feat(bs-renderflipdot): scrolling and paging display

TODO: - render_flipdot has become a somewhat mostrous function at
        least in terms of parameters and should be refactored.
      - render_flipdot's functionality could be interesting to
        expose in an additional mini library of some kind.

2 files changed, 149 insertions, 34 deletions

diff --git a/bs-renderflipdot.c b/bs-renderflipdot.c
index e237645..03ea185 100644
--- a/bs-renderflipdot.c
+++ b/bs-renderflipdot.c
@@ -1,11 +1,13 @@
 #define _POSIX_C_SOURCE 200112L /* getopt, getaddrinfo, ... */
 #include <errno.h>
 #include <netdb.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/types.h>
 #include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/time.h>
 #include <unistd.h>
 
 #include <buchstabensuppe.h>
@@ -16,6 +18,15 @@
 #define DEFAULT_HOST "localhost"
 #define DEFAULT_PORT "2323"
 
+#define SCROLL_DELAY_MICROSECONDS 125000 // 8 FPS
+#define PAGE_DELAY_SECONDS 2
+
+enum render_mode {
+  RENDER_NORMAL,
+  RENDER_PAGE,
+  RENDER_SCROLL,
+};
+
 void print_error(const char *name, const char *err) {
   fputs(name, stderr);
   fputs(": ", stderr);
@@ -32,7 +43,7 @@ void print_usage(const char *name) {
   for(size_t i = 0; i < name_len; i++) {
     fputc(' ', stderr);
   }
-  fputs(" [-4|-6] [-h HOST] [-p PORT] [-W WIDTH] [-H HEIGHT] TEXT\n", stderr);
+  fputs(" [-4|-6] [-S|-P] [-h HOST] [-p PORT] [-W WIDTH] [-H HEIGHT] TEXT\n", stderr);
 
   fputs(name, stderr);
   fputs(" -?\n", stderr);
@@ -43,6 +54,8 @@ void print_usage(const char *name) {
     "  -f    font to use, can be specified multiple times, fallback in given order\n"
     "  -s    font size to use, must be specified before font(s) (default: %d)\n"
     "  -i    invert the bitmap (so text is black on white)\n"
+    "  -S    scroll text through the screen\n"
+    "  -P    page text if it overflows\n"
     "  -h    hostname of the flipdots to use (default: %s)\n"
     "  -p    port of the flipdots to use (default: %s)\n"
     "  -W    width of the target flipdot display (default: %d)\n"
@@ -54,12 +67,55 @@ void print_usage(const char *name) {
     DEFAULT_FLIPDOT_WIDTH, DEFAULT_FLIPDOT_HEIGHT);
 }
 
-bool send_bitarray(const char *host, const char *port, int family, uint8_t *bits, ssize_t bits_size, const char *progname) {
+bool scroll_next_view(bs_view_t *view, int flipdot_width) {
+  if(view->bs_view_offset_x >= view->bs_view_bitmap.bs_bitmap_width) {
+    view->bs_view_offset_x = -flipdot_width;
+    return true;
+  } else {
+    view->bs_view_offset_x++;
+    return false;
+  }
+}
+
+bool page_next_view(bs_view_t *view, int flipdot_width) {
+  if(view->bs_view_offset_x + view->bs_view_width
+      >= view->bs_view_bitmap.bs_bitmap_width) {
+    return true;
+  } else {
+    view->bs_view_offset_x += flipdot_width;
+  }
+  return false;
+}
+
+void ignore_signal(int signum) {
+  (void) signum;
+}
+
+bool render_flipdot(const char *host, const char *port, int family, const char *progname, bs_bitmap_t *bitmap, enum render_mode mode, struct itimerval delay, int flipdot_width, int flipdot_height, bool invert) {
+  if(mode == RENDER_NORMAL && (bitmap->bs_bitmap_width < flipdot_width ||
+      bitmap->bs_bitmap_height < flipdot_height)) {
+    bs_bitmap_extend(bitmap, flipdot_width, flipdot_height, invert);
+  } else {
+    bs_bitmap_extend(bitmap, bitmap->bs_bitmap_width, flipdot_height, invert);
+  }
+
+  bs_view_t view;
+
+  // initial state
+  view.bs_view_bitmap = *bitmap;
+  view.bs_view_width = flipdot_width;
+  view.bs_view_height = flipdot_height;
+  view.bs_view_offset_y = 0;
+
+  if(mode == RENDER_SCROLL) {
+    view.bs_view_offset_x = -flipdot_width;
+  } else {
+    view.bs_view_offset_x = 0;
+  }
+
   struct addrinfo *addrs;
   struct addrinfo hints;
 
-  bool result = false;
-
   memset(&hints, 0, sizeof(hints));
 
   hints.ai_family = family;
@@ -73,18 +129,67 @@ bool send_bitarray(const char *host, const char *port, int family, uint8_t *bits
 
   int sockfd = socket(addrs->ai_family, SOCK_DGRAM, IPPROTO_UDP);
 
+  bool failure = false;
+
   if(sockfd < 0) {
     print_error(progname, "could not create socket");
   } else {
-    result = sendto(sockfd, bits, bits_size, 0,
-        addrs->ai_addr, addrs->ai_addrlen) == bits_size;
+    bool multiple_frames = mode == RENDER_SCROLL ||
+      mode == RENDER_PAGE;
+    bool finished = false;
+
+    // render first frame immediately
+
+    size_t bits_size;
+    uint8_t *bits = bs_view_bitarray(view, &bits_size);
+
+    if(multiple_frames) {
+      // TODO use sigaction
+      // TODO handle SIGINT and SIGTERM
+      signal(SIGALRM, ignore_signal);
+
+      failure = setitimer(ITIMER_REAL, &delay, NULL) != 0;
+    }
+
+    while(!finished && !failure) {
+      if(bits == NULL) {
+        failure = true;
+        break;
+      }
+
+      failure = sendto(sockfd, bits, bits_size, 0,
+          addrs->ai_addr, addrs->ai_addrlen) != (ssize_t) bits_size;
+
+      if(multiple_frames) {
+        // restore handler which is removed by sendto
+        signal(SIGALRM, ignore_signal);
+      }
+
+      free(bits);
+
+      if(mode == RENDER_SCROLL) {
+        finished = scroll_next_view(&view, flipdot_width);
+      } else if(mode == RENDER_PAGE) {
+        finished = page_next_view(&view, flipdot_width);
+      }
+
+      if(!multiple_frames) {
+        finished = true;
+      } else if(!finished) {
+        bits = bs_view_bitarray(view, &bits_size);
+        pause();
+      }
+    }
+
+    const struct itimerval timer_off = { { 0, 0 }, { 0, 0 } };
+    setitimer(ITIMER_REAL, &timer_off, NULL);
 
     close(sockfd);
   }
 
   freeaddrinfo(addrs);
 
-  return result;
+  return !failure;
 }
 
 int main(int argc, char **argv) {
@@ -97,6 +202,9 @@ int main(int argc, char **argv) {
   bool dry_run = false;
   bool invert = false;
   int ip_family = AF_UNSPEC;
+  enum render_mode mode = RENDER_NORMAL;
+  struct itimerval delay;
+  memset(&delay, 0, sizeof(struct itimerval));
 
   int opt;
   int fontcount = 0;
@@ -108,8 +216,20 @@ int main(int argc, char **argv) {
 
   bool parse_error = false;
 
-  while(!parse_error && (opt = getopt(argc, argv, "46inh:p:s:f:?W:H:")) != -1) {
+  while(!parse_error && (opt = getopt(argc, argv, "SP46inh:p:s:f:?W:H:")) != -1) {
     switch(opt) {
+      case 'S':
+        mode = RENDER_SCROLL;
+        memset(&delay, 0, sizeof(struct itimerval));
+        delay.it_interval.tv_usec = SCROLL_DELAY_MICROSECONDS;
+        delay.it_value.tv_usec = SCROLL_DELAY_MICROSECONDS;
+        break;
+      case 'P':
+        mode = RENDER_PAGE;
+        memset(&delay, 0, sizeof(struct itimerval));
+        delay.it_interval.tv_sec = PAGE_DELAY_SECONDS;
+        delay.it_value.tv_sec = PAGE_DELAY_SECONDS;
+        break;
       case '4':
         ip_family = AF_INET;
         break;
@@ -208,38 +328,14 @@ int main(int argc, char **argv) {
     bs_bitmap_map(bitmap, bs_pixel_invert_binary);
   }
 
-  if(!dry_run && (bitmap.bs_bitmap_width < flipdot_width ||
-      bitmap.bs_bitmap_height < flipdot_height)) {
-    bs_bitmap_extend(&bitmap, flipdot_width, flipdot_height, invert);
-  }
-
   bs_bitmap_print(bitmap, true);
 
   if(!dry_run) {
     printf("Sending image to %s:%s\n", host, port);
 
-    bs_view_t view;
-    view.bs_view_bitmap = bitmap;
-    view.bs_view_offset_x = 0;
-    view.bs_view_offset_y = 0;
-    view.bs_view_width = flipdot_width;
-    view.bs_view_height = flipdot_height;
-
-    size_t size;
-    uint8_t *bits = bs_view_bitarray(view, &size);
-
-    if(size > 0) {
-      if(!send_bitarray(host, port, ip_family, bits, (ssize_t) size, argv[0])) {
-        status = 1;
-      }
-    } else {
-      print_error(argv[0], "bs_view_bitarray failed");
+    if(!render_flipdot(host, port, ip_family, argv[0], &bitmap, mode, delay, flipdot_width, flipdot_height, invert)) {
       status = 1;
     }
-
-    if(bits != NULL) {
-      free(bits);
-    }
   }
 
   bs_bitmap_free(&bitmap);
diff --git a/doc/man/bs-renderflipdot.1 b/doc/man/bs-renderflipdot.1
index 47ee44b..865964c 100644
--- a/doc/man/bs-renderflipdot.1
+++ b/doc/man/bs-renderflipdot.1
@@ -11,6 +11,8 @@
 .Op Fl s Ar size
 .Fl f Ar font
 .Op Fl f Ar font Op Fl f Ar ...
+.Op Fl S
+.Op Fl P
 .Op Fl W Ar width
 .Op Fl H Ar height
 .Op Fl h Ar host
@@ -53,6 +55,23 @@ Add a font file.
 The added fonts are used as fallback fonts in the order they are given on the command line, meaning the first given font will be checked first for glyphs.
 If the font file contains multiple fonts, the one with index 0 is always used.
 Must be specified at least once.
+.It Fl S
+Scroll the text through the screen instead of cutting it off at the edge of the screen if it overflows.
+The scrolling motion is rendered at 8 FPS so a real flipdot can keep up, which means that
+.Nm
+takes roughly
+.Sy (screen_width * 2 + bitmap_width) * (1s / 8)
+to finish.
+.It Fl P
+Page the text instead of cutting it off at the edge of the screen.
+This means the rendered bitmap would be cut up into pieces of
+.Sy screen_width .
+Each of these pieces is shown for 2s which means
+.Nm
+takes roughly
+.Sy floor(bitmap_width / screen_width) * 2s
+to finish.
+
 .It Fl W Ar width
 Width of the target flipdot display.
 Only relevant if