From 5e925db5214276563a8f3e62313c8e4b4e31cf1e Mon Sep 17 00:00:00 2001
From: "Jeffrey C. Ollie" <jeff@ocjtech.us>
Date: Sun, 1 Sep 2024 13:10:10 -0500
Subject: [PATCH] kitty graphics: fix usage of "m" key for local-only
 transmission mediums

If the transmission medium is a local-only medium, ignore the "m"
key. The Kitty graphics protocol specification does not explicitly
call out this behavior (although the "m" key is only mentioned in
connection with remote clients) but that's how it's implemented in
Kitty and at least one client (mpv) relies on this behavior when
using the shared memory transmission medium.

https://sw.kovidgoyal.net/kitty/graphics-protocol/#the-transmission-medium
https://github.com/kovidgoyal/kitty/blob/ccc3bee9af794f332b4e9adcd714a649f639c397/kitty/graphics.c#L547-L592
---
 src/terminal/kitty/graphics_command.zig | 49 ++++++++++++++++++++++++-
 1 file changed, 47 insertions(+), 2 deletions(-)

diff --git a/src/terminal/kitty/graphics_command.zig b/src/terminal/kitty/graphics_command.zig
index 649d83f34..a3031a91e 100644
--- a/src/terminal/kitty/graphics_command.zig
+++ b/src/terminal/kitty/graphics_command.zig
@@ -451,8 +451,19 @@ pub const Transmission = struct {
             };
         }
 
-        if (kv.get('m')) |v| {
-            result.more_chunks = v > 0;
+        // If the transmission medium is a local-only medium, ignore the "m"
+        // key. The Kitty graphics protocol specification does not explicitly
+        // call out this behavior (although the "m" key is only mentioned in
+        // connection with remote clients) but that's how it's implemented in
+        // Kitty and at least one client (mpv) relies on this behavior when
+        // using the shared memory transmission medium.
+        //
+        // https://sw.kovidgoyal.net/kitty/graphics-protocol/#the-transmission-medium
+        // https://github.com/kovidgoyal/kitty/blob/ccc3bee9af794f332b4e9adcd714a649f639c397/kitty/graphics.c#L547-L592
+        if (result.medium == .direct) {
+            if (kv.get('m')) |v| {
+                result.more_chunks = v > 0;
+            }
         }
 
         return result;
@@ -911,6 +922,40 @@ test "transmission command" {
     try testing.expectEqual(@as(u32, 20), v.height);
 }
 
+test "transmission ignores 'm' if medium is not direct" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+    var p = Parser.init(alloc);
+    defer p.deinit();
+
+    const input = "a=t,t=t,m=1";
+    for (input) |c| try p.feed(c);
+    const command = try p.complete();
+    defer command.deinit(alloc);
+
+    try testing.expect(command.control == .transmit);
+    const v = command.control.transmit;
+    try testing.expectEqual(Transmission.Medium.temporary_file, v.medium);
+    try testing.expect(!v.more_chunks);
+}
+
+test "transmission respects 'm' if medium is direct" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+    var p = Parser.init(alloc);
+    defer p.deinit();
+
+    const input = "a=t,t=d,m=1";
+    for (input) |c| try p.feed(c);
+    const command = try p.complete();
+    defer command.deinit(alloc);
+
+    try testing.expect(command.control == .transmit);
+    const v = command.control.transmit;
+    try testing.expectEqual(Transmission.Medium.direct, v.medium);
+    try testing.expect(v.more_chunks);
+}
+
 test "query command" {
     const testing = std.testing;
     const alloc = testing.allocator;