Replace {map,edit}Display with {map,edit}Max in LinesInfo

No real changes, just store the maximum possible values for the first
visible line in both controls instead of storing the number of display
lines as we only really need the former.

samples/stc/stctest.cpp

@@ -1068,8 +1068,16 @@ private:
         LinesInfo lineInfo;
         lineInfo.mapVisible = LinesOnScreen();
         lineInfo.editVisible = m_edit->LinesOnScreen();
-        lineInfo.mapDisplay = GetDisplayLineCount();
-        lineInfo.editDisplay = m_edit->GetDisplayLineCount();
+
+        auto const mapDisplay = GetDisplayLineCount();
+        lineInfo.mapMax = mapDisplay > lineInfo.mapVisible
+            ? mapDisplay - lineInfo.mapVisible
+            : 0;
+
+        auto const editDisplay = m_edit->GetDisplayLineCount();
+        lineInfo.editMax = editDisplay > lineInfo.editVisible
+            ? editDisplay - lineInfo.editVisible
+            : 0;
 
         if ( lineInfo == m_lines )
             return false;
@@ -1091,10 +1099,8 @@ private:
         if ( firstLine < 0 )
             return 0;
 
-        auto const
-            lastValid = m_lines.editDisplay - m_lines.editVisible;
-        if ( firstLine > lastValid )
-            return lastValid;
+        if ( firstLine > m_lines.editMax )
+            return m_lines.editMax;
 
         return firstLine;
     }
@@ -1140,41 +1146,22 @@ private:
     // Scroll the editor to correspond to the current position in the map.
     void SyncEditPosition()
     {
-        if ( m_lines.editVisible >= m_lines.editDisplay )
-        {
-            SetEditFirstVisibleLine(0);
-            return;
-        }
+        auto const mapFirst = GetFirstVisibleLine();
 
         SetEditFirstVisibleLine
         (
-            wxMulDivInt32
-            (
-                GetFirstVisibleLine(),
-                m_lines.editDisplay - m_lines.editVisible,
-                m_lines.mapDisplay - m_lines.mapVisible
-            )
+            wxMulDivInt32(mapFirst, m_lines.editMax, m_lines.mapMax)
         );
     }
 
     // Scroll the map to correspond to the current position in the editor.
     void SyncMapPosition()
     {
-        // First check for the special case when all lines are visible.
-        if ( m_lines.editVisible >= m_lines.editDisplay )
-        {
-            SetMapFirstVisibleLine(0);
-            return;
-        }
+        auto const editFirst = m_edit->GetFirstVisibleLine();
 
         SetMapFirstVisibleLine
         (
-            wxMulDivInt32
-            (
-                m_edit->GetFirstVisibleLine(),
-                m_lines.mapDisplay - m_lines.mapVisible,
-                m_lines.editDisplay - m_lines.editVisible
-            )
+            wxMulDivInt32(editFirst, m_lines.mapMax, m_lines.editMax)
         );
 
         Refresh();
@@ -1351,11 +1338,6 @@ private:
         // when the dragging started.
         pos.y -= m_dragOffset;
 
-        // Define the maximum possible value for the first visible line in the
-        // editor and the map respectively.
-        auto const editMax = m_lines.editDisplay - m_lines.editVisible;
-        auto const mapMax = m_lines.mapDisplay - m_lines.mapVisible;
-
         // We need to find the editor first line such that the thumb will be
         // positioned with its middle at pos.y but the trouble is that we can't
         // invert the GetThumbInfo() calculation easily as conversion between
@@ -1370,8 +1352,8 @@ private:
         int editNew = editOld + (pos.y - m_dragLastY) / m_mapLineHeight;
         if ( editNew < 0 )
             editNew = 0;
-        else if ( editNew > editMax )
-            editNew = editMax;
+        else if ( editNew > m_lines.editMax )
+            editNew = m_lines.editMax;
 
             wxLogTrace(wxTRACE_STC_MAP, "Dragging: initial estimate=%d",
                        editNew);
@@ -1386,7 +1368,8 @@ private:
         for ( int direction = 0;; )
             {
                 // This would be the first visible line in the map.
-                auto const mapNew = wxMulDivInt32(editNew, mapMax, editMax);
+            auto const mapNew =
+                wxMulDivInt32(editNew, m_lines.mapMax, m_lines.editMax);
 
                 // This is similar to the code in GetThumbInfo() but uses the
                 // given line instead of the first currently visible one.
@@ -1401,7 +1384,7 @@ private:
             if ( thumbMiddle < thumbWanted )
                 {
                 // We can't go any further.
-                    if ( editNew >= editMax )
+                if ( editNew >= m_lines.editMax )
                         break;
 
                 // We overshot the correct value, we won't get any closer to it
@@ -1497,11 +1480,11 @@ private:
         // Number of lines visible in the editor.
         int editVisible = 0;
 
-        // Total number of physical lines in the map.
-        int mapDisplay = 0;
+        // Last valid value for the first map line.
+        int mapMax = 0;
 
-        // Total number of physical lines in the editor.
-        int editDisplay = 0;
+        // Last valid value for the first editor line.
+        int editMax = 0;
 
         LinesInfo() = default;
         LinesInfo(const LinesInfo& other) = default;
@@ -1511,8 +1494,8 @@ private:
         {
             return mapVisible == rhs.mapVisible &&
                    editVisible == rhs.editVisible &&
-                   mapDisplay == rhs.mapDisplay &&
-                   editDisplay == rhs.editDisplay;
+                   mapMax == rhs.mapMax &&
+                   editMax == rhs.editMax;
         }
 
         bool operator!=(const LinesInfo& rhs) const
@@ -1524,8 +1507,8 @@ private:
         {
             return wxString::Format
                    (
-                    "map/edit visible: %d/%d, map/edit physical: %d/%d",
-                    mapVisible, editVisible, mapDisplay, editDisplay
+                    "map/edit visible: %d/%d, map/edit first line max: %d/%d",
+                    mapVisible, editVisible, mapMax, editMax
                    );
         }
     } m_lines;