MCGR: tdf#155479 repair gradient SVG export for MCGR

Unfortunately SVG export is based on metafiles and thus there
is (in principle) no way to get the BGradient/ColorStop/MCGR
data transfered as needed. For that, using UNO API to read the
model or using B2DPrimitives would help - as is better for the
export respectively.

Since there is not the time to re-design SVG export I added
this 'compromize' as a fix. It gets the needed data transported
over the metafile (that part is the compromize). It then
exports the MCGR data to SVG (at least - as was already there -
if it's a linear/axial gradient). This happens now with all
Gradient Stops when there is a MCGR gradient. That part is/will
hopefully be re-usable if SVG export  gets redesigned.

I also added a handling for StepCount feature, so when used (in
LO, others do not have that) 'hard' color stops get generated
to make the gradient look identical for SVG export.

Had to make adding of that extra-information in metafiles
dependent on exporting really to SVG. There are 51 cases which
use 'MetaActionType::COMMENT' which would potentially have
to be adapted.

Also added code to solve the problem for TransparencePrimitive2D
at VclMetafileProcessor2D::processTransparencePrimitive2D. This
will now - also only for SVG export - directly create the needed
MetaFloatTransparentAction and add additional MCGR information.
This will be used on SVG export to write a 'Mask' as was done
before. This is now capable of creating fill MCGR-Masks in
the sense that any number of TransparencyStops will be supported.

Change-Id: Ic6d022714eae96b8fbc09e60652851ac5799b757
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152623
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>
(cherry picked from commit a6e72e2b314e64f3199f3eaf1ecf78157446f6dd)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152882
Reviewed-by: Xisco Fauli <xiscofauli@libreoffice.org>

4 files changed, 38 insertions, 3 deletions

diff --git a/include/basegfx/utils/bgradient.hxx b/include/basegfx/utils/bgradient.hxx
index 1f42b23c6321..3e2acf9a4b67 100644
--- a/include/basegfx/utils/bgradient.hxx
+++ b/include/basegfx/utils/bgradient.hxx
@@ -96,6 +96,8 @@ public:
         return getStopOffset() == rCandidate.getStopOffset()
                && getStopColor() == rCandidate.getStopColor();
     }
+
+    bool operator!=(const BColorStop& rCandidate) const { return !(*this == rCandidate); }
 };
 
 /* MCGR: Provide ColorStops definition to the FillGradientAttribute
@@ -276,6 +278,13 @@ public:
 
     // returns true if the color stops are symmetrical in color and offset, otherwise false.
     bool isSymmetrical() const;
+    // assume that the color stops represent an Axial gradient
+    // and replace with gradient stops to represent the same
+    // gradient as linear gradient
+    void doApplyAxial();
+
+    // apply Steps as 'hard' color stops
+    void doApplySteps(sal_uInt16 nStepCount);
 };
 
 class BASEGFX_DLLPUBLIC BGradient final
@@ -337,7 +346,11 @@ public:
     /// Tooling method to fill awt::Gradient2 from data contained in the given basegfx::BGradient
     css::awt::Gradient2 getAsGradient2() const;
 
-    /// Tooling to handle border correction/integration and StartStopIntensity
+    // Tooling to handle
+    // - border correction/integration
+    // - apply StartStopIntensity to color stops
+    // - convert type from 'axial' to linear
+    // - apply Steps as 'hard' color stops
     void tryToRecreateBorder(basegfx::BColorStops* pAssociatedTransparencyStops = nullptr);
     void tryToApplyBorder();
     void tryToApplyStartEndIntensity();
@@ -345,6 +358,8 @@ public:
     // If a linear gradient is symmetrical it is converted to an axial gradient.
     // Does nothing in other cases and for other gradient types.
     void tryToConvertToAxial();
+    void tryToApplyAxial();
+    void tryToApplySteps();
 };
 }
 
diff --git a/include/svx/svdxcgv.hxx b/include/svx/svdxcgv.hxx
index 11e16b2ebcdb..2d7f04455913 100644
--- a/include/svx/svdxcgv.hxx
+++ b/include/svx/svdxcgv.hxx
@@ -79,10 +79,14 @@ public:
         The object (can also be a group object) to retrieve a Graphic
         for.
 
+        @param bSVG
+        tdf#155479 need to know it's SVG export, default is false
+
+
         @return a graphical representation of the given object, as it
         appears on screen (e.g. with rotation, if any, applied).
      */
-    static Graphic GetObjGraphic(const SdrObject& rSdrObject);
+    static Graphic GetObjGraphic(const SdrObject& rSdrObject, bool bSVG = false);
 
     // The new Draw objects are marked for all paste methods.
     // If bAddMark is true, the new Draw objects are added to an existing
diff --git a/include/vcl/gdimtf.hxx b/include/vcl/gdimtf.hxx
index f8637675482d..d62cd899623b 100644
--- a/include/vcl/gdimtf.hxx
+++ b/include/vcl/gdimtf.hxx
@@ -67,6 +67,9 @@ private:
     bool            m_bRecord;
     bool            m_bUseCanvas;
 
+    // tdf#155479 need to know if it's SVG export
+    bool            m_bSVG;
+
 
     SAL_DLLPRIVATE static Color         ImplColAdjustFnc( const Color& rColor, const void* pColParam );
     SAL_DLLPRIVATE static BitmapEx      ImplBmpAdjustFnc( const BitmapEx& rBmpEx, const void* pBmpParam );
@@ -186,6 +189,10 @@ public:
     void            UseCanvas( bool _bUseCanvas );
     bool            GetUseCanvas() const { return m_bUseCanvas; }
 
+    // tdf#155479
+    bool getSVG() const { return m_bSVG; }
+    void setSVG(bool bNew) { m_bSVG = bNew; }
+
     /// Dumps the meta actions as XML in metafile.xml.
     void dumpAsXml(const char* pFileName = nullptr) const;
 };
diff --git a/include/vcl/metaact.hxx b/include/vcl/metaact.hxx
index 06357c74a7eb..3f2e85dff6b4 100644
--- a/include/vcl/metaact.hxx
+++ b/include/vcl/metaact.hxx
@@ -43,6 +43,7 @@
 #include <vcl/region.hxx>
 #include <vcl/rendercontext/RasterOp.hxx>
 #include <vcl/wall.hxx>
+#include <basegfx/utils/bgradient.hxx>
 
 #include <memory>
 
@@ -1569,7 +1570,7 @@ public:
     bool                IsTransparent() const override { return true; }
 };
 
-class SAL_DLLPUBLIC_RTTI MetaFloatTransparentAction final : public MetaAction
+class VCL_DLLPUBLIC MetaFloatTransparentAction final : public MetaAction
 {
 private:
 
@@ -1578,6 +1579,9 @@ private:
     Size                maSize;
     Gradient            maGradient;
 
+    // tdf#155479 allow holding MCGR infos
+    std::optional<basegfx::BColorStops> maSVGTransparencyColorStops;
+
 public:
                         MetaFloatTransparentAction();
     MetaFloatTransparentAction(MetaFloatTransparentAction const &) = default;
@@ -1605,6 +1609,11 @@ public:
     void                SetSize(const Size& rSize) { maSize = rSize; }
     void                SetGradient(const Gradient& rGradient) { maGradient = rGradient; }
     bool                IsTransparent() const override { return true; }
+
+    // tdf#155479 allow holding MCGR infos
+    const basegfx::BColorStops* getSVGTransparencyColorStops() const
+    { return !maSVGTransparencyColorStops ? nullptr : &(*maSVGTransparencyColorStops); }
+    void addSVGTransparencyColorStops(const basegfx::BColorStops& rSVGTransparencyColorStops);
 };
 
 class VCL_DLLPUBLIC MetaEPSAction final : public MetaAction