Setting line join style in Apache Poi Powerpoint shapes

Question

I have a multi-segment line in an Apache Poi XSLFFreeformShape.

By default, the corner join style appears to be Round.

How do I set it to Bevel or Miter?

I'm not finding join styles among the stroke style methods supported by superclass XSLFSimpleShape.

EDIT

Here's what I'm doing for other line attributes:

private void applyLineState( @Nonnull XSLFFreeformShape shape) {
    shape.setLineWidth( ...);
    shape.setLineDash( ... );
    shape.setLineColor( ... );
    shape.setLineHeadDecoration(DecorationShape.NONE);
    shape.setLineCap(LineCap.FLAT);

    // Q: How to set join style for corners?
}

Answer 1

Seems apache poi does not provide setting any line join properties until now. But one could have a look at source code of XSLFSimpleShape for how to set other CTLineProperties. Then program the needed methods using the low level org.openxmlformats.schemas.drawingml.x2006.main.* classes.

Following complete example shows this:

import java.io.FileOutputStream;

import org.apache.poi.xslf.usermodel.*;
import org.apache.poi.sl.usermodel.*;

import org.apache.xmlbeans.XmlObject;
import org.openxmlformats.schemas.drawingml.x2006.main.*;
import org.openxmlformats.schemas.presentationml.x2006.main.CTShape;

import java.awt.Rectangle;
import java.awt.geom.Path2D;

public class CreatePPTXFreeformShapeFromPath {
    
 private static CTLineProperties getLn(XSLFShape shape) {
  XmlObject o = shape.getXmlObject();
  if (!(o instanceof CTShape)) return null; 
  CTShape sp = (CTShape)o;
  CTShapeProperties spr = sp.getSpPr();
  if (spr == null) return null;
  return (spr.isSetLn()) ? spr.getLn() : spr.addNewLn();
 }
 
 private enum LineJoinProperty {
  ROUND, MITER, BEVEL
 }
 
 public static void setLineJoinProperty(XSLFSimpleShape shape, LineJoinProperty property) {
  CTLineProperties ln = getLn(shape);
  if (ln == null) return;
  if (ln.isSetBevel()) ln.unsetBevel();
  if (ln.isSetMiter()) ln.unsetMiter();
  if (ln.isSetRound()) ln.unsetRound();
  if (property == LineJoinProperty.BEVEL) {
   CTLineJoinBevel bevel = ln.addNewBevel();
  } else if (property == LineJoinProperty.MITER) { 
   CTLineJoinMiterProperties miter = ln.addNewMiter();
  } else if (property == LineJoinProperty.ROUND) { 
   CTLineJoinRound round = ln.addNewRound();
  }
 }

 public static void main(String[] args) throws Exception {

  XMLSlideShow slideShow = new XMLSlideShow();
  XSLFSlide slide = slideShow.createSlide();

  Path2D.Double path2D = new Path2D.Double();
  path2D.moveTo(0d,0d);
  path2D.lineTo(20d,0d);
  path2D.lineTo(20d,20d);
  path2D.lineTo(40d,20d);
  path2D.lineTo(40d,40d);
  path2D.lineTo(60d,40d);
  path2D.lineTo(60d,60d);
  path2D.lineTo(80d,60d);
  path2D.lineTo(80d,80d);
  path2D.lineTo(100d,80d);
  path2D.lineTo(100d,100d);
  path2D.closePath();

  XSLFFreeformShape shape;
  
  //default
  shape = slide.createFreeform();
  shape.setPath(path2D);
  shape.setLineWidth(5.0);
  shape.setLineColor(java.awt.Color.BLACK);
  shape.setAnchor(new Rectangle(50, 100, 300, 300));

  //miter
  shape = slide.createFreeform();
  shape.setPath(path2D);
  shape.setLineWidth(5.0);
  shape.setLineColor(java.awt.Color.BLACK);
  shape.setAnchor(new Rectangle(200, 100, 300, 300));
  setLineJoinProperty(shape, LineJoinProperty.MITER);

  //bevel
  shape = slide.createFreeform();
  shape.setPath(path2D);
  shape.setLineWidth(5.0);
  shape.setLineColor(java.awt.Color.BLACK);
  shape.setAnchor(new Rectangle(350, 100, 300, 300));
  setLineJoinProperty(shape, LineJoinProperty.BEVEL);
  
  FileOutputStream out = new FileOutputStream("CreatePPTXFreeformShapeFromPath.pptx");
  slideShow.write(out);
  out.close();
 }
}

This is tested using apache poi 4.1.2 and ooxml-schemas-1.4.jar. Note, this example needs ooxml-schemas-1.4.jar as poi-ooxml-schemas-4.1.2.jar only contains org.openxmlformats.schemas.drawingml.x2006.main.* classes which are used by apache poi 4.1.2 directly.