Hi all,

I have made some progress. But a new problem comes up.

I have changed WinSalGraphicsImpl::drawPolyLine [3] so that it gets an additional parameter fMiterMinimumAngle (same meaning as in createAreaGeometryForJoin) and uses it for gdi+. The rendering in edit-mode in Draw and Impress is correct then with gdi+ on Windows. Even Text in SVG works out of the box. [BTW: The current rendering using gdi+ is wrong, see my report bug#99102.]

The behavior of gdi+ is described in [1]. To get the same kind of behavior as in LO, when the miter limit is exceeded, the LineJoin type 'LineJoinMiterClipped' has to be used.

Being only in LibreOffice and SVG, that would be no problem. But MS seems to use different defaults. The rendering in PowerPoint looks like gdi+ type 'LineJoinMiter'. The specification for 'lim' in ECMA-376, Part 1, chapter 20.1.8.43, has no details, and I have not found details otherwhere.

This gdi+ type 'LineJoinMiter' kind of clipping (see the image in the article [1]) will be used in SVG 2 [2] too under the identifier 'miter-clip'.

So my question: Ignore interoperability with MS? If not, how to solve it?

Kind regards
Regina

[1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms534148%28v=vs.85%29.aspx

[2] https://www.w3.org/TR/svg-strokes/#StrokeShape

[3]
diff --git a/vcl/win/gdi/gdiimpl.cxx b/vcl/win/gdi/gdiimpl.cxx
index 7febbe8..36ecb31 100644
--- a/vcl/win/gdi/gdiimpl.cxx
+++ b/vcl/win/gdi/gdiimpl.cxx
@@ -2031,7 +2031,8 @@ bool WinSalGraphicsImpl::drawPolyLine(
     double fTransparency,
     const basegfx::B2DVector& rLineWidths,
     basegfx::B2DLineJoin eLineJoin,
-    css::drawing::LineCap eLineCap)
+    css::drawing::LineCap eLineCap,
+    double fMiterMinimumAngle)
 {
     const sal_uInt32 nCount(rPolygon.count());

@@ -2064,9 +2065,9 @@ bool WinSalGraphicsImpl::drawPolyLine(
             }
             case basegfx::B2DLineJoin::Miter :
             {
-                const Gdiplus::REAL aMiterLimit(15.0);
+ const Gdiplus::REAL aMiterLimit(1/sin(fMiterMinimumAngle/2.0)); Gdiplus::DllExports::GdipSetPenMiterLimit(pTestPen, aMiterLimit); - Gdiplus::DllExports::GdipSetPenLineJoin(pTestPen, Gdiplus::LineJoinMiter); + Gdiplus::DllExports::GdipSetPenLineJoin(pTestPen, Gdiplus::LineJoinMiterClipped);
                 break;
             }
             case basegfx::B2DLineJoin::Round :

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