gg: setup ctx.window.user_data and ctx.user_data on ctx.run(), instead of in gg.new_context, to allow for embedding gg.Context in ui (#17169)

examples/gg/cursor.v

@@ -5,12 +5,13 @@ import gx
 import sokol.sapp
 
 fn main() {
-	gg.new_context(
+	mut ctx := gg.new_context(
 		bg_color: gx.white
 		window_title: 'Cursor'
 		frame_fn: frame
 		init_fn: init
-	).run()
+	)
+	ctx.run()
 }
 
 fn init(mut ctx gg.Context) {

examples/pendulum-simulation/modules/sim/anim/app.v

@@ -13,7 +13,7 @@ struct Pixel {
 	color gx.Color
 }
 
-struct App {
+pub struct App {
 pub:
 	args         simargs.ParallelArgs
 	request_chan chan &sim.SimRequest

vlib/gg/gg.c.v

@@ -458,14 +458,7 @@ pub fn new_context(cfg Config) &Context {
 		ft: 0
 		ui_mode: cfg.ui_mode
 		native_rendering: cfg.native_rendering
-	}
-	if cfg.user_data == unsafe { nil } {
-		ctx.user_data = ctx
-	}
-	ctx.set_bg_color(cfg.bg_color)
-	// C.printf('new_context() %p\n', cfg.user_data)
-	window := sapp.Desc{
-		user_data: ctx
+		window: sapp.Desc{
 			init_userdata_cb: gg_init_sokol_window
 			frame_userdata_cb: gg_frame_fn
 			event_userdata_cb: gg_event_fn
@@ -485,12 +478,22 @@ pub fn new_context(cfg Config) &Context {
 			max_dropped_file_path_length: cfg.max_dropped_file_path_length
 			swap_interval: cfg.swap_interval
 		}
-	ctx.window = window
+	}
+	ctx.set_bg_color(cfg.bg_color)
+	// C.printf('new_context() %p\n', cfg.user_data)
 	return ctx
 }
 
 // run starts the main loop of the context.
-pub fn (ctx &Context) run() {
+pub fn (mut ctx Context) run() {
+	// set context late, in case it changed (e.g., due to embedding)
+	ctx.window = sapp.Desc{
+		...ctx.window
+		user_data: ctx
+	}
+	if ctx.user_data == unsafe { nil } {
+		ctx.user_data = ctx
+	}
 	sapp.run(&ctx.window)
 }
 

vlib/gg/gg.js.v

@@ -328,9 +328,6 @@ pub fn new_context(cfg Config) &Context {
 	sz.height = g.height
 	sz.width = g.width
 	g.config = cfg
-	if isnil(cfg.user_data) {
-		g.user_data = g
-	}
 	g.window = dom.window()
 	document := dom.document
 	canvas_elem := document.getElementById(cfg.canvas.str) or {
@@ -453,6 +450,11 @@ pub fn new_context(cfg Config) &Context {
 }
 
 pub fn (mut ctx Context) run() {
+	// set context late, in case it changed (e.g., due to embedding)
+	if isnil(ctx.user_data) {
+		ctx.user_data = ctx
+	}
+
 	gg_animation_frame_fn(mut ctx)
 }