ncselector_redraw(): don't call notcurses_render() #627

NEWS.md

@@ -1,6 +1,11 @@
 This document attempts to list user-visible changes and any major internal
 rearrangements of Notcurses.
 
+* 1.6.12 (not yet released)
+  * `ncselector_redraw()` and `ncmultiselector_redraw()` no longer call
+    `notcurses_render()`. You will need to call `notcurses_render()` for the
+    display to reflect any changes.
+
 * 1.6.11 (2020-08-03)
   * `cell_egc_idx()` is no longer exported; it was never intended to be.
 

USAGE.md

@@ -174,8 +174,8 @@ updated to reflect the changes:
 // successful call to notcurses_render().
 int notcurses_render(struct notcurses* nc);
 
-// Write the last rendered frame, in its entirety, to 'fp'. This is not valid
-// until notcurses_render() has been successfully called at least once.
+// Write the last rendered frame, in its entirety, to 'fp'. If
+// notcurses_render() has not yet been called, nothing will be written.
 int notcurses_render_to_file(struct notcurses* nc, FILE* fp);
 
 // Retrieve the contents of the specified cell as last rendered. The EGC is

include/notcurses/notcurses.h

@@ -909,8 +909,8 @@ API int notcurses_stop(struct notcurses* nc);
 // successful call to notcurses_render().
 API int notcurses_render(struct notcurses* nc);
 
-// Write the last rendered frame, in its entirety, to 'fp'. This is not valid
-// until notcurses_render() has been successfully called at least once.
+// Write the last rendered frame, in its entirety, to 'fp'. If
+// notcurses_render() has not yet been called, nothing will be written.
 API int notcurses_render_to_file(struct notcurses* nc, FILE* fp);
 
 // Return the topmost ncplane, of which there is always at least one.

src/lib/reel.c

@@ -24,6 +24,17 @@ typedef struct nctablet {
 // Fourth rule: the focused tablet should remain where it is across redraws,
 //              except as necessary to accommodate the prior rules.
 //
+// At any time, you can make three types of moves:
+//  - move up from the topmost tablet
+//  - move down from the bottommost tablet
+//  - move otherwise
+// The first two are simple -- draw the focused tablet next to the appropriate
+// border of the reel, and then draw what we can in the other direction until
+// running out of space (and then shift up if there is more than one line of
+// gap at the top, or if we were moving up from the topmost tablet). This can
+// be done independently of all other tablets; it is immaterial if some were
+// removed, added, etc.
+//
 // The visible screen can be reconstructed from four things:
 //  * which tablet is focused (pointed at by ncreel->tablets)
 //  * which row the focused tablet starts at (derived from focused tablet)

src/lib/selector.c

@@ -141,7 +141,7 @@ ncselector_draw(ncselector* n){
     }
   }
   n->darrowy = yoff;
-  return notcurses_render(n->ncp->nc);
+  return 0;
 }
 
 // calculate the necessary dimensions based off properties of the selector and
@@ -599,7 +599,7 @@ ncmultiselector_draw(ncmultiselector* n){
     ncplane_putegc_yx(n->ncp, yoff, n->arrowx, "↓", NULL);
   }
   n->darrowy = yoff;
-  return notcurses_render(n->ncp->nc);
+  return 0;
 }
 
 const char* ncmultiselector_previtem(ncmultiselector* n){

src/lib/visual.cpp

@@ -486,7 +486,6 @@ auto ncvisual_simple_streamer(ncvisual* ncv, struct ncvisual_options* vopts,
   }
   int ret = 0;
   if(curry){
-    // need a cast for C++ callers
     ncplane* subncp = static_cast<ncplane*>(curry);
     char* subtitle = ncvisual_subtitle(ncv);
     if(subtitle){