ncdirect_cursor_yx, ncdirect_cursor_pop, ncdirect_cursor_push #401 (#492)

* ncdirect_cursor_{push, pop, yx} declarations #401
* direct PoC: invoke ncdirect_cursor_yx() #401
* direct PoC: move to top of screen #401
* OTHERS.md: mention blessings
* ncdirect_cursor_yx working #401
* CHANGELOG: mention ncdirect_cursor_*() #401

CHANGELOG.md

@@ -1,6 +1,13 @@
 This document attempts to list user-visible changes and any major internal
 rearrangements of Notcurses.
 
+* 1.3.2 (not yet released)
+  * `ncdirect_cursor_push()`, `notcurses_cursor_pop()`, and
+    `ncdirect_cursor_yx()` have been added. These are not supported on all
+    terminals. `ncdirect_cursor_yx()` ought be considered experimental; it
+    must read a response from the terminal, and this can interact poorly with
+    other uses of standard input.
+
 * 1.3.1 (2020-04-18)
   * `ncplane_at_yx()` and `ncplane_at_cursor()` have been changed to return a
     heap-allocated EGC, and write the attributes and channels to value-result

OTHERS.md

@@ -0,0 +1,23 @@
+# Other TUI libraries of note
+
+* [NCURSES](https://invisible-island.net/ncurses/) (C)
+* [tui-rs](https://github.com/fdehau/tui-rs) (Rust)
+* [blessed-contrib](https://github.com/yaronn/blessed-contrib) (Javascript)
+* [FINAL CUT](https://github.com/gansm/finalcut) (C++)
+* [crossterm](https://github.com/crossterm-rs/crossterm) (Rust)
+* [tty-cursor](https://github.com/piotrmurach/tty-cursor) (Ruby)
+* [caca](http://caca.zoy.org/wiki/libcaca) (C)
+* [Newt](https://pagure.io/newt) (C)
+* [vty](http://hackage.haskell.org/package/vty) (Haskell)
+* [hscharm](https://hackage.haskell.org/package/hscharm) (Haskell)
+* [S-Lang](http://www.jedsoft.org/slang/) (S-Lang)
+* [termbox-go](https://github.com/nsf/termbox-go) (Go)
+* [tcell](https://github.com/gdamore/tcell) (Go)
+* [termui](https://github.com/gizak/termui) (Go)
+* [gocui](https://github.com/jroimartin/gocui) (Go)
+* [tview](https://github.com/rivo/tview) (Go)
+* [blessings](https://github.com/erikrose/blessings) [Python]
+
+## Declarative
+
+* [brick](https://github.com/jtdaugherty/brick) (Haskell, atop vty)

README.md

@@ -2647,12 +2647,6 @@ up someday **FIXME**.
 * Portable: [terminfo(5)](http://man7.org/linux/man-pages/man5/terminfo.5.html)
 * Portable: [user_caps(5)](http://man7.org/linux/man-pages/man5/user_caps.5.html)
 
-### Other TUI libraries of note
-
-* [tui-rs](https://github.com/fdehau/tui-rs) (Rust)
-* [blessed-contrib](https://github.com/yaronn/blessed-contrib) (Javascript)
-* [FINAL CUT](https://github.com/gansm/finalcut) (C++)
-
 ### History
 
 * 2020-04-12: notcurses [1.3.0 "hypnotize"](https://github.com/dankamongmen/notcurses/releases/tag/v1.3.0).

include/notcurses/notcurses.h

@@ -83,6 +83,16 @@ API int ncdirect_cursor_left(struct ncdirect* nc, int num);
 API int ncdirect_cursor_right(struct ncdirect* nc, int num);
 API int ncdirect_cursor_down(struct ncdirect* nc, int num);
 
+// Get the cursor position, when supported. This requires writing to the
+// terminal, and then reading from it. If the terminal doesn't reply, or
+// doesn't reply in a way we understand, the results might be deleterious.
+API int ncdirect_cursor_yx(struct ncdirect* n, int* y, int* x);
+
+// Push or pop the cursor location to the terminal's stack. The depth of this
+// stack, and indeed its existence, is terminal-dependent.
+API int ncdirect_cursor_push(struct ncdirect* n);
+API int ncdirect_cursor_pop(struct ncdirect* n);
+
 // Clear the screen.
 API int ncdirect_clear(struct ncdirect* nc);
 

src/lib/direct.c

@@ -1,3 +1,7 @@
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <termios.h>
 #include "internal.h"
 
 int ncdirect_cursor_up(ncdirect* nc, int num){
@@ -100,6 +104,112 @@ int ncdirect_cursor_move_yx(ncdirect* n, int y, int x){
   return -1;
 }
 
+static int
+cursor_yx_get(FILE* outfp, FILE* infp, int* y, int* x){
+  if(fprintf(outfp, "\033[6n") != 4){
+    return -1;
+  }
+  int in;
+  bool done = false;
+  enum { // what we expect now
+    CURSOR_ESC, // 27 (0x1b)
+    CURSOR_LSQUARE,
+    CURSOR_ROW, // delimited by a semicolon
+    CURSOR_COLUMN,
+    CURSOR_R,
+  } state = CURSOR_ESC;
+  int row = 0, column = 0;
+  while((in = getc(infp)) != EOF){
+    bool valid = false;
+    switch(state){
+      case CURSOR_ESC: valid = (in == '\x1b'); ++state; break;
+      case CURSOR_LSQUARE: valid = (in == '['); ++state; break;
+      case CURSOR_ROW:
+        if(isdigit(in)){
+          row *= 10;
+          row += in - '0';
+          valid = true;
+        }else if(in == ';'){
+          ++state;
+          valid = true;
+        }
+        break;
+      case CURSOR_COLUMN:
+        if(isdigit(in)){
+          column *= 10;
+          column += in - '0';
+          valid = true;
+        }else if(in == 'R'){
+          ++state;
+          valid = true;
+        }
+        break;
+      case CURSOR_R: default: // logical error, whoops
+        break;
+    }
+    if(!valid){
+      fprintf(stderr, "Unexpected result from terminal: %d\n", in);
+      break;
+    }
+    if(state == CURSOR_R){
+      done = true;
+      break;
+    }
+  }
+  if(!done){
+    return -1;
+  }
+  if(y){
+    *y = row;
+  }
+  if(x){
+    *x = column;
+  }
+  return 0;
+}
+
+// no terminfo capability for this. dangerous!
+int ncdirect_cursor_yx(ncdirect* n, int* y, int* x){
+  int infd = fileno(stdin); // FIXME n->ttyfp?
+  if(infd < 0){
+    fprintf(stderr, "Couldn't get file descriptor from stdin\n");
+    return -1;
+  }
+  // do *not* close infd!
+  struct termios termio, oldtermios;
+  if(tcgetattr(infd, &termio)){
+    fprintf(stderr, "Couldn't get terminal info from %d (%s)\n", infd, strerror(errno));
+    return -1;
+  }
+  memcpy(&oldtermios, &termio, sizeof(termio));
+  termio.c_lflag &= ~(ICANON | ECHO);
+  if(tcsetattr(infd, TCSAFLUSH, &termio)){
+    fprintf(stderr, "Couldn't put terminal into cbreak mode via %d (%s)\n",
+            infd, strerror(errno));
+    return -1;
+  }
+  int ret = cursor_yx_get(n->ttyfp, stdin, y, x);
+  if(tcsetattr(infd, TCSANOW, &oldtermios)){
+    fprintf(stderr, "Couldn't restore terminal mode on %d (%s)\n",
+            infd, strerror(errno)); // don't return error for this
+  }
+  return ret;
+}
+
+int ncdirect_cursor_push(ncdirect* n){
+  if(n->sc == NULL){
+    return -1;
+  }
+  return term_emit("sc", n->sc, n->ttyfp, false);
+}
+
+int ncdirect_cursor_pop(ncdirect* n){
+  if(n->rc == NULL){
+    return -1;
+  }
+  return term_emit("rc", n->rc, n->ttyfp, false);
+}
+
 int ncdirect_stop(ncdirect* nc){
   int ret = 0;
   if(nc){
@@ -116,4 +226,3 @@ int ncdirect_stop(ncdirect* nc){
   }
   return ret;
 }
-

src/lib/internal.h

@@ -273,9 +273,11 @@ typedef struct ncdirect {
   char* initc;    // set a palette entry's RGB value
   char* oc;       // restore original colors
   char* clear;    // clear the screen
+  FILE* ttyfp;    // FILE* for controlling tty, from opts->ttyfp
+  char* sc;       // push the cursor location onto the stack
+  char* rc;       // pop the cursor location off the stack
   bool RGBflag;   // terminfo-reported "RGB" flag for 24bpc truecolor
   bool CCCflag;   // terminfo-reported "CCC" flag for palette set capability
-  FILE* ttyfp;    // FILE* for controlling tty, from opts->ttyfp
   palette256 palette; // 256-indexed palette can be used instead of/with RGB
   uint16_t fgrgb, bgrgb; // last RGB values of foreground/background
   bool fgdefault, bgdefault; // are FG/BG currently using default colors?

src/poc/direct.c

@@ -24,30 +24,6 @@ int main(void){
     }
   }
   fflush(stdout);
-  notcurses_options opts;
-  memset(&opts, 0, sizeof(opts));
-  opts.inhibit_alternate_screen = true;
-  struct notcurses* nc = notcurses_init(&opts, stdout);
-  if(!nc){
-    fprintf(stderr, "Couldn't initialize notcurses\n");
-    return EXIT_FAILURE;
-  }
-  ncplane_set_fg(notcurses_stdplane(nc), 0x00ff00);
-  if(ncplane_putstr_aligned(notcurses_stdplane(nc), geom.ws_row - 2, NCALIGN_CENTER, " erperperp ") <= 0){
-    notcurses_stop(nc);
-    fprintf(stderr, "Error printing\n");
-    return EXIT_FAILURE;
-  }
-  if(notcurses_render(nc)){
-    notcurses_stop(nc);
-    fprintf(stderr, "Error rendering\n");
-    return EXIT_FAILURE;
-  }
-  sleep(2);
-  if(notcurses_stop(nc)){
-    fprintf(stderr, "Error stopping notcurses\n");
-    return EXIT_FAILURE;
-  }
   struct ncdirect* n; // see bug #391
   if((n = ncdirect_init(NULL, stdout)) == NULL){
     return EXIT_FAILURE;
@@ -65,5 +41,30 @@ int main(void){
   ret |= ncdirect_cursor_right(n, geom.ws_col / 2);
   ret |= ncdirect_cursor_up(n, geom.ws_row / 2);
   printf(" erperperp! \n");
+  int y = -420, x = -420;
+  // FIXME try a push/pop
+  if(ncdirect_cursor_yx(n, &y, &x) == 0){
+    printf("\n\tRead cursor position: y: %d x: %d\n", y, x);
+    y += 2; // we just went down two lines
+    while(y > 3){
+      const int up = y >= 3 ? 3 : y;
+      ret |= ncdirect_cursor_up(n, up);
+      fflush(stdout);
+      y -= up;
+      int newy;
+      if(ncdirect_cursor_yx(n, &newy, NULL)){
+        ret = -1;
+        return EXIT_FAILURE;
+      }
+      if(newy != y){
+        fprintf(stderr, "Expected %d, got %d\n", y, newy);
+        return EXIT_FAILURE;
+      }
+      printf("\n\tRead cursor position: y: %d x: %d\n", newy, x);
+      y += 2;
+    }
+  }else{
+    ret = -1;
+  }
   return ret ? EXIT_FAILURE : EXIT_SUCCESS;
 }