Add event listener subscribe/unsubsribe system

2026-09-20 18:26:09 +02:00
parent 22be96ee45
commit cbc320b7f5
4 changed files with 226 additions and 77 deletions
@@ -24,7 +24,7 @@ odin build game/ -show-timings \
 	-collection:gram=vendor/gram/src \
 	-collection:wgpu=vendor \
 	-build-mode:dynamic \
-	-out:build/game_tmp -microarch:native -define:VERSION="$VERSION-debug" -debug "$@"
+	-out:build/game_tmp -microarch:native -o:minimal -use-separate-modules -define:VERSION="$VERSION-debug" -debug "$@"

 # Need to use a temp file on Linux/macOS because it first writes an empty file,
 # which the engine will load before it is actually fully written.
@@ -49,7 +49,7 @@ if [ "$OPTION" = "debug" ]; then
 		-collection:sindri=src \
 		-collection:gram=vendor/gram/src \
 		-collection:wgpu=vendor \
-		-out:build/$PROJECT -microarch:native -use-separate-modules -define:VERSION="$VERSION-debug" -debug "$@"
+		-out:build/$PROJECT -microarch:native -o:minimal -use-separate-modules -define:VERSION="$VERSION-debug" -debug "$@"
 	exit 0
 fi

@@ -4,6 +4,11 @@ This document contains specifics about the workings of the Odin programming
 language, dynamic linking and state management design patterns. These are
 tested and validated findings, for continued reference by me.

+## Compiler
+
+Odin's compiler is demand-driver: a procedure's body is only semantically
+analyzed when the proc is actually referenced.
+
 ## Dynamic Library Memory

 When a program loads in a dynamic library, what happens with package globals?
@@ -1,5 +1,7 @@
 package base

+import "base:intrinsics"
+import "base:runtime"
 import "core:fmt"

 // -----------------------------------------
@@ -7,8 +9,7 @@ import "core:fmt"

 // event category, bitfield (?)

-// Event_Data :: union {
-Event :: union {
+Event_Data :: union {
 	Window_Close_Event,
 	Window_Resize_Event,
 	Joystick_Connect_Event,
@@ -22,115 +23,246 @@ Event :: union {
 	Mouse_Scroll_Event,
 }

-// Event :: struct {
-// 	data:    Event_Data,
-// 	handled: bool,
-// }
-
-Window_Close_Event :: struct {
+Event :: struct {
+	data:    Event_Data,
 	handled: bool,
 }

+Window_Close_Event :: struct {}
+
 Window_Resize_Event :: struct {
-	handled: bool,
 	width:  i32,
 	height: i32,
 }

-Joystick_Connect_Event :: struct {
-	handled: bool,
-	id:      i32,
-}
-
-Joystick_Disconnect_Event :: struct {
-	handled: bool,
-	id:      i32,
-}
-
 Key_Press_Event :: struct {
-	handled: bool,
 	key:  Key,
 	mods: Mod_Set,
 }

 Key_Release_Event :: struct {
-	handled: bool,
 	key:  Key,
 	mods: Mod_Set,
 }

 Key_Repeat_Event :: struct {
-	handled: bool,
 	key:  Key,
 	mods: Mod_Set,
 }

 Mouse_Button_Press_Event :: struct {
-	handled: bool,
 	button: Mouse_Button,
 	mods:   Mod_Set,
 }

 Mouse_Button_Release_Event :: struct {
-	handled: bool,
 	button: Mouse_Button,
 	mods:   Mod_Set,
 }

 Mouse_Position_Event :: struct {
-	handled: bool,
 	x_pos: f32,
 	y_pos: f32,
 }

 Mouse_Scroll_Event :: struct {
-	handled:  bool,
 	x_offset: f32,
 	y_offset: f32,
 }

+Joystick_Connect_Event :: struct {
+	id: i32,
+}
+
+Joystick_Disconnect_Event :: struct {
+	id: i32,
+}
+
+// Message Receiver
+@(private)
+Listener :: struct {
+	callback: proc(event: ^Event_Data, user_ptr: rawptr) -> bool, // return true = don't propagate
+	user_ptr: rawptr,
+	// TODO: test if hot_reload keeps the same function pointers and the listeners remain working.
+	//       if they dont add a flag "engine_listener: bool", which engine calls should set true,
+	//       then clear all game listeners
+}
+
+// Transfers messages between Sender and Receiver
+Event_Bus :: struct {
+	queue:     [dynamic]Event,
+	listeners: map[typeid][dynamic]Listener,
+	allocator: runtime.Allocator,
+}
+
 // -----------------------------------------
 // Variables

-// I want to have a list of Listeners per Event type, but this is state
-// listeners: map[typeid][dynamic]Listener
+event_bus: Event_Bus
+
+// -----------------------------------------
+// Constructor/destructor
+
+event_bus_init :: proc(allocator := context.allocator) {
+	// make() doesnt allocate until there's capacity, so set it > 0
+	queue := make([dynamic]Event, 0, 4, allocator)
+	listeners := make(map[typeid][dynamic]Listener, 4, allocator)
+	event_bus = {
+		queue     = queue,
+		listeners = listeners,
+		allocator = allocator,
+	}
+}
+
+event_bus_destroy :: proc() {
+	assert(event_bus.queue != nil)
+	assert(event_bus.listeners != nil)
+
+	for _, ls in event_bus.listeners do delete(ls)
+
+	delete(event_bus.queue)
+	delete(event_bus.listeners)
+
+	event_bus.queue = nil
+	event_bus.listeners = nil
+}

 // -----------------------------------------
 // Public functions

-// Dispatcher(Event) -> forwards to the right function
-on_event :: proc(event: Event) {
+event_subscribe :: proc(
+	$T: typeid,
+	callback: proc(event: ^T, user_ptr: rawptr) -> bool,
+	user_ptr: rawptr = nil,
+) where intrinsics.type_is_variant_of(Event_Data, T) {
+	cb := cast(proc(_: ^Event_Data, _: rawptr) -> bool)callback // upcast
+	event_subscribe_raw(T, cb, user_ptr)
+}
+
+event_unsubscribe :: proc(
+	$T: typeid,
+	callback: proc(event: ^T, user_ptr: rawptr) -> bool,
+	user_ptr: rawptr = nil,
+) where intrinsics.type_is_variant_of(Event_Data, T) {
+	cb := cast(proc(_: ^Event_Data, _: rawptr) -> bool)callback // upcast
+	event_unsubscribe_raw(T, cb, user_ptr)
+}
+
+on_event :: proc(data: Event_Data) {
+	assert(event_bus.queue != nil)
+
+	append(&event_bus.queue, Event{data = data})
+}
+
+// Drain all the events that have been queued up, in enqueue order
+drain_event_queue :: proc() {
+	assert(event_bus.queue != nil)
+
 	fmt.println("toby!")

-	#partial switch e in event {
+	for &event in event_bus.queue {
+
+		#partial switch e in event.data {
 			case Window_Close_Event:
+				event_dispatch(Window_Close_Event, &event)
 				fmt.println("Close")
 			case Window_Resize_Event:
+				event_dispatch(Window_Resize_Event, &event)
 				fmt.println("Resize:", e.width, e.height)

 			case Key_Press_Event:
+				event_dispatch(Key_Press_Event, &event)
 				fmt.println("Key press", e.key, e.mods)
 			case Key_Release_Event:
+				event_dispatch(Key_Release_Event, &event)
 				fmt.println("Key release", e.key, e.mods)
 			case Key_Repeat_Event:
+				event_dispatch(Key_Repeat_Event, &event)
 				fmt.println("Key repeat", e.key, e.mods)

 			case Mouse_Button_Press_Event:
+				event_dispatch(Mouse_Button_Press_Event, &event)
 				fmt.println("Mouse press", e.button, e.mods)
 			case Mouse_Button_Release_Event:
+				event_dispatch(Mouse_Button_Release_Event, &event)
 				fmt.println("Mouse release", e.button, e.mods)
 			case Mouse_Position_Event:
+				event_dispatch(Mouse_Position_Event, &event)
 				fmt.printfln("Mouse pos: {}x{}", e.x_pos, e.y_pos)
+			case Mouse_Scroll_Event:
+				event_dispatch(Mouse_Scroll_Event, &event)
+				fmt.printfln("Mouse scroll: {}x{}", e.x_offset, e.y_offset)

 			case Joystick_Connect_Event:
+				event_dispatch(Joystick_Connect_Event, &event)
 				fmt.println("Joy con:", e.id)
 			case Joystick_Disconnect_Event:
+				event_dispatch(Joystick_Disconnect_Event, &event)
 				fmt.println("Joy dis:", e.id)
+
+			case:
+				panic("[event] unimplemented event")
 		}
+	}
+
+	clear(&event_bus.queue)
 }

-/*
-   Notes:
+// Dispatch to the listeners registered for T, in reverse subscription order.
+// First listener to return true claims the event and stops propagation
+event_dispatch :: proc(
+	$T: typeid,
+	event: ^Event,
+) -> bool where intrinsics.type_is_variant_of(Event_Data, T) {
+	assert(event_bus.listeners != nil)

-   Have the events queued up into a frame buffer that gets drained at a specific time.
- */
+	ls, ok := event_bus.listeners[T]
+	if !ok do return false
+
+	#reverse for &l in ls {
+		callback := cast(proc(_: ^T, _: rawptr) -> bool)l.callback // downcast
+		if callback(&event.data.(T), l.user_ptr) {
+			event.handled = true
+			return true
+		}
+	}
+
+	return false
+}
+
+// -----------------------------------------
+// Private functions
+
+@(private)
+event_subscribe_raw :: proc(
+	$T: typeid,
+	callback: proc(event: ^Event_Data, user_ptr: rawptr) -> bool,
+	user_ptr: rawptr = nil,
+) where intrinsics.type_is_variant_of(Event_Data, T) {
+	assert(event_bus.listeners != nil)
+
+	if _, ok := event_bus.listeners[T]; !ok {
+		event_bus.listeners[T] = make([dynamic]Listener, event_bus.allocator)
+	}
+
+	append(&event_bus.listeners[T], Listener{callback, user_ptr})
+}
+
+@(private)
+event_unsubscribe_raw :: proc(
+	$T: typeid,
+	callback: proc(event: ^Event_Data, user_ptr: rawptr) -> bool,
+	user_ptr: rawptr = nil,
+) where intrinsics.type_is_variant_of(Event_Data, T) {
+	assert(event_bus.listeners != nil)
+
+	ls, ok := event_bus.listeners[T]
+	if !ok do return
+
+	for i, l in ls {
+		if l.callback == callback && l.user_ptr == user_ptr {
+			ordered_remove(&event_bus.listeners[T], i) // preserve subscription order
+			return
+		}
+	}
+}
@@ -17,6 +17,12 @@ main :: proc() {
 	hr, err := base.hot_reload_init()
 	defer base.hot_reload_destroy(&hr)

+	// Event system
+	base.event_bus_init()
+	defer base.event_bus_destroy()
+
+	base.event_subscribe(base.Key_Press_Event, test)
+
 	api := base.active_lib(&hr)
 	settings := api.settings()

@@ -39,6 +45,7 @@ main :: proc() {
 		start := time.tick_now()

 		platform.os_poll_events()
+		base.drain_event_queue()
 		api.update(dt)

 		platform.frame(dt)
@@ -53,3 +60,8 @@ main :: proc() {

 	api.destroy()
 }
+
+test :: proc(e: ^base.Key_Press_Event, _: rawptr) -> bool {
+	fmt.println("main: @@@@@@@@@@@", e)
+	return true
+}