display_modpack/font_api/font.lua

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--[[
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/>.
--]]
-- Local functions
------------------
-- Table deep copy
local function deep_copy(input)
local output = {}
local key, value
for key, value in pairs(input) do
if type(value) == 'table' then
output[key] = deep_copy(value)
else
output[key] = value
end
end
return output
end
-- Returns next char, managing ascii and unicode plane 0 (0000-FFFF).
local function get_next_char(text, pos)
local msb = text:byte(pos)
-- 1 byte char, ascii equivalent codepoints
if msb < 0x80 then
return msb, pos + 1
end
-- 4 bytes char not managed (Only 16 bits codepoints are managed)
if msb >= 0xF0 then
return 0, pos + 4
end
-- 3 bytes char
if msb >= 0xE0 then
return (msb - 0xE0) * 0x1000
+ text:byte(pos + 1) % 0x40 * 0x40
+ text:byte(pos + 2) % 0x40,
pos + 3
end
-- 2 bytes char (little endian)
if msb >= 0xC2 then
return (msb - 0xC2) * 0x40 + text:byte(pos + 1),
pos + 2
end
-- Not an UTF char
return 0, pos + 1
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
font_api.Font = {}
function font_api.Font:new(def)
if type(def) ~= "table" then
minetest.log("error", "Font definition must be a table.")
return nil
end
if def.height == nil or def.height <= 0 then
minetest.log("error", "Font definition must have a positive height.")
return nil
end
if type(def.widths) ~= "table" then
minetest.log("error", "Font definition must have a widths array.")
return nil
end
if def.widths[0] == nil then
minetest.log("error",
"Font must have a char with codepoint 0 (=unknown char).")
return nil
end
local font = deep_copy(def)
setmetatable(font, self)
self.__index = self
return font
end
--- Returns the width of a given char
-- @param char : codepoint of the char
-- @return Char width
function font_api.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_api.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_api.Font:get_width(line)
local char
local width = 0
local pos = 1
-- TODO: Use iterator
while pos <= #line do
char, pos = get_next_char(line, pos)
width = width + self:get_char_width(char)
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_api.Font:make_line_texture(line, texturew, x, y)
local texture = ""
local char
local pos = 1
-- TODO: Use iterator
while pos <= #line do
char, pos = get_next_char(line, pos)
-- Replace chars with no texture by the NULL(0) char
if self.widths[char] == nil
then
print(string.format("["..font_api.name
.."] Missing char %d (%04x)",char,char))
char = 0
end
-- Add image only if it is visible (at least partly)
if x + self.widths[char] >= 0 and x <= texturew then
texture = texture..
string.format(":%d,%d=font_%s_%04x.png",
x, y, self.name, char)
end
x = x + self.widths[char]
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_api.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