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Pierre-Yves Rollo
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font_api/API.md
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font_api/API.md
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# Font API
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This document describes Font API. Font API creates textures for font display on entities.
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## Settings
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### default_font
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Name of the font to be used when no font is given. The font should be registered.
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If no default\_font given or if default\_font given but not registered, the first registered font will be used as default.
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## Use font_api with display_api (to display text on nodes)
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### Base setup
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Font_api offers a direct integration with display_api to display text on nodes.
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First of all, create a display node with an entity.
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To do this, refer to API.md in display_api mod, in particular "Howto register a display node".
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The only requirement then is to connect the `on_display_update` callback of the display entity to `font_api.on_display_update`:
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```
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minetest.register_node("mymod:test_text_node", {
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...
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paramtype2 = "facedir",
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...
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groups = { display_api = 1, ... },
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...
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display_entities = {
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["mymod:text"] = {
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depth = -0.5 - display_api.entity_spacing,
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on_display_update = font_api.on_display_update },
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}
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...
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on_place = display_api.on_place,
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on_construct = display_api.on_construct,
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on_destruct = display_api.on_destruct,
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on_rotate = display_api.on_rotate,
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...
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})
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```
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At this step, your node already displays text form "display_text" (by default) node meta. If you want to store your text into another meta data field, add a `meta_text` field to display entity definition.
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But it uses defaults (default font, default size, default color). Likely you need something more.
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### Style your text
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Font style and size can be chosen by adding some more entries to the display_entities definition table.
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#### Font size
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Font size can be defined in various ways (maybe more in the future).
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Start with a number of lines, and font_api will make it fit to the entity size.
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* `maxlines` or `lines`: Number of maximum lines of text to be displayed. The font height will be adjusted accordingly.
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Then specify the char width. Two methods available:
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* `aspect_ratio`: Defines the aspect ratio of chars. Works with all fonts. Should not be used if `columns` is specified.
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* `columns`: Only if using a fixed width font, specifies the number of columns to display.
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#### Font style
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* `font_name`: name of the font to use. Should correspond to a registered font (from a font mod). If not specified or font not found, default font is used.
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* `color`: color to be used (default black).
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* `halign`: Horizontal alignment: "left", "center" or "right" (default "center").
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* `valign`: Vertical alignement: "top", "middle" or "bottom" (default "middle").
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### Example
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Using blue //botic// font, three lines height, aligned top left. Text stored in "text" node meta.
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```
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minetest.register_node("mymod:test_text_node", {
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...
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...
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display_entities = {
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["mymod:text"] = {
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depth = -0.5 - display_api.entity_spacing,
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on_display_update = font_api.on_display_update
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meta_text = "text",
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font_name = "botic",
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color = "#0000FF",
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maxlines = 3,
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aspect_ratio = 0.5,
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halign = "left",
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valign = "top",
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},
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}
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...
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})
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```
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## Provided methods
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### font_api.get_default_font_name()
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Returns de default font name.
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### font_api.register_font(font_name, font_def)
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Register a new font.
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* `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...).
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* `font_def`: Font definition table (see **Font definition table** below).
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### font_api.on_display_update(pos, objref)
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Standard on_display_update entity callback.
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* `pos`: Node position
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* `objref`: Object reference of entity
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Node should have a corresponding display_entity with size, resolution and maxlines fields and optionally halign, valign and color fields.
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## Font definition table
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Font definition table used by **font_api.register_font** and **font\_api.Font:new** may/can contain following elements:
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* `height` (required): Font height in pixels (all font textures should have the same height) .
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* `widths` (required): Array of character widths in pixels, indexed by UTF codepoints.
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* `margintop` (optional): Margin (in texture pixels) added on top of each char texture.
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* `marginbottom` (optional): Margin (in texture pixels) added at bottom of each char texture.
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* `linespacing` (optional): Spacing (in texture pixels) between each lines.
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`margintop`, `marginbottom` and `linespacing` can be negative numbers (default 0) and are to be used to adjust various font styles to each other.
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Font attributes around a single char:\
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Font attributes effects on several lines:\
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#### Additional requirements
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Font must have a char 0 which will be used to display any unknown char.
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All textures corresponding to the indexes in widths array should be present in textures directory with a name matching the pattern :
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> font\_**{font_name}**_**{utf_code}**.png
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**{font\_name}**: Name of the font as given in the first argument
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**{utf\_code}**: UTF code of the char in 4 hexadecimal digits
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Example : font_courrier_0041.png is for the "A" char in the "courrier" font.
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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).
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## Provided tools
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Still in early stage of development, these tools are helpers to create font mods.
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### make_font_texture.sh
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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.
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__Advice__
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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.
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__Syntax__
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**make\_font\_texture.sh {fontfile} {fontname} {fontsize}**
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**{fontfile}**: A TTF font file to use to create textures.
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**{fontname}**: The font name to be used in font_api (should be simple, with no spaces).
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**{fontsize}**: Font height to be rendered.
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### make_font_lua.sh
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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.
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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.
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__Syntax__
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**make\_font_lua.sh {fontname}**
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**{fontname}**: The font name to be used in font_api (same as given to make\_font\_texture.sh)
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### An exemple generating a font mod
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mkdir font_myfont
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cd font_myfont
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/<path_to_font_api>/tools/make_font_texture.sh myfont.ttf myfont 12
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/<path_to_font_api>/tools/make_font_lua.sh myfont
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mv font_myfont.lua init.lua
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## Font class
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A font usable with font API. This class is supposed to be for internal use but who knows.
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### font\_api.Font:new(def)
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Create a new font object.
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* `def` is a table containing font definition. See **Font definition table** above.
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### font:get_char_width(codepoint)
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Returns the width of char `codepoint` in texture pixels.
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* `codepoint`: Unicode codepoint of char.
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### font:get_height(nb_of_lines)
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Returns line(s) height. Takes care of top and bottom margins and line spacing.
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* `nb_of_lines`: Number of lines in the text.
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### font:get_width(line)
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Returns the width of a text line. Beware, if line contains any new line char, they are ignored.
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* `line`: Line of text which the width will be computed.
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### font:renter(text, texturew, textureh, style)
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Builds texture for a multiline colored text.
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* `text`: Text to be rendered.
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* `texturew`: Width of the texture (extra text will be truncated).
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* `textureh`: Height of the texture (extra text will be truncated).
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* `style`: A table with style indications:
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- `lines` or `maxlines`: Maximum number of lines (default none).
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- `halign`: Horizontal text align: "left"/"center"/"right" (default "center")
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- `valign`: Vertical text align: "top"/"middle"/"bottom" (default "middle")
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- `color`: Color of the text (default black)
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