refactor(screen): screen.c delenda est

drawscreen.c vs screen.c makes absolutely no sense.
The screen exists only to draw upon it, therefore helper functions
are distributed randomly between screen.c and the file that
does the redrawing. In addition screen.c does a lot of drawing on the
screen.

It made more sense for vim/vim as our grid.c is their screen.c

Not sure if we want to dump all the code for option chars into
optionstr.c, so keep these in a optionchar.c for now.

1 files changed, 83 insertions, 4 deletions

diff --git a/src/nvim/drawline.c b/src/nvim/drawline.c
index a46f383f64..d9a8c6a6d9 100644
--- a/src/nvim/drawline.c
+++ b/src/nvim/drawline.c
@@ -21,6 +21,7 @@
 #include "nvim/decoration_provider.h"
 #include "nvim/diff.h"
 #include "nvim/drawline.h"
+#include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/extmark_defs.h"
 #include "nvim/fold.h"
@@ -40,7 +41,6 @@
 #include "nvim/plines.h"
 #include "nvim/pos.h"
 #include "nvim/quickfix.h"
-#include "nvim/screen.h"
 #include "nvim/sign.h"
 #include "nvim/spell.h"
 #include "nvim/state.h"
@@ -384,6 +384,70 @@ static void handle_foldcolumn(win_T *wp, winlinevars_T *wlv)
   }
 }
 
+/// Fills the foldcolumn at "p" for window "wp".
+/// Only to be called when 'foldcolumn' > 0.
+///
+/// @param[out] p  Char array to write into
+/// @param lnum    Absolute current line number
+/// @param closed  Whether it is in 'foldcolumn' mode
+///
+/// Assume monocell characters
+/// @return number of chars added to \param p
+size_t fill_foldcolumn(char *p, win_T *wp, foldinfo_T foldinfo, linenr_T lnum)
+{
+  int i = 0;
+  int level;
+  int first_level;
+  int fdc = compute_foldcolumn(wp, 0);    // available cell width
+  size_t char_counter = 0;
+  int symbol = 0;
+  int len = 0;
+  bool closed = foldinfo.fi_lines > 0;
+  // Init to all spaces.
+  memset(p, ' ', MAX_MCO * (size_t)fdc + 1);
+
+  level = foldinfo.fi_level;
+
+  // If the column is too narrow, we start at the lowest level that
+  // fits and use numbers to indicate the depth.
+  first_level = level - fdc - closed + 1;
+  if (first_level < 1) {
+    first_level = 1;
+  }
+
+  for (i = 0; i < MIN(fdc, level); i++) {
+    if (foldinfo.fi_lnum == lnum
+        && first_level + i >= foldinfo.fi_low_level) {
+      symbol = wp->w_p_fcs_chars.foldopen;
+    } else if (first_level == 1) {
+      symbol = wp->w_p_fcs_chars.foldsep;
+    } else if (first_level + i <= 9) {
+      symbol = '0' + first_level + i;
+    } else {
+      symbol = '>';
+    }
+
+    len = utf_char2bytes(symbol, &p[char_counter]);
+    char_counter += (size_t)len;
+    if (first_level + i >= level) {
+      i++;
+      break;
+    }
+  }
+
+  if (closed) {
+    if (symbol != 0) {
+      // rollback previous write
+      char_counter -= (size_t)len;
+      memset(&p[char_counter], ' ', (size_t)len);
+    }
+    len = utf_char2bytes(wp->w_p_fcs_chars.foldclosed, &p[char_counter]);
+    char_counter += (size_t)len;
+  }
+
+  return MAX(char_counter + (size_t)(fdc - i), (size_t)fdc);
+}
+
 /// Get information needed to display the sign in line "wlv->lnum" in window "wp".
 /// If "nrcol" is true, the sign is going to be displayed in the number column.
 /// Otherwise the sign is going to be displayed in the sign column.
@@ -469,6 +533,21 @@ static int get_sign_attrs(buf_T *buf, winlinevars_T *wlv, int *sign_num_attrp, i
   return num_signs;
 }
 
+/// Returns width of the signcolumn that should be used for the whole window
+///
+/// @param wp window we want signcolumn width from
+/// @return max width of signcolumn (cell unit)
+///
+/// @note Returns a constant for now but hopefully we can improve neovim so that
+///       the returned value width adapts to the maximum number of marks to draw
+///       for the window
+/// TODO(teto)
+int win_signcol_width(win_T *wp)
+{
+  // 2 is vim default value
+  return 2;
+}
+
 static inline void get_line_number_str(win_T *wp, linenr_T lnum, char *buf, size_t buf_len)
 {
   long num;
@@ -553,7 +632,7 @@ static void handle_lnum_col(win_T *wp, winlinevars_T *wlv, int num_signs, int si
           }
         }
         if (wp->w_p_rl) {                       // reverse line numbers
-          // like rl_mirror(), but keep the space at the end
+          // like rl_mirror_ascii(), but keep the space at the end
           char *p2 = skipwhite(wlv->extra);
           p2 = skiptowhite(p2) - 1;
           for (char *p1 = skipwhite(wlv->extra); p1 < p2; p1++, p2--) {
@@ -1799,7 +1878,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
         // Non-BMP character : display as ? or fullwidth ?.
         transchar_hex(wlv.extra, mb_c);
         if (wp->w_p_rl) {  // reverse
-          rl_mirror(wlv.extra);
+          rl_mirror_ascii(wlv.extra);
         }
 
         wlv.p_extra = wlv.extra;
@@ -2297,7 +2376,7 @@ int win_line(win_T *wp, linenr_T lnum, int startrow, int endrow, bool nochange,
             wlv.n_extra = byte2cells(c) - 1;
           }
           if ((dy_flags & DY_UHEX) && wp->w_p_rl) {
-            rl_mirror(wlv.p_extra);                 // reverse "<12>"
+            rl_mirror_ascii(wlv.p_extra);                 // reverse "<12>"
           }
           wlv.c_extra = NUL;
           wlv.c_final = NUL;