Resolves tdf#156182 - Automatic text color unreadable with darker cells

Change-Id: Ia5e405fc05613726b5011174c8d00ca204eb31b2
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/154352
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins
Reviewed-by: Heiko Tietze <heiko.tietze@documentfoundation.org>
diff --git a/include/tools/color.hxx b/include/tools/color.hxx
index 296d606..41826ec 100644
--- a/include/tools/color.hxx
+++ b/include/tools/color.hxx
@@ -311,8 +311,8 @@ public:
      */
    bool IsDark() const
    {
        // 62 is the number that means it also triggers on Ubuntu in dark mode
        return GetLuminance() <= 62;
        // tdf#156182 
        return GetLuminance() <= 156;
    }

    /** Comparison with luminance thresholds.
diff --git a/sd/qa/unit/data/xml/tdf92001_0.xml b/sd/qa/unit/data/xml/tdf92001_0.xml
index d67952e..234f751 100644
--- a/sd/qa/unit/data/xml/tdf92001_0.xml
+++ b/sd/qa/unit/data/xml/tdf92001_0.xml
@@ -1,6 +1,6 @@
<?xml version="1.0"?>
<XShapes>
 <XShape positionX="4826" positionY="4826" sizeX="19557" sizeY="12953" type="com.sun.star.drawing.CustomShape" fontHeight="18.000000" fontColor="000000" textAutoGrowHeight="false" textAutoGrowWidth="false" textContourFrame="false" textFitToSize="NONE" textHorizontalAdjust="BLOCK" textVerticalAdjust="CENTER" textLeftDistance="325" textRightDistance="325" textUpperDistance="200" textLowerDistance="200" textMaximumFrameHeight="0" textMaximumFrameWidth="0" textMinimumFrameHeight="0" textMinimumFrameWidth="0" textAnimationAmount="0" textAnimationCount="0" textAnimationDelay="0" textAnimationDirection="LEFT" textAnimationKind="NONE" textAnimationStartInside="false" textAnimationStopInside="false" textWritingMode="LR_TB" fillStyle="SOLID" fillColor="729fcf" fillTransparence="0" fillTransparenceGradientName="">
 <XShape positionX="4826" positionY="4826" sizeX="19557" sizeY="12953" type="com.sun.star.drawing.CustomShape" fontHeight="18.000000" fontColor="ffffff" textAutoGrowHeight="false" textAutoGrowWidth="false" textContourFrame="false" textFitToSize="NONE" textHorizontalAdjust="BLOCK" textVerticalAdjust="CENTER" textLeftDistance="325" textRightDistance="325" textUpperDistance="200" textLowerDistance="200" textMaximumFrameHeight="0" textMaximumFrameWidth="0" textMinimumFrameHeight="0" textMinimumFrameWidth="0" textAnimationAmount="0" textAnimationCount="0" textAnimationDelay="0" textAnimationDirection="LEFT" textAnimationKind="NONE" textAnimationStartInside="false" textAnimationStopInside="false" textWritingMode="LR_TB" fillStyle="SOLID" fillColor="729fcf" fillTransparence="0" fillTransparenceGradientName="">
  <FillTransparenceGradient style="LINEAR" startColor="000000" endColor="000000" angle="0" border="0" xOffset="50" yOffset="50" startIntensity="100" endIntensity="100" stepCount="0"/>
  <FillGradient style="LINEAR" startColor="3465a4" endColor="ffffff" angle="0" border="0" xOffset="50" yOffset="50" startIntensity="100" endIntensity="100" stepCount="0"/>
  <FillHatch style="SINGLE" color="3465a4" distance="20" angle="0"/>