From d6a6eb82d804fc1e7e2d1092ff5cf083fd56277e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christopher=20Mo=CC=88ller?= <chrtze@gmail.com>
Date: Thu, 29 Oct 2020 17:57:31 +0100
Subject: [PATCH] refactor pan/zoom behaviour, implement pan on scroll #359,
 edit interaction example

---
 example/src/Interaction/index.js     | 32 ++++++++++----
 src/container/FlowRenderer/index.tsx |  4 ++
 src/container/GraphView/index.tsx    |  4 ++
 src/container/ReactFlow/index.tsx    |  3 ++
 src/hooks/useD3Zoom.ts               | 65 ++++++++++++++++++----------
 src/store/index.ts                   | 21 +++++++++
 6 files changed, 96 insertions(+), 33 deletions(-)

diff --git a/example/src/Interaction/index.js b/example/src/Interaction/index.js
index af7aafd9..ba2f11fa 100644
--- a/example/src/Interaction/index.js
+++ b/example/src/Interaction/index.js
@@ -26,6 +26,7 @@ const InteractionFlow = () => {
   const [isDraggable, setIsDraggable] = useState(false);
   const [isConnectable, setIsConnectable] = useState(false);
   const [zoomOnScroll, setZoomOnScroll] = useState(false);
+  const [panOnScroll, setPanOnScroll] = useState(true);
   const [zoomOnDoubleClick, setZoomOnDoubleClick] = useState(false);
   const [paneMoveable, setPaneMoveable] = useState(true);
   const [captureZoomClick, setCaptureZoomClick] = useState(false);
@@ -39,6 +40,7 @@ const InteractionFlow = () => {
       nodesConnectable={isConnectable}
       nodesDraggable={isDraggable}
       zoomOnScroll={zoomOnScroll}
+      panOnScroll={panOnScroll}
       zoomOnDoubleClick={zoomOnDoubleClick}
       onConnect={onConnect}
       onElementClick={captureElementClick ? onElementClick : undefined}
@@ -55,7 +57,7 @@ const InteractionFlow = () => {
       <div style={{ position: 'absolute', left: 10, top: 10, zIndex: 4 }}>
         <div>
           <label htmlFor="draggable">
-            draggable
+            nodesDraggable
             <input
               id="draggable"
               type="checkbox"
@@ -67,7 +69,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="connectable">
-            connectable
+            nodesConnectable
             <input
               id="connectable"
               type="checkbox"
@@ -79,7 +81,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="selectable">
-            selectable
+            elementsSelectable
             <input
               id="selectable"
               type="checkbox"
@@ -91,7 +93,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="zoomonscroll">
-            zoom on scroll
+            zoomOnScroll
             <input
               id="zoomonscroll"
               type="checkbox"
@@ -101,9 +103,21 @@ const InteractionFlow = () => {
             />
           </label>
         </div>
+        <div>
+          <label htmlFor="panonscroll">
+            panOnScroll
+            <input
+              id="panonscroll"
+              type="checkbox"
+              checked={panOnScroll}
+              onChange={(event) => setPanOnScroll(event.target.checked)}
+              className="react-flow__panonscroll"
+            />
+          </label>
+        </div>
         <div>
           <label htmlFor="zoomondbl">
-            zoom on double click
+            zoomOnDoubleClick
             <input
               id="zoomondbl"
               type="checkbox"
@@ -115,7 +129,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="panemoveable">
-            pane moveable
+            paneMoveable
             <input
               id="panemoveable"
               type="checkbox"
@@ -127,7 +141,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="capturezoompaneclick">
-            capture zoom pane click
+            capture onPaneClick
             <input
               id="capturezoompaneclick"
               type="checkbox"
@@ -139,7 +153,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="capturezoompanescroll">
-            capture zoom pane scroll
+            capture onPaneScroll
             <input
               id="capturezoompanescroll"
               type="checkbox"
@@ -151,7 +165,7 @@ const InteractionFlow = () => {
         </div>
         <div>
           <label htmlFor="captureelementclick">
-            capture element click
+            capture onElementClick
             <input
               id="captureelementclick"
               type="checkbox"
diff --git a/src/container/FlowRenderer/index.tsx b/src/container/FlowRenderer/index.tsx
index da3f8e1b..83b9be95 100644
--- a/src/container/FlowRenderer/index.tsx
+++ b/src/container/FlowRenderer/index.tsx
@@ -36,7 +36,9 @@ const FlowRenderer = ({
   onMoveStart,
   onMoveEnd,
   selectionKeyCode,
+  elementsSelectable,
   zoomOnScroll,
+  panOnScroll,
   zoomOnDoubleClick,
   paneMoveable,
   defaultPosition,
@@ -61,7 +63,9 @@ const FlowRenderer = ({
     onMoveStart,
     onMoveEnd,
     selectionKeyPressed,
+    elementsSelectable,
     zoomOnScroll,
+    panOnScroll,
     zoomOnDoubleClick,
     paneMoveable,
     defaultPosition,
diff --git a/src/container/GraphView/index.tsx b/src/container/GraphView/index.tsx
index 0dcafc0f..07fb32d5 100644
--- a/src/container/GraphView/index.tsx
+++ b/src/container/GraphView/index.tsx
@@ -70,6 +70,7 @@ export interface GraphViewProps {
   arrowHeadColor: string;
   markerEndId?: string;
   zoomOnScroll?: boolean;
+  panOnScroll?: boolean;
   zoomOnDoubleClick?: boolean;
   paneMoveable?: boolean;
 }
@@ -118,6 +119,7 @@ const GraphView = ({
   arrowHeadColor,
   markerEndId,
   zoomOnScroll,
+  panOnScroll,
   zoomOnDoubleClick,
   paneMoveable,
   onPaneClick,
@@ -245,11 +247,13 @@ const GraphView = ({
       onElementsRemove={onElementsRemove}
       deleteKeyCode={deleteKeyCode}
       selectionKeyCode={selectionKeyCode}
+      elementsSelectable={elementsSelectable}
       onMove={onMove}
       onMoveStart={onMoveStart}
       onMoveEnd={onMoveEnd}
       zoomOnScroll={zoomOnScroll}
       zoomOnDoubleClick={zoomOnDoubleClick}
+      panOnScroll={panOnScroll}
       paneMoveable={paneMoveable}
       defaultPosition={defaultPosition}
       defaultZoom={defaultZoom}
diff --git a/src/container/ReactFlow/index.tsx b/src/container/ReactFlow/index.tsx
index dd6d0507..2edbbd8c 100644
--- a/src/container/ReactFlow/index.tsx
+++ b/src/container/ReactFlow/index.tsx
@@ -98,6 +98,7 @@ export interface ReactFlowProps extends Omit<HTMLAttributes<HTMLDivElement>, 'on
   arrowHeadColor?: string;
   markerEndId?: string;
   zoomOnScroll?: boolean;
+  panOnScroll?: boolean;
   zoomOnDoubleClick?: boolean;
 }
 
@@ -147,6 +148,7 @@ const ReactFlow = ({
   arrowHeadColor = '#b1b1b7',
   markerEndId,
   zoomOnScroll = true,
+  panOnScroll = false,
   zoomOnDoubleClick = true,
   paneMoveable = true,
   onPaneClick,
@@ -203,6 +205,7 @@ const ReactFlow = ({
           markerEndId={markerEndId}
           zoomOnScroll={zoomOnScroll}
           zoomOnDoubleClick={zoomOnDoubleClick}
+          panOnScroll={panOnScroll}
           paneMoveable={paneMoveable}
           onPaneClick={onPaneClick}
           onPaneScroll={onPaneScroll}
diff --git a/src/hooks/useD3Zoom.ts b/src/hooks/useD3Zoom.ts
index 48f15ffc..07d6a1e6 100644
--- a/src/hooks/useD3Zoom.ts
+++ b/src/hooks/useD3Zoom.ts
@@ -6,7 +6,9 @@ import { FlowTransform, TranslateExtent } from '../types';
 interface UseD3ZoomParams {
   zoomPane: MutableRefObject<Element | null>;
   selectionKeyPressed: boolean;
+  elementsSelectable?: boolean;
   zoomOnScroll?: boolean;
+  panOnScroll?: boolean;
   zoomOnDoubleClick?: boolean;
   paneMoveable?: boolean;
   defaultPosition?: [number, number];
@@ -34,8 +36,10 @@ export default ({
   onMoveStart,
   onMoveEnd,
   zoomOnScroll = true,
+  panOnScroll = false,
   zoomOnDoubleClick = true,
   selectionKeyPressed,
+  elementsSelectable,
   paneMoveable = true,
   defaultPosition = [0, 0],
   defaultZoom = 1,
@@ -46,6 +50,7 @@ export default ({
 
   const initD3 = useStoreActions((actions) => actions.initD3);
   const updateTransform = useStoreActions((actions) => actions.updateTransform);
+  const updateTransformDelta = useStoreActions((actions) => actions.updateTransformDelta);
 
   useEffect(() => {
     if (zoomPane.current) {
@@ -55,20 +60,22 @@ export default ({
 
   useEffect(() => {
     if (d3Zoom) {
-      if (selectionKeyPressed) {
-        d3Zoom.on('zoom', null);
-      } else {
-        d3Zoom.on('zoom', (event: any) => {
+      d3Zoom.on('zoom', (event: any) => {
+        if (panOnScroll && event.sourceEvent.type === 'wheel') {
+          const { deltaX, deltaY } = event.sourceEvent;
+          updateTransformDelta({ x: deltaX, y: deltaY });
+        } else {
           updateTransform(event.transform);
 
+          // todo: should we move this into the store or into a wrapper component with useEffect?
           if (onMove) {
             const flowTransform = eventToFlowTransform(event.transform);
             onMove(flowTransform);
           }
-        });
-      }
+        }
+      });
     }
-  }, [selectionKeyPressed, d3Zoom, updateTransform, onMove]);
+  }, [selectionKeyPressed, panOnScroll, d3Zoom, updateTransform, updateTransformDelta, onMove]);
 
   useEffect(() => {
     if (d3Zoom) {
@@ -107,34 +114,44 @@ export default ({
   useEffect(() => {
     if (d3Zoom) {
       d3Zoom.filter((event: any) => {
-        if (selectionKeyPressed) {
+        // if all interactions are disabled, we prevent all zoom events
+        if (!paneMoveable && !zoomOnScroll && !panOnScroll && !zoomOnDoubleClick) {
           return false;
         }
 
-        // only allow zoom on nodes
-        if (event.target.closest('.react-flow__node') && event.type !== 'wheel') {
-          return false;
-        }
-
-        // only allow zoom on user selection
-        if (event.target.closest('.react-flow__nodesselection') && event.type !== 'wheel') {
-          return false;
-        }
-
-        if (!paneMoveable) {
-          return false;
-        }
-
-        if (!zoomOnScroll && event.type === 'wheel') {
+        // during a selection we prevent all other interactions
+        if (elementsSelectable && selectionKeyPressed) {
           return false;
         }
 
+        // if zoom on double click is disabled, we prevent the double click event
         if (!zoomOnDoubleClick && event.type === 'dblclick') {
           return false;
         }
 
+        // when the target element is a node, we still allow zooming
+        if (event.target.closest('.react-flow__node') && event.type !== 'wheel') {
+          return false;
+        }
+
+        // when the target element is a node selection, we still allow zooming
+        if (event.target.closest('.react-flow__nodesselection') && event.type !== 'wheel') {
+          return false;
+        }
+
+        // when there is no scroll handling enabled, we prevent all wheel events
+        if (!zoomOnScroll && !panOnScroll && event.type === 'wheel') {
+          return false;
+        }
+
+        // if the pane is not movable, we prevent dragging it with the mouse
+        if (!paneMoveable && event.type === 'mousedown') {
+          return false;
+        }
+
+        // default filter for d3-zoom, prevents zooming on buttons and when ctrl is pressed
         return !event.ctrlKey && !event.button;
       });
     }
-  }, [d3Zoom, zoomOnScroll, zoomOnDoubleClick, paneMoveable, selectionKeyPressed]);
+  }, [d3Zoom, zoomOnScroll, panOnScroll, zoomOnDoubleClick, paneMoveable, selectionKeyPressed, elementsSelectable]);
 };
diff --git a/src/store/index.ts b/src/store/index.ts
index d55d04b1..d08c6c61 100644
--- a/src/store/index.ts
+++ b/src/store/index.ts
@@ -37,6 +37,12 @@ type TransformXYK = {
   k: number;
 };
 
+type TransformDeltas = {
+  x?: number;
+  y?: number;
+  k?: number;
+};
+
 type NodeDimensionUpdate = {
   id: ElementId;
   nodeElement: HTMLDivElement;
@@ -109,6 +115,7 @@ export interface StoreModel {
   setSelectedElements: Action<StoreModel, Elements | Node | Edge>;
 
   updateTransform: Action<StoreModel, TransformXYK>;
+  updateTransformDelta: Action<StoreModel, TransformDeltas>;
 
   setInitTransform: Action<StoreModel, TransformXYK>;
 
@@ -351,6 +358,20 @@ export const storeModel: StoreModel = {
     state.transform[2] = transform.k;
   }),
 
+  updateTransformDelta: action((state, deltas) => {
+    const { x = 0, y = 0, k = 0 } = deltas;
+
+    state.transform[0] += x;
+    state.transform[1] += y;
+    state.transform[2] += k;
+
+    if (state.d3Selection) {
+      const updatedTransform = zoomIdentity.translate(state.transform[0], state.transform[1]).scale(state.transform[2]);
+      // we need to sync the d3 zoom transform with the updated transform
+      state.d3Selection.property('__zoom', updatedTransform);
+    }
+  }),
+
   setInitTransform: action((state, transform) => {
     state.transform[0] = transform.x;
     state.transform[1] = transform.y;