Aspose.Slides FOSS
.NET
How to Connect Shapes with Connectors in .NET

How to Connect Shapes with Connectors in .NET

Connectors in Aspose.Slides FOSS are line shapes that attach to connection sites on other shapes. When you move a connected shape, the connector endpoint moves with it. The most common connector type is BentConnector3, which routes around obstacles with a single elbow bend.

Prerequisites 

dotnet add package Aspose.Slides.Foss

Connection Site Indexes

Every shape has four numbered connection sites:

IndexPosition
0Top center
1Left center
2Bottom center
3Right center

Connect Two Shapes 

using Aspose.Slides.Foss;
using Aspose.Slides.Foss.Export;

using var prs = new Presentation();
var slide = prs.Slides[0];

// Add two rectangles
var box1 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 50, 200, 200, 100);
var box2 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 450, 200, 200, 100);

box1.AddTextFrame("Start");
box2.AddTextFrame("End");

// Add a bent connector (initial bounds are overwritten by the connection)
var conn = slide.Shapes.AddConnector(ShapeType.BentConnector3, 0, 0, 10, 10);

// Connect right side of box1 (site 3) to left side of box2 (site 1)
conn.StartShapeConnectedTo = box1;
conn.StartShapeConnectionSiteIndex = 3;
conn.EndShapeConnectedTo = box2;
conn.EndShapeConnectionSiteIndex = 1;

prs.Save("connected.pptx", SaveFormat.Pptx);

The placeholder bounds (0, 0, 10, 10) passed to AddConnector are ignored once the connection endpoints are set; PowerPoint re-routes the connector to the attached shapes.

Connector Types 

// Straight line
ShapeType.StraightConnector1

// Single elbow (L-shape)
ShapeType.BentConnector2

// Double elbow (Z-shape): most common
ShapeType.BentConnector3

// Curved connector
ShapeType.CurvedConnector3

Style the Connector Line 

using Aspose.Slides.Foss;
using Aspose.Slides.Foss.Drawing;
using Aspose.Slides.Foss.Export;

using var prs = new Presentation();
var slide = prs.Slides[0];

var box1 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 50, 150, 180, 80);
var box2 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 500, 300, 180, 80);

var conn = slide.Shapes.AddConnector(ShapeType.BentConnector3, 0, 0, 10, 10);
conn.StartShapeConnectedTo = box1;
conn.StartShapeConnectionSiteIndex = 2;   // bottom of box1
conn.EndShapeConnectedTo = box2;
conn.EndShapeConnectionSiteIndex = 0;     // top of box2

// Style: dashed blue line, 2 pt width
var lf = conn.LineFormat;
lf.Width = 2.0;
lf.FillFormat.SolidFillColor.Color = Color.Blue;
lf.DashStyle = LineDashStyle.Dash;

prs.Save("styled-connector.pptx", SaveFormat.Pptx);

Flowchart with Multiple Connectors 

using Aspose.Slides.Foss;
using Aspose.Slides.Foss.Export;

using var prs = new Presentation();
var slide = prs.Slides[0];

// Three-step flowchart
var step1 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 350, 50, 200, 70);
var step2 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 350, 220, 200, 70);
var step3 = slide.Shapes.AddAutoShape(ShapeType.Rectangle, 350, 390, 200, 70);

step1.AddTextFrame("Step 1");
step2.AddTextFrame("Step 2");
step3.AddTextFrame("Step 3");

void ConnectVertical(IShapeCollection shapes, IShape topShape, IShape bottomShape)
{
    var c = shapes.AddConnector(ShapeType.BentConnector3, 0, 0, 10, 10);
    c.StartShapeConnectedTo = topShape;
    c.StartShapeConnectionSiteIndex = 2;   // bottom
    c.EndShapeConnectedTo = bottomShape;
    c.EndShapeConnectionSiteIndex = 0;     // top
}

ConnectVertical(slide.Shapes, step1, step2);
ConnectVertical(slide.Shapes, step2, step3);

prs.Save("flowchart.pptx", SaveFormat.Pptx);

Read Connector Properties 

using Aspose.Slides.Foss;

using var prs = new Presentation("connected.pptx");
foreach (var shape in prs.Slides[0].Shapes)
{
    if (shape is Connector connector)
    {
        var start = connector.StartShapeConnectedTo;
        var end = connector.EndShapeConnectedTo;
        Console.WriteLine($"Connector: {start?.Name ?? "?"} -> {end?.Name ?? "?"}");
    }
}

See Also