Example 3 — Union: Merge Rectangle and Circle

Created: 2026-05-27 · Updated: 2026-05-27

Two overlapping shapes are merged into a single new shape using Union. Demonstrates the core pattern of all Boolean operations: select → operate → retrieve result.

Result

Code

/* PARAMS */
float left  = 80f;
float top   = 100f;
float size  = 150f;
int   rgb   = System.Drawing.ColorTranslator.ToOle(
                  System.Drawing.Color.FromArgb(155, 89, 182));
/* END PARAMS */

// Create rectangle and circle (overlapping)
var oRect   = ppptools.AddRect(left, top, size, size);
var oCircle = ppptools.AddOval(left + size * 0.6f, top, size, size);

// Union — merge both shapes into one
oRect.Select(MsoTriState.msoTrue);
oCircle.Select(MsoTriState.msoFalse);
ppptools.Union();

// Style the result shape
foreach (dynamic sh in ppptools.GetSelectedRange())
{
    sh.Name = "UnionShape";
    sh.Fill.ForeColor.RGB = rgb;
    sh.Fill.Transparency  = 0f;
    sh.Line.Visible       = MsoTriState.msoFalse;
}

Step-by-Step Explanation

1. Creating Two Overlapping Shapes

var oRect   = ppptools.AddRect(left, top, size, size);
var oCircle = ppptools.AddOval(left + size * 0.6f, top, size, size);

The circle starts at left + size * 0.6f, i.e., 60% of the size to the right of the rectangle's left edge. This makes it overlap the rectangle by 40% — enough for a clear merge.

2. Building the Selection — the Core of All Boolean Operations

oRect.Select(MsoTriState.msoTrue);    // First shape: replaces current selection
oCircle.Select(MsoTriState.msoFalse); // Second shape: adds to current selection

Parameter	Meaning
`msoTrue`	Replace — clears the current selection first
`msoFalse`	Add — appends to the existing selection

This selection method is the only reliable way in Roslyn scripts to mark multiple shapes for a Boolean operation. List<Shape> doesn't work due to the namespace conflict.

3. Executing the Boolean Operation

ppptools.Union();

ppptools.Union() corresponds to PowerPoint's "Merge Shapes → Union" command. The selected shapes are merged into one single shape. The original shapes are deleted in the process.

ppptools Method	Result
`ppptools.Union()`	All selected shapes merge into one
`ppptools.Intersect()`	Only the overlapping area remains
`ppptools.Combine()`	Union, but the overlap is punched out (hole)
`ppptools.Subtract()`	Second shape is subtracted from the first

4. Retrieving and Styling the Result

foreach (dynamic sh in ppptools.GetSelectedRange())
{
    sh.Name = "UnionShape";
    sh.Fill.ForeColor.RGB = rgb;
    sh.Fill.Transparency  = 0f;
    sh.Line.Visible       = MsoTriState.msoFalse;
}

After ppptools.Union(), the resulting shape is automatically selected. ppptools.GetSelectedRange() returns the ShapeRange object. Since Union always produces exactly one shape, the foreach only loops once — but it's still more robust than ppptools.GetSelected() for code that should also work with Intersect (which can produce multiple parts).

What's Special About This Example

Selection order — msoTrue for the first shape, then msoFalse for each additional one. Wrong order leads to wrong results.
Originals are deleted — after ppptools.Union(), oRect and oCircle no longer exist. Don't use them again!
foreach instead of [1] — with Union the result is always one shape; foreach is still more idiomatic because it also works with Intersect which may produce multiple parts.
int rgb — stored as int (OLE integer) since it's reused in the foreach loop. More concise than calling ToOle() each time.

Back: Example 2 — Circle · Next: Example 4 — Hole (Combine)