Package 'lofifonts'

Create a data.frame of pixel coordinate information of the rendered text

Description

Create a data.frame of pixel coordinate information of the rendered text

Usage

bitmap_text_coords(text, font = "unifont", dx = 0L, dy = 0L, missing = NULL)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of bitmap font, or a 'lofi' font object. Default: 'unifont'. Use get_lofi_names('bitmap') to retrieve a list of all valid bitmap fonts included in this package. To create a 'lofi' font object use convert_bm_font_to_lofi()
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

data.frame of coordinate information

char_idx

The index of the glyph within the provided text string

codepoint

Unicode codepoint (integer)

x

Pixel coordinate x value for display

y

Pixel coordinate y value for display

line

Line number within input text where this character appears

x0

Original untransformed x-coordinate

y0

Original untransformed y-coordinate

See Also

Other bitmap text functions: bitmap_text_matrix(), bitmap_text_raster()

Examples

bitmap_text_coords('Hi')

---

Create a binary matrix of the rendered text

Description

Create a binary matrix of the rendered text

Usage

bitmap_text_matrix(
  text,
  font = "unifont",
  dx = 0L,
  dy = 0L,
  scale_matrix = 1,
  missing = NULL
)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of bitmap font, or a 'lofi' font object. Default: 'unifont'. Use get_lofi_names('bitmap') to retrieve a list of all valid bitmap fonts included in this package. To create a 'lofi' font object use convert_bm_font_to_lofi()
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
scale_matrix	Integer size scale factor. Default: 1. Must be an integer value >= 1. Scale up the matrix or raster result by this factor
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

Binary matrix representation of the rendered text

See Also

Other bitmap text functions: bitmap_text_coords(), bitmap_text_raster()

Examples

bitmap_text_matrix('Hi')

---

Create a raster image of the rendered text

Description

Create a raster image of the rendered text

Usage

bitmap_text_raster(
  text,
  font = "unifont",
  dx = 0L,
  dy = 0L,
  scale_matrix = 1,
  missing = NULL
)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of bitmap font, or a 'lofi' font object. Default: 'unifont'. Use get_lofi_names('bitmap') to retrieve a list of all valid bitmap fonts included in this package. To create a 'lofi' font object use convert_bm_font_to_lofi()
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
scale_matrix	Integer size scale factor. Default: 1. Must be an integer value >= 1. Scale up the matrix or raster result by this factor
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

Raster image representation of the rendered text

See Also

Other bitmap text functions: bitmap_text_coords(), bitmap_text_matrix()

Examples

ras <- bitmap_text_raster('Hi')
plot(ras)

---

Convert a 'bittermelon' 'bm_font' to a lofi font

Description

Convert a 'bittermelon' 'bm_font' to a lofi font

Usage

convert_bm_font_to_lofi(font, font_name = "Unknown")

Arguments

font	font object of class bm_font
font_name	Name of font

Value

lofi font object

Examples

filename <- system.file("fonts/spleen/spleen-8x16.hex.gz", package = "bittermelon")
bmfont <- bittermelon::read_hex(filename)
lofi <- convert_bm_font_to_lofi(bmfont)
lofi

---

Fetch an included 'lofi' font

Description

Fetch an included 'lofi' font

Usage

get_lofi_font(font_name)

Arguments

font_name

Name of font e.g. 'unifont'

Value

'lofi' font object. See lofi for details of this data structure

Examples

get_lofi_font('unifont')

---

Return the names of all included fonts

Description

Return the names of all included fonts

Usage

get_lofi_names(type)

Arguments

type	font type. Either 'bitmap', 'vector' or 'all'

Value

List of two elements: names of bitmap fonts, names of vector fonts

Examples

get_lofi_names('bitmap')

---

A description of the 'lofi' font format used to store fonts for this package

Description

This package uses a custom data structure to store font information. This data structure is optimized for access to random sequences of glyphs which can be quickly assembled into a data.frame of points (for bitmap fonts) or strokes (for vector fonts). This data structure also needs to be compact and avoid unnecessary repetition. This is because the 'unifont' font contains pixel coordinates for over 100,000 codepoints and all this data must not exceed package size limitations for CRAN.

Details

Each 'lofi' font is a list object with the following members:

coords

A data frame of 'x', 'y' coordinates. For vector fonts this also includes a 'stroke_idx' to delineate the individual strokes within a single glyph. This is a simple concatenation of all points (or strokes) in a font. Extracting this font data for a particular codepoint requires the use of other indexing elements in the 'lofi' structure. NOTE: For bitmap fonts, (x, y) coordinates must be numeric, integer or raw values with no values below zero.

codepoint_to_idx

An integer vector. Use a codepoint (integer) to access the row index into the 'glyph_info' data.frame which holds the meta-information about this glyph. Because codepoints are indexed from 0, but R indexes vectors from 1, to access the row index: codepoint_to_idx[codepoint + 1]

line_height

Integer. The line height of this font in pixels

default_codepoing

Integer. The default unicode codepoint to use if the font does not contain a given glyph

baseline_offset

Numeric value. The offset between the bottom of the font data and the baseline for the text

name

name of font

glyph_info

A data.frame of meta-information about each glyph. One row per glyph

codepoint

Glyph codepoint (integer value)

npoints

The number of rows of data in 'coords' data.frame which are used to define this font

row_start

The index of the first row in 'coords' data.frame which contains data for this font

row_end

The index of the last row in 'coords' data.frame which contains data for this font

width

Glyph width (in pixels)

Usage

This section describes the process of extracting the data for a single glyph

1. Convert the glyph to an integer codepoint using codepoint <- utf8ToInt(x)

2. Use row <- codepoint_to_idx[codepoint + 1] to determine the row index of glyph_info which contains information for this codepoint.

3. if row is NA this indicates that the font does not support the glyph, and the row corresponding to default_codepoint should be used instead

4. info <- glyph_info[row, ]

5. Subset coords data.frame for the coordinates associated with this glyph: coords[info$row_start:info$row_end, ]

Examples

lifo <- get_lofi_font('unifont')
x <- 'a'
codepoint <- utf8ToInt(x)
row <- lifo$codepoint_to_idx[codepoint + 1]
info <- lifo$glyph_info[row,]
coords <- lifo$coords[seq(info$row_start, info$row_end), ]
coords
plot(coords$x, coords$y, asp = 1, ann = FALSE, axes = FALSE)

# Regular users should just use the functions provided in this package which
# add extra font information and layout sequences of characters 
# over multiple lines
bitmap_text_coords('a', 'unifont')
bitmap_text_raster('a', 'unifont') |> plot()

---

Plot a lofi raster

Description

Plot a lofi raster

Usage

## S3 method for class ''lofi-raster''
plot(x, interpolate = FALSE, ...)

Arguments

x	lofi raster rendering
interpolate	default: FALSE
...	extra arguments passed to plot()

Value

None

Examples

ras <- bitmap_text_raster("Hi")
plot(ras)

---

Print summary information about a lofi font

Description

Print summary information about a lofi font

Usage

## S3 method for class 'lofi'
print(x, ...)

Arguments

x	lofi font object
...	other arguments ignored

Value

None

Examples

font <- get_lofi_font('unscii-8')
print(font)

---

Create data.frame of glyph information for the given text.

Description

Text input can contain multiple lines separated by carriage returns

Usage

vector_text_coords(
  text,
  font = c("gridfont_smooth", "gridfont", "arcade"),
  dx = 0L,
  dy = 0L,
  missing = utf8ToInt("?")
)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of vector font, or a vector 'lofi' font object. Default: 'gridfont_smooth'. Use get_lofi_names('vector') to retrieve a list of all valid vector fonts included in this package.
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

data.frame of stroke information

char_idx

The index of the character within the provided text string

codepoint

Unicode codepoint (integer)

stroke_idx

Index of the stroke within each character

x

Pixel coordinate x value for display

y

Pixel coordinate y value for display

line

Line number within input text where this character appears

x0

Original untransformed x-coordinate

y0

Original untransformed y-coordinate

See Also

Other vector text functions: vector_text_matrix(), vector_text_raster()

Examples

vector_text_coords('Hi')

---

Create a binary matrix of the rendered text

Description

Create a binary matrix of the rendered text

Usage

vector_text_matrix(
  text,
  font = c("gridfont_smooth", "gridfont", "arcade"),
  scale_coords = 1,
  scale_matrix = 1,
  dx = NULL,
  dy = NULL,
  missing = utf8ToInt("?")
)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of vector font, or a vector 'lofi' font object. Default: 'gridfont_smooth'. Use get_lofi_names('vector') to retrieve a list of all valid vector fonts included in this package.
scale_coords	Scale factor for text rendering. Numeric value greater than zero. Default: 1
scale_matrix	Integer size scale factor. Default: 1. Must be an integer value >= 1. Scale up the matrix or raster result by this factor after rendering the coordinates.
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

Binary matrix rendering of the font

See Also

Other vector text functions: vector_text_coords(), vector_text_raster()

Examples

vector_text_matrix("Hi")

---

Create a raster image of the rendered text

Description

Create a raster image of the rendered text

Usage

vector_text_raster(
  text,
  font = c("gridfont_smooth", "gridfont", "arcade"),
  scale_coords = 10,
  scale_matrix = 1,
  dx = NULL,
  dy = NULL,
  missing = utf8ToInt("?")
)

Arguments

text	Single text string. Can include carriage returns to split text over multiple lines.
font	Name of vector font, or a vector 'lofi' font object. Default: 'gridfont_smooth'. Use get_lofi_names('vector') to retrieve a list of all valid vector fonts included in this package.
scale_coords	Scale factor for text rendering. Numeric value greater than zero. Default: 1
scale_matrix	Integer size scale factor. Default: 1. Must be an integer value >= 1. Scale up the matrix or raster result by this factor after rendering the coordinates.
dx	Additional character spacing in the horizontal direction. Default: 0
dy	Additional character spacing in the vertical direction i.e. between rows of text. Default: 0
missing	Codepoint to use if glyph not found in font. Default: NULL means to use the default specified by the font internally. Otherwise it will default to the codepoint for '?'

Value

Raster image of rendered text

See Also

Other vector text functions: vector_text_coords(), vector_text_matrix()

Examples

ras <- vector_text_raster("Hi")
plot(ras)

---