CairoSDPR: Direct support for RGBA Gradients (I)

Detect where created when a RGBA gradient could be
used directly and create a primitive representing
that, a PolyPolygonRGBAGradientPrimitive2D.
That primitive decomposes to what was created before,
so no primitive renderer has to be touched, all will
work as before.
NOTE: That helper primitive just holds references to
what would be created anyways, so one depth step
added but not really any additional data.
This is the 1st step for direct support, the 2nd is
to then detect and use that primitive in SDPR
implementations directly.

Change-Id: I4f247636ce58a8a1fd1e0df32dabed0d6cc10d0e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/170527
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/basegfx/source/tools/bgradient.cxx b/basegfx/source/tools/bgradient.cxx
index e27ab160463b..bac738ad3221 100644
--- a/basegfx/source/tools/bgradient.cxx
+++ b/basegfx/source/tools/bgradient.cxx
@@ -746,6 +746,25 @@ void BColorStops::tryToApplyBColorModifierStack(const BColorModifierStack& rBCol
     }
 }
 
+bool BColorStops::sameSizeAndDistances(const BColorStops& rComp) const
+{
+    if (size() != rComp.size())
+    {
+        return false;
+    }
+
+    BColorStops::const_iterator EntryA(begin());
+    BColorStops::const_iterator EntryB(rComp.begin());
+
+    while (EntryA != end() && fTools::equal(EntryA->getStopOffset(), EntryB->getStopOffset()))
+    {
+        EntryA++;
+        EntryB++;
+    }
+
+    return EntryA == end();
+}
+
 std::string BGradient::GradientStyleToString(css::awt::GradientStyle eStyle)
 {
     switch (eStyle)