Touchscreen `modify` command doesn't handle `item_grid` correctly

[OgelGames]

Currently the modify command looks at the start of the element string to identify the element that it contains, however this does not work with the custom item_grid element, because that element string consists of multiple item_image or item_image_button.

Possible solutions:

• Change how elements are stored in metadata so that the modify command does not need to use pattern matching.
• Add code specifically for item_grid modification. (and tables too)
• Something else?

Relevant code:

digistuff/touchscreen.lua

Lines 20 to 33 in 71b606c

	local function modify_element_string(old, values)
	local e = string.match(old, "^(.-)%[")
	local element = formspec_elements[e]
	if type(element) == "function" then
	return old -- No-op for special elements, as there is no format string
	end
	local old_values = {string.match(old, element[5])}
	local new_values = {}
	for i,name in ipairs(element[2]) do
	local value = element[4][i](values[name], old_values[i] or element[3][i])
	table.insert(new_values, value)
	end
	return string.format(element[1], unpack(new_values))
	end

digistuff/formspec_elements.lua

Lines 351 to 383 in 71b606c

	formspec_elements.item_grid = function(values)
	for v,d in pairs({X = 0, Y = 0, W = 1, H = 1, spacing = 0, size = 1, offset = 1}) do
	if type(values[v]) ~= "number" then
	values[v] = d
	end
	end
	local name = str(values.name, "grid").."_"
	local items = type(values.items) == "table" and values.items or {}
	local offset = math.max(1, math.floor(values.offset)) - 1
	local x, y, n, item = values.X, values.Y, 1
	local grid = {}
	for _=1, values.H do
	for _=1, values.W do
	item = items[n + offset]
	if type(item) ~= "string" then
	return table.concat(grid)
	end
	item = string.match(item, "^[^ %[%]\\,;]* ?%d* ?%d*")
	if values.interactable ~= false then
	grid[n] = string.format("item_image_button[%s,%s;%s,%s;%s;%s;]",
	x, y, values.size, values.size, item, name..n)
	else
	grid[n] = string.format("item_image[%s,%s;%s,%s;%s]",
	x, y, values.size, values.size, item)
	end
	n = n + 1
	x = x + values.size + values.spacing
	end
	x = values.X
	y = y + values.size + values.spacing
	end
	return table.concat(grid)
	end