Add competitive multiplayer support.

Last input wins, canvas size is adjusted to active connection.

4 files changed, 23 insertions, 1 deletions

diff --git a/include/app.h b/include/app.h
index a203858..92f2f85 100644
--- a/include/app.h
+++ b/include/app.h
@@ -5,6 +5,7 @@
 #ifndef SLOSH_APP_H
 #define SLOSH_APP_H
 
+#include "graphics.h"
 #include "kdl.h"
 #include "project.h"
 #include "shader.h"
@@ -22,10 +23,16 @@ void app_event(app_t *a, const input_event_t *ev);
 /* Kitty graphics for this frame: the bytes the client's terminal needs, and
  * the same thing as JSON for tests. Bytes are borrowed until the next call. */
 const char *app_graphics(app_t *a, size_t *len);
+/* The same frame for one attached terminal. `state` is that terminal's own
+ * transmission/deletion history; the viewport is in canonical screen cells. */
+const char *app_graphics_view(app_t *a, graphics_t *state, uint16_t x,
+                              uint16_t y, uint16_t cols, uint16_t rows,
+                              size_t *len);
 void app_graphics_reset(app_t *a);
 /* Did the last app_graphics() stream reach the client? Undelivered frames
  * are regenerated: transmissions repeat and deletions stay owed. */
 void app_graphics_commit(app_t *a, bool delivered);
+void app_graphics_view_commit(graphics_t *state, bool delivered);
 char *app_graphics_json(app_t *a);
 
 /* Transient announcements, drawn bottom-right and expiring on their own. */
@@ -87,6 +94,12 @@ bool app_should_quit(const app_t *a);
 /* C-a d asks the client to leave while the session keeps running. */
 bool app_detach_requested(const app_t *a);
 void app_clear_detach(app_t *a);
+/* A different display took over the shared input stream. End state that cannot
+ * safely span clients (leader chord, pointer drag and hover position). */
+void app_cancel_client_interaction(app_t *a);
+/* A release over client-side filler has no canonical target, but still ends a
+ * pointer gesture without disturbing that client's keyboard leader state. */
+void app_cancel_client_pointer(app_t *a);
 size_t app_pane_count(const app_t *a);
 
 /* Tabs. A tab is a layout tree; panes in every tab keep running. */
diff --git a/include/graphics.h b/include/graphics.h
index 6a338df..13cc5dc 100644
--- a/include/graphics.h
+++ b/include/graphics.h
@@ -66,6 +66,7 @@ typedef struct {
   uint32_t x_off, y_off;           /* offset within the first cell, in pixels */
   uint32_t sx, sy, sw, sh;         /* source rectangle, in image pixels */
   uint32_t px_w, px_h;             /* the image's own size */
+  uint32_t cell_px_w, cell_px_h;   /* canonical pixels represented by a cell */
   int format, compression;
   const uint8_t *data; /* NULL once the client has it */
   size_t data_len;
diff --git a/include/proto.h b/include/proto.h
index 67b45f0..4df52a6 100644
--- a/include/proto.h
+++ b/include/proto.h
@@ -30,7 +30,7 @@ enum {
 enum {
   EXIT_SESSION_ENDED = 0, /* the last pane closed */
   EXIT_DETACHED = 1,      /* the user detached */
-  EXIT_REPLACED = 2,      /* another client attached */
+  EXIT_REPLACED = 2, /* legacy: retained so new clients speak to old servers */
 };
 
 typedef struct {
diff --git a/include/slosh.h b/include/slosh.h
index e624bda..75aa658 100644
--- a/include/slosh.h
+++ b/include/slosh.h
@@ -76,6 +76,14 @@ void screen_init(screen_t *s, uint16_t cols, uint16_t rows);
 void screen_free(screen_t *s);
 void screen_resize(screen_t *s, uint16_t cols, uint16_t rows);
 void screen_clear(screen_t *s);
+/* Project a canonical screen into a client-sized one. The source starts at
+ * (x,y); anything beyond its edges is blank filler. Diff history in `dst` is
+ * deliberately left alone, so every attached terminal advances independently. */
+void screen_project(screen_t *dst, const screen_t *src, uint16_t x, uint16_t y);
+/* Move an existing client viewport only as far as needed to keep the canonical
+ * cursor visible, then clamp it to the canonical screen. */
+void screen_follow_cursor(const screen_t *src, uint16_t cols, uint16_t rows,
+                          uint16_t *x, uint16_t *y);
 cell_t *screen_at(screen_t *s, uint16_t x, uint16_t y);
 void screen_put_utf8(screen_t *s, uint16_t x, uint16_t y, const char *txt,
                      size_t len, color_t fg, color_t bg, uint16_t attrs);