X-Git-Url: https://plomlompom.com/repos/?a=blobdiff_plain;f=src%2Fwindows.c;h=b075b80a11bd02c8de5e538166c2ff8b24ec8350;hb=6ed13cec71fa9b348f609707c2fc02978609b249;hp=98c8cf8b46da0bbdd73c4b9659a4c27dbfe48c3a;hpb=e9d8b1aca776341c9cdaa2ea6406336661d82a76;p=plomrogue

diff --git a/src/windows.c b/src/windows.c
index 98c8cf8..b075b80 100644
--- a/src/windows.c
+++ b/src/windows.c
@@ -1,300 +1,687 @@
-#include <stdlib.h>
-#include <stdint.h>
-#include <ncurses.h>
-#include <string.h>
+/* windows.c */
+
 #include "windows.h"
+#include <stdint.h>    /* for uint8_t, uint16_t, uint32_t, UINT16_MAX */
+#include <ncurses.h>   /* for typedefs WINDOW, chtype, wresize(), getmaxx(), */
+                       /* getmaxy(), delwin(), mvwaddch(), mvwaddstr(),      */
+                       /* newpad(), wnoutrefres(), erase(), werase(),        */
+                       /* pnoutrefresh(), doupdate(), getmaxyx()   */
+#include <stdlib.h>    /* for malloc(), free() */
+#include <string.h>    /* for strlen(), strnlen(), memcpy() */
+#include "yx_uint16.h" /* for struct yx_uint16 */
+#include "misc.h"      /* for center_offset(), try_malloc() */
+#include "main.h"      /* for world global */
+#include "rexit.h"     /* for exit_err() */
 
-struct Corners {
-  struct yx_uint16 tl;
-  struct yx_uint16 tr;
-  struct yx_uint16 bl;
-  struct yx_uint16 br; };
-
-static void refit_pad (struct WinMeta *);
-static void place_win (struct WinMeta *, struct Win *);
-static void update_wins (struct WinMeta *, struct Win *);
-static void destroy_win (struct Win *);
-static void draw_wins_borders (struct Win *, struct Win *, struct Corners *, uint16_t);
-static void draw_win_borders (struct Win *, char);
-static void draw_wins (struct Win *);
-
-extern struct WinMeta init_win_meta (WINDOW * screen) {
-// Create and populate WinMeta struct with sane default values.
-  struct WinMeta wmeta;
-  wmeta.screen = screen;
-  wmeta.pad.size.y = getmaxy(screen);
-  wmeta.pad.size.x = getmaxx(screen);
-  wmeta.chain_start = 0;
-  wmeta.chain_end = 0;
-  wmeta.pad_offset = 0;
-  wmeta.pad.curses_win = newpad(wmeta.pad.size.y, 1);
-  wmeta.active = 0;
-  return wmeta; }
-
-extern struct Win init_win (struct WinMeta * wmeta, char * title, void * data, void * func) {
-// Create and populate Win struct with sane default values.
-  struct Win w;
-  w.prev = 0;
-  w.next = 0;
-  w.frame.curses_win = 0;
-  w.title = title;
-  w.frame.size.x = 20;
-  w.frame.size.y = wmeta->pad.size.y - 1;
-  w.data = data;
-  w.draw = func;
-  return w; }
-
-extern void append_win (struct WinMeta * wmeta, struct Win * w) {
-// Append win to window chain. Set active, if first window. Update geometry of windows from new window on.
-  if (0 != wmeta->chain_start) {
-    w->prev = wmeta->chain_end;
-    wmeta->chain_end->next = w; }
-  else {
-    wmeta->active = w;
-    wmeta->chain_start = w; }
-  wmeta->chain_end = w;
-  update_wins(wmeta, w); }
-
-static void refit_pad (struct WinMeta * wmeta) {
-// Fit pad width to minimum width demanded by current windows' geometries.
-  uint16_t lastwincol = 0;
-  struct Win * w_p = wmeta->chain_start;
-  while (w_p != 0) {
-    if (w_p->start.x + w_p->frame.size.x > lastwincol + 1)
-      lastwincol = w_p->start.x + w_p->frame.size.x - 1;
-    w_p = w_p->next; }
-  if (getmaxx(wmeta->pad.curses_win) != lastwincol)
-    wresize(wmeta->pad.curses_win, getmaxy(wmeta->pad.curses_win), lastwincol + 2); }
-
-extern void suspend_win (struct WinMeta * wmeta, struct Win * w) {
-// Destroy win, suspend from chain. Update geometry of following rows and pad, as well as activity selection.
-  destroy_win(w);
-  if (wmeta->chain_start != w)         // Give win's position in the chain to element next to it in the chain.
-    w->prev->next = w->next;
-  else
-    wmeta->chain_start = w->next;
-  char pad_refitted = 0;
-  if (wmeta->chain_end != w) {                      // Let chain element next to win know its new predecessor.
-    w->next->prev = w->prev;
-    if (wmeta->active == w)                               // If win was active, shift active window pointer to
-      wmeta->active = w->next;                            // the next chain element, if that is a window ...
-    update_wins(wmeta, w->next);
-    pad_refitted = 1; }
-  else {
-    wmeta->chain_end = w->prev;
-    if (wmeta->active == w)                                            // ... or else to the previous element.
-      wmeta->active = w->prev; }
-  w->prev = 0;
-  w->next = 0;
-  if (0 == pad_refitted)                                                            // Refit pad if necessary.
-    refit_pad(wmeta); }
-
-static void place_win (struct WinMeta * wmeta, struct Win * w) {
-// Based on position and sizes of previous window, find fitting place for current window.
-  w->start.x = 0;                                  // if window is first in chain, place it on top-left corner
-  w->start.y = 1;
-  if (0 != w->prev) {
-    struct Win * w_top = w->prev;
-    while (w_top->start.y != 1)
-      w_top = w_top->prev;                                       // else, default to placing window in new top
-    w->start.x = w_top->start.x + w_top->frame.size.x + 1;       // column to the right of the last one
-    uint16_t w_prev_maxy = w->prev->start.y + getmaxy(w->prev->frame.curses_win);
-    if (w->frame.size.x <= w->prev->frame.size.x && w->frame.size.y < wmeta->pad.size.y - w_prev_maxy) {
-      w->start.x = w->prev->start.x;                       // place window below previous window if it fits
-      w->start.y = w_prev_maxy + 1; }                      // vertically and is not wider than its predecessor
-    else {
-      struct Win * w_up = w->prev;
-      struct Win * w_upup = w_up;
-      uint16_t widthdiff;
-      while (w_up != w_top) {
-        w_upup = w_up->prev;
-        while (1) {
-          if (w_up->start.y != w_upup->start.y)
-            break;
-          w_upup = w_upup->prev; }
-        w_prev_maxy = w_upup->start.y + getmaxy(w_upup->frame.curses_win);
-        widthdiff = (w_upup->start.x + w_upup->frame.size.x) - (w_up->start.x + w_up->frame.size.x);
-        if (w->frame.size.y < wmeta->pad.size.y - w_prev_maxy && w->frame.size.x < widthdiff) {
-          w->start.x = w_up->start.x + w_up->frame.size.x + 1 ; // else try to open new sub column under
-          w->start.y = w_prev_maxy + 1;                        // last window below which enough space remains
-          break; }
-        w_up = w_upup; } } } }
-
-static void update_wins (struct WinMeta * wmeta, struct Win * w) {
-// Update geometry of win and its next of kin. Destroy (if visible), (re-)build window. If need, resize pad.
-  if (0 != w->frame.curses_win)
-    destroy_win (w);
-  place_win(wmeta, w);
-  refit_pad(wmeta);
-  w->frame.curses_win=subpad(wmeta->pad.curses_win, w->frame.size.y, w->frame.size.x, w->start.y, w->start.x);
-  if (0 != w->next)
-    update_wins (wmeta, w->next); }
-
-static void destroy_win (struct Win * w) {
-// Delete window.
-  delwin(w->frame.curses_win);
-  w->frame.curses_win = 0; }
-
-static void draw_win_borders (struct Win * w, char active) {
-// Draw borders of window win, including title. Decorate in a special way if window is marked as active.
-  uint16_t y, x;
-  for (y = w->start.y; y <= w->start.y + w->frame.size.y; y++) {
-    mvwaddch(wgetparent(w->frame.curses_win), y, w->start.x - 1, '|');
-    mvwaddch(wgetparent(w->frame.curses_win), y, w->start.x + w->frame.size.x, '|'); }
-  for (x = w->start.x; x <= w->start.x + w->frame.size.x; x++) {
-    mvwaddch(wgetparent(w->frame.curses_win), w->start.y - 1, x, '-');
-    mvwaddch(wgetparent(w->frame.curses_win), w->start.y + w->frame.size.y, x, '-'); }
-  char min_title_length_visible = 3;        // 1 char minimal, plus 2 chars for decoration left/right of title
-  if (w->frame.size.x >= min_title_length_visible) {
-    uint16_t title_offset = 0;
-    if (w->frame.size.x > strlen(w->title) + 2)
-      title_offset = (w->frame.size.x - (strlen(w->title) + 2)) / 2;                  // + 2 is for decoration
-    uint16_t length_visible = strnlen(w->title, w->frame.size.x - 2);
-    char title[length_visible + 3];
-    char decoration = ' ';
-    if (1 == active)
-      decoration = '$';
-    memcpy(title + 1, w->title, length_visible);
-    title[0] = title[length_visible + 1] = decoration;
-    title[length_visible + 2] = '\0';
-    mvwaddstr(wgetparent(w->frame.curses_win), w->start.y - 1, w->start.x + title_offset, title); } }
-
-static void draw_wins_borders (struct Win * w, struct Win * w_active, struct Corners * corners, uint16_t i) {
-// Call draw_win_borders() for all windows in chain from win on. Save current window's border corners.
-  char active = 0;
-  if (w == w_active)
-    active = 1;
-  draw_win_borders(w, active);
-  corners[i].tl.y = w->start.y - 1;
-  corners[i].tl.x = w->start.x - 1;
-  corners[i].tr.y = w->start.y - 1;
-  corners[i].tr.x = w->start.x + w->frame.size.x;
-  corners[i].bl.y = w->start.y + w->frame.size.y;
-  corners[i].bl.x = w->start.x - 1;
-  corners[i].br.y = w->start.y + w->frame.size.y;
-  corners[i].br.x = w->start.x + w->frame.size.x;
-  if (0 != w->next) {
-    draw_wins_borders (w->next, w_active, corners, i + 1); } }
-
-static void draw_wins (struct Win * w) {
-// Draw contents of all windows in window chain from win on.
-  w->draw(w);
-  if (0 != w->next) {
-    draw_wins (w->next); } }
-
-extern void draw_scroll_hint (struct Frame * frame, uint16_t pos, uint32_t dist, char dir) {
-// Draw scroll hint into frame at pos (row or col dependend on dir), mark distance of dist cells into dir.
-  char more[] = "more";
-  char unit_cols[] = "columns";
-  char unit_rows[] = "lines";
-  uint16_t dsc_space = frame->size.x;
-  char * unit = unit_rows;
-  if ('<' == dir || '>' == dir) {
-    dsc_space = frame->size.y;
-    unit = unit_cols; }
-  char * scrolldsc = malloc((4 * sizeof(char)) + strlen(more) + strlen(unit) + 10);  // 10 = uint32 max strlen
-  sprintf(scrolldsc, " %d %s %s ", dist, more, unit);
-  char offset = 1, q;
-  if (dsc_space > strlen(scrolldsc) + 1)
-    offset = (dsc_space - strlen(scrolldsc)) / 2;
-  chtype symbol;
-  for (q = 0; q < dsc_space; q++) {
-    if (q >= offset && q < strlen(scrolldsc) + offset)
-      symbol = scrolldsc[q - offset] | A_REVERSE;
-    else
-      symbol = dir | A_REVERSE;
+
+
+/* Fit virtual screen's width to minimum width demanded by current windows'
+ * geometries.
+ */
+static void refit_pad();
+
+/* Update geometry (sizes, positions) of window "w" and its successors in the
+ * window chain. For the positioning algorithm place_win() is used.
+ */
+static void update_wins(struct Win * w);
+static void place_win(struct Win * w);
+
+/* Draw scroll hint (a line saying that there are "dist" more elements of
+ * "unit" further into the direction symbolized by the "dir" char) into virtual
+ * screen pad, onto an appropriate edge of either a window or the screen; the
+ * left or right edge if "dir" is "<" or ">", or the upper or lower edge if it
+ * is "^" or "v". "start" should be either the start coordinate of a window's
+ * frame or .y=0, .x=wm->pad_offset if it describes the virtual screen pad.
+ * winscroll_hint() and padscroll_hint() are wrappers to simplify these uses.
+ */
+static void scroll_hint(struct yx_uint16 fsize, char dir, uint16_t dist,
+                        char * unit, struct yx_uint16 start);
+static void winscroll_hint(struct Win * w, char dir, uint16_t dist);
+static void padscroll_hint(char dir, uint16_t dist);
+
+/* Draw contents of all windows in window chain from window "w" onwards. */
+static void draw_wins(struct Win * w);
+
+/* draw_win_borderlines() draws the vertical and horizontal borders of window
+ * "w" sans corners into the virtual screen "pad", and draws the top border
+ * line as the windows' title bar (highlighted if the window is described
+ * active by "active" being == 1).
+ *
+ * draw_wins_borderlines() calls draw_win_borderlines() recursively on all
+ * windows from "w" on. "w_active" is a pointer to the one window that
+ * draw_win_borderlines() is supposed to handle as the active window.
+ *
+ * Finally, draw_wins_bordercorners() draws into "pad" the borders of window "w"
+ * and all its successors.
+ */
+static void draw_win_borderlines(struct Win * w, char active, WINDOW * pad);
+static void draw_wins_borderlines(struct Win * w, struct Win * w_active,
+                                  WINDOW * pad);
+static void draw_wins_bordercorners(struct Win * w, WINDOW * pad);
+
+/* Shift active window forwards / backwards in window chain. */
+static void shift_win_forward();
+static void shift_win_backward();
+
+
+
+static void refit_pad()
+{
+    /* Determine rightmost window column. */
+    uint32_t lastwcol = 0;
+    struct Win * wp = world.wmeta->chain_start;
+    while (wp != 0)
+    {
+        if ((uint32_t) wp->start.x + (uint32_t) wp->framesize.x > lastwcol + 1)
+        {
+            lastwcol = (uint32_t) wp->start.x + (uint32_t) wp->framesize.x - 1;
+        }
+        wp = wp->next;
+    }
+
+    /* Only resize the pad if the rightmost window column has changed. */
+    char * err_s = "refit_pad() extends virtual screen beyond legal sizes.";
+    char * err_m = "refit_pad() triggers memory alloc error via wresize().";
+    if (getmaxx(world.wmeta->pad) + 1 != lastwcol)
+    {
+        uint8_t t = (lastwcol + 2 > UINT16_MAX);
+        exit_err(t, err_s);
+        t = wresize(world.wmeta->pad, getmaxy(world.wmeta->pad), lastwcol + 2);
+        exit_err(t, err_m);
+    }
+}
+
+
+
+static void update_wins(struct Win * w)
+{
+    place_win(w);
+    refit_pad();
+    if (0 != w->next)
+    {
+        update_wins(w->next);
+    }
+}
+
+
+
+static void place_win(struct Win * w)
+{
+    /* If w is first window, it goes into the upper-left corner. */
+    w->start.x = 0;
+    w->start.y = 1;                             /* Leave space for title bar. */
+    if (0 != w->prev)
+    {
+
+        /* If w is not first winddow, fit its top left corner to the top right
+         * corner of w_top, the last predecessor window starting at the top.
+         */
+        struct Win * w_top = w->prev;
+        while (w_top->start.y != 1)
+        {
+            w_top = w_top->prev;
+        }
+        w->start.x = w_top->start.x + w_top->framesize.x + 1;
+
+        /* Fit w's top left corner to bottom left corner of its immediate
+         * predecessor window if enough empty space is found there.
+         */
+        uint16_t w_prev_maxy = w->prev->start.y + w->prev->framesize.y;
+        if (   w->framesize.x <= w->prev->framesize.x
+            && w->framesize.y <  world.wmeta->padsize.y - w_prev_maxy)
+        {
+            w->start.x = w->prev->start.x;
+            w->start.y = w_prev_maxy + 1;
+        }
+
+        /* Failing that, try to fit the top left corner to the top right corner
+         * of the last predecessor w_test 1) not followed by top windows or any
+         * other windows with a left corner further rightwards than its own left
+         * corner 2) with enough space rightwards for w until the bottom right
+         * corner of w_thro directly throning over it 3) and with this same
+         * space extending for enough to the bottom for fitting in w.
+         */
+        else
+        {
+            struct Win * w_test = w->prev;
+            struct Win * w_thro;
+            while (w_test != w_top)
+            {
+                w_thro = w_test->prev;
+                while (w_test->start.y <= w_thro->start.y)
+                {
+                    w_thro = w_thro->prev;
+                }
+                uint16_t w_thro_bottom = w_thro->start.y + w_thro->framesize.y;
+                uint16_t free_width = (w_thro->start.x + w_thro->framesize.x)
+                                      - (w_test->start.x + w_test->framesize.x);
+                if (   w->framesize.y < world.wmeta->padsize.y - w_thro_bottom
+                    && w->framesize.x < free_width)
+                {
+                    w->start.x = w_test->start.x + w_test->framesize.x + 1;
+                    w->start.y = w_thro_bottom + 1;
+                    break;
+                }
+                w_test = w_thro;
+            }
+        }
+    }
+}
+
+
+
+static void scroll_hint(struct yx_uint16 fsize, char dir, uint16_t dist,
+                        char * unit, struct yx_uint16 start)
+{
+    /* Decide on alignment (vertical/horizontal?), thereby hint text space. */
+    char * more = "more";
+    uint16_t dsc_space = fsize.x;
     if ('<' == dir || '>' == dir)
-      mvwaddch(frame->curses_win, q, pos, symbol);
+    {
+        dsc_space = fsize.y;
+    }                                  /* vv-- 10 = max strlen for uint16_t */
+    char scrolldsc[1 + strlen(more) + 1 + 10 + 1 + strlen(unit) + 1 + 1];
+    sprintf(scrolldsc, " %d %s %s ", dist, more, unit);
+
+    /* Decide on offset of the description text inside the scroll hint line. */
+    uint16_t dsc_offset = 1;
+    if (dsc_space > strlen(scrolldsc) + 1)
+    {
+        dsc_offset = (dsc_space - strlen(scrolldsc)) / 2;
+    }
+
+    /* Draw scroll hint line as dir symbols bracketing description text. */
+    uint16_t draw_offset = 0;
+    if      ('>' == dir)
+    {
+        draw_offset = fsize.x - 1;
+    }
+    else if ('v' == dir)
+    {
+        draw_offset = fsize.y - 1;
+    }
+    uint16_t q = 0;
+    for (; q < dsc_space; q++)
+    {
+        chtype c = dir | A_REVERSE;
+        if (q >= dsc_offset && q < strlen(scrolldsc) + dsc_offset)
+        {
+            c = scrolldsc[q - dsc_offset] | A_REVERSE;
+        }
+        if ('<' == dir || '>' == dir)
+        {
+            mvwaddch(world.wmeta->pad, start.y + q, start.x + draw_offset, c);
+        }
+        else
+        {
+            mvwaddch(world.wmeta->pad, start.y + draw_offset, start.x + q, c);
+        }
+    }
+}
+
+
+static void padscroll_hint(char dir, uint16_t dist)
+{
+    struct yx_uint16 start;
+    start.y = 0;
+    start.x = world.wmeta->pad_offset;
+    scroll_hint(world.wmeta->padsize, dir, dist, "columns", start);
+}
+
+
+
+static void winscroll_hint(struct Win * w, char dir, uint16_t dist)
+{
+    char * unit = "lines";
+    if ('<' == dir || '>' == dir)
+    {
+        unit = "columns";
+    }
+    struct yx_uint16 start = w->start;
+    scroll_hint(w->framesize, dir, dist, unit, start);
+}
+
+
+
+static void draw_wins(struct Win * w)
+{
+    w->draw(w);
+    uint16_t y, x, size_y, size_x;
+    size_y = w->winmapsize.y;
+    size_x = w->winmapsize.x;
+    uint16_t offset_y = center_offset(w->center.y, size_y, w->framesize.y);
+    uint16_t offset_x = center_offset(w->center.x, size_x, w->framesize.x);
+    for (y = offset_y; y < w->framesize.y + offset_y && y < size_y; y++)
+    {
+        for (x = offset_x; x < w->framesize.x + offset_x && x < size_x; x++)
+        {
+            chtype ch = w->winmap[(y * w->winmapsize.x) + x];
+            mvwaddch(world.wmeta->pad, w->start.y + (y - offset_y),
+                                       w->start.x + (x - offset_x), ch);
+        }
+    }
+    free(w->winmap);
+    w->winmap = NULL;
+    w->winmapsize.y = 0;
+    w->winmapsize.x = 0;
+    if (offset_y > 0)
+    {
+        winscroll_hint(w, '^', offset_y + 1);
+    }
+    if (size_y > offset_y + w->framesize.y)
+    {
+        winscroll_hint(w, 'v', size_y - ((offset_y + w->framesize.y) - 1));
+    }
+    if (offset_x > 0)
+    {
+        winscroll_hint(w, '<', offset_x + 1);
+    }
+    if (size_x > offset_x + w->framesize.x)
+    {
+        winscroll_hint(w, '>', size_x - ((offset_x + w->framesize.x) - 1));
+    }
+    if (0 != w->next)
+    {
+        return draw_wins(w->next);
+    }
+}
+
+
+
+static void draw_win_borderlines(struct Win * w, char active, WINDOW * pad)
+{
+    /* Draw vertical and horizontal border lines. */
+    uint16_t y, x;
+    for (y = w->start.y; y <= w->start.y + w->framesize.y; y++)
+    {
+        mvwaddch(pad, y, w->start.x - 1,              '|');
+        mvwaddch(pad, y, w->start.x + w->framesize.x, '|');
+    }
+    for (x = w->start.x; x <= w->start.x + w->framesize.x; x++)
+    {
+        mvwaddch(pad, w->start.y - 1,              x, '-');
+        mvwaddch(pad, w->start.y + w->framesize.y, x, '-');
+    }
+
+    /* Draw as much as possible of the title into center of top border line. */
+    char min_title_length_visible = 3;  /* min. 1 char + 2 padding/decoration */
+    if (w->framesize.x >= min_title_length_visible)
+    {
+        uint16_t title_offset = 0;
+        if (w->framesize.x > strlen(w->title) + 2)
+        {
+            title_offset = (w->framesize.x - (strlen(w->title) + 2)) / 2;
+        }                                    /* +2 is for padding/decoration */
+        uint16_t length_visible = strnlen(w->title, w->framesize.x - 2);
+        char title[length_visible + 3];
+        char decoration = ' ';
+        if (1 == active)
+        {
+            decoration = '$';
+        }
+        memcpy(title + 1, w->title, length_visible);
+        title[0] = title[length_visible + 1] = decoration;
+        title[length_visible + 2] = '\0';
+        mvwaddstr(pad, w->start.y - 1, w->start.x + title_offset, title);
+    }
+}
+
+
+
+static void draw_wins_borderlines(struct Win * w, struct Win * w_active,
+                                  WINDOW * pad)
+{
+    char active = 0;
+    if (w == w_active)
+    {
+        active = 1;
+    }
+    draw_win_borderlines(w, active, pad);
+    if (0 != w->next)
+    {
+        draw_wins_borderlines(w->next, w_active, pad);
+    }
+}
+
+
+
+static void draw_wins_bordercorners(struct Win * w, WINDOW * pad)
+{
+    mvwaddch(pad, w->start.y - 1, w->start.x - 1, '+');
+    mvwaddch(pad, w->start.y - 1, w->start.x + w->framesize.x, '+');
+    mvwaddch(pad, w->start.y + w->framesize.y, w->start.x - 1, '+');
+    mvwaddch(pad, w->start.y + w->framesize.y, w->start.x + w->framesize.x,'+');
+    if (0 != w->next)
+    {
+        draw_wins_bordercorners(w->next, pad);
+    }
+}
+
+
+
+static void shift_win_forward()
+{
+    if (world.wmeta->active == world.wmeta->chain_end)
+    {
+        world.wmeta->chain_end = world.wmeta->active->prev;
+        world.wmeta->chain_end->next = 0;
+        world.wmeta->active->next = world.wmeta->chain_start;
+        world.wmeta->active->next->prev = world.wmeta->active;
+        world.wmeta->chain_start = world.wmeta->active;
+        world.wmeta->chain_start->prev = 0;
+    }
+    else
+    {
+        struct Win * old_prev = world.wmeta->active->prev;
+        struct Win * old_next = world.wmeta->active->next;
+        if (world.wmeta->chain_end == world.wmeta->active->next)
+        {
+            world.wmeta->chain_end = world.wmeta->active;
+            world.wmeta->active->next = 0;
+        }
+        else
+        {
+            world.wmeta->active->next = old_next->next;
+            world.wmeta->active->next->prev = world.wmeta->active;
+        }
+        if (world.wmeta->chain_start == world.wmeta->active)
+        {
+            world.wmeta->chain_start = old_next;
+        }
+        else
+        {
+            old_prev->next = old_next;
+        }
+        old_next->prev = old_prev;
+        old_next->next = world.wmeta->active;
+        world.wmeta->active->prev = old_next;
+    }
+}
+
+
+
+static void shift_win_backward()
+{
+    if (world.wmeta->active == world.wmeta->chain_start)
+    {
+        world.wmeta->chain_start = world.wmeta->active->next;
+        world.wmeta->chain_start->prev = 0;
+        world.wmeta->active->prev = world.wmeta->chain_end;
+        world.wmeta->active->prev->next = world.wmeta->active;
+        world.wmeta->chain_end = world.wmeta->active;
+        world.wmeta->chain_end->next = 0;
+    }
+    else
+    {
+        struct Win * old_prev = world.wmeta->active->prev;
+        struct Win * old_next = world.wmeta->active->next;
+        if (world.wmeta->chain_start == world.wmeta->active->prev)
+        {
+            world.wmeta->chain_start = world.wmeta->active;
+            world.wmeta->active->prev = 0;
+        }
+        else
+        {
+            world.wmeta->active->prev = old_prev->prev;
+            world.wmeta->active->prev->next = world.wmeta->active;
+        }
+        if (world.wmeta->chain_end == world.wmeta->active)
+        {
+            world.wmeta->chain_end = old_prev;
+        }
+        else
+        {
+            old_next->prev = old_prev;
+        }
+        old_prev->next = old_next;
+        old_prev->prev = world.wmeta->active;
+        world.wmeta->active->next = old_prev;
+    }
+}
+
+
+
+extern void init_win_meta(WINDOW * screen)
+{
+    char * f_name = "init_win_meta()";
+    char * err_s = "init_win_meta() creates virtual screen beyond legal size.";
+    char * err_m = "init_win_meta() triggers memory alloc error via newpad().";
+    world.wmeta         = try_malloc(sizeof(struct WinMeta), f_name);
+    world.wmeta->screen = screen;
+    uint32_t maxy_test  = getmaxy(screen);
+    uint32_t maxx_test  = getmaxx(screen);
+    uint8_t test = (maxy_test > UINT16_MAX || maxx_test > UINT16_MAX);
+    exit_err(test, err_s);
+    world.wmeta->padsize.y   = maxy_test;
+    world.wmeta->padsize.x   = maxx_test;
+    world.wmeta->chain_start = 0;
+    world.wmeta->chain_end   = 0;
+    world.wmeta->pad_offset  = 0;
+    world.wmeta->pad         = newpad(world.wmeta->padsize.y, 1);
+    exit_err(NULL == world.wmeta->pad, err_m);
+    world.wmeta->active      = 0;
+}
+
+
+
+extern void init_win(struct Win ** wp, char * title, int16_t height,
+                     int16_t width, void * func)
+{
+    char * f_name = "init_win()";
+    struct Win * w  = try_malloc(sizeof(struct Win), f_name);
+    w->prev         = 0;
+    w->next         = 0;
+    w->winmapsize.y = 0;
+    w->winmapsize.x = 0;
+    w->winmap = NULL;
+    w->title        = try_malloc(strlen(title) + 1, f_name);
+    sprintf(w->title, "%s", title);
+    w->draw         = func;
+    w->center.y     = 0;
+    w->center.x     = 0;
+    if      (0 < width)
+    {
+        w->framesize.x = width;
+    }
+    else if (0 >= width)
+    {
+        w->framesize.x = world.wmeta->padsize.x + width;
+    }
+    if      (0 < height && height <= world.wmeta->padsize.y - 1)
+    {
+        w->framesize.y = height;
+    }
+    else if (0 >= height && world.wmeta->padsize.y + (height - 1) > 0)
+    {
+        w->framesize.y = world.wmeta->padsize.y + (height - 1);
+    }
+    *wp = w;
+}
+
+
+
+extern void free_winmeta()
+{
+    delwin(world.wmeta->pad);
+    free(world.wmeta);
+}
+
+
+
+extern void free_win(struct Win * win)
+{
+    free(win->title);
+    free(win);
+}
+
+
+
+extern void append_win(struct Win * w)
+{
+    if (0 != world.wmeta->chain_start)
+    {
+        w->prev = world.wmeta->chain_end;
+        world.wmeta->chain_end->next = w;
+    }
     else
-      mvwaddch(frame->curses_win, pos, q, symbol); }
-  free(scrolldsc); }
-
-extern void draw_all_wins (struct WinMeta * wmeta) {
-// Draw pad with all windows and their borders, plus scrolling hints.
-  erase();
-  wnoutrefresh(wmeta->screen);
-  werase(wmeta->pad.curses_win);
-  if (wmeta->chain_start) {
-    uint16_t n_wins = 1, i;
-    struct Win * win_p = wmeta->chain_start;
-    while (0 != win_p->next) {
-      win_p = win_p->next;
-      n_wins++; }
-    struct Corners * all_corners = malloc(sizeof(struct Corners) * n_wins);
-    draw_wins (wmeta->chain_start);
-    draw_wins_borders (wmeta->chain_start, wmeta->active, all_corners, 0);
-    for (i = 0; i < n_wins; i++) {
-      mvwaddch(wmeta->pad.curses_win, all_corners[i].tl.y, all_corners[i].tl.x, '+');
-      mvwaddch(wmeta->pad.curses_win, all_corners[i].tr.y, all_corners[i].tr.x, '+');
-      mvwaddch(wmeta->pad.curses_win, all_corners[i].bl.y, all_corners[i].bl.x, '+');
-      mvwaddch(wmeta->pad.curses_win, all_corners[i].br.y, all_corners[i].br.x, '+'); }
-    free(all_corners);
-    if (wmeta->pad_offset > 0)
-      draw_scroll_hint(&wmeta->pad, wmeta->pad_offset, wmeta->pad_offset + 1, '<');
-    if (wmeta->pad_offset + wmeta->pad.size.x < getmaxx(wmeta->pad.curses_win) - 1)
-      draw_scroll_hint(&wmeta->pad, wmeta->pad_offset + wmeta->pad.size.x - 1,
-                       getmaxx(wmeta->pad.curses_win) - (wmeta->pad_offset + wmeta->pad.size.x), '>');
-    pnoutrefresh(wmeta->pad.curses_win, 0, wmeta->pad_offset, 0, 0, wmeta->pad.size.y, wmeta->pad.size.x-1); }
-  doupdate(); }
-
-extern void resize_active_win (struct WinMeta * wmeta, uint16_t height, uint16_t width) {
-// Grow or shrink currently active window. Correct its geometry and that of its followers.
-  if (0 != wmeta->active && width > 0 && height > 0 && height < wmeta->pad.size.y) {
-    wmeta->active->frame.size.y = height;
-    wmeta->active->frame.size.x = width;
-    update_wins(wmeta, wmeta->chain_start); } }
-
-extern void cycle_active_win (struct WinMeta * wmeta, char dir) {
-// Cycle active window selection forwards (dir = 'n') or backwards.
-  if (0 != wmeta->active) {
-    if ('n' == dir) {
-      if (wmeta->active->next != 0)
-        wmeta->active = wmeta->active->next;
-      else
-        wmeta->active = wmeta->chain_start; }
-    else {
-      if (wmeta->active->prev != 0)
-        wmeta->active = wmeta->active->prev;
-      else
-        wmeta->active = wmeta->chain_end; } } }
-
-extern void shift_active_win (struct WinMeta * wmeta, char dir) {
-// Move active window forward/backward in window chain. If jumping beyond start/end, move to other chain end.
-  if (0 != wmeta->active && wmeta->chain_start != wmeta->chain_end && (dir == 'f' || dir == 'b')) {
-    struct Win * w_shift = wmeta->active, * w_p, * w_p_next;
-    char wrap = 0;
-    if ((dir == 'f' && w_shift == wmeta->chain_end) || (dir == 'b' && w_shift == wmeta->chain_start))
-      wrap = 1;
-    uint16_t i, i_max;
-    for (i_max = 1, w_p = wmeta->chain_start; w_p != wmeta->chain_end; i_max++)
-      w_p = w_p->next;
-    struct Win ** wins = malloc(i_max * sizeof(struct Win *));
-    for (i = 0, w_p = wmeta->chain_start; i < i_max; i++) {
-      w_p_next = w_p->next;
-      suspend_win(wmeta, w_p);
-      wins[i] = w_p;
-      w_p = w_p_next; }
-    if (wrap)
-      if (dir == 'f') {
-        append_win(wmeta, w_shift);
-        for (i = 0; i < i_max - 1; i++)
-          append_win(wmeta, wins[i]); }
-      else {
-        for (i = 1; i < i_max; i++)
-          append_win(wmeta, wins[i]);
-        append_win(wmeta, w_shift); }
+    {
+        world.wmeta->active = w;
+        world.wmeta->chain_start = w;
+    }
+    world.wmeta->chain_end = w;
+    update_wins(w);
+}
+
+
+
+extern void suspend_win(struct Win * w)
+{
+    if (world.wmeta->chain_start != w)
+    {
+        w->prev->next = w->next;
+    }
     else
-      for (i = 0; i < i_max; i++)
-        if ((dir == 'f' && w_shift == wins[i]) || (dir == 'b' && w_shift == wins[i+1])) {
-          append_win(wmeta, wins[i+1]);
-          append_win(wmeta, wins[i]);
-          i++; }
+    {
+        world.wmeta->chain_start = w->next;
+    }
+    char pad_refitted = 0;
+    if (world.wmeta->chain_end != w)
+    {
+        w->next->prev = w->prev;
+        if (world.wmeta->active == w)
+        {
+            world.wmeta->active = w->next;
+        }
+        update_wins(w->next);      /* Positioning of successor windows may be */
+        pad_refitted = 1;          /* affected / need correction. Note that   */
+    }                              /* update_wins() already refits the pad,   */
+    else                           /* voiding later need for that.            */
+    {
+        world.wmeta->chain_end = w->prev;
+        if (world.wmeta->active == w)
+        {
+            world.wmeta->active = w->prev;
+        }
+    }
+
+    w->prev = 0;
+    w->next = 0;
+
+    if (0 == pad_refitted)
+    {
+        refit_pad();
+    }
+}
+
+
+
+extern void reset_pad_offset(uint16_t new_offset)
+{
+    if (new_offset >= 0
+        && (new_offset < world.wmeta->pad_offset
+            || new_offset + world.wmeta->padsize.x < getmaxx(world.wmeta->pad)))
+    {
+        world.wmeta->pad_offset = new_offset;
+    }
+}
+
+
+
+extern void resize_active_win(struct yx_uint16 size)
+{
+    if (0 != world.wmeta->active
+        && size.x > 0 && size.y > 0 && size.y < world.wmeta->padsize.y)
+    {
+        world.wmeta->active->framesize = size;
+        update_wins(world.wmeta->active);         /* Positioning of following */
+    }                                             /* windows may be affected. */
+}
+
+
+
+extern void cycle_active_win(char dir)
+{
+    if (0 != world.wmeta->active)
+    {
+        if ('f' == dir)
+        {
+            if (world.wmeta->active->next != 0)
+            {
+                world.wmeta->active = world.wmeta->active->next;
+            }
+            else
+            {
+                world.wmeta->active = world.wmeta->chain_start;
+            }
+        }
         else
-          append_win(wmeta, wins[i]);
-    free(wins);
-    wmeta->active = w_shift; } }
-
-extern void reset_pad_offset(struct WinMeta * wmeta, uint16_t new_offset) {
-// Apply new_offset to windows pad, if it proves to be sane.
-  if (new_offset >= 0 && new_offset + wmeta->pad.size.x < getmaxx(wmeta->pad.curses_win))
-    wmeta->pad_offset = new_offset; }
+        {
+            if (world.wmeta->active->prev != 0)
+            {
+                world.wmeta->active = world.wmeta->active->prev;
+            }
+            else
+            {
+                world.wmeta->active = world.wmeta->chain_end;
+            }
+        }
+    }
+}
+
+
+
+extern void shift_active_win(char dir)
+{
+    if (   0 == world.wmeta->active  /* No shifting with < 2 windows visible. */
+        || world.wmeta->chain_start == world.wmeta->chain_end)
+    {
+        return;
+    }
+    if ('f' == dir)
+    {
+        shift_win_forward();
+    }
+    else
+    {
+        shift_win_backward();
+    }
+    update_wins(world.wmeta->chain_start);
+}
+
+
+
+extern void draw_all_wins()
+{
+    /* Empty everything before filling it a-new. */
+    erase();
+    wnoutrefresh(world.wmeta->screen);
+    werase(world.wmeta->pad);
+    if (world.wmeta->chain_start)
+    {
+
+        /* Draw windows' borders first, then windows. */
+        draw_wins_borderlines(world.wmeta->chain_start, world.wmeta->active,
+                              world.wmeta->pad);
+        draw_wins_bordercorners(world.wmeta->chain_start, world.wmeta->pad);
+        draw_wins(world.wmeta->chain_start);
+
+        /* Draw virtual screen scroll hints. */
+        if (world.wmeta->pad_offset > 0)
+        {
+            padscroll_hint('<', world.wmeta->pad_offset + 1);
+        }
+        uint16_t size_x = getmaxx(world.wmeta->pad);
+        uint16_t right_edge = world.wmeta->pad_offset + world.wmeta->padsize.x;
+        if (right_edge < size_x - 1)
+        {
+            padscroll_hint('>', size_x - right_edge);
+        }
+
+        /* Write pad segment to be shown on physical screen to screen buffer. */
+        pnoutrefresh(world.wmeta->pad, 0, world.wmeta->pad_offset, 0, 0,
+                     world.wmeta->padsize.y, world.wmeta->padsize.x - 1);
+    }
+
+    /* Only at the end write accumulated changes to the physical screen. */
+    doupdate();
+}