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display_modpack/font_api/font.lua
2018-12-11 12:01:16 +01:00

275 lines
7.1 KiB
Lua

--[[
font_api mod for Minetest - Library creating textures with fonts and text
(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 and str:byte(2) ~= nil then
return (str:byte(1) - 0xC2) * 0x40
+ str:byte(2)
elseif bytes == 3 and str:byte(2) ~= nil and str:byte(3) ~= nil then
return (str:byte(1) - 0xE0) * 0x1000
+ str:byte(2) % 0x40 * 0x40
+ str:byte(3) % 0x40
elseif bytes == 4 and str:byte(2) ~= nil and str:byte(3) ~= nil
and str:byte(4) ~= nil 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
--------------------------------------------------------------------------------
--- 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
-- Check if fixedwidth
for codepoint, width in pairs(font.widths) do
font.fixedwidth = font.fixedwidth or width
if width ~= font.fixedwidth then
font.fixedwidth = nil
break
end
end
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)
if codepoint == nil then
minetest.log("warning",
"[font_api] Encountered a non UTF char, not displaying text.")
return nil, ''
end
-- 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(codepoint)
if self.fixedwidth then
return self.fixedwidth
elseif self.widths[codepoint] then
return self.widths[codepoint]
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)
if codepoint == nil then return 0 end -- UTF Error
width = width + self:get_char_width(codepoint)
end
return width
end
--- Legacy make_text_texture method (replaced by "render" - Dec 2018)
function Font:make_text_texture(text, texturew, textureh, maxlines,
halign, valign, color)
return self:render(text, texturew, textureh, {
lines = maxlines,
valign = valign,
halign = halign,
color = color
})
end
--- Render text with the font in a view
-- @param text Text to be rendered
-- @param texturew Width (in pixels) of the texture (extra text will be truncated)
-- @param textureh Height (in pixels) of the texture (extra text will be truncated)
-- @param style Style of the rendering:
-- - lines: maximum number of text lines (if text is limited)
-- - halign: horizontal align ("left"/"center"/"right")
-- - valign: vertical align ("top"/"center"/"bottom")
-- - color: color of the text ("#rrggbb")
-- @return Texture string
function Font:render(text, texturew, textureh, style)
local style = style or {}
-- Split text into lines (and limit to style.lines # of lines)
local lines = {}
local pos = 1
local found, line
repeat
found = string.find(text, "\n", pos) or (#text + 1)
line = string.sub(text, pos, found - 1)
lines[#lines + 1] = { text = line, width = self:get_width(line) }
pos = found + 1
until (style.lines and (#lines >= style.lines)) or (pos > (#text + 1))
if not #lines then
return ""
end
local x, y, codepoint
local texture = ""
local textheight = self:get_height(#lines)
if style.valign == "top" then
y = 0
elseif style.valign == "bottom" then
y = textureh - textheight
else
y = (textureh - textheight) / 2
end
y = y + (self.margintop or 0)
for _, line in pairs(lines) do
if style.halign == "left" then
x = 0
elseif style.halign == "right" then
x = texturew - line.width
else
x = (texturew - line.width) / 2
end
while line.text ~= '' do
codepoint, line.text = self:get_next_char(line.text)
if codepoint == nil then return '' end -- UTF Error
-- 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
y = y + self:get_height() + (self.linespacing or 0)
end
texture = string.format("[combine:%dx%d", texturew, textureh)..texture
if style.color then
texture = texture.."^[colorize:"..style.color
end
return texture
end