share the cairo polyline drawing code

Change-Id: I35c04f33f3a87962a3d0e731213228d5b2e8590e
Reviewed-on: https://gerrit.libreoffice.org/55179
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

3 files changed, 47 insertions, 138 deletions

diff --git a/vcl/headless/svpgdi.cxx b/vcl/headless/svpgdi.cxx
index 553b43ed9f6b..8bc15fb861dc 100644
--- a/vcl/headless/svpgdi.cxx
+++ b/vcl/headless/svpgdi.cxx
@@ -875,7 +875,10 @@ void SvpSalGraphics::drawLine( long nX1, long nY1, long nX2, long nY2 )
     releaseCairoContext(cr, false, extents);
 }
 
-bool SvpSalGraphics::drawPolyLine(
+basegfx::B2DRange SvpSalGraphics::drawPolyLine(
+    cairo_t* cr,
+    const Color& rLineColor,
+    bool bAntiAliasB2DDraw,
     const basegfx::B2DPolygon& rPolyLine,
     double fTransparency,
     const basegfx::B2DVector& rLineWidths,
@@ -883,18 +886,8 @@ bool SvpSalGraphics::drawPolyLine(
     css::drawing::LineCap eLineCap,
     double fMiterMinimumAngle)
 {
-    // short circuit if there is nothing to do
-    const int nPointCount = rPolyLine.count();
-    if (nPointCount <= 0)
-    {
-        return true;
-    }
-
     const bool bNoJoin = (basegfx::B2DLineJoin::NONE == eLineJoin && basegfx::fTools::more(rLineWidths.getX(), 0.0));
 
-    cairo_t* cr = getCairoContext(false);
-    clipRegion(cr);
-
     // setup line attributes
     cairo_line_join_t eCairoLineJoin = CAIRO_LINE_JOIN_MITER;
     switch (eLineJoin)
@@ -936,9 +929,9 @@ bool SvpSalGraphics::drawPolyLine(
         }
     }
 
-    cairo_set_source_rgba(cr, m_aLineColor.GetRed()/255.0,
-                              m_aLineColor.GetGreen()/255.0,
-                              m_aLineColor.GetBlue()/255.0,
+    cairo_set_source_rgba(cr, rLineColor.GetRed()/255.0,
+                              rLineColor.GetGreen()/255.0,
+                              rLineColor.GetBlue()/255.0,
                               1.0-fTransparency);
 
     cairo_set_line_join(cr, eCairoLineJoin);
@@ -951,12 +944,13 @@ bool SvpSalGraphics::drawPolyLine(
 
     if (!bNoJoin)
     {
-        AddPolygonToPath(cr, rPolyLine, rPolyLine.isClosed(), !getAntiAliasB2DDraw(), true);
+        AddPolygonToPath(cr, rPolyLine, rPolyLine.isClosed(), !bAntiAliasB2DDraw, true);
         extents = getClippedStrokeDamage(cr);
         cairo_stroke(cr);
     }
     else
     {
+        const int nPointCount = rPolyLine.count();
         // emulate rendering::PathJoinType::NONE by painting single edges
         const sal_uInt32 nEdgeCount(rPolyLine.isClosed() ? nPointCount : nPointCount - 1);
         basegfx::B2DPolygon aEdge;
@@ -970,7 +964,7 @@ bool SvpSalGraphics::drawPolyLine(
             aEdge.setNextControlPoint(0, rPolyLine.getNextControlPoint(i % nPointCount));
             aEdge.setPrevControlPoint(1, rPolyLine.getPrevControlPoint(nNextIndex));
 
-            AddPolygonToPath(cr, aEdge, false, !getAntiAliasB2DDraw(), true);
+            AddPolygonToPath(cr, aEdge, false, !bAntiAliasB2DDraw, true);
 
             extents.expand(getStrokeDamage(cr));
 
@@ -983,6 +977,27 @@ bool SvpSalGraphics::drawPolyLine(
         extents.intersect(getClipBox(cr));
     }
 
+    return extents;
+}
+
+bool SvpSalGraphics::drawPolyLine(
+    const basegfx::B2DPolygon& rPolyLine,
+    double fTransparency,
+    const basegfx::B2DVector& rLineWidths,
+    basegfx::B2DLineJoin eLineJoin,
+    css::drawing::LineCap eLineCap,
+    double fMiterMinimumAngle)
+{
+    // short circuit if there is nothing to do
+    if (rPolyLine.count() <= 0)
+        return true;
+
+    cairo_t* cr = getCairoContext(false);
+    clipRegion(cr);
+
+    basegfx::B2DRange extents = drawPolyLine(cr, m_aLineColor, getAntiAliasB2DDraw(), rPolyLine,
+                                             fTransparency, rLineWidths, eLineJoin, eLineCap, fMiterMinimumAngle);
+
     releaseCairoContext(cr, false, extents);
 
     return true;
diff --git a/vcl/inc/headless/svpgdi.hxx b/vcl/inc/headless/svpgdi.hxx
index 25e828e8618c..37ae2822bf53 100644
--- a/vcl/inc/headless/svpgdi.hxx
+++ b/vcl/inc/headless/svpgdi.hxx
@@ -96,6 +96,17 @@ public:
     cairo_surface_t* getSurface() const { return m_pSurface; }
     static cairo_user_data_key_t* getDamageKey();
 
+    static basegfx::B2DRange drawPolyLine(
+        cairo_t* cr,
+        const Color& rLineColor,
+        bool bAntiAliasB2DDraw,
+        const basegfx::B2DPolygon& rPolyLine,
+        double fTransparency,
+        const basegfx::B2DVector& rLineWidths,
+        basegfx::B2DLineJoin eLineJoin,
+        css::drawing::LineCap eLineCap,
+        double fMiterMinimumAngle);
+
 private:
     void invert(const basegfx::B2DPolygon &rPoly, SalInvert nFlags);
     void copySource(const SalTwoRect& rTR, cairo_surface_t* source);
diff --git a/vcl/unx/generic/gdi/salgdi.cxx b/vcl/unx/generic/gdi/salgdi.cxx
index bc31846f0159..dd09e8d3c62b 100644
--- a/vcl/unx/generic/gdi/salgdi.cxx
+++ b/vcl/unx/generic/gdi/salgdi.cxx
@@ -39,6 +39,8 @@
 #include <basegfx/polygon/b2dtrapezoid.hxx>
 #include <basegfx/curve/b2dcubicbezier.hxx>
 
+#include <headless/svpgdi.hxx>
+
 #include <vcl/jobdata.hxx>
 #include <vcl/sysdata.hxx>
 #include <vcl/virdev.hxx>
@@ -732,129 +734,10 @@ bool X11SalGraphics::drawPolyLine(
     {
         cairo_t* cr = getCairoContext();
         clipRegion(cr);
-        cairo_line_join_t eCairoLineJoin(CAIRO_LINE_JOIN_MITER);
-        bool bNoJoin(false);
-
-        switch(eLineJoin)
-        {
-            case basegfx::B2DLineJoin::Bevel:
-                eCairoLineJoin = CAIRO_LINE_JOIN_BEVEL;
-                break;
-            case basegfx::B2DLineJoin::Round:
-                eCairoLineJoin = CAIRO_LINE_JOIN_ROUND;
-                break;
-            case basegfx::B2DLineJoin::NONE:
-                bNoJoin = true;
-                SAL_FALLTHROUGH;
-            case basegfx::B2DLineJoin::Miter:
-                eCairoLineJoin = CAIRO_LINE_JOIN_MITER;
-                break;
-        }
-
-        // setup cap attribute
-        cairo_line_cap_t eCairoLineCap(CAIRO_LINE_CAP_BUTT);
-        switch(eLineCap)
-        {
-            default: // css::drawing::LineCap_BUTT:
-            {
-                eCairoLineCap = CAIRO_LINE_CAP_BUTT;
-                break;
-            }
-            case css::drawing::LineCap_ROUND:
-            {
-                eCairoLineCap = CAIRO_LINE_CAP_ROUND;
-                break;
-            }
-            case css::drawing::LineCap_SQUARE:
-            {
-                eCairoLineCap = CAIRO_LINE_CAP_SQUARE;
-                break;
-            }
-        }
-
-        cairo_set_source_rgba(cr,
-            mnPenColor.GetRed()/255.0,
-            mnPenColor.GetGreen()/255.0,
-            mnPenColor.GetBlue()/255.0,
-            1.0 - fTransparency);
-        cairo_set_line_join(cr, eCairoLineJoin);
-        cairo_set_line_cap(cr, eCairoLineCap);
-        cairo_set_line_width(cr, (fabs(rLineWidth.getX()) + fabs(rLineWidth.getY())) * 0.5);
-
-        if(CAIRO_LINE_JOIN_MITER == eCairoLineJoin)
-        {
-            cairo_set_miter_limit(cr, 15.0);
-        }
-
-        const sal_uInt32 nEdgeCount(rPolygon.isClosed() ? nPointCount : nPointCount - 1);
 
-        if(nEdgeCount)
-        {
-            const bool bSnapPoints(!getAntiAliasB2DDraw());
-            static basegfx::B2DHomMatrix aHalfPointTransform(basegfx::utils::createTranslateB2DHomMatrix(0.5, 0.5));
-            basegfx::B2DCubicBezier aEdge;
-            basegfx::B2DPoint aStart;
-
-            for(sal_uInt32 i = 0; i < nEdgeCount; ++i)
-            {
-                rPolygon.getBezierSegment(i, aEdge);
-
-                aEdge.transform(aHalfPointTransform);
-
-                if(bSnapPoints)
-                {
-                    aEdge.fround();
-                }
-
-                if(!i || bNoJoin)
-                {
-                    aStart = aEdge.getStartPoint();
-                    cairo_move_to(cr, aStart.getX(), aStart.getY());
-                }
-
-                const basegfx::B2DPoint aEnd(aEdge.getEndPoint());
-
-                if(aEdge.isBezier())
-                {
-                    basegfx::B2DPoint aCP1(aEdge.getControlPointA());
-                    basegfx::B2DPoint aCP2(aEdge.getControlPointB());
-
-                    // tdf#99165 cairo has problems in creating the evtl. needed
-                    // miter graphics (and maybe others) when empty control points
-                    // are used, so fallback to the mathematical 'default' control
-                    // points in that case
-                    // tdf#101026 The 1st attempt to create a mathematically correct replacement control
-                    // vector was wrong. Best alternative is one as close as possible which means short.
-                    if (aStart.equal(aCP1))
-                    {
-                        aCP1 = aStart + ((aCP2 - aStart) * 0.0005);
-                    }
-
-                    if(aEnd.equal(aCP2))
-                    {
-                        aCP2 = aEnd + ((aCP1 - aEnd) * 0.0005);
-                    }
-
-                    cairo_curve_to(cr,
-                        aCP1.getX(), aCP1.getY(),
-                        aCP2.getX(), aCP2.getY(),
-                        aEnd.getX(), aEnd.getY());
-                }
-                else
-                {
-                    cairo_line_to(cr, aEnd.getX(), aEnd.getY());
-                }
-
-                aStart = aEnd;
-            }
-
-            if(rPolygon.isClosed() && !bNoJoin)
-            {
-                cairo_close_path(cr);
-            }
-
-            cairo_stroke(cr);
-        }
+        SvpSalGraphics::drawPolyLine(cr, mnPenColor, getAntiAliasB2DDraw(),
+                                     rPolygon, fTransparency, rLineWidth,
+                                     eLineJoin, eLineCap, fMiterMinimumAngle);
 
         releaseCairoContext(cr);
         return true;