From 243df4b8e199442278b4118eff6156ee46ec5d23 Mon Sep 17 00:00:00 2001
From: Gavin Nishizawa <gavin@terrastruct.com>
Date: Tue, 20 Dec 2022 14:03:40 -0800
Subject: [PATCH] use elk layout's edge label position

---
 d2exporter/export.go            | 3 +++
 d2graph/d2graph.go              | 1 +
 d2layouts/d2elklayout/layout.go | 3 ++-
 d2target/d2target.go            | 8 ++++++--
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/d2exporter/export.go b/d2exporter/export.go
index 952a85662..6724283e8 100644
--- a/d2exporter/export.go
+++ b/d2exporter/export.go
@@ -242,6 +242,9 @@ func toConnection(edge *d2graph.Edge, theme *d2themes.Theme) d2target.Connection
 	if edge.LabelPercentage != nil {
 		connection.LabelPercentage = *edge.LabelPercentage
 	}
+	if edge.LabelTL != nil {
+		connection.LabelTL = edge.LabelTL.Copy()
+	}
 	connection.Route = edge.Route
 	connection.IsCurve = edge.IsCurve
 
diff --git a/d2graph/d2graph.go b/d2graph/d2graph.go
index a6ec263f0..9ef90ed4c 100644
--- a/d2graph/d2graph.go
+++ b/d2graph/d2graph.go
@@ -664,6 +664,7 @@ type Edge struct {
 	LabelDimensions d2target.TextDimensions `json:"label_dimensions"`
 	LabelPosition   *string                 `json:"labelPosition,omitempty"`
 	LabelPercentage *float64                `json:"labelPercentage,omitempty"`
+	LabelTL         *geo.Point              `json:"labelTL,omitempty"`
 
 	IsCurve bool         `json:"isCurve"`
 	Route   []*geo.Point `json:"route,omitempty"`
diff --git a/d2layouts/d2elklayout/layout.go b/d2layouts/d2elklayout/layout.go
index fb364ceba..75ada9428 100644
--- a/d2layouts/d2elklayout/layout.go
+++ b/d2layouts/d2elklayout/layout.go
@@ -308,7 +308,8 @@ func Layout(ctx context.Context, g *d2graph.Graph) (err error) {
 		points[endIndex] = shape.TraceToShapeBorder(dstShape, points[endIndex], points[endIndex-1])
 
 		if edge.Attributes.Label.Value != "" {
-			edge.LabelPosition = go2.Pointer(string(label.InsideMiddleCenter))
+			// using the edge label position from elk layout
+			edge.LabelTL = geo.NewPoint(e.Labels[0].X+parentX, e.Labels[0].Y+parentY)
 		}
 
 		edge.Route = points
diff --git a/d2target/d2target.go b/d2target/d2target.go
index ae098fd28..053a11687 100644
--- a/d2target/d2target.go
+++ b/d2target/d2target.go
@@ -210,8 +210,9 @@ type Connection struct {
 	Fill        string  `json:"fill,omitempty"`
 
 	Text
-	LabelPosition   string  `json:"labelPosition"`
-	LabelPercentage float64 `json:"labelPercentage"`
+	LabelPosition   string     `json:"labelPosition"`
+	LabelPercentage float64    `json:"labelPercentage"`
+	LabelTL         *geo.Point `json:"labelTL,omitempty"`
 
 	Route   []*geo.Point `json:"route"`
 	IsCurve bool         `json:"isCurve,omitempty"`
@@ -239,6 +240,9 @@ func BaseConnection() *Connection {
 }
 
 func (c *Connection) GetLabelTopLeft() *geo.Point {
+	if c.LabelTL != nil {
+		return c.LabelTL
+	}
 	return label.Position(c.LabelPosition).GetPointOnRoute(
 		c.Route,
 		float64(c.StrokeWidth),