attempt to lessen screentearing

cursetree/cursetree.c

@@ -1,11 +1,45 @@
+#include <signal.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "_ncurses.h"
 #include "ncrswrap.h"
+#include "ncurses.h"
 #include "node.h"
 #include "tree.h"
 
+volatile sig_atomic_t got_winch = 0;
+
+void handle_SIGWINCH(int sig) {
+  // endwin();
+  // Needs to be called after an endwin() so ncurses will initialize
+  // itself with the new terminal dimensions.
+  got_winch = 1;
+}
+
+/*
+ * If ncurses is configured to supply its own SIGWINCH handler,
+ *   - on receipt of a SIGWINCH, the handler sets a flag
+ *   - which is tested in wgetch(3X), doupdate(3X) and restartterm(3X),
+ *   - in turn, calling the resizeterm function,
+ *   - which ungetch's a KEY_RESIZE which will be read on the next call to
+ * wgetch. REF: `man resizeterm(3x)`
+ */
+static void bind_SIGWINCH(void) {
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = handle_SIGWINCH;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = SA_RESTART; /* Restart functions if
+                               interrupted by handler */
+  if (sigaction(SIGWINCH, &sa, NULL) == -1) {
+    perror("bind_SIGWINCH");
+    exit(2);
+  }
+}
+
 int ct_init(struct ct_tree **const tree) {
+  // bind_SIGWINCH();
   /* Initialise NCurses Library & Root Node */
   init_ncurses();
   init_tree(tree);
@@ -34,10 +68,13 @@ static int __update_rec(struct ct_node *const node) {
      */
     dims = IS_ROOT_NODE(node) ? termdims() : dup_dims(node->surface->dims);
     resize_node(node, dims);
+    node->flags &= ~NFLAG_RESIZE;
     result = 1;
   }
   if (node->surface->updatereq) {
-    sfflush(node->surface);
+    // TODO: is this necessary or does mvresize_win do this for us?
+    wnoutrefresh(node->surface->win);
+    node->surface->updatereq = 0;
   }
 
   for (int i = 0; i < node->cindex; i++) {
@@ -47,7 +84,17 @@ static int __update_rec(struct ct_node *const node) {
 }
 
 void ct_update(struct ct_tree *const tree) {
+  // WARNING: update_rec does not flush the screen, wgetch will do that for us
+  if (__update_rec(tree->root)) {
+    doupdate();
+    // redrawwin(curscr);
+    // wrefresh(curscr);
+  }
+}
+
+void ct_process(struct ct_tree *const tree) {
   const int key = wgetch(curscr);
+  // int key = -1;
 
   /* ncurses binds a SIGWINCH handler if SIGWINCH has SIG_DFL disposition
    * when initscr(3x) is called. This handler emits KEY_RESIZE (decimal 410) to
@@ -58,8 +105,9 @@ void ct_update(struct ct_tree *const tree) {
     // wclear(tree->root->surface->win);
     // mvwprintw(tree->root->surface->win, 0, 0, "    \r-1\n");
     // wrefresh(tree->root->surface->win);
-    return;
+    break;
   case KEY_RESIZE:
+    // got_winch = 1;
     tree->root->flags |= NFLAG_RESIZE;
     break;
   default:
@@ -69,7 +117,12 @@ void ct_update(struct ct_tree *const tree) {
     break;
   }
 
-  if (__update_rec(tree->root)) {
-    ct_redraw();
-  }
+  // if (got_winch == 1) {
+  //   tree->root->flags |= NFLAG_RESIZE;
+  //   got_winch = 0;
+  // }
+
+  // if (__update_rec(tree->root)) {
+  //   ct_redraw();
+  // }
 }

cursetree/cursetree.h

@@ -6,5 +6,6 @@
 /* === External Interface === */
 int ct_init(struct ct_tree **const tree);
 void ct_update(struct ct_tree *const tree);
+void ct_process(struct ct_tree *const tree);
 
 #endif /* CURSETREE_CURSETREE_H */