[kitty] fix default background workaround, erp

src/info/main.c

@@ -338,9 +338,13 @@ display_logo(struct ncplane* n, const char* path){
 static void
 tinfo_debug_bitmaps(struct ncplane* n, const tinfo* ti, const char* indent){
   if(!(ti->bg_collides_default & 0x80000000)){
-    ncplane_printf(n, "%sdefault background 0x%06lx %sconsidered transparent", indent,
-                  ti->bg_collides_default & 0xfffffful,
-                  (ti->bg_collides_default & 0x01000000) ? "" : "not ");
+    if(!(ti->bg_collides_default & 0x01000000)){
+      ncplane_printf(n, "%sdefault background 0x%06lx", indent,
+                    ti->bg_collides_default & 0xfffffful);
+    }else{
+      ncplane_printf(n, "%sdefault background 0x%06lx considered transparent", indent,
+                    ti->bg_collides_default & 0xfffffful);
+    }
   }else{
     ncplane_printf(n, "couldn't detect default background");
   }

src/lib/in.c

@@ -850,7 +850,7 @@ build_cflow_automaton(inputctx* ictx){
     { "[?2;3;0S", NULL, }, // negative pixels XTSMGRAPHICS
     { "[?1;0;\\NS", xtsmgraphics_cregs_cb, },
     { "[?2;0;\\N;\\NS", xtsmgraphics_sixel_cb, },
-    { "[>\\N;\\N;\\Nc", da2_cb, }, // "VT100"
+    { "[>\\N;\\N;\\Nc", da2_cb, },
     { "[=\\Sc", da3_cb, }, // CSI da3 form as issued by WezTerm
     // DCS (\eP...ST)
     { "P1+r\\S", tcap_cb, }, // positive XTGETTCAP

src/lib/render.c

@@ -693,14 +693,12 @@ term_bg_rgb8(const tinfo* ti, fbuf* f, unsigned r, unsigned g, unsigned b){
   // If it doesn't work, eh, it doesn't work. Fuck the world; save yourself.
   if(ti->caps.rgb){
     if((ti->bg_collides_default & 0xff000000) == 0x01000000){
-      if((r == (ti->bg_collides_default & 0xff0000lu)) &&
-         (g == (ti->bg_collides_default & 0xff00lu)) &&
-         (b == (ti->bg_collides_default & 0xfflu))){
-        if(b < 255){
-          ++b;
-        }else{
-          --b;
-        }
+      if((r == ncchannel_r(ti->bg_collides_default)) &&
+         (g == ncchannel_g(ti->bg_collides_default)) &&
+         (b == ncchannel_b(ti->bg_collides_default))){
+        // the human eye has fewer blue cones than red or green. toggle
+        // the last bit in the blue component to avoid a collision.
+        b ^= 0x00000001;
       }
     }
     return term_esc_rgb(f, false, r, g, b);