scrolloff is now a line,column pair

Fixes #152

3 files changed, 32 insertions, 13 deletions

diff --git a/src/option_manager.cc b/src/option_manager.cc
index ce806b27..8b7c2f76 100644
--- a/src/option_manager.cc
+++ b/src/option_manager.cc
@@ -134,8 +134,8 @@ GlobalOptions::GlobalOptions()
     declare_option("tabstop", "size of a tab character", 8);
     declare_option("indentwidth", "indentation width", 4);
     declare_option("scrolloff",
-                   "number of lines to keep visible main cursor when scrolling",
-                   0);
+                   "number of lines and columns to keep visible main cursor when scrolling",
+                   CharCoord{0,0});
     declare_option("eolformat", "end of line format: 'crlf' or 'lf'", "lf"_str);
     declare_option("BOM", "insert a byte order mark when writing buffer",
                    "no"_str);
diff --git a/src/option_types.hh b/src/option_types.hh
index 3d8e7476..e68ddc30 100644
--- a/src/option_types.hh
+++ b/src/option_types.hh
@@ -4,6 +4,7 @@
 #include "exception.hh"
 #include "string.hh"
 #include "units.hh"
+#include "coord.hh"
 
 #include <tuple>
 #include <vector>
@@ -171,6 +172,22 @@ bool option_add(T&, const T&)
     throw runtime_error("no add operation supported for this option type");
 }
 
+template<typename EffectiveType, typename LineType, typename ColumnType>
+inline void option_from_string(const String& str, LineAndColumn<EffectiveType, LineType, ColumnType>& opt)
+{
+    auto vals = split(str, '|');
+    if (vals.size() != 2)
+        throw runtime_error("expected <line>|<column>");
+    opt.line = str_to_int(vals[0]);
+    opt.column = str_to_int(vals[1]);
+}
+
+template<typename EffectiveType, typename LineType, typename ColumnType>
+inline String option_to_string(const LineAndColumn<EffectiveType, LineType, ColumnType>& opt)
+{
+    return to_string(opt.line) + '|' + to_string(opt.column);
+}
+
 enum YesNoAsk
 {
     Yes,
diff --git a/src/window.cc b/src/window.cc
index da2b5f06..e76dcc8d 100644
--- a/src/window.cc
+++ b/src/window.cc
@@ -116,7 +116,7 @@ static LineCount adapt_view_pos(LineCount line, LineCount offset,
     return view_pos;
 }
 
-static CharCount adapt_view_pos(const DisplayBuffer& display_buffer,
+static CharCount adapt_view_pos(const DisplayBuffer& display_buffer, CharCount offset,
                                 ByteCoord pos, CharCount view_pos, CharCount view_size)
 {
     CharCount buffer_column = 0;
@@ -144,11 +144,11 @@ static CharCount adapt_view_pos(const DisplayBuffer& display_buffer,
                         pos_end = pos_beg + atom.length();
                     }
 
-                    if (pos_beg < view_pos)
-                        return pos_beg;
+                    if (pos_beg - offset < view_pos)
+                        return std::max(0_char, pos_beg - offset);
 
-                    if (pos_end >= view_pos + view_size - non_buffer_column)
-                        return pos_end - view_size + non_buffer_column;
+                    if (pos_end + offset >= view_pos + view_size - non_buffer_column)
+                        return pos_end + offset - view_size + non_buffer_column;
                 }
                 buffer_column += atom.length();
             }
@@ -165,13 +165,15 @@ void Window::scroll_to_keep_selection_visible_ifn(const Context& context)
     const auto& anchor = selection.anchor();
     const auto& cursor  = selection.cursor();
 
-    const LineCount offset = std::min<LineCount>(options()["scrolloff"].get<int>(),
-                                                 (m_dimensions.line - 1) / 2);
+    const CharCoord max_offset{(m_dimensions.line - 1)/2,
+                               (m_dimensions.column - 1)/2};
+    const CharCoord offset = std::min(options()["scrolloff"].get<CharCoord>(),
+                                      max_offset);
 
     // scroll lines if needed, try to get as much of the selection visible as possible
-    m_position.line = adapt_view_pos(anchor.line, offset, m_position.line,
+    m_position.line = adapt_view_pos(anchor.line, offset.line, m_position.line,
                                      m_dimensions.line, buffer().line_count());
-    m_position.line = adapt_view_pos(cursor.line,  offset, m_position.line,
+    m_position.line = adapt_view_pos(cursor.line,  offset.line, m_position.line,
                                      m_dimensions.line, buffer().line_count());
 
     // highlight only the line containing the cursor
@@ -187,10 +189,10 @@ void Window::scroll_to_keep_selection_visible_ifn(const Context& context)
     // (this is only valid if highlighting one line and multiple lines put
     // the cursor in the same position, however I do not find any sane example
     // of highlighters not doing that)
-    m_position.column = adapt_view_pos(display_buffer,
+    m_position.column = adapt_view_pos(display_buffer, offset.column,
                                        anchor.line == cursor.line ? anchor : cursor.line,
                                        m_position.column, m_dimensions.column);
-    m_position.column = adapt_view_pos(display_buffer, cursor,
+    m_position.column = adapt_view_pos(display_buffer, offset.column, cursor,
                                        m_position.column, m_dimensions.column);
 }