShape": "p",
              "outgoingShape": "y"
             }
-           ],
-           "container": "B"
+           ]
           }
          ],
          "x": 143,
@@ -625,8 +621,7 @@ class EdgeCoordsTest {
              "incomingShape": "y",
              "outgoingShape": "z"
             }
-           ],
-           "container": "B"
+           ]
           },
           {
            "id": "e2",
@@ -677,8 +672,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "z"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e3",
@@ -702,8 +696,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "p"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e4",
@@ -727,8 +720,7 @@ class EdgeCoordsTest {
              "incomingShape": "p",
              "outgoingShape": "y"
             }
-           ],
-           "container": "B"
+           ]
           }
          ],
          "x": 143,
@@ -1051,8 +1043,7 @@ class EdgeCoordsTest {
              "incomingShape": "y",
              "outgoingShape": "z"
             }
-           ],
-           "container": "B"
+           ]
           },
           {
            "id": "e2",
@@ -1103,8 +1094,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "z"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e3",
@@ -1128,8 +1118,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "p"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e4",
@@ -1153,8 +1142,7 @@ class EdgeCoordsTest {
              "incomingShape": "p",
              "outgoingShape": "y"
             }
-           ],
-           "container": "B"
+           ]
           }
          ],
          "x": 155,
@@ -1265,8 +1253,7 @@ class EdgeCoordsTest {
              "incomingShape": "y",
              "outgoingShape": "z"
             }
-           ],
-           "container": "B"
+           ]
           },
           {
            "id": "e2",
@@ -1317,8 +1304,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "z"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e3",
@@ -1342,8 +1328,7 @@ class EdgeCoordsTest {
              "incomingShape": "x",
              "outgoingShape": "p"
             }
-           ],
-           "container": "A"
+           ]
           },
           {
            "id": "e4",
@@ -1367,8 +1352,7 @@ class EdgeCoordsTest {
              "incomingShape": "p",
              "outgoingShape": "y"
             }
-           ],
-           "container": "B"
+           ]
           }
          ],
          "x": 155,