ncplayer: add -n option for noninterpolative scaling #1738

NEWS.md

@@ -16,6 +16,7 @@ rearrangements of Notcurses.
     here, but `ncdirect_renderf()` was introduced pretty recently (2.3.1).
     As a result, `ncdirect_renderf()` and `ncdirect_stream()` now honor
     `NCVISUAL_OPTION_BLEND` and `NCVISUAL_OPTION_NOINTERPOLATE`.
+  * `ncplayer` now accepts `-n` to force non-interpolative scaling.
 
 * 2.3.2 (2021-06-03)
   * Fixed a bug affecting certain scalings of `ncvisual` objects created from

doc/man/man1/ncplayer.1.md

@@ -8,7 +8,7 @@ ncplayer - Render images and video to a terminal
 
 # SYNOPSIS
 
-**ncplayer** [**-h**] [**-V**] [**-q**] [**-d** ***delaymult***] [**-l** ***loglevel***] [**-b** ***blitter***] [**-s** ***scalemode***] [**-k**] [**-L**] [**-t** ***seconds***] [**-a**] files
+**ncplayer** [**-h**] [**-V**] [**-q**] [**-d** ***delaymult***] [**-l** ***loglevel***] [**-b** ***blitter***] [**-s** ***scalemode***] [**-k**] [**-L**] [**-t** ***seconds***] [**-n**] [**-a**] files
 
 # DESCRIPTION
 
@@ -43,6 +43,8 @@ be any non-negative number.
 
 **-a**: Treat color 0x000000 as if it were transparent.
 
+**-n**: Use non-interpolative scaling. The result is usually less pleasing to the eye, but it doesn't introduce new colors.
+
 **-V**: Print the program name and version, and exit with success.
 
 **-h**: Print help information, and exit with success.

src/player/play.cpp

@@ -19,7 +19,7 @@ static void usage(std::ostream& os, const char* name, int exitcode)
   __attribute__ ((noreturn));
 
 void usage(std::ostream& o, const char* name, int exitcode){
-  o << "usage: " << name << " [ -h ] [ -q ] [ -m margins ] [ -l loglevel ] [ -d mult ] [ -s scaletype ] [ -k ] [ -L ] [ -t seconds ] [ -a ] files" << '\n';
+  o << "usage: " << name << " [ -h ] [ -q ] [ -m margins ] [ -l loglevel ] [ -d mult ] [ -s scaletype ] [ -k ] [ -L ] [ -t seconds ] [ -n ] [ -a ] files" << '\n';
   o << " -h: display help and exit with success\n";
   o << " -V: print program name and version\n";
   o << " -q: be quiet (no frame/timing information along top of screen)\n";
@@ -31,6 +31,7 @@ void usage(std::ostream& o, const char* name, int exitcode){
   o << " -b blitter: one of 'ascii', 'half', 'quad', 'sex', 'braille', or 'pixel'\n";
   o << " -m margins: margin, or 4 comma-separated margins\n";
   o << " -a: replace color 0x000000 with a transparent channel\n";
+  o << " -n: force non-interpolative scaling\n";
   o << " -d mult: non-negative floating point scale for frame time" << std::endl;
   exit(exitcode);
 }
@@ -184,13 +185,14 @@ auto perframe(struct ncvisual* ncv, struct ncvisual_options* vopts,
 // can exit() directly. returns index in argv of first non-option param.
 auto handle_opts(int argc, char** argv, notcurses_options& opts, bool* quiet,
                  float* timescale, ncscale_e* scalemode, ncblitter_e* blitter,
-                 float* displaytime, bool* loop, uint32_t* transcolor)
+                 float* displaytime, bool* loop, bool* noninterp,
+                 uint32_t* transcolor)
                  -> int {
   *timescale = 1.0;
   *scalemode = NCSCALE_STRETCH;
   *displaytime = -1;
   int c;
-  while((c = getopt(argc, argv, "Vhql:d:s:b:t:m:kLa")) != -1){
+  while((c = getopt(argc, argv, "Vhql:d:s:b:t:m:kLan")) != -1){
     switch(c){
       case 'h':
         usage(std::cout, argv[0], EXIT_SUCCESS);
@@ -198,6 +200,13 @@ auto handle_opts(int argc, char** argv, notcurses_options& opts, bool* quiet,
       case 'V':
         printf("ncplayer version %s\n", notcurses_version());
         exit(EXIT_SUCCESS);
+      case 'n':
+        if(*noninterp){
+          std::cerr <<  "Provided -n twice!" << std::endl;
+          usage(std::cerr, argv[0], EXIT_FAILURE);
+        }
+        *noninterp = true;
+        break;
       case 'a':
         if(*transcolor){
           std::cerr <<  "Provided -a twice!" << std::endl;
@@ -311,7 +320,7 @@ int perframe_direct(struct ncvisual* ncv, struct ncvisual_options* vopts,
 // argc/argv ought already be reduced to only the media arguments
 int direct_mode_player(int argc, char** argv, ncscale_e scalemode,
                        ncblitter_e blitter, int lmargin,
-                       unsigned transcolor){
+                       bool noninterp, unsigned transcolor){
   Direct dm{};
   if(!dm.canopen_images()){
     std::cerr << "Notcurses was compiled without multimedia support\n";
@@ -341,6 +350,9 @@ int direct_mode_player(int argc, char** argv, ncscale_e scalemode,
     vopts.scaling = scalemode;
     vopts.x = static_cast<int>(a);
     vopts.flags = NCVISUAL_OPTION_HORALIGNED;
+    if(noninterp){
+      vopts.flags |= NCVISUAL_OPTION_NOINTERPOLATE;
+    }
     if(transcolor){
       vopts.flags |= NCVISUAL_OPTION_ADDALPHA;
     }
@@ -362,7 +374,7 @@ int rendered_mode_player_inner(NotCurses& nc, int argc, char** argv,
                                ncscale_e scalemode, ncblitter_e blitter,
                                bool quiet, bool loop,
                                double timescale, double displaytime,
-                               uint32_t transcolor){
+                               bool noninterp, uint32_t transcolor){
   int dimy, dimx;
   std::unique_ptr<Plane> stdn(nc.get_stdplane(&dimy, &dimx));
   uint64_t transchan = 0;
@@ -389,6 +401,9 @@ int rendered_mode_player_inner(NotCurses& nc, int argc, char** argv,
     struct ncvisual_options vopts{};
     int r;
     vopts.flags |= NCVISUAL_OPTION_HORALIGNED | NCVISUAL_OPTION_VERALIGNED;
+    if(noninterp){
+      vopts.flags |= NCVISUAL_OPTION_NOINTERPOLATE;
+    }
     if(transcolor){
       vopts.flags |= NCVISUAL_OPTION_ADDALPHA;
     }
@@ -468,7 +483,7 @@ int rendered_mode_player(int argc, char** argv, ncscale_e scalemode,
                          ncblitter_e blitter, notcurses_options& ncopts,
                          bool quiet, bool loop,
                          double timescale, double displaytime,
-                         uint32_t transcolor){
+                         bool noninterp, uint32_t transcolor){
   // no -k, we're using full rendered mode (and the alternate screen).
   ncopts.flags |= NCOPTION_INHIBIT_SETLOCALE;
   if(quiet){
@@ -484,7 +499,7 @@ int rendered_mode_player(int argc, char** argv, ncscale_e scalemode,
     }
     r = rendered_mode_player_inner(nc, argc, argv, scalemode, blitter,
                                    quiet, loop, timescale, displaytime,
-                                   transcolor);
+                                   noninterp, transcolor);
     if(!nc.stop()){
       return -1;
     }
@@ -515,17 +530,18 @@ auto main(int argc, char** argv) -> int {
   uint32_t transcolor = 0;
   bool quiet = false;
   bool loop = false;
+  bool noninterp = false;
   auto nonopt = handle_opts(argc, argv, ncopts, &quiet, &timescale, &scalemode,
-                            &blitter, &displaytime, &loop, &transcolor);
+                            &blitter, &displaytime, &loop, &noninterp, &transcolor);
   int r;
   // if -k was provided, we now use direct mode rather than simply not using the
   // alternate screen, so that output is inline with the shell.
   if(ncopts.flags & NCOPTION_NO_ALTERNATE_SCREEN){
     r = direct_mode_player(argc - nonopt, argv + nonopt, scalemode, blitter,
-                           ncopts.margin_l, transcolor);
+                           ncopts.margin_l, noninterp, transcolor);
   }else{
     r = rendered_mode_player(argc - nonopt, argv + nonopt, scalemode, blitter, ncopts,
-                             quiet, loop, timescale, displaytime, transcolor);
+                             quiet, loop, timescale, displaytime, noninterp, transcolor);
   }
   if(r){
     return EXIT_FAILURE;