display_modpack/font_api/font.lua
2018-11-01 10:47:39 +01:00

273 lines
6.9 KiB
Lua

--[[
font_api mod for Minetest - Library to add font display capability
to display_api 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/>.
--]]
-- Fallback table
local fallbacks = dofile(font_api.path.."/fallbacks.lua")
-- Local functions
------------------
-- Returns number of UTF8 bytes of the first char of the string
local function get_char_bytes(str)
local msb = str:byte(1)
if msb ~= nil then
if msb < 0x80 then return 1 end
if msb >= 0xF0 then return 4 end
if msb >= 0xE0 then return 3 end
if msb >= 0xC2 then return 2 end
end
end
-- Returns the unicode codepoint of the first char of the string
local function char_to_codepoint(str)
local bytes = get_char_bytes(str)
if bytes == 1 then
return str:byte(1)
elseif bytes == 2 then
return (str:byte(1) - 0xC2) * 0x40
+ str:byte(2)
elseif bytes == 3 then
return (str:byte(1) - 0xE0) * 0x1000
+ str:byte(2) % 0x40 * 0x40
+ str:byte(3) % 0x40
elseif bytes == 4 then -- Not tested
return (str:byte(1) - 0xF0) * 0x40000
+ str:byte(2) % 0x40 * 0x1000
+ str:byte(3) % 0x40 * 0x40
+ str:byte(4) % 0x40
end
end
-- Split multiline text into array of lines, with <maxlines> maximum lines.
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
--------------------------------------------------------------------------------
--- Font class
local Font = {}
font_api.Font = Font
function Font:new(def)
if type(def) ~= "table" then
minetest.log("error",
"[font_api] Font definition must be a table.")
return nil
end
if def.height == nil or def.height <= 0 then
minetest.log("error",
"[font_api] Font definition must have a positive height.")
return nil
end
if type(def.widths) ~= "table" then
minetest.log("error",
"[font_api] Font definition must have a widths array.")
return nil
end
if def.widths[0] == nil then
minetest.log("error",
"[font_api] Font must have a char with codepoint 0 (=unknown char).")
return nil
end
local font = table.copy(def)
setmetatable(font, self)
self.__index = self
return font
end
--- Gets the next char of a text
-- @return Codepoint of first char,
-- @return Remaining string without this first char
function Font:get_next_char(text)
local bytes = get_char_bytes(text)
if bytes == nil then
minetest.log("warning",
"[font_api] Encountered a non UTF char, not displaying text.")
return nil, ''
end
local codepoint = char_to_codepoint(text)
-- Fallback mechanism
if self.widths[codepoint] == nil then
local char = text:sub(1, bytes)
if fallbacks[char] then
return self:get_next_char(fallbacks[char]..text:sub(bytes+1))
else
return 0, text:sub(bytes+1) -- Ultimate fallback
end
else
return codepoint, text:sub(bytes+1)
end
end
--- Returns the width of a given char
-- @param char : codepoint of the char
-- @return Char width
function Font:get_char_width(char)
-- Replace chars with no texture by the NULL(0) char
if self.widths[char] ~= nil then
return self.widths[char]
else
return self.widths[0]
end
end
--- Text height for multiline text including margins and line spacing
-- @param nb_of_lines : number of text lines (default 1)
-- @return Text height
function Font:get_height(nb_of_lines)
if nb_of_lines == nil then nb_of_lines = 1 end
if nb_of_lines > 0 then
return
(
(self.height or 0) +
(self.margintop or 0) +
(self.marginbottom or 0)
) * nb_of_lines +
(self.linespacing or 0) * (nb_of_lines -1)
else
return nb_of_lines == 0 and 0 or nil
end
end
--- Computes text width for a given text (ignores new lines)
-- @param line Line of text which the width will be computed.
-- @return Text width
function Font:get_width(line)
local codepoint
local width = 0
line = line or ''
while line ~= "" do
codepoint, line = self:get_next_char(line)
width = width + self:get_char_width(codepoint)
end
return width
end
--- Builds texture part for a text line
-- @param line Text line 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:make_line_texture(line, texturew, x, y)
local codepoint
local texture = ""
line = line or ''
while line ~= '' do
codepoint, line = self:get_next_char(line)
-- Add image only if it is visible (at least partly)
if x + self.widths[codepoint] >= 0 and x <= texturew then
texture = texture..
string.format(":%d,%d=font_%s_%04x.png",
x, y, self.name, codepoint)
end
x = x + self.widths[codepoint]
end
return texture
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 halign Horizontal text align ("left"/"center"/"right") (optional)
-- @param valign Vertical text align ("top"/"center"/"bottom") (optional)
-- @param color Color of the text (optional)
-- @return Texture string
function Font:make_text_texture(text, texturew, textureh, maxlines,
halign, valign, color)
local texture = ""
local lines = {}
local textheight = 0
local y
-- Split text into lines (limited to maxlines fist lines)
for num, line in pairs(split_lines(text, maxlines)) do
lines[num] = { text = line, width = self:get_width(line) }
end
textheight = self:get_height(#lines)
if #lines then
if valign == "top" then
y = 0
elseif valign == "bottom" then
y = textureh - textheight
else
y = (textureh - textheight) / 2
end
end
y = y + (self.margintop or 0)
for _, line in pairs(lines) do
if halign == "left" then
texture = texture..
self:make_line_texture(line.text, texturew,
0, y)
elseif halign == "right" then
texture = texture..
self:make_line_texture(line.text, texturew,
texturew - line.width, y)
else
texture = texture..
self:make_line_texture(line.text, texturew,
(texturew - line.width) / 2, y)
end
y = y + self:get_height() + (self.linespacing or 0)
end
texture = string.format("[combine:%dx%d", texturew, textureh)..texture
if color then texture = texture.."^[colorize:"..color end
return texture
end