From 26b9464f51eb8b31412ff6ac83f991912ed8db8f Mon Sep 17 00:00:00 2001
From: Tim Marston <tim@ed.am>
Date: Tue, 31 Jan 2023 16:22:20 +0000
Subject: [PATCH] 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 +-
 .../modules/sim/anim/app.v                    |  2 +-
 vlib/gg/gg.c.v                                | 55 ++++++++++---------
 vlib/gg/gg.js.v                               |  8 ++-
 4 files changed, 38 insertions(+), 32 deletions(-)

diff --git a/examples/gg/cursor.v b/examples/gg/cursor.v
index c883e9b04f..7a3812bf14 100644
--- a/examples/gg/cursor.v
+++ b/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) {
diff --git a/examples/pendulum-simulation/modules/sim/anim/app.v b/examples/pendulum-simulation/modules/sim/anim/app.v
index d393c0b4ec..4262c86870 100644
--- a/examples/pendulum-simulation/modules/sim/anim/app.v
+++ b/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
diff --git a/vlib/gg/gg.c.v b/vlib/gg/gg.c.v
index 53035e56c1..41c7dcde5f 100644
--- a/vlib/gg/gg.c.v
+++ b/vlib/gg/gg.c.v
@@ -458,39 +458,42 @@ 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
+		window: sapp.Desc{
+			init_userdata_cb: gg_init_sokol_window
+			frame_userdata_cb: gg_frame_fn
+			event_userdata_cb: gg_event_fn
+			fail_userdata_cb: gg_fail_fn
+			cleanup_userdata_cb: gg_cleanup_fn
+			window_title: &char(cfg.window_title.str)
+			html5_canvas_name: &char(cfg.window_title.str)
+			width: cfg.width
+			height: cfg.height
+			sample_count: cfg.sample_count
+			high_dpi: true
+			fullscreen: cfg.fullscreen
+			__v_native_render: cfg.native_rendering
+			// drag&drop
+			enable_dragndrop: cfg.enable_dragndrop
+			max_dropped_files: cfg.max_dropped_files
+			max_dropped_file_path_length: cfg.max_dropped_file_path_length
+			swap_interval: cfg.swap_interval
+		}
 	}
 	ctx.set_bg_color(cfg.bg_color)
 	// C.printf('new_context() %p\n', cfg.user_data)
-	window := sapp.Desc{
-		user_data: ctx
-		init_userdata_cb: gg_init_sokol_window
-		frame_userdata_cb: gg_frame_fn
-		event_userdata_cb: gg_event_fn
-		fail_userdata_cb: gg_fail_fn
-		cleanup_userdata_cb: gg_cleanup_fn
-		window_title: &char(cfg.window_title.str)
-		html5_canvas_name: &char(cfg.window_title.str)
-		width: cfg.width
-		height: cfg.height
-		sample_count: cfg.sample_count
-		high_dpi: true
-		fullscreen: cfg.fullscreen
-		__v_native_render: cfg.native_rendering
-		// drag&drop
-		enable_dragndrop: cfg.enable_dragndrop
-		max_dropped_files: cfg.max_dropped_files
-		max_dropped_file_path_length: cfg.max_dropped_file_path_length
-		swap_interval: cfg.swap_interval
-	}
-	ctx.window = window
 	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)
 }
 
diff --git a/vlib/gg/gg.js.v b/vlib/gg/gg.js.v
index fef344976b..4ca9366b80 100644
--- a/vlib/gg/gg.js.v
+++ b/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)
 }