terminal/kitty: convert Format, Medium, Compression to lib.Enum

Convert the Transmission.Format, Transmission.Medium, and
Transmission.Compression types from plain Zig enums to lib.Enum so
they get a C-compatible backing type when building with c_abi. This
lets the C API layer reuse the types directly instead of maintaining
separate mirror enums.

Move Format.bpp() to a standalone Transmission.formatBpp() function
since lib.Enum types cannot have decls.

In the C API layer, rename kitty_gfx to kitty_storage and command to
kitty_cmd for clarity, and simplify the format/compression getters
to direct assignment now that the types are shared.

src/terminal/c/kitty_graphics.zig

@@ -2,13 +2,14 @@ const std = @import("std");
 const build_options = @import("terminal_options");
 const lib = @import("../lib.zig");
 const CAllocator = lib.alloc.Allocator;
-const kitty_gfx = @import("../kitty/graphics_storage.zig");
+const kitty_storage = @import("../kitty/graphics_storage.zig");
+const kitty_cmd = @import("../kitty/graphics_command.zig");
 const Image = @import("../kitty/graphics_image.zig").Image;
 const Result = @import("result.zig").Result;
 
 /// C: GhosttyKittyGraphics
 pub const KittyGraphics = if (build_options.kitty_graphics)
-    *kitty_gfx.ImageStorage
+    *kitty_storage.ImageStorage
 else
     *anyopaque;
 
@@ -22,8 +23,8 @@ else
 pub const PlacementIterator = ?*PlacementIteratorWrapper;
 
 const PlacementMap = std.AutoHashMapUnmanaged(
-    kitty_gfx.ImageStorage.PlacementKey,
-    kitty_gfx.ImageStorage.Placement,
+    kitty_storage.ImageStorage.PlacementKey,
+    kitty_storage.ImageStorage.Placement,
 );
 
 const PlacementIteratorWrapper = struct {
@@ -117,19 +118,10 @@ fn getTyped(
 }
 
 /// C: GhosttyKittyImageFormat
-pub const ImageFormat = enum(c_int) {
-    rgb = 0,
-    rgba = 1,
-    png = 2,
-    gray_alpha = 3,
-    gray = 4,
-};
+pub const ImageFormat = kitty_cmd.Transmission.Format;
 
 /// C: GhosttyKittyImageCompression
-pub const ImageCompression = enum(c_int) {
-    none = 0,
-    zlib_deflate = 1,
-};
+pub const ImageCompression = kitty_cmd.Transmission.Compression;
 
 /// C: GhosttyKittyGraphicsImageData
 pub const ImageData = enum(c_int) {
@@ -195,17 +187,8 @@ fn imageGetTyped(
         .number => out.* = image.number,
         .width => out.* = image.width,
         .height => out.* = image.height,
-        .format => out.* = switch (image.format) {
-            .rgb => .rgb,
-            .rgba => .rgba,
-            .png => .png,
-            .gray_alpha => .gray_alpha,
-            .gray => .gray,
-        },
-        .compression => out.* = switch (image.compression) {
-            .none => .none,
-            .zlib_deflate => .zlib_deflate,
-        },
+        .format => out.* = image.format,
+        .compression => out.* = image.compression,
         .data_ptr => out.* = image.data.ptr,
         .data_len => out.* = image.data.len,
     }
@@ -306,7 +289,8 @@ test "placement_iterator next on empty storage" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);
@@ -334,7 +318,8 @@ test "placement_iterator get before next returns invalid" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);
@@ -364,7 +349,8 @@ test "placement_iterator with transmit and display" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);
@@ -416,7 +402,8 @@ test "placement_iterator with multiple placements" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);
@@ -472,7 +459,8 @@ test "image_get_handle returns null for missing id" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);
@@ -492,7 +480,8 @@ test "image_get_handle and image_get with transmitted image" {
 
     var t: terminal_c.Terminal = null;
     try testing.expectEqual(Result.success, terminal_c.new(
-        &lib.alloc.test_allocator, &t,
+        &lib.alloc.test_allocator,
+        &t,
         .{ .cols = 80, .rows = 24, .max_scrollback = 0 },
     ));
     defer terminal_c.free(t);

src/terminal/kitty/graphics_command.zig

@@ -3,6 +3,7 @@ const assert = @import("../../quirks.zig").inlineAssert;
 const Allocator = std.mem.Allocator;
 const ArenaAllocator = std.heap.ArenaAllocator;
 const simd = @import("../../simd/main.zig");
+const lib = @import("../lib.zig");
 
 const log = std.log.scoped(.kitty_gfx);
 
@@ -394,39 +395,38 @@ pub const Transmission = struct {
     compression: Compression = .none, // o
     more_chunks: bool = false, // m
 
-    pub const Format = enum {
-        rgb, // 24
-        rgba, // 32
-        png, // 100
-
+    pub const Format = lib.Enum(lib.target, &.{
+        "rgb", // 24
+        "rgba", // 32
+        "png", // 100
         // The following are not supported directly via the protocol
         // but they are formats that a png may decode to that we
         // support.
-        gray_alpha,
-        gray,
+        "gray_alpha",
+        "gray",
+    });
 
-        pub fn bpp(self: Format) u8 {
-            return switch (self) {
-                .gray => 1,
-                .gray_alpha => 2,
-                .rgb => 3,
-                .rgba => 4,
-                .png => unreachable, // Must be validated before
-            };
-        }
-    };
+    pub const Medium = lib.Enum(lib.target, &.{
+        "direct", // d
+        "file", // f
+        "temporary_file", // t
+        "shared_memory", // s
+    });
 
-    pub const Medium = enum {
-        direct, // d
-        file, // f
-        temporary_file, // t
-        shared_memory, // s
-    };
+    pub const Compression = lib.Enum(lib.target, &.{
+        "none",
+        "zlib_deflate", // z
+    });
 
-    pub const Compression = enum {
-        none,
-        zlib_deflate, // z
-    };
+    pub fn formatBpp(format: Format) u8 {
+        return switch (format) {
+            .gray => 1,
+            .gray_alpha => 2,
+            .rgb => 3,
+            .rgba => 4,
+            .png => unreachable, // Must be validated before
+        };
+    }
 
     fn parse(kv: KV) !Transmission {
         var result: Transmission = .{};

src/terminal/kitty/graphics_image.zig

@@ -202,8 +202,8 @@ pub const LoadingImage = struct {
             .png => stat_size,
 
             // For these formats we have a size we must have.
-            .gray, .gray_alpha, .rgb, .rgba => |f| size: {
-                const bpp = f.bpp();
+            .gray, .gray_alpha, .rgb, .rgba => size: {
+                const bpp = command.Transmission.formatBpp(self.image.format);
                 break :size self.image.width * self.image.height * bpp;
             },
         };
@@ -390,7 +390,7 @@ pub const LoadingImage = struct {
         if (img.width > max_dimension or img.height > max_dimension) return error.DimensionsTooLarge;
 
         // Data length must be what we expect
-        const bpp = img.format.bpp();
+        const bpp = command.Transmission.formatBpp(img.format);
         const expected_len = img.width * img.height * bpp;
         const actual_len = self.data.items.len;
         if (actual_len != expected_len) {