fixes and improvements for databar length calculation

Now min length and max length are also respected when the axis is in the
middle.

Additionally when the axis is in the middle we now scale the negative
and the positive part with the same factor. This is better for itnerop
and makes more sense.

Change-Id: If4c1adc0977d8ed66b8f22d937b0b3933288d012

sc/source/core/data/colorscale.cxx

@@ -915,24 +915,41 @@ ScDataBarInfo* ScDataBarFormat::GetDataBarInfo(const ScAddress& rAddr) const
                 nMinPositive = nMin;
             if (mpFormatData->mpUpperLimit->GetType() == COLORSCALE_MAX && nMax < 0)
                 nMaxNegative = nMax;
-        }
-        else if( mpFormatData->meAxisPosition == databar::MIDDLE)
-            pInfo->mnZero = 50;
 
-        //calculate the length
-        if(nValue < 0)
-        {
-            if (nValue < nMin)
-                pInfo->mnLength = -100;
+            //calculate the length
+            if(nValue < 0)
+            {
+                if (nValue < nMin)
+                    pInfo->mnLength = -100;
+                else
+                    pInfo->mnLength = -100 * (nValue-nMaxNegative)/(nMin-nMaxNegative);
+            }
             else
-                pInfo->mnLength = -100 * (nValue-nMaxNegative)/(nMin-nMaxNegative);
+            {
+                if ( nValue > nMax )
+                    pInfo->mnLength = 100;
+                else
+                    pInfo->mnLength = (nValue-nMinPositive)/(nMax-nMinPositive)*100;
+            }
         }
-        else
+        else if( mpFormatData->meAxisPosition == databar::MIDDLE)
         {
-            if ( nValue > nMax )
-                pInfo->mnLength = 100;
+            pInfo->mnZero = 50;
+            double nAbsMax = std::max(std::abs(nMin), std::abs(nMax));
+            if (nValue < 0)
+            {
+                if (nValue < nMin)
+                    pInfo->mnLength = -nMaxLength;
+                else
+                    pInfo->mnLength = nMaxLength * (nValue/nAbsMax);
+            }
             else
-                pInfo->mnLength = (nValue-nMinPositive)/(nMax-nMinPositive)*100;
+            {
+                if (nValue > nMax)
+                    pInfo->mnLength = nMaxLength;
+                else
+                    pInfo->mnLength = nMaxLength * (nValue/nAbsMax);
+            }
         }
     }