From 35d28abd65908e884a8cf1258c54f9c34683a293 Mon Sep 17 00:00:00 2001
From: braks <78412429+bcakmakoglu@users.noreply.github.com>
Date: Wed, 1 Feb 2023 23:07:44 +0100
Subject: [PATCH] feat(core): add pan on connection drag

Signed-off-by: braks <78412429+bcakmakoglu@users.noreply.github.com>
---
 packages/core/src/composables/useHandle.ts | 24 ++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/packages/core/src/composables/useHandle.ts b/packages/core/src/composables/useHandle.ts
index 6c0f1fe7..b4a6c90d 100644
--- a/packages/core/src/composables/useHandle.ts
+++ b/packages/core/src/composables/useHandle.ts
@@ -35,7 +35,9 @@ export default function useHandle({
     connectionClickStartHandle,
     nodesConnectable,
     defaultEdgeOptions,
+    autoPanOnConnect,
     findNode,
+    panBy,
     getNodes,
     startConnection,
     updateConnection,
@@ -61,6 +63,8 @@ export default function useHandle({
 
       let prevClosestHandle: ConnectionHandle | null
 
+      let autoPanId = 0
+
       const { x, y } = getEventPosition(event)
       const clickedHandle = doc?.elementFromPoint(x, y)
       const handleType = getHandleType(unref(edgeUpdaterType), clickedHandle)
@@ -72,6 +76,7 @@ export default function useHandle({
 
       let prevActiveHandle: Element
       let connectionPosition = getEventPosition(event, containerBounds)
+      let autoPanStarted = false
 
       const handleLookup = getHandleLookup({
         nodes: getNodes.value,
@@ -80,6 +85,17 @@ export default function useHandle({
         handleType,
       })
 
+      // when the user is moving the mouse close to the edge of the canvas while connecting we move the canvas
+      const autoPan = () => {
+        if (!autoPanOnConnect) {
+          return
+        }
+        const [xMovement, yMovement] = calcAutoPan(connectionPosition, containerBounds)
+
+        panBy({ x: xMovement, y: yMovement })
+        autoPanId = requestAnimationFrame(autoPan)
+      }
+
       startConnection(
         {
           nodeId: unref(nodeId),
@@ -104,6 +120,11 @@ export default function useHandle({
           handleLookup,
         )
 
+        if (!autoPanStarted) {
+          autoPan()
+          autoPanStarted = true
+        }
+
         const { connection, handleDomNode, isValid } = isValidHandle(
           event,
           prevClosestHandle,
@@ -140,6 +161,9 @@ export default function useHandle({
       }
 
       function onPointerUp(event: MouseEvent | TouchEvent) {
+        cancelAnimationFrame(autoPanId)
+        autoPanStarted = false
+
         if (prevClosestHandle) {
           const { connection, isValid } = isValidHandle(
             event,