From e82495d98c8192343548effe8eaf5d8e07031eed Mon Sep 17 00:00:00 2001
From: frogTheSecond <74461678+TheEt1234@users.noreply.github.com>
Date: Thu, 6 Nov 2025 11:42:26 +0100
Subject: [PATCH] Allow image formats other than PNG for game backgrounds in
 the main menu (#16395)

---
 .luacheckrc                     |  2 +-
 builtin/common/misc_helpers.lua |  4 ++
 builtin/game/chat.lua           |  2 +-
 builtin/mainmenu/game_theme.lua | 89 ++++++++++++++++++---------------
 4 files changed, 56 insertions(+), 41 deletions(-)

diff --git a/.luacheckrc b/.luacheckrc
index 9ed9c7817e..cab0e9f370 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -23,7 +23,7 @@ read_globals = {
 	"tracy",
 
 	string = {fields = {"split", "trim"}},
-	table  = {fields = {"copy", "copy_with_metatables", "getn", "indexof", "keyof", "insert_all"}},
+	table  = {fields = {"copy", "copy_with_metatables", "getn", "indexof", "keyof", "insert_all", "shuffle"}},
 	math   = {fields = {"hypot", "round"}},
 }
 
diff --git a/builtin/common/misc_helpers.lua b/builtin/common/misc_helpers.lua
index 87af191199..714ffec0f3 100644
--- a/builtin/common/misc_helpers.lua
+++ b/builtin/common/misc_helpers.lua
@@ -119,6 +119,9 @@ end
 -- }]]
 function dump(value, indent)
 	indent = indent or "\t"
+
+	assert(type(indent) == "string", "dump()'s second argument should be a string or nil.")
+
 	local newline = indent == "" and "" or "\n"
 
 	local rope = {}
@@ -873,3 +876,4 @@ function core.parse_coordinates(x, y, z, relative_to)
 	local rz = core.parse_relative_number(z, relative_to.z)
 	return rx and ry and rz and vector.new(rx, ry, rz)
 end
+
diff --git a/builtin/game/chat.lua b/builtin/game/chat.lua
index c143f304b9..ac64650da9 100644
--- a/builtin/game/chat.lua
+++ b/builtin/game/chat.lua
@@ -43,7 +43,7 @@ end
 -- Chat command handler
 --
 
-core.chatcommands = core.registered_chatcommands -- BACKWARDS COMPATIBILITY
+core.chatcommands = core.registered_chatcommands -- backwards compatibility
 
 local msg_time_threshold =
 	tonumber(core.settings:get("chatcommand_msg_time_threshold")) or 0.1
diff --git a/builtin/mainmenu/game_theme.lua b/builtin/mainmenu/game_theme.lua
index 7291100255..b9e7e1d4bb 100644
--- a/builtin/mainmenu/game_theme.lua
+++ b/builtin/mainmenu/game_theme.lua
@@ -2,7 +2,6 @@
 -- Copyright (C) 2013 sapier
 -- SPDX-License-Identifier: LGPL-2.1-or-later
 
-
 mm_game_theme = {}
 
 --------------------------------------------------------------------------------
@@ -21,7 +20,7 @@ function mm_game_theme.set_engine(hide_decorations)
 
 	core.set_topleft_text("")
 
-	local have_bg      = false
+	local have_bg = false
 	local have_overlay = mm_game_theme.set_engine_single("overlay")
 
 	if not have_overlay then
@@ -58,7 +57,7 @@ function mm_game_theme.set_game(gamedetails)
 
 	core.set_topleft_text(gamedetails.name)
 
-	local have_bg      = false
+	local have_bg = false
 	local have_overlay = mm_game_theme.set_game_single("overlay", gamedetails)
 
 	if not have_overlay then
@@ -83,17 +82,25 @@ end
 
 --------------------------------------------------------------------------------
 function mm_game_theme.clear_single(identifier)
-	core.set_background(identifier,"")
+	core.set_background(identifier, "")
 end
 
+--------------------------------------------------------------------------------
+local valid_image_extensions = {
+	".png",
+	".jpg",
+	".jpeg",
+}
+
 --------------------------------------------------------------------------------
 function mm_game_theme.set_engine_single(identifier)
 	--try texture pack first
 	if mm_game_theme.texturepack ~= nil then
-		local path = mm_game_theme.texturepack .. DIR_DELIM .."menu_" ..
-										identifier .. ".png"
-		if core.set_background(identifier,path) then
-			return true
+		for _, extension in pairs(valid_image_extensions) do
+			local path = mm_game_theme.texturepack .. DIR_DELIM .. "menu_" .. identifier .. extension
+			if core.set_background(identifier, path) then
+				return true
+			end
 		end
 	end
 
@@ -106,49 +113,53 @@ function mm_game_theme.set_engine_single(identifier)
 end
 
 --------------------------------------------------------------------------------
-function mm_game_theme.set_game_single(identifier, gamedetails)
-	assert(gamedetails ~= nil)
 
-	if mm_game_theme.texturepack ~= nil then
-		local path = mm_game_theme.texturepack .. DIR_DELIM ..
-			gamedetails.id .. "_menu_" .. identifier .. ".png"
+
+function mm_game_theme.set_game_single(identifier, gamedetails)
+	local extensions_randomised = table.copy(valid_image_extensions)
+	table.shuffle(extensions_randomised)
+	for _, extension in pairs(extensions_randomised) do
+		assert(gamedetails ~= nil)
+
+		if mm_game_theme.texturepack ~= nil then
+			local path = mm_game_theme.texturepack .. DIR_DELIM .. gamedetails.id .. "_menu_" .. identifier .. extension
+			if core.set_background(identifier, path) then
+				return true
+			end
+		end
+
+		-- Find out how many randomized textures the game provides
+		local n = 0
+		local filename
+		local menu_files = core.get_dir_list(gamedetails.path .. DIR_DELIM .. "menu", false)
+		for i = 1, #menu_files do
+			filename = identifier .. "." .. i .. extension
+			if table.indexof(menu_files, filename) == -1 then
+				n = i - 1
+				break
+			end
+		end
+		-- Select random texture, 0 means standard texture
+		n = math.random(0, n)
+		if n == 0 then
+			filename = identifier .. extension
+		else
+			filename = identifier .. "." .. n .. extension
+		end
+
+		local path = gamedetails.path .. DIR_DELIM .. "menu" .. DIR_DELIM .. filename
 		if core.set_background(identifier, path) then
 			return true
 		end
-	end
 
-	-- Find out how many randomized textures the game provides
-	local n = 0
-	local filename
-	local menu_files = core.get_dir_list(gamedetails.path .. DIR_DELIM .. "menu", false)
-	for i = 1, #menu_files do
-		filename = identifier .. "." .. i .. ".png"
-		if table.indexof(menu_files, filename) == -1 then
-			n = i - 1
-			break
-		end
 	end
-	-- Select random texture, 0 means standard texture
-	n = math.random(0, n)
-	if n == 0 then
-		filename = identifier .. ".png"
-	else
-		filename = identifier .. "." .. n .. ".png"
-	end
-
-	local path = gamedetails.path .. DIR_DELIM .. "menu" ..
-		DIR_DELIM .. filename
-	if core.set_background(identifier, path) then
-		return true
-	end
-
 	return false
 end
 
 --------------------------------------------------------------------------------
 function mm_game_theme.set_dirt_bg()
 	if mm_game_theme.texturepack ~= nil then
-		local path = mm_game_theme.texturepack .. DIR_DELIM .."default_dirt.png"
+		local path = mm_game_theme.texturepack .. DIR_DELIM .. "default_dirt.png"
 		if core.set_background("background", path, true, 128) then
 			return true
 		end