Implement new features for svg components + improve form properties (#25)

- Make Dimension an actual svg line
- Implement XPositionReference
- Select the container above after delete
- Remove DimensionLayer
- Improve form properties

Reviewed-on: https://git.siklos-chaneru.duckdns.org/Siklos/svg-layout-designer-react/pulls/25

src/Components/Editor/ContainerOperations.ts

@@ -55,7 +55,9 @@ export function DeleteContainer(
     throw new Error(`[DeleteContainer] Tried to delete a container that is not present in the main container: ${containerId}`);
   }
 
-  if (container === mainContainerClone) {
+  if (container === mainContainerClone ||
+    container.parent === undefined ||
+    container.parent === null) {
     // TODO: Implement alert
     throw new Error('[DeleteContainer] Tried to delete the main container! Deleting the main container is not allowed!');
   }
@@ -64,18 +66,25 @@ export function DeleteContainer(
     throw new Error('[DeleteContainer] Container model was not found among children of the main container!');
   }
 
-  if (container.parent != null) {
-    const index = container.parent.children.indexOf(container);
-    if (index > -1) {
-      container.parent.children.splice(index, 1);
-    }
+  const index = container.parent.children.indexOf(container);
+  if (index > -1) {
+    container.parent.children.splice(index, 1);
+  } else {
+    throw new Error('[DeleteContainer] Could not find container among parent\'s children');
   }
 
+  // Select the previous container
+  // or select the one above
+  const SelectedContainer = findContainerById(mainContainerClone, current.SelectedContainerId) ??
+    container.parent.children.at(index - 1) ??
+    container.parent;
+  const SelectedContainerId = SelectedContainer.properties.id;
+
   setHistory(history.concat([{
     LastAction: `Delete container ${containerId}`,
     MainContainer: mainContainerClone,
-    SelectedContainer: null,
-    SelectedContainerId: '',
+    SelectedContainer,
+    SelectedContainerId,
     TypeCounters: Object.assign({}, current.TypeCounters)
   }]));
   setHistoryCurrentStep(history.length);
@@ -182,6 +191,7 @@ export function AddContainer(
       width: properties?.Width,
       height: parentClone.properties.height,
       isRigidBody: false,
+      XPositionReference: properties.XPositionReference,
       ...properties.Style
     },
     [],