From 54f949a97239f080a6543d9e6128b64fa9ee2c95 Mon Sep 17 00:00:00 2001
From: Jon Bake <jonmbake@gmail.com>
Date: Sun, 28 Feb 2021 11:08:14 -0600
Subject: [PATCH] :bug: Fixes #1364 - Incorrect mouse selection when zoomed in
 or out (#1498)

Prior to this change, the mouse selection box had a fixed position on the page. Nodes have absolute
position within NodeView. This inconsistency in positioning caused issues when calculating
if a node was positioned within the mouse selection. This solution makes both nodes
and mouse selection have consistent positioning, along with correctly calculating the
mouse click position within NodeView when making a selection.
---
 .../src/components/mixins/mouseSelect.ts      | 47 ++++++++++++-------
 packages/editor-ui/src/views/NodeView.vue     |  1 +
 2 files changed, 30 insertions(+), 18 deletions(-)

diff --git a/packages/editor-ui/src/components/mixins/mouseSelect.ts b/packages/editor-ui/src/components/mixins/mouseSelect.ts
index 0b280297f0..ad7fae8f07 100644
--- a/packages/editor-ui/src/components/mixins/mouseSelect.ts
+++ b/packages/editor-ui/src/components/mixins/mouseSelect.ts
@@ -23,14 +23,15 @@ export const mouseSelect = mixins(
 			this.selectBox.id = 'select-box';
 			this.selectBox.style.margin = '0px auto';
 			this.selectBox.style.border = '2px dotted #FF0000';
-			this.selectBox.style.position = 'fixed';
+			// Positioned absolutely within #node-view. This is consistent with how nodes are positioned.
+			this.selectBox.style.position = 'absolute';
 			this.selectBox.style.zIndex = '100';
 			this.selectBox.style.visibility = 'hidden';
 
 			this.selectBox.addEventListener('mouseup', this.mouseUpMouseSelect);
 
-			// document.body.appendChild(this.selectBox);
-			this.$el.appendChild(this.selectBox);
+			const nodeViewEl = this.$el.querySelector('#node-view') as HTMLDivElement;
+			nodeViewEl.appendChild(this.selectBox);
 		},
 		isCtrlKeyPressed (e: MouseEvent | KeyboardEvent): boolean {
 			if (this.isTouchDevice === true) {
@@ -41,14 +42,28 @@ export const mouseSelect = mixins(
 			}
 			return e.ctrlKey;
 		},
+		/**
+		 * Gets mouse position within the node view. Both node view offset and scale (zoom) are considered when
+		 * calculating position.
+		 *
+		 * @param event - mouse event within node view
+		 */
+		getMousePositionWithinNodeView (event: MouseEvent) {
+			// @ts-ignore
+			const nodeViewScale = this.nodeViewScale;
+			const offsetPosition = this.$store.getters.getNodeViewOffsetPosition;
+			return {
+				x: (event.pageX - offsetPosition[0]) / nodeViewScale,
+				y: (event.pageY - offsetPosition[1]) / nodeViewScale,
+			};
+		},
 		showSelectBox (event: MouseEvent) {
-			// @ts-ignore
-			this.selectBox.x = event.pageX;
-			// @ts-ignore
-			this.selectBox.y = event.pageY;
+			this.selectBox = Object.assign(this.selectBox, this.getMousePositionWithinNodeView(event));
 
-			this.selectBox.style.left = event.pageX + 'px';
-			this.selectBox.style.top = event.pageY + 'px';
+			// @ts-ignore
+			this.selectBox.style.left = this.selectBox.x + 'px';
+			// @ts-ignore
+			this.selectBox.style.top = this.selectBox.y + 'px';
 			this.selectBox.style.visibility = 'visible';
 
 			this.selectActive = true;
@@ -75,25 +90,21 @@ export const mouseSelect = mixins(
 			this.selectActive = false;
 		},
 		getSelectionBox (event: MouseEvent) {
+			const {x, y} = this.getMousePositionWithinNodeView(event);
 			return {
 				// @ts-ignore
-				x: Math.min(event.pageX, this.selectBox.x),
+				x: Math.min(x, this.selectBox.x),
 				// @ts-ignore
-				y: Math.min(event.pageY, this.selectBox.y),
+				y: Math.min(y, this.selectBox.y),
 				// @ts-ignore
-				width: Math.abs(event.pageX - this.selectBox.x),
+				width: Math.abs(x - this.selectBox.x),
 				// @ts-ignore
-				height: Math.abs(event.pageY - this.selectBox.y),
+				height: Math.abs(y - this.selectBox.y),
 			};
 		},
 		getNodesInSelection (event: MouseEvent): INodeUi[] {
 			const returnNodes: INodeUi[] = [];
 			const selectionBox = this.getSelectionBox(event);
-			const offsetPosition = this.$store.getters.getNodeViewOffsetPosition;
-
-			// Consider the offset of the workflow when it got moved
-			selectionBox.x -= offsetPosition[0];
-			selectionBox.y -= offsetPosition[1];
 
 			// Go through all nodes and check if they are selected
 			this.$store.getters.allNodes.forEach((node: INodeUi) => {
diff --git a/packages/editor-ui/src/views/NodeView.vue b/packages/editor-ui/src/views/NodeView.vue
index 173f0bbf71..65852033ef 100644
--- a/packages/editor-ui/src/views/NodeView.vue
+++ b/packages/editor-ui/src/views/NodeView.vue
@@ -2139,6 +2139,7 @@ export default mixins(
 	position: relative;
 	width: 100%;
 	height: 100%;
+	transform-origin: 0 0;
 }
 
 .node-view-background {