term: move coordinate origin to top left

Having the origin at the top left instead of the bottom left is more
conventional and ergonomic. The only thing this complicates is
prompt-specific logic, where we care about the coordinates of the
bottom-most line on the screen.

For that reason, the bulk of the changes here are in vere, where we
treat the bottom-most line specially, drawing the spinner onto it.
Webterm is likewise updated to account for the new coordinate system.

Drum now opts to accept clicks anywhere on the screen, and does its best
to move the cursor as close to the clicked location as possible (within
the confines of the prompt).

pkg/arvo/lib/hood/drum.hoon

@@ -687,10 +687,9 @@
   ++  ta-hit                                          ::  hear click
     |=  [x=@ud y=@ud]
     ^+  +>
-    ?.  =(0 y)  +>
     =/  pol=@ud
       (lent-char:klr (make:klr cad.pom))
-    ?:  (lth x pol)  +>.$
+    =?  x  (lth x pol)  pol
     +>.$(pos.inp (min (sub x pol) (lent buf.say.inp)))
   ::
   ++  ta-erl                                          ::  hear local error

pkg/interface/webterm/Buffer.tsx

@@ -90,7 +90,7 @@ const readInput = (term: Terminal, e: string): Belt[] => {
             if (1 === m) {
               const c = e.charCodeAt(2) - 32;
               const r = e.charCodeAt(3) - 32;
-              belts.push({ hit: { y: term.rows - r, x: c - 1 } });
+              belts.push({ hit: { y: r - 1, x: c - 1 } });
             }
             e = e.slice(3);
             break;

pkg/interface/webterm/lib/blit.ts

@@ -21,7 +21,7 @@ export const showBlit = (term: Terminal, blit: Blit) => {
     if (typeof blit.hop === 'number') {
       out += csi('H', term.rows, blit.hop + 1);
     } else {
-      out += csi('H', term.rows - blit.hop.y, blit.hop.x + 1);
+      out += csi('H', blit.hop.y + 1, blit.hop.x + 1);
     }
     out += csi('s');  //  save cursor position
   } else if ('put' in blit) {

pkg/urbit/vere/io/term.c

@@ -385,7 +385,7 @@ _term_it_clear_line(u3_utty* uty_u)
 
   //  if we're clearing the bottom line, clear our mirror of it too
   //
-  if ( 0 == uty_u->tat_u.mir.rus_w ) {
+  if ( uty_u->tat_u.siz.row_l - 1 == uty_u->tat_u.mir.rus_w ) {
     _term_it_free_line(uty_u);
   }
 }
@@ -401,7 +401,7 @@ _term_it_show_blank(u3_utty* uty_u)
 
 /*  _term_it_move_cursor(): move cursor to row & column
  *
- *    row 0 is at the bottom, col 0 is to the left.
+ *    row 0 is at the top, col 0 is to the left.
  *    if the given position exceeds the known window size,
  *    it is clipped to stay within the window.
  */
@@ -413,7 +413,7 @@ _term_it_move_cursor(u3_utty* uty_u, c3_w col_w, c3_w row_w)
   if ( row_w >= row_l ) { row_w = row_l - 1; }
   if ( col_w >= col_l ) { col_w = col_l - 1; }
 
-  _term_it_send_csi(uty_u, 'H', 2, row_l - row_w, col_w + 1);
+  _term_it_send_csi(uty_u, 'H', 2, row_w + 1, col_w + 1);
   _term_it_dump_buf(uty_u, &uty_u->ufo_u.suc_u);
 
   uty_u->tat_u.mir.rus_w = row_w;
@@ -473,7 +473,7 @@ _term_it_restore_line(u3_utty* uty_u)
 {
   u3_utat* tat_u = &uty_u->tat_u;
 
-  _term_it_send_csi(uty_u, 'H', 2, tat_u->siz.row_l, 0);
+  _term_it_send_csi(uty_u, 'H', 2, tat_u->siz.row_l, 1);
   _term_it_dump_buf(uty_u, &uty_u->ufo_u.cel_u);
   _term_it_send_stub(uty_u, u3k(tat_u->mir.lin));
   //NOTE  send_stub restores cursor position
@@ -490,7 +490,8 @@ _term_it_save_stub(u3_utty* uty_u, u3_noun tub)
   //  keep track of changes to bottom-most line, to aid spinner drawing logic.
   //  -t mode doesn't need this logic, because it doesn't render the spinner.
   //
-  if ( (0 == tat_u->mir.rus_w) && (c3n == u3_Host.ops_u.tem)) {
+  if ( ( tat_u->siz.row_l - 1 == tat_u->mir.rus_w ) &&
+       ( c3n == u3_Host.ops_u.tem ) ) {
     lin = u3dq("wail:klr:format", lin, tat_u->mir.cus_w, u3k(tub), ' ');
     lin = u3do("pact:klr:format", lin);
   }
@@ -513,8 +514,8 @@ _term_it_show_nel(u3_utty* uty_u)
   }
 
   uty_u->tat_u.mir.cus_w = 0;
-  if ( uty_u->tat_u.mir.rus_w > 0 ) {
+  if ( uty_u->tat_u.mir.rus_w < uty_u->tat_u.siz.row_l - 1 ) {
-    uty_u->tat_u.mir.rus_w--;
+    uty_u->tat_u.mir.rus_w++;
   }
   else {
     //  newline at bottom of screen, so bottom line is now empty
@@ -716,11 +717,9 @@ _term_io_suck_char(u3_utty* uty_u, c3_y cay_y)
     }
     else {
       c3_y row_y = cay_y - 32;
-      //  only acknowledge button 1 presses within our window
+      //  only acknowledge button 1 presses within our known window
       if ( 1 != tat_u->esc.ton_y && row_y <= tat_u->siz.row_l ) {
-        _term_io_spit(uty_u, u3nt(c3__hit,
+        _term_io_spit(uty_u, u3nt(c3__hit, tat_u->esc.col_y - 1, row_y - 1));
-                                  tat_u->esc.col_y - 1,
-                                  tat_u->siz.row_l - row_y));
       }
       tat_u->esc.mou = c3n;
       tat_u->esc.ton_y = tat_u->esc.col_y = 0;
@@ -907,8 +906,8 @@ _term_spin_step(u3_utty* uty_u)
       //  if we know where the bottom line is, and the cursor is not on it,
       //  move it to the bottom left
       //
-      if ( tat_u->siz.row_l && tat_u->mir.rus_w > 0 ) {
+      if ( tat_u->siz.row_l && tat_u->mir.rus_w < tat_u->siz.row_l - 1 ) {
-        _term_it_send_csi(uty_u, 'H', 2, tat_u->siz.row_l, 0);
+        _term_it_send_csi(uty_u, 'H', 2, tat_u->siz.row_l, 1);
       }
 
       c3_w i_w;
@@ -1357,7 +1356,7 @@ _term_ef_blit(u3_utty* uty_u,
     case c3__hop: {
       u3_noun pos = u3t(blt);
       if ( c3y == u3r_ud(pos) ) {
-        _term_it_move_cursor(uty_u, pos, 0);
+        _term_it_move_cursor(uty_u, pos, uty_u->tat_u.siz.row_l - 1);
       }
       else {
         _term_it_move_cursor(uty_u, u3h(pos), u3t(pos));
@@ -1369,7 +1368,7 @@ _term_ef_blit(u3_utty* uty_u,
     } break;
 
     case c3__lin: {  //TMP  backwards compatibility
-      _term_it_move_cursor(uty_u, 0, 0);
+      _term_it_move_cursor(uty_u, 0, uty_u->tat_u.siz.row_l - 1);
       _term_it_clear_line(uty_u);
     }  //
     case c3__put: {