Initial commit

.luacheckrc

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+max_line_length = 80
+
+globals = {
+    'formspec_ast',
+    'fs51',
+    'minetest',
+}
+
+read_globals = {
+    string = {fields = {'split', 'trim'}},
+    table = {fields = {'copy'}}
+}

LICENSE.md

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+
+# The MIT License (MIT)
+
+Copyright © 2019-2021 by luk3yx.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# fs51
+
+A compatibility layer that makes formspec_version 3 (and later) formspecs
+render more correctly in Minetest 5.1.0 and earlier.
+
+This will work with most mods without any additional configuration. If you want
+to disable automatic formspec translation, add
+`fs51.disable_monkey_patching = true` to minetest.conf.
+
+## Why?
+
+Minetest 5.1.0 introduced changes to formspecs that made them much less painful
+to create and work with. However, formspecs are interpreted client-side and to
+take advantage of these changes you would normally need to force everyone to
+upgrade Minetest. This mod detects these older clients and modifies formspecs
+sent to them to try and make sure they are at least usable.
+
+## How to use
+
+1. Install the mod
+2. Hope it works properly and doesn't break anything
+
+## Troubleshooting
+
+ - If your mod stores `minetest.show_formspec` during load time, you'll need to
+   add `fs51` as an optional dependency to `mod.conf` so it can use the patched
+   show_formspec code.
+
+## Dependencies
+
+This mod depends on my [formspec_ast] library.
+
+## API functions
+
+You probably don't need to use these unless you're embedding fs51 outside of
+Minetest or are using node formspecs.
+
+ - `fs51.backport(tree)`: Applies backports to a [formspec_ast] tree and
+    returns the modified tree. This does not modify the existing tree in place.
+ - `fs51.backport_string(formspec)`: Similar to
+    `formspec_ast.unparse(fs51.backport(formspec_ast.parse(formspec)))`.
+
+*Unlike the automatic backporting, these functions will preserve newer elements
+such as hypertext and background9 so the formspec will still work properly with
+newer clients.*
+
+ [formspec_ast]: https://git.minetest.land/luk3yx/formspec_ast

depends.txt

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+formspec_ast

init.lua

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+--
+-- fs51 - Compatibility layer for Minetest formspecs
+--
+-- Copyright © 2019-2021 by luk3yx.
+--
+
+fs51 = {}
+local fs51 = fs51
+
+local padding, spacing_x, spacing_y = 3/8, 5/4, 15/13
+
+-- Random offsets
+local random_offsets = {
+    -- box = {{0, 0}, {0.2, 0.125}},
+    label = {{0, 0.3}},
+    field = {{-padding, -0.33}, {-0.25, -0.2}},
+    pwdfield = {{-padding, -0.33}, {-0.25, 0}},
+    -- textarea = {{-0.3, -0.33}, {-0.2, 0}},
+    textarea = {{-padding, 0}, {-0.25, -padding}},
+    dropdown = {{0, 0}, {-0.25, 0}},
+    checkbox = {{0, 0.5}},
+    background = {{(1 - spacing_x) / 2, (1 - spacing_y) / 2}},
+    tabheader = {{-padding, -padding}},
+}
+
+local fixers = {}
+
+local function fix_pos(elem, random_offset)
+    if type(elem.x) == 'number' and type(elem.y) == 'number' then
+        if random_offset then
+            elem.x = elem.x - random_offset[1][1]
+            elem.y = elem.y - random_offset[1][2]
+        end
+
+        elem.x = (elem.x - padding) / spacing_x
+        elem.y = (elem.y - padding) / spacing_y
+    end
+end
+
+local function default_fixer(elem)
+    local random_offset = random_offsets[elem.type]
+    fix_pos(elem, random_offset)
+
+    if type(elem.w) == 'number' then
+        if random_offset and random_offset[2] then
+            elem.w = elem.w - random_offset[2][1]
+        end
+        elem.w = elem.w / spacing_x
+    end
+
+    if type(elem.h) == 'number' then
+        if random_offset and random_offset[2] then
+            elem.h = elem.h - random_offset[2][2]
+        end
+        elem.h = elem.h / spacing_y
+    end
+end
+
+-- Other fixers
+function fixers.image_button(elem)
+    fix_pos(elem, random_offsets[elem.type])
+    elem.w = elem.w * 0.8 + 0.205
+    elem.h = elem.h * 0.866 + 0.134
+end
+fixers.item_image_button = fixers.image_button
+fixers.image_button_exit = fixers.image_button
+
+function fixers.textarea(elem)
+    local h = elem.h
+    default_fixer(elem)
+    elem.h = h + 0.15
+end
+
+fixers.image = fix_pos
+fixers.item_image = fixers.image
+
+function fixers.button(elem)
+    elem.type = 'image_' .. elem.type
+    elem.texture_name = 'blank.png'
+    return fixers.image_button(elem)
+end
+fixers.button_exit = fixers.button
+
+function fixers.size(elem)
+    elem.w = elem.w / spacing_x - padding * 2 + 0.36
+    elem.h = elem.h / spacing_y - padding * 2
+end
+
+function fixers.list(elem, next_elem)
+    fix_pos(elem)
+    if elem.h < 2 then return end
+
+    -- Split the list[] into multiple list[]s.
+    local start = math.max(elem.starting_item_index or 0, 0)
+    for row = 1, elem.h do
+        local r = row - 1
+        elem[row] = {
+            type = 'list',
+            inventory_location = elem.inventory_location,
+            list_name = elem.list_name,
+            x = 0,
+            y = (r * 1.25) / spacing_y,
+            w = elem.w,
+            h = 1,
+            starting_item_index = start + (elem.w * r),
+        }
+
+        -- Swap the second element and any listring[]
+        if row == 2 and next_elem and next_elem.type == 'listring' and
+                not next_elem.inventory_location then
+            for k, v in pairs(elem[2]) do
+                next_elem[k] = v
+            end
+            next_elem.x = elem.x
+            next_elem.y = elem.y + next_elem.y
+            elem[2] = {type = 'listring'}
+        end
+    end
+
+    -- Convert the base element to a container
+    for k, _ in pairs(elem) do
+        if type(k) ~= 'number' and k ~= 'x' and k ~= 'y' then
+            elem[k] = nil
+        end
+    end
+    elem.type = 'container'
+end
+
+-- Remove the "height" attribute on dropdowns.
+function fixers.dropdown(elem)
+    fix_pos(elem)
+    elem.w = elem.w / spacing_y
+    elem.h = nil
+    elem.index_event = nil
+end
+
+--
+local pre_types = {size = true, position = true, anchor = true,
+                   no_prepend = true}
+local xywh = {'x', 'y', 'w', 'h'}
+function fs51.backport(tree)
+    -- Flatten the tree (this will also copy it).
+    tree = formspec_ast.flatten(tree)
+    local real_coordinates = type(tree.formspec_version) == 'number' and
+        tree.formspec_version >= 2
+    tree.formspec_version = 1
+
+    -- Check for an initial real_coordinates[].
+    if not real_coordinates then
+        for _, elem in ipairs(tree) do
+            if elem.type == 'real_coordinates' then
+                real_coordinates = elem.bool
+                break
+            elseif not pre_types[elem.type] then
+                break
+            end
+        end
+    end
+
+    -- Allow deletion of real_coordinates[]
+    local i = 1
+    while tree[i] ~= nil do
+        local elem = tree[i]
+        if elem.type == 'real_coordinates' then
+            real_coordinates = elem.bool
+            table.remove(tree, i)
+            i = i - 1
+        elseif elem.type == 'list' and real_coordinates then
+            fixers.list(elem, tree[i + 1])
+
+            -- Flatten containers
+            if elem.type == 'container' and elem[1] then
+                formspec_ast.apply_offset(elem, elem.x, elem.y)
+                tree[i] = elem[1]
+                for j = 2, #elem do
+                    i = i + 1
+                    table.insert(tree, i, elem[j])
+                end
+            end
+        elseif real_coordinates then
+            (fixers[elem.type] or default_fixer)(elem)
+            for _, n in ipairs(xywh) do
+                if elem[n] then
+                    elem[n] = math.floor(elem[n] * 1000) / 1000
+                end
+            end
+        end
+
+        i = i + 1
+    end
+
+    return tree
+end
+
+local minetest_log = rawget(_G, 'minetest') and minetest.log or print
+function fs51.backport_string(formspec)
+    local fs, err = formspec_ast.parse(formspec)
+    if not fs then
+        minetest_log('warning', '[fs51] Error parsing formspec: ' ..
+            tostring(err))
+        return nil, err
+    end
+    return formspec_ast.unparse(fs51.backport(fs))
+end
+
+-- Monkey patch Minetest's code
+if rawget(_G, 'minetest') and minetest.register_on_player_receive_fields and
+        not minetest.settings:get_bool('fs51.disable_monkey_patching') then
+    dofile(minetest.get_modpath('fs51') .. '/monkey_patching.lua')
+end

mod.conf

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+name = fs51
+depends = formspec_ast

monkey_patching.lua

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+--
+-- fs51 - Compatibility layer for Minetest formspecs
+--
+-- Copyright © 2021 by luk3yx.
+--
+
+local get_player_information = minetest.get_player_information
+local type = type
+local function backport_for(name, formspec)
+    local info = get_player_information(name)
+    local formspec_version = info and info.formspec_version or 1
+    if formspec_version >= 3 then return formspec end
+
+    local tree, err = formspec_ast.parse(formspec)
+    if not tree then
+        minetest.log('warning', '[fs51] Error parsing formspec (in ' ..
+            'monkey_patching.lua): ' .. tostring(err))
+        return formspec
+    end
+
+    -- Add some placeholders
+    local modified
+    for node in formspec_ast.walk(tree) do
+        local node_type = node.type
+        if formspec_version == 1 and node_type == 'background9' then
+            -- No need to set modified here
+            node.type = 'background'
+            node.middle_x, node.middle_y = nil, nil
+            node.middle_x2, node.middle_y2 = nil, nil
+        elseif node_type == 'animated_image' then
+            modified = true
+            node.type = 'image'
+            local frame_start = node.frame_start or 1
+            node.texture_name = ('(%s)^[verticalframe:%d:%d'):format(
+                node.texture_name, node.frame_count, frame_start - 1)
+        elseif node_type == 'model' and node.textures[1] then
+            modified = true
+            node.type = 'image'
+            node.texture_name = node.textures[1]
+        elseif node_type == 'hypertext' then
+            -- Convert hypertext elements to regular textareas
+            modified = true
+            node.type = 'textarea'
+            node.name = ''
+            node.label = ''
+            node.default = node.text:gsub('<[^>]+>', '')
+            node.text = nil
+        elseif node_type == 'scroll_container' then
+            modified = true
+            node.type = 'container'
+            -- Scroll containers are always going to be broken on older clients
+            for i = #node, 1, -1 do
+                local inner_node = node[i]
+                if inner_node.x and inner_node.y and
+                        (inner_node.x >= node.w or inner_node.y >= node.h) then
+                    table.remove(node, i)
+                end
+            end
+        elseif formspec_version == 1 and node_type == 'tabheader' then
+            node.w, node.h = nil, nil
+        end
+    end
+
+    if formspec_version == 1 then
+        modified = true
+        tree = fs51.backport(tree)
+    end
+
+    if modified then
+        return assert(formspec_ast.unparse(tree))
+    end
+    return formspec
+end
+
+-- Patch minetest.show_formspec()
+local show_formspec = minetest.show_formspec
+function minetest.show_formspec(pname, formname, formspec)
+    return show_formspec(pname, formname, backport_for(pname, formspec))
+end
+
+-- Patch player:set_inventory_formspec()
+local old_set_inventory_formspec
+local function new_set_inventory_formspec(self, formspec, ...)
+    return old_set_inventory_formspec(self,
+        backport_for(self:get_player_name(), formspec), ...)
+end
+
+minetest.register_on_joinplayer(function(player)
+    if old_set_inventory_formspec == nil then
+        assert(type(player) == 'userdata', 'Fake player object?')
+        local cls = getmetatable(player)
+        old_set_inventory_formspec = cls.set_inventory_formspec
+        cls.set_inventory_formspec = new_set_inventory_formspec
+
+        -- In case the inventory formspec has been set in the meantime
+        player:set_inventory_formspec(player:get_inventory_formspec())
+    end
+end)
+
+-- Patch minetest.get_meta()
+-- Inspired by https://gitlab.com/sztest/nodecore/-/blob/master/mods/nc_api
+local old_nodemeta_set_string
+local function new_nodemeta_set_string(self, k, v)
+    if k == 'formspec' and type(v) == 'string' then
+        v = fs51.backport_string(v) or v
+    end
+    return old_nodemeta_set_string(self, k, v)
+end
+
+local get_meta = minetest.get_meta
+function minetest.get_meta(...)
+    local meta = get_meta(...)
+    if type(meta) == 'userdata' then
+        minetest.get_meta = get_meta
+        local cls = getmetatable(meta)
+        old_nodemeta_set_string = cls.set_string
+        cls.set_string = new_nodemeta_set_string
+    end
+    return meta
+end