related tdf#126533 tdf#159824 VML: don't export: negative angles

and stop an automatic 180 reversal on import.

Some documents had gradient reversals on every round trip,
typically when the angle was 0-179
(mainly seen in ODT examples,
since DOCX/RTF imports defaulted to be angle 180).

The negative sign has special meaning,
indicating that the start and end colors
should be swapped.

Well, swapping colors was not intentional in the export logic.
Previously there was a mistaken idea
that any angles > 180 needed to be swapped on import,
and likely that is what prompted this overly complicated formula
to try to avoid any angle > 180 during export
by allowing negative angles.

This tdf#126533 patchset has already eliminated import checks
for angles > 180, so now a sane formula can be applied on export.

In order to do that, we have to avoid emulating color swaps
with 180 degree rotations at import time.
So ONLY do color swapping with start/end,
and leave the angle alone.
That GREATLY helps unit tests (which otherwise would flip-flop
the angle and the color start/stop).

Very unhelpful was an undocumented, indecipherable
inversion when converting to DML angle.

Boy, I hope I got this right...

make CppunitTest_sw_rtfexport8 \
   CPPUNIT_TEST_NAME=testTdf159824_gradientAngle3
make CppunitTest_sw_rtfexport8 \
   CPPUNIT_TEST_NAME=testTdf159824_gradientAngle4
make CppunitTest_sw_ooxmlexport7 \
   CPPUNIT_TEST_NAME=testTdf126533_axialAngle2

Eliminating the inversion for ooxml7 test is fine
since inversion does nothing to an axial.

Otherwise, eliminating inversions corresponds to a color swap.

Change-Id: I2aae0a7595807569ffc740689ff3840692d6159d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/163798
Tested-by: Jenkins
Reviewed-by: Justin Luth <jluth@mail.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/oox/source/vml/vmlformatting.cxx b/oox/source/vml/vmlformatting.cxx
index f4022d0639d6..5fb422e63b9d 100644
--- a/oox/source/vml/vmlformatting.cxx
+++ b/oox/source/vml/vmlformatting.cxx
@@ -800,22 +800,29 @@ void FillModel::pushToPropMap( ShapePropertyMap& rPropMap, const GraphicHelper&
                     }
                     else    // focus of -100%, 0%, and 100% is linear gradient
                     {
+                        // LO linear gradients: top == start, but for MSO bottom == start == moColor
+                        bool bSwapColors = true;
+
                         /*  According to spec, a focus of -100% or 100% swaps the
                             start and stop colors, effectively reversing the gradient.
                             If the angle was provided as a negative,
                             then the colors are also (again) reversed. */
                         if( fFocus < -0.5 || fFocus > 0.5 )
-                            nVmlAngle = (nVmlAngle + 180) % 360;
+                            bSwapColors = !bSwapColors;
                         if (moAngle.value_or(0) < 0)
-                            nVmlAngle = (nVmlAngle + 180) % 360;
+                            bSwapColors = !bSwapColors;
 
+                        const Color& rStartColor = bSwapColors ? aColor2 : aColor1;
+                        const Color& rEndColor = bSwapColors ? aColor1 : aColor2;
                         // set the start and stop colors
-                        lcl_setGradientStop( aFillProps.maGradientProps.maGradientStops, 0.0, aColor1 );
-                        lcl_setGradientStop( aFillProps.maGradientProps.maGradientStops, 1.0, aColor2 );
+                        lcl_setGradientStop(aFillProps.maGradientProps.maGradientStops, 0.0,
+                                            rStartColor);
+                        lcl_setGradientStop(aFillProps.maGradientProps.maGradientStops, 1.0,
+                                            rEndColor);
                     }
 
                     // VML counts counterclockwise from bottom, DrawingML clockwise from left
-                    sal_Int32 nDmlAngle = (630 - nVmlAngle) % 360;
+                    sal_Int32 nDmlAngle = NormAngle360(90 - nVmlAngle);
                     aFillProps.maGradientProps.moShadeAngle = nDmlAngle * ::oox::drawingml::PER_DEGREE;
                 }
                 else    // XML_gradientRadial is rectangular gradient