5.3 KiB
Font Lib API
This document describes Font Lib API. Font Lib creates textures for font display on entities.
Settings
default_font
Name of the font to be used when no font is given. The font should be registered.
If no default_font given or if default_font given but not registered, the first registered font will be used as default.
Provided methods
font_api.get_default_font_name()
Returns de default font name.
font_api.register_font(font_name, font_def)
Register a new font. font_name: Name of the font to register. If registering different sizes of the same font, add size in the font name (e.g. times_10, times_12...). font_def: Font definition table (see Font definition table below).
font_api.on_display_update(pos, objref)
Standard on_display_update entity callback.
pos: Node position
objref: Object reference of entity
Node should have a corresponding display_entity with size, resolution and maxlines fields and optionally halign, valign and color fields.
Font definition table
Font definition table used by font_api.register_font and font_api.Font:new may/can contain following elements:
- height (required): Font height in pixels (all font textures should have the same height) .
- widths (required): Array of character widths in pixels, indexed by UTF codepoints.
- margintop (optional): Margin (in texture pixels) added on top of each char texture.
- marginbottom (optional): Margin (in texture pixels) added at bottom of each char texture.
- linespacing (optional): Spacing (in texture pixels) between each lines.
margintop, marginbottom and linespacing can be negative numbers (default 0) and are to be used to adjust various font styles to each other.
Font must have a char 0 which will be used to display any unknown char.
All textures corresponding to the indexes in widths array should be present in textures directory with a name matching the pattern :
font_{font_name}_{utf_code}.png
{font_name}: Name of the font as given in the first argument
{utf_code}: UTF code of the char in 4 hexadecimal digits
Example : font_courrier_0041.png is for the "A" char in the "courrier" font.
To ease that declaration (specially to build the widths array), a shell is provided to build a {font_name}.lua file from the texture files (see provided tools).
Provided tools
Still in early stage of development, these tools are helpers to create font mods.
make_font_texture.sh
This scripts takes a .ttf file as input and create one .png file per char, that can be used as font texture. Launch it from your future font mod directory.
Advice
This script works much better with pixels font, providing the correct height. There is no antialiasing at all, vector fonts and bad heights gives very ugly results.
Syntax
make_font_texture.sh {fontfile} {fontname} {fontsize}
{fontfile}: A TTF font file to use to create textures. {fontname}: The font name to be used in font_api (should be simple, with no spaces). {fontsize}: Font height to be rendered.
make_font_lua.sh
This script analyses textures in textures directory and creates a font_{font_name}.lua files with a call to register_font with images information. Launch it from your future font mod directory.
Once the font_{font_name}.lua created, it can be included by a init.lua file or directly renamed to init.lua if you are creating a simple font mod.
Syntax
make_font_lua.sh {fontname}
{fontname}: The font name to be used in font_api (same as given to make_font_texture.sh)
An exemple generating a font mod
mkdir font_myfont
cd font_myfont
/<path_to_font_api>/tools/make_font_texture.sh myfont.ttf myfont 12
/<path_to_font_api>/tools/make_font_lua.sh myfont
mv font_myfont.lua init.lua
Font class
A font usable with font API. This class is supposed to be for internal use but who knows.
font_api.Font:new(def)
Create a new font object.
def is a table containing font definition. See Font definition table above.
font:get_char_width(char)
Returns the width of char char in texture pixels.
char: Unicode codepoint of char.
font:get_height(nb_of_lines)
Returns line(s) height. Takes care of top and bottom margins and line spacing.
nb_of_lines: Number of lines in the text.
font:get_width(line)
Returns the width of a text line. Beware, if line contains any new line char, they are ignored.
line: Line of text which the width will be computed.
font:make_line_texture(line, texturew, x, y)
Create a texture for a text line.
line: Line of text to be rendered in texture.
texturew: Width of the texture (extra text is not rendered).
x: Starting x position in texture.
y: Vertical position of the line in texture.
font:make_text_texture(text, texturew, textureh, maxlines, halign, valign, color)
Builds texture for a multiline colored text.
text: Text to be rendered.
texturew: Width of the texture (extra text will be truncated).
textureh: Height of the texture.
maxlines: Maximum number of lines.
halign: Horizontal text align ("left"/"center"/"right") (optional).
valign: Vertical text align ("top"/"center"/"bottom") (optional).
color: Color of the text (optional).