mitab-precision.patch

diff --git a/ogr/ogrsf_frmts/mitab/mitab_bounds.cpp b/ogr/ogrsf_frmts/mitab/mitab_bounds.cpp
index f66ef0b..09d540e 100644
--- a/ogr/ogrsf_frmts/mitab/mitab_bounds.cpp
+++ b/ogr/ogrsf_frmts/mitab/mitab_bounds.cpp
@@ -85,6 +85,7 @@ static MapInfoBoundsInfo gasBoundsList[] = {
 {{3, 0, 3, {-84.3666666667,41.5,42.1,43.6666666667,13123359.58,0}, 0,0,0,0, {0,0,0,0,0}},  -318674512.717618, -308729738.1419, 344921231.877618, 354866006.453336},
 {{3, 0, 3, {-84.3666666667,43.3166666667,44.1833333333,45.7,19685039.37,0}, 0,0,0,0, {0,0,0,0,0}},  -334588341.234808, -332680007.139814, 373958419.974808, 375866754.069803},
 {{3, 0, 3, {-87,44.7833333333,45.4833333333,47.0833333333,26246719.16,0}, 0,0,0,0, {0,0,0,0,0}},  -343541891.912548, -349200540.720143, 396035330.232548, 390376681.424953},
+{{3, 0, 7, {3,46.5,49,44,700000,6600000}, 0,0,0,0, {0,0,0,0,0}},  -357823.2365, 6037008.6939, 1313632.3628, 7230727.3772},
 {{3, 0, 7, {-100,39.8333333333,40,43,500000,0}, 0,0,0,0, {0,0,0,0,0}},  -96293653.747449, -89392122.913416, 97293653.747449, 104195184.581482},
 {{3, 0, 7, {-100,43.8333333333,44.4166666667,45.6833333333,600000,0}, 0,0,0,0, {0,0,0,0,0}},  -107757768.605122, -101845373.546917, 108957768.605122, 114870163.663327},
 {{3, 0, 7, {-100.3333333333,29.6666666667,30.1166666667,31.8833333333,700000,3000000}, 0,0,0,0, {0,0,0,0,0}},  -70389655.9882633, -57319094.8848422, 71789655.9882633, 84860217.0916844},
diff --git a/ogr/ogrsf_frmts/mitab/mitab_coordsys.cpp b/ogr/ogrsf_frmts/mitab/mitab_coordsys.cpp
index c4090e7..52abe9a 100644
--- a/ogr/ogrsf_frmts/mitab/mitab_coordsys.cpp
+++ b/ogr/ogrsf_frmts/mitab/mitab_coordsys.cpp
@@ -1335,10 +1335,30 @@ char *MITABSpatialRef2CoordSys( OGRSpatialReference * poSR )
 /* -------------------------------------------------------------------- */
 /*      Append Projection Parms.                                        */
 /* -------------------------------------------------------------------- */
-    for( int iParm = 0; iParm < nParmCount; iParm++ )
-        sprintf( szCoordSys + strlen(szCoordSys),
-                 ", %.15g",
-                 parms[iParm] );
+    if( nProjection == 3 
+          && nDatum == 33
+          && nEllipsoid == 0
+          && parms[3] == 44.0
+          && parms[2] == 49.0)
+    {
+       for( int iParm = 0; iParm < nParmCount; iParm++ )
+       {
+          // Swap standard parallel 1 and 2 when writing epsg:2154 L93
+          // (MapInfo save and read these parameters in reverse order
+          //  compared to spec)
+          if (iParm==2)
+             sprintf( szCoordSys + strlen(szCoordSys), ", %.15g", parms[3] );
+          else if (iParm==3)
+             sprintf( szCoordSys + strlen(szCoordSys), ", %.15g", parms[2] );
+          else
+             sprintf( szCoordSys + strlen(szCoordSys), ", %.15g", parms[iParm] );
+       }
+    }
+    else
+       for( int iParm = 0; iParm < nParmCount; iParm++ )
+           sprintf( szCoordSys + strlen(szCoordSys),
+                    ", %.15g",
+                    parms[iParm] );
 
 /* -------------------------------------------------------------------- */
 /*      Report on translation                                           */
diff --git a/ogr/ogrsf_frmts/mitab/mitab_mapheaderblock.cpp b/ogr/ogrsf_frmts/mitab/mitab_mapheaderblock.cpp
index 155684b..2682569 100644
--- a/ogr/ogrsf_frmts/mitab/mitab_mapheaderblock.cpp
+++ b/ogr/ogrsf_frmts/mitab/mitab_mapheaderblock.cpp
@@ -138,6 +138,12 @@
 
 #include "mitab.h"
 
+#ifdef WIN32
+inline double round(double r) {
+    return (r > 0.0) ? floor(r + 0.5) : ceil(r - 0.5);
+}
+#endif
+
 /*---------------------------------------------------------------------
  * Set various constants used in generating the header block.
  *--------------------------------------------------------------------*/
@@ -241,6 +247,9 @@ TABMAPHeaderBlock::TABMAPHeaderBlock(TABAccess eAccessMode /*= TABRead*/):
     m_sProj.dAffineParamD = 0.0;
     m_sProj.dAffineParamE = 0.0;
     m_sProj.dAffineParamF = 0.0;
+
+    m_XPrecision = -1;  // not specified
+    m_YPrecision = -1;  // not specified
 }
 
 /**********************************************************************
@@ -405,6 +414,22 @@ int     TABMAPHeaderBlock::InitBlockFromData(GByte *pabyBuf,
         }
     }
 
+    if( m_sProj.nProjId == 3 
+          && m_sProj.nDatumId == 33
+          && m_sProj.nEllipsoidId == 0
+          && m_sProj.adProjParams[3] == 49.0
+          && m_sProj.adProjParams[2] == 44.0)
+    {
+       // Swap SP1 and SP2 if in EPSG:2154 (L93)
+       // (MapInfo save and read these parameters in reverse order
+       //  compared to spec)
+       const double swap = m_sProj.adProjParams[3];
+       m_sProj.adProjParams[3] = m_sProj.adProjParams[2];
+       m_sProj.adProjParams[2] = swap;
+    }
+
+    UpdatePrecision();
+
     return 0;
 }
 
@@ -444,6 +469,12 @@ int TABMAPHeaderBlock::Int2Coordsys(GInt32 nX, GInt32 nY,
     else
         dY = (nY - m_YDispl) / m_YScale;
 
+    if (m_XPrecision > -1.0 && m_YPrecision > -1.0)
+    {
+       dX = round(dX*m_XPrecision)/static_cast<double>(m_XPrecision);
+       dY = round(dY*m_YPrecision)/static_cast<double>(m_YPrecision);
+    }
+
 //printf("Int2Coordsys: (%d, %d) -> (%.10g, %.10g)\n", nX, nY, dX, dY);
 
     return 0;
@@ -664,6 +695,8 @@ int TABMAPHeaderBlock::SetCoordsysBounds(double dXMin, double dYMin,
     m_nXMax = 1000000000;
     m_nYMax = 1000000000;
 
+    UpdatePrecision();
+
     return 0;
 }
 
@@ -1010,6 +1043,21 @@ int     TABMAPHeaderBlock::InitNewBlock(FILE *fpSrc, int nBlockSize,
 
 
 /**********************************************************************
+ *                   TABMAPHeaderBlock::UpdatePrecision()
+ *
+ * Update x and y maximum achievable precision given current scales 
+ * (m_XScale and m_YScale)
+ **********************************************************************/
+
+void TABMAPHeaderBlock::UpdatePrecision()
+{
+    const double rawXPrecision = 1.0/m_XScale;
+    m_XPrecision = static_cast<int>(pow(10.0, round(log10(1.0/rawXPrecision))));
+    const double rawYPrecision = 1.0/m_YScale;
+    m_YPrecision = static_cast<int>(pow(10.0, round(log10(1.0/rawYPrecision))));
+}
+
+/**********************************************************************
  *                   TABMAPHeaderBlock::Dump()
  *
  * Dump block contents... available only in DEBUG mode.
diff --git a/ogr/ogrsf_frmts/mitab/mitab_priv.h b/ogr/ogrsf_frmts/mitab/mitab_priv.h
index 1096057..b3d0e0f 100644
--- a/ogr/ogrsf_frmts/mitab/mitab_priv.h
+++ b/ogr/ogrsf_frmts/mitab/mitab_priv.h
@@ -911,6 +911,8 @@ class TABMAPHeaderBlock: public TABRawBinBlock
     int         GetProjInfo(TABProjInfo *psProjInfo);
     int         SetProjInfo(TABProjInfo *psProjInfo);
 
+    void        UpdatePrecision();
+
 #ifdef DEBUG
     virtual void Dump(FILE *fpOut = NULL);
 #endif
@@ -955,6 +957,9 @@ class TABMAPHeaderBlock: public TABRawBinBlock
     double      m_YScale;
     double      m_XDispl;
     double      m_YDispl;
+
+    GInt32      m_XPrecision; // maximum achievable precision along X axis depending on bounds extent
+    GInt32      m_YPrecision; // maximum achievable precision along Y axis depending on bounds extent
     
 };
 
diff --git a/ogr/ogrsf_frmts/mitab/mitab_spatialref.cpp b/ogr/ogrsf_frmts/mitab/mitab_spatialref.cpp
index 5a942ef..255ae4f 100644
--- a/ogr/ogrsf_frmts/mitab/mitab_spatialref.cpp
+++ b/ogr/ogrsf_frmts/mitab/mitab_spatialref.cpp
@@ -639,29 +639,12 @@ OGRSpatialReference *TABFile::GetSpatialRef()
          * Lambert Conic Conformal
          *-------------------------------------------------------------*/
       case 3:
-        if( sTABProj.nProjId == 3 
-              && sTABProj.nDatumId == 33
-              && sTABProj.nEllipsoidId == 0
-              && sTABProj.adProjParams[3] == 49.0
-              && sTABProj.adProjParams[2] == 44.0)
-        {
-           // Swap SP1 and SP2 if in EPSG:2154 (L93)
-           // (MapInfo save and read these parameters in reverse order
-           //  compared to spec)
-           m_poSpatialRef->SetLCC( sTABProj.adProjParams[3],
-                                   sTABProj.adProjParams[2],
-                                   sTABProj.adProjParams[1],
-                                   sTABProj.adProjParams[0],
-                                   sTABProj.adProjParams[4],
-                                   sTABProj.adProjParams[5] );
-        }
-        else
-           m_poSpatialRef->SetLCC( sTABProj.adProjParams[2],
-                                   sTABProj.adProjParams[3],
-                                   sTABProj.adProjParams[1],
-                                   sTABProj.adProjParams[0],
-                                   sTABProj.adProjParams[4],
-                                   sTABProj.adProjParams[5] );
+        m_poSpatialRef->SetLCC( sTABProj.adProjParams[2],
+                                sTABProj.adProjParams[3],
+                                sTABProj.adProjParams[1],
+                                sTABProj.adProjParams[0],
+                                sTABProj.adProjParams[4],
+                                sTABProj.adProjParams[5] );
         break;
 
         /*--------------------------------------------------------------