From f56656929992b98a3473944fd2a395e05d5c42f0 Mon Sep 17 00:00:00 2001
From: Alex Grozav <alex@grozav.com>
Date: Tue, 19 Apr 2022 13:28:31 +0300
Subject: [PATCH] feat(editor): Add drag and drop from nodes panel (#3123)

* :sparkles: Added support for drag and drop from nodes main panel.

:sparkles: Added node draggable placeholder.

* :sparkles: Added snapping to grid. Changed how draggable ghost follows the cursor.

* :lipstick: Changed node drag anchor position to be centered.

* :sparkles: Added drag and drop animation. Added event cancellation when dropping node on main panel.

* :recycle: Simplified drag and drop code and cleaned up prop-drilling.

* :bug: Added check for nodeTypeName in dataTransfer when draging and dropping nodes.

* :bug: Ensured MS Edge compatibility. MS edge does not send datatransfer in ondragover event.

Co-authored-by: Mutasem <mutdmour@gmail.com>
---
 .../components/NodeCreator/CreatorItem.vue    |  10 +-
 .../components/NodeCreator/ItemIterator.vue   |  15 ++-
 .../src/components/NodeCreator/MainPanel.vue  |  28 ++--
 .../components/NodeCreator/NodeCreator.vue    |  32 ++++-
 .../src/components/NodeCreator/NodeItem.vue   | 125 +++++++++++++++++-
 .../NodeCreator/SubcategoryPanel.vue          |   9 +-
 packages/editor-ui/src/views/NodeView.vue     | 101 ++++++++++----
 7 files changed, 259 insertions(+), 61 deletions(-)

diff --git a/packages/editor-ui/src/components/NodeCreator/CreatorItem.vue b/packages/editor-ui/src/components/NodeCreator/CreatorItem.vue
index a024c2ec4..9c8597cbd 100644
--- a/packages/editor-ui/src/components/NodeCreator/CreatorItem.vue
+++ b/packages/editor-ui/src/components/NodeCreator/CreatorItem.vue
@@ -5,8 +5,8 @@
 			clickable: props.clickable,
 			active: props.active,
 		}"
-		@click="listeners['click']"
-		>
+		@click="listeners.click"
+	>
 		<CategoryItem
 			v-if="props.item.type === 'category'"
 			:item="props.item"
@@ -21,7 +21,9 @@
 			v-else-if="props.item.type === 'node'"
 			:nodeType="props.item.properties.nodeType"
 			:bordered="!props.lastNode"
-		></NodeItem>
+			@dragstart="listeners.dragstart"
+			@dragend="listeners.dragend"
+		/>
 	</div>
 </template>
 
@@ -54,4 +56,4 @@ export default {
 	}
 }
 
-</style>
\ No newline at end of file
+</style>
diff --git a/packages/editor-ui/src/components/NodeCreator/ItemIterator.vue b/packages/editor-ui/src/components/NodeCreator/ItemIterator.vue
index 39d0437d4..e07b5fed6 100644
--- a/packages/editor-ui/src/components/NodeCreator/ItemIterator.vue
+++ b/packages/editor-ui/src/components/NodeCreator/ItemIterator.vue
@@ -8,7 +8,12 @@
 			@before-leave="beforeLeave"
 			@leave="leave"
 		>
-			<div v-for="(item, index) in elements" :key="item.key" :class="item.type" :data-key="item.key">
+			<div
+				v-for="(item, index) in elements"
+				:key="item.key"
+				:class="item.type"
+				:data-key="item.key"
+			>
 				<CreatorItem
 					:item="item"
 					:active="activeIndex === index && !disabled"
@@ -16,7 +21,9 @@
 					:lastNode="
 						index === elements.length - 1 || elements[index + 1].type !== 'node'
 					"
-					@click="() => selected(item)"
+					@click="$emit('selected', item)"
+					@dragstart="emit('dragstart', item, $event)"
+					@dragend="emit('dragend', item, $event)"
 				/>
 			</div>
 		</div>
@@ -36,12 +43,12 @@ export default Vue.extend({
 	},
 	props: ['elements', 'activeIndex', 'disabled', 'transitionsEnabled'],
 	methods: {
-		selected(element: INodeCreateElement) {
+		emit(eventName: string, element: INodeCreateElement, event: Event) {
 			if (this.$props.disabled) {
 				return;
 			}
 
-			this.$emit('selected', element);
+			this.$emit(eventName, { element, event });
 		},
 		beforeEnter(el: HTMLElement) {
 			el.style.height = '0';
diff --git a/packages/editor-ui/src/components/NodeCreator/MainPanel.vue b/packages/editor-ui/src/components/NodeCreator/MainPanel.vue
index dbff0d758..1f03e81b4 100644
--- a/packages/editor-ui/src/components/NodeCreator/MainPanel.vue
+++ b/packages/editor-ui/src/components/NodeCreator/MainPanel.vue
@@ -1,7 +1,18 @@
 <template>
-	<div @click="onClickInside" class="container">
+	<div
+		class="container"
+		ref="mainPanelContainer"
+		@click="onClickInside"
+	>
 		<SlideTransition>
-			<SubcategoryPanel v-if="activeSubcategory" :elements="subcategorizedNodes" :title="activeSubcategory.properties.subcategory" :activeIndex="activeSubcategoryIndex" @close="onSubcategoryClose" @selected="selected" />
+			<SubcategoryPanel
+				v-if="activeSubcategory"
+				:elements="subcategorizedNodes"
+				:title="activeSubcategory.properties.subcategory"
+				:activeIndex="activeSubcategoryIndex"
+				@close="onSubcategoryClose"
+				@selected="selected"
+			/>
 		</SlideTransition>
 		<div class="main-panel">
 			<SearchBar
@@ -35,7 +46,10 @@
 					@selected="selected"
 				/>
 			</div>
-			<NoResults v-else @nodeTypeSelected="nodeTypeSelected" />
+			<NoResults
+				v-else
+				@nodeTypeSelected="$emit('nodeTypeSelected', $event)"
+			/>
 		</div>
 	</div>
 </template>
@@ -56,7 +70,6 @@ import { ALL_NODE_FILTER, CORE_NODES_CATEGORY, REGULAR_NODE_FILTER, TRIGGER_NODE
 import SlideTransition from '../transitions/SlideTransition.vue';
 import { matchesNodeType, matchesSelectType } from './helpers';
 
-
 export default mixins(externalHooks).extend({
 	name: 'NodeCreateList',
 	components: {
@@ -235,18 +248,13 @@ export default mixins(externalHooks).extend({
 		},
 		selected(element: INodeCreateElement) {
 			if (element.type === 'node') {
-				const properties = element.properties as INodeItemProps;
-
-				this.nodeTypeSelected(properties.nodeType.name);
+				this.$emit('nodeTypeSelected', (element.properties as INodeItemProps).nodeType.name);
 			} else if (element.type === 'category') {
 				this.onCategorySelected(element.category);
 			} else if (element.type === 'subcategory') {
 				this.onSubcategorySelected(element);
 			}
 		},
-		nodeTypeSelected(nodeTypeName: string) {
-			this.$emit('nodeTypeSelected', nodeTypeName);
-		},
 		onCategorySelected(category: string) {
 			if (this.activeCategory.includes(category)) {
 				this.activeCategory = this.activeCategory.filter(
diff --git a/packages/editor-ui/src/components/NodeCreator/NodeCreator.vue b/packages/editor-ui/src/components/NodeCreator/NodeCreator.vue
index 9ba458709..b9bb41763 100644
--- a/packages/editor-ui/src/components/NodeCreator/NodeCreator.vue
+++ b/packages/editor-ui/src/components/NodeCreator/NodeCreator.vue
@@ -1,8 +1,20 @@
 <template>
 	<div>
 		<SlideTransition>
-			<div class="node-creator" v-if="active" v-click-outside="onClickOutside">
-				<MainPanel @nodeTypeSelected="nodeTypeSelected" :categorizedItems="categorizedItems" :categoriesWithNodes="categoriesWithNodes" :searchItems="searchItems"></MainPanel>
+			<div
+				v-if="active"
+				class="node-creator"
+				ref="nodeCreator"
+			 	v-click-outside="onClickOutside"
+			 	@dragover="onDragOver"
+			 	@drop="onDrop"
+			>
+				<MainPanel
+					@nodeTypeSelected="nodeTypeSelected"
+					:categorizedItems="categorizedItems"
+					:categoriesWithNodes="categoriesWithNodes"
+					:searchItems="searchItems"
+				/>
 			</div>
 		</SlideTransition>
 	</div>
@@ -94,6 +106,22 @@ export default Vue.extend({
 		nodeTypeSelected (nodeTypeName: string) {
 			this.$emit('nodeTypeSelected', nodeTypeName);
 		},
+		onDragOver(event: DragEvent) {
+			event.preventDefault();
+		},
+		onDrop(event: DragEvent) {
+			if (!event.dataTransfer) {
+				return;
+			}
+
+			const nodeTypeName = event.dataTransfer.getData('nodeTypeName');
+			const nodeCreatorBoundingRect = (this.$refs.nodeCreator as Element).getBoundingClientRect();
+
+			// Abort drag end event propagation if dropped inside nodes panel
+			if (nodeTypeName && event.pageX >= nodeCreatorBoundingRect.x && event.pageY >= nodeCreatorBoundingRect.y) {
+				event.stopPropagation();
+			}
+		},
 	},
 	watch: {
 		nodeTypes(newList) {
diff --git a/packages/editor-ui/src/components/NodeCreator/NodeItem.vue b/packages/editor-ui/src/components/NodeCreator/NodeItem.vue
index d7372c865..13ebd584c 100644
--- a/packages/editor-ui/src/components/NodeCreator/NodeItem.vue
+++ b/packages/editor-ui/src/components/NodeCreator/NodeItem.vue
@@ -1,5 +1,10 @@
 <template>
-	<div :class="{[$style['node-item']]: true, [$style.bordered]: bordered}">
+	<div
+		draggable
+		@dragstart="onDragStart"
+		@dragend="onDragEnd"
+		:class="{[$style['node-item']]: true, [$style.bordered]: bordered}"
+	>
 		<NodeIcon :class="$style['node-icon']" :nodeType="nodeType" />
 		<div>
 			<div :class="$style.details">
@@ -11,7 +16,7 @@
 					}}
 				</span>
 				<span :class="$style['trigger-icon']">
-					<TriggerIcon v-if="$options.isTrigger(nodeType)" />
+					<TriggerIcon v-if="isTrigger" />
 				</span>
 			</div>
 			<div :class="$style.description">
@@ -21,14 +26,26 @@
 					})
 				}}
 			</div>
+
+			<div :class="$style['draggable-data-transfer']" ref="draggableDataTransfer" />
+			<transition name="node-item-transition">
+				<div
+					:class="$style.draggable"
+					:style="draggableStyle"
+					ref="draggable"
+					v-show="dragging"
+				>
+					<NodeIcon class="node-icon" :nodeType="nodeType" :size="40" :shrink="false" />
+				</div>
+			</transition>
 		</div>
 	</div>
 </template>
 
 <script lang="ts">
 
+import {getNewNodePosition, NODE_SIZE} from '@/views/canvasHelpers';
 import Vue from 'vue';
-import { INodeTypeDescription } from 'n8n-workflow';
 
 import NodeIcon from '../NodeIcon.vue';
 import TriggerIcon from '../TriggerIcon.vue';
@@ -44,14 +61,73 @@ export default Vue.extend({
 		'nodeType',
 		'bordered',
 	],
+	data() {
+		return {
+			dragging: false,
+			draggablePosition: {
+				x: -100,
+				y: -100,
+			},
+		};
+	},
 	computed: {
-		shortNodeType() {
+		shortNodeType(): string {
 			return this.$locale.shortNodeType(this.nodeType.name);
 		},
+		isTrigger (): boolean {
+			return this.nodeType.group.includes('trigger');
+		},
+		draggableStyle(): { top: string; left: string; } {
+			return {
+				top: `${this.draggablePosition.y}px`,
+				left: `${this.draggablePosition.x}px`,
+			};
+		},
 	},
-	// @ts-ignore
-	isTrigger (nodeType: INodeTypeDescription): boolean {
-		return nodeType.group.includes('trigger');
+	mounted() {
+		/**
+		 * Workaround for firefox, that doesn't attach the pageX and pageY coordinates to "ondrag" event.
+		 * All browsers attach the correct page coordinates to the "dragover" event.
+		 * @bug https://bugzilla.mozilla.org/show_bug.cgi?id=505521
+		 */
+		document.body.addEventListener("dragover", this.onDragOver);
+	},
+	destroyed() {
+		document.body.removeEventListener("dragover", this.onDragOver);
+	},
+	methods: {
+		onDragStart(event: DragEvent): void {
+			const { pageX: x, pageY: y } = event;
+
+			this.$emit('dragstart', event);
+
+			if (event.dataTransfer) {
+				event.dataTransfer.effectAllowed = "copy";
+				event.dataTransfer.dropEffect = "copy";
+				event.dataTransfer.setData('nodeTypeName', this.nodeType.name);
+				event.dataTransfer.setDragImage(this.$refs.draggableDataTransfer as Element, 0, 0);
+			}
+
+			this.dragging = true;
+			this.draggablePosition = { x, y };
+		},
+		onDragOver(event: DragEvent): void {
+			if (!this.dragging || event.pageX === 0 && event.pageY === 0) {
+				return;
+			}
+
+			const [x,y] = getNewNodePosition([], [event.pageX - NODE_SIZE / 2, event.pageY - NODE_SIZE / 2]);
+
+			this.draggablePosition = { x, y };
+		},
+		onDragEnd(event: DragEvent): void {
+			this.$emit('dragend', event);
+
+			this.dragging = false;
+			setTimeout(() => {
+				this.draggablePosition = { x: -100, y: -100 };
+			}, 300);
+		},
 	},
 });
 </script>
@@ -100,4 +176,39 @@ export default Vue.extend({
 	display: flex;
 }
 
+.draggable {
+	width: 100px;
+	height: 100px;
+	position: fixed;
+	z-index: 1;
+	opacity: 0.66;
+	border: 2px solid var(--color-foreground-xdark);
+	border-radius: var(--border-radius-large);
+	background-color: var(--color-background-xlight);
+	display: flex;
+	justify-content: center;
+	align-items: center;
+}
+
+.draggable-data-transfer {
+	width: 1px;
+	height: 1px;
+}
+</style>
+
+<style lang="scss" scoped>
+.node-item-transition {
+	&-enter-active,
+	&-leave-active {
+		transition-property: opacity, transform;
+		transition-duration: 300ms;
+		transition-timing-function: ease;
+	}
+
+	&-enter,
+	&-leave-to {
+		opacity: 0;
+		transform: scale(0);
+	}
+}
 </style>
diff --git a/packages/editor-ui/src/components/NodeCreator/SubcategoryPanel.vue b/packages/editor-ui/src/components/NodeCreator/SubcategoryPanel.vue
index f7d16d525..75b737b79 100644
--- a/packages/editor-ui/src/components/NodeCreator/SubcategoryPanel.vue
+++ b/packages/editor-ui/src/components/NodeCreator/SubcategoryPanel.vue
@@ -13,7 +13,9 @@
 			<ItemIterator
 				:elements="elements"
 				:activeIndex="activeIndex"
-				@selected="selected"
+				@selected="$emit('selected', $event)"
+				@dragstart="$emit('dragstart', $event)"
+				@dragend="$emit('dragend', $event)"
 			/>
 		</div>
 	</div>
@@ -38,9 +40,6 @@ export default Vue.extend({
 		},
 	},
 	methods: {
-		selected(element: INodeCreateElement) {
-			this.$emit('selected', element);
-		},
 		onBackArrowClick() {
 			this.$emit('close');
 		},
@@ -101,4 +100,4 @@ export default Vue.extend({
 	}
 }
 
-</style>
\ No newline at end of file
+</style>
diff --git a/packages/editor-ui/src/views/NodeView.vue b/packages/editor-ui/src/views/NodeView.vue
index 18c4b83c7..41a5cc796 100644
--- a/packages/editor-ui/src/views/NodeView.vue
+++ b/packages/editor-ui/src/views/NodeView.vue
@@ -1,5 +1,9 @@
 <template>
-	<div class="node-view-root">
+	<div
+		class="node-view-root"
+	 	@dragover="onDragOver"
+	 	@drop="onDrop"
+	>
 		<div
 			class="node-view-wrapper"
 			:class="workflowClasses"
@@ -10,27 +14,31 @@
 			v-touch:tap="touchTap"
 			@mouseup="mouseUp"
 			@wheel="wheelScroll"
+		>
+			<div id="node-view-background" class="node-view-background" :style="backgroundStyle" />
+			<div
+				id="node-view"
+				class="node-view"
+				:style="workflowStyle"
 			>
-			<div id="node-view-background" class="node-view-background" :style="backgroundStyle"></div>
-			<div id="node-view" class="node-view" :style="workflowStyle">
 				<node
-				v-for="nodeData in nodes"
-				@duplicateNode="duplicateNode"
-				@deselectAllNodes="deselectAllNodes"
-				@deselectNode="nodeDeselectedByName"
-				@nodeSelected="nodeSelectedByName"
-				@removeNode="removeNode"
-				@runWorkflow="runWorkflow"
-				@moved="onNodeMoved"
-				@run="onNodeRun"
-				:id="'node-' + getNodeIndex(nodeData.name)"
-				:key="getNodeIndex(nodeData.name)"
-				:name="nodeData.name"
-				:isReadOnly="isReadOnly"
-				:instance="instance"
-				:isActive="!!activeNode && activeNode.name === nodeData.name"
-				:hideActions="pullConnActive"
-				></node>
+					v-for="nodeData in nodes"
+					@duplicateNode="duplicateNode"
+					@deselectAllNodes="deselectAllNodes"
+					@deselectNode="nodeDeselectedByName"
+					@nodeSelected="nodeSelectedByName"
+					@removeNode="removeNode"
+					@runWorkflow="runWorkflow"
+					@moved="onNodeMoved"
+					@run="onNodeRun"
+					:id="'node-' + getNodeIndex(nodeData.name)"
+					:key="getNodeIndex(nodeData.name)"
+					:name="nodeData.name"
+					:isReadOnly="isReadOnly"
+					:instance="instance"
+					:isActive="!!activeNode && activeNode.name === nodeData.name"
+					:hideActions="pullConnActive"
+				/>
 			</div>
 		</div>
 		<DataDisplay :renaming="renamingActive" @valueChanged="valueChanged"/>
@@ -41,7 +49,7 @@
 			:active="createNodeActive"
 			@nodeTypeSelected="nodeTypeSelected"
 			@closeNodeCreator="closeNodeCreator"
-			></node-creator>
+		/>
 		<div :class="{ 'zoom-menu': true, 'regular-zoom-menu': !isDemo, 'demo-zoom-menu': isDemo, expanded: !sidebarMenuCollapsed }">
 			<button @click="zoomToFit" class="button-white" :title="$locale.baseText('nodeView.zoomToFit')">
 				<font-awesome-icon icon="expand"/>
@@ -177,6 +185,11 @@ import {
 import '../plugins/N8nCustomConnectorType';
 import '../plugins/PlusEndpointType';
 
+interface AddNodeOptions {
+	position?: XYPosition;
+	dragAndDrop?: boolean;
+}
+
 export default mixins(
 	copyPaste,
 	externalHooks,
@@ -1227,6 +1240,27 @@ export default mixins(
 				this.createNodeActive = false;
 			},
 
+			onDragOver(event: DragEvent) {
+				event.preventDefault();
+			},
+
+			onDrop(event: DragEvent) {
+				if (!event.dataTransfer) {
+					return;
+				}
+
+				const nodeTypeName = event.dataTransfer.getData('nodeTypeName');
+				if (nodeTypeName) {
+					const mousePosition = this.getMousePositionWithinNodeView(event);
+
+					this.addNodeButton(nodeTypeName, {
+						position: [mousePosition[0] - CanvasHelpers.NODE_SIZE / 2, mousePosition[1] - CanvasHelpers.NODE_SIZE / 2],
+						dragAndDrop: true,
+					});
+					this.createNodeActive = false;
+				}
+			},
+
 			nodeDeselectedByName (nodeName: string) {
 				const node = this.$store.getters.getNodeByName(nodeName);
 				if (node) {
@@ -1267,7 +1301,7 @@ export default mixins(
 					duration: 0,
 				});
 			},
-			async injectNode (nodeTypeName: string) {
+			async injectNode (nodeTypeName: string, options: AddNodeOptions = {}) {
 				const nodeTypeData: INodeTypeDescription | null = this.$store.getters.nodeType(nodeTypeName);
 
 				if (nodeTypeData === null) {
@@ -1297,7 +1331,10 @@ export default mixins(
 
 				// when pulling new connection from node or injecting into a connection
 				const lastSelectedNode = this.lastSelectedNode;
-				if (lastSelectedNode) {
+
+				if (options.position) {
+					newNodeData.position = CanvasHelpers.getNewNodePosition(this.nodes, options.position);
+				} else if (lastSelectedNode) {
 					const lastSelectedConnection = this.lastSelectedConnection;
 					if (lastSelectedConnection) { // set when injecting into a connection
 						const [diffX] = CanvasHelpers.getConnectorLengths(lastSelectedConnection);
@@ -1308,10 +1345,12 @@ export default mixins(
 
 					// set when pulling connections
 					if (this.newNodeInsertPosition) {
-						newNodeData.position = CanvasHelpers.getNewNodePosition(this.nodes, [this.newNodeInsertPosition[0] + CanvasHelpers.GRID_SIZE, this.newNodeInsertPosition[1] - CanvasHelpers.NODE_SIZE / 2]);
+						newNodeData.position = CanvasHelpers.getNewNodePosition(this.nodes, [
+							this.newNodeInsertPosition[0] + CanvasHelpers.GRID_SIZE,
+							this.newNodeInsertPosition[1] - CanvasHelpers.NODE_SIZE / 2,
+						]);
 						this.newNodeInsertPosition = null;
-					}
-					else {
+					} else {
 						let yOffset = 0;
 
 						if (lastSelectedConnection) {
@@ -1353,7 +1392,11 @@ export default mixins(
 				this.$store.commit('setStateDirty', true);
 
 				this.$externalHooks().run('nodeView.addNodeButton', { nodeTypeName });
-				this.$telemetry.trackNodesPanel('nodeView.addNodeButton', { node_type: nodeTypeName, workflow_id: this.$store.getters.workflowId });
+				this.$telemetry.trackNodesPanel('nodeView.addNodeButton', {
+					node_type: nodeTypeName,
+					workflow_id: this.$store.getters.workflowId,
+					drag_and_drop: options.dragAndDrop,
+				} as IDataObject);
 
 				// Automatically deselect all nodes and select the current one and also active
 				// current node
@@ -1396,7 +1439,7 @@ export default mixins(
 
 				this.__addConnection(connectionData, true);
 			},
-			async addNodeButton (nodeTypeName: string) {
+			async addNodeButton (nodeTypeName: string, options: AddNodeOptions = {}) {
 				if (this.editAllowedCheck() === false) {
 					return;
 				}
@@ -1405,7 +1448,7 @@ export default mixins(
 				const lastSelectedNode = this.lastSelectedNode;
 				const lastSelectedNodeOutputIndex = this.$store.getters.lastSelectedNodeOutputIndex;
 
-				const newNodeData = await this.injectNode(nodeTypeName);
+				const newNodeData = await this.injectNode(nodeTypeName, options);
 				if (!newNodeData) {
 					return;
 				}