display_modpack/font_lib/init.lua

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--[[
font_lib mod for Minetest - Library to add font display capability
to display_lib mod.
(c) Pierre-Yves Rollo
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
--]]
font_lib = {}
font_lib.path = minetest.get_modpath("font_lib")
font_lib.font_height = 10
font_lib.font = {}
-- Get png width, suposing png width is less than 256 (it is the case for all font textures)
local function get_png_width(filename)
local file=assert(io.open(filename,"rb"))
-- All font png are smaller than 256x256 --> read only last byte
file:seek("set",19)
local w = file:read(1)
file:close()
return w:byte()
end
-- Computes line width for a given font height and text
-- @param text Text to be rendered
-- @return Rendered text width
function font_lib.get_line_width(text)
local char
local width = 0
for p=1,#text
do
char = text:sub(p,p):byte()
if font_lib.font[char] then
width = width + font_lib.font[char].width
end
end
return width
end
--- Builds texture part for a text line
-- @param text Text to be rendered
-- @param texturew Width of the texture (extra text is not rendered)
-- @param x Starting x position in texture
-- @param y Vertical position of the line in texture
-- @return Texture string
function font_lib.make_line_texture(text, texturew, x, y)
local char
local texture = ""
for p=1,#text
do
char = text:sub(p,p):byte()
if font_lib.font[char] then
-- Add image only if it is visible (at least partly)
if x + font_lib.font[char].width >= 0 and x <= texturew then
texture = texture..string.format(":%d,%d=%s", x, y, font_lib.font[char].filename)
end
x = x + font_lib.font[char].width
end
end
return texture
end
local function split_lines(text, maxlines)
local splits = text:split("\n")
if maxlines then
local lines = {}
for num = 1,maxlines do
lines[num] = splits[num]
end
return lines
else
return splits
end
end
--- Builds texture for a multiline colored text
-- @param text Text to be rendered
-- @param texturew Width of the texture (extra text will be truncated)
-- @param textureh Height of the texture
-- @param maxlines Maximum number of lines
-- @param valign Vertical text align ("top" or "center")
-- @param color Color of the text
-- @return Texture string
function font_lib.make_multiline_texture(text, texturew, textureh, maxlines, valign, color)
local texture = ""
local lines = split_lines(text, maxlines)
local y
if valign == "top" then
y = font_lib.font_height / 2
else
y = (textureh - font_lib.font_height * #lines) / 2 + 1
end
for _, line in pairs(lines) do
texture = texture..font_lib.make_line_texture(line, texturew,
(texturew - font_lib.get_line_width(line)) / 2, y)
y = y + font_lib.font_height
end
texture = string.format("[combine:%dx%d", texturew, textureh)..texture
if color then texture = texture.."^[colorize:"..color end
return texture
end
--- Standard on_display_update entity callback.
-- Node should have a corresponding display_entity with size, resolution and maxlines fields and
-- optionally valign and color fields
-- @param pos Node position
-- @param objref Object reference of entity
function font_lib.on_display_update(pos, objref)
local meta = minetest.get_meta(pos)
local text = meta:get_string("display_text")
local ndef = minetest.registered_nodes[minetest.get_node(pos).name]
local entity = objref:get_luaentity()
if entity and ndef.display_entities[entity.name] then
local def = ndef.display_entities[entity.name]
objref:set_properties({
textures={font_lib.make_multiline_texture(
text, def.size.x*def.resolution.x, def.size.y*def.resolution.y,
def.maxlines, def.valign, def.color)},
visual_size = def.size
})
end
end
-- Populate fonts table
local w, filename
for charnum=32,126 do
filename = string.format("font_lib_%02x.png", charnum)
w = get_png_width(font_lib.path.."/textures/"..filename)
font_lib.font[charnum] = {filename=filename, width=w}
end