fix(editor): Support middle click to scroll when using a mouse on new canvas (#11384)

packages/editor-ui/src/components/canvas/Canvas.spec.ts

@@ -220,4 +220,20 @@ describe('Canvas', () => {
 			expect(container.querySelector('#diagonalHatch')).toBeInTheDocument();
 		});
 	});
+
+	describe('pane', () => {
+		describe('onPaneMouseDown', () => {
+			it('should enable panning when middle mouse button is pressed', async () => {
+				const { getByTestId } = renderComponent();
+				const canvas = getByTestId('canvas');
+				const pane = canvas.querySelector('.vue-flow__pane');
+
+				if (!pane) throw new Error('VueFlow pane not in the document');
+
+				await fireEvent.mouseDown(canvas, { button: 1, view: window });
+
+				expect(canvas).toHaveClass('draggable');
+			});
+		});
+	});
 });

packages/editor-ui/src/components/canvas/Canvas.vue

@@ -43,6 +43,7 @@ import { onKeyDown, onKeyUp, useDebounceFn } from '@vueuse/core';
 import CanvasArrowHeadMarker from './elements/edges/CanvasArrowHeadMarker.vue';
 import { CanvasNodeRenderType } from '@/types';
 import CanvasBackgroundStripedPattern from './elements/CanvasBackgroundStripedPattern.vue';
+import { isMiddleMouseButton } from '@/utils/eventUtils';
 
 const $style = useCssModule();
 
@@ -107,6 +108,7 @@ const props = withDefaults(
 );
 
 const {
+	vueFlowRef,
 	getSelectedNodes: selectedNodes,
 	addSelectedNodes,
 	removeSelectedNodes,
@@ -143,18 +145,16 @@ const disableKeyBindings = computed(() => !props.keyBindings);
  * @see https://developer.mozilla.org/en-US/docs/Web/API/UI_Events/Keyboard_event_key_values#whitespace_keys
  */
 
-const isPanningEnabled = ref(false);
 const panningKeyCode = ' ';
+const isPanningEnabled = ref(false);
 const selectionKeyCode = ref<true | null>(true);
 
 onKeyDown(panningKeyCode, () => {
-	isPanningEnabled.value = true;
-	selectionKeyCode.value = null;
+	setPanningEnabled(true);
 });
 
 onKeyUp(panningKeyCode, () => {
-	isPanningEnabled.value = false;
-	selectionKeyCode.value = true;
+	setPanningEnabled(false);
 });
 
 const keyMap = computed(() => ({
@@ -186,6 +186,16 @@ const keyMap = computed(() => ({
 
 useKeybindings(keyMap, { disabled: disableKeyBindings });
 
+function setPanningEnabled(value: boolean) {
+	if (value) {
+		isPanningEnabled.value = true;
+		selectionKeyCode.value = null;
+	} else {
+		isPanningEnabled.value = false;
+		selectionKeyCode.value = true;
+	}
+}
+
 /**
  * When the window is focused, the selection key code is lost.
  * We trigger a value refresh to ensure that the selection key code is set correctly again.
@@ -384,12 +394,28 @@ function setReadonly(value: boolean) {
 	elementsSelectable.value = true;
 }
 
+function onPaneMouseDown(event: MouseEvent) {
+	if (isMiddleMouseButton(event)) {
+		setPanningEnabled(true);
+
+		// Re-emit the event to start panning after setting the panning state to true
+		// This workaround is necessary because the Vue Flow library does not provide a way to
+		// start panning programmatically
+		void nextTick(() =>
+			vueFlowRef.value
+				?.querySelector('.vue-flow__pane')
+				?.dispatchEvent(new MouseEvent('mousedown', event)),
+		);
+	}
+}
+
 function onPaneMoveStart() {
 	isPaneMoving.value = true;
 }
 
 function onPaneMoveEnd() {
 	isPaneMoving.value = false;
+	setPanningEnabled(false);
 }
 
 /**
@@ -559,6 +585,7 @@ provide(CanvasKey, {
 		@nodes-change="onNodesChange"
 		@move-start="onPaneMoveStart"
 		@move-end="onPaneMoveEnd"
+		@mousedown="onPaneMouseDown"
 	>
 		<template #node-canvas-node="canvasNodeProps">
 			<Node
@@ -647,6 +674,10 @@ provide(CanvasKey, {
 		cursor: grab;
 	}
 
+	:global(.vue-flow__pane) {
+		cursor: default;
+	}
+
 	:global(.vue-flow__pane.dragging) {
 		cursor: grabbing;
 	}

packages/editor-ui/src/styles/plugins/_vueflow.scss

@@ -58,17 +58,6 @@
 	}
 }
 
-/**
- * Pane
- */
-
-.vue-flow__pane {
-	&,
-	&.draggable {
-		cursor: default;
-	}
-}
-
 /**
  * Nodes
  */

packages/editor-ui/src/utils/eventUtils.ts

@@ -0,0 +1,3 @@
+export function isMiddleMouseButton(event: MouseEvent) {
+	return event.which === 2 || event.button === 1;
+}