zgpu

commit 0632a496f0f5d313cfe07f3620c0dc81eec837f6
parent 67797425147031b412ecbe1653008b8ff9f1e235
Author: Christian Ermann <christianermann@gmail.com>
Date:   Wed, 23 Apr 2025 18:45:09 -0700

Add 'Callback' function to convert Zig functions into WGPU callbacks

Diffstat:
A
src/callback.zig
 | 
29
+++++++++++++++++++++++++++++
M
src/logging.zig
 | 
17
+++--------------
M
src/main.zig
 | 
3
++-

3 files changed, 34 insertions(+), 15 deletions(-)
diff --git a/src/callback.zig b/src/callback.zig
@@ -0,0 +1,29 @@
+const std = @import("std");
+
+fn CallbackType(comptime T: type) type {
+    const enum_type = switch (@typeInfo(T)) {
+        .@"fn" => |f| f.params[0].type.?,
+        else => unreachable,
+    };
+    return fn (enum_type, ?[*:0]const u8, ?*anyopaque) callconv(.C) void;
+}
+
+pub fn Callback(
+    user_callback: anytype,
+) CallbackType(@TypeOf(user_callback)) {
+    const enum_type = switch (@typeInfo(@TypeOf(user_callback))) {
+        .@"fn" => |f| f.params[0].type.?,
+        else => @compileError("callback must be a function"),
+    };
+    return struct {
+        const callback = user_callback;
+        fn wrapped_callback(
+            enum_value: enum_type,
+            message: ?[*:0]const u8,
+            userdata: ?*anyopaque,
+        ) callconv(.C) void {
+            _ = userdata;
+            callback(enum_value, std.mem.span(message.?));
+        }
+    }.wrapped_callback;
+}
diff --git a/src/logging.zig b/src/logging.zig
@@ -11,23 +11,12 @@ pub const LogLevel = enum(u32) {
     trace = 0x00000005,
 };
 
-pub const LogCallback = fn (LogLevel, []const u8) void;
+pub const LogCallback = fn (LogLevel, ?[*:0]const u8, ?*anyopaque) callconv(.C) void;
 
 pub fn setLogLevel(level: LogLevel) void {
     c.wgpuSetLogLevel(@intCast(@intFromEnum(level)));
 }
 
-pub fn setLogCallback(comptime callback: LogCallback) void {
-    const Callback = struct {
-        const user_callback = callback;
-        pub fn callback_c(
-            level: c_int,
-            message: ?[*:0]const u8,
-            userdata: ?*anyopaque,
-        ) callconv(.C) void {
-            _ = userdata;
-            user_callback(@enumFromInt(level), std.mem.span(message.?));
-        }
-    };
-    c.wgpuSetLogCallback(@ptrCast(&Callback.callback_c), null);
+pub fn setLogCallback(callback: *const LogCallback) void {
+    c.wgpuSetLogCallback(@ptrCast(callback), null);
 }
diff --git a/src/main.zig b/src/main.zig
@@ -3,6 +3,7 @@ const std = @import("std");
 const glfw = @import("glfw.zig");
 const Instance = @import("instance.zig").Instance;
 const Logging = @import("logging.zig");
+const Callback = @import("callback.zig").Callback;
 
 pub fn zgpu_log_callback(level: Logging.LogLevel, message: []const u8) void {
     switch (level) {
@@ -32,7 +33,7 @@ pub fn main() !void {
     const display = try glfw.native.getX11Display();
     const window_id = try glfw.native.getX11Window(window);
 
-    Logging.setLogCallback(zgpu_log_callback);
+    Logging.setLogCallback(Callback(zgpu_log_callback));
     Logging.setLogLevel(.warn);
 
     const instance = Instance.create(&.{