Graphics.Text.PCF

Rendering bitmap text with pcf-font is easy. For instance, a program that renders text into a PNG is trivial:

import Codec.Picture.Png
import Codec.Picture.Types
import Data.List
import Graphics.Text.PCF
import System.Environment

-- | USAGE: program <font.pcf.gz> <output.png> <text>
main :: IO ()
main = do
    [input_file, output_file, text] <- getArgs
    pcf <- either fail return =<< loadPCF input_file
    case renderPCFText pcf text of
        Just (PCFText _ w h img) ->
            writePng output_file (Image w h img :: Image Pixel8)
        Nothing ->
            putStrLn "ERROR: Unable to render input text."

Rendering some text as an ASCII bitmap is also convenient:

import Graphics.Text.PCF
import System.Environment

-- | USAGE: program <font.pcf.gz> <text>
main :: IO ()
main = do
    [font_file, text] <- getArgs
    pcf <- either fail return =<< loadPCF font_file
    case renderPCFText pcf text of
        Just pcf_text ->
            putStrLn $ pcf_text_ascii pcf_text
        Nothing ->
            putStrLn "ERROR: Unable to render input text."

Decoding

loadPCF :: FilePath -> IO (Either String PCF)

Load a PCF font file. Both uncompressed and GZip compressed files are allowed, i.e. ".pcf" and ".pcf.gz" files.

decodePCF :: ByteString -> Either String PCF

Decode a PCF font from an in-memory ByteString. Uncompressed and GZip compressed input are allowed.

Rendering

renderPCFText

Arguments

:: PCF

Font to render with

-> String

Text to render

-> Maybe PCFText

Just width, height, and rendering; Nothing if an unrenderable character is encountered

Generate a vector of black and white pixels from a PCF font and a string.

getPCFGlyph :: PCF -> Char -> Maybe PCFGlyph

Extract a single glyph bitmap from a PCF font.

getPCFGlyphPixel

Arguments

:: PCFGlyph

-> Int

X

-> Int

Y

-> Bool

True if pixel at (x,y) is opaque; False if pixel at (x,y) is transparent or (x,y) is out of the glyph's bounds

Calculate the color of a pixel in a glyph given its (x,y) coordinates.

foldPCFGlyphPixels

Arguments

:: PCFGlyph

-> (Int -> Int -> Bool -> a -> a)

Function that takes x, y, pixel value at (x,y), and an accumulator, returning a modified accumulator

-> a

Initial accumulator

-> a

Scan over every pixel in a glyph, constructing some value in the process.

ASCII Rendering

pcf_text_ascii :: PCFText -> String

ASCII rendering of a whole PCFText string rendering.

glyph_ascii :: PCFGlyph -> String

Render glyph bitmap as a string where X represents opaque pixels and whitespace represents blank pixels.

glyph_ascii_lines :: PCFGlyph -> [String]

Render glyph bitmap as a list of strings representing lines where X represents opaque pixels and whitespace represents blank pixels.

Metadata

getPCFProps :: PCF -> [(ByteString, Either ByteString Int)]

List key-value pairs found in PCF properties table.

Types

data PCF

Container of tables extracted from a PCF font file.

data PCFGlyph

Container of a single glyph bitmap and its metadata.

Constructors

PCFGlyph

Fields

• glyph_metrics :: Metrics
• glyph_char :: Char

  Unicode character corresponding to glyph

• glyph_width :: Int

  Pixel width of glyph once rendered

• glyph_height :: Int

  Pixel height of glyph once rendered

• glyph_pitch :: Int

  Number of bytes in each bitmap row

• glyph_bitmap :: ByteString

  glyph_height rows of glyph_pitch bytes containing the glyph's bitmap image starting from the left-most bit and ending at the glyph_width bit in each row

Instances

Show PCFGlyph

Methods

showsPrec :: Int -> PCFGlyph -> ShowS

show :: PCFGlyph -> String

showList :: [PCFGlyph] -> ShowS

data PCFText

Representation of string and its corresponding bitmap content. Metadata regarding source font is not included.

Constructors

PCFText

Fields

• pcf_text_glyphs :: [PCFGlyph]

  Metadata of each glyph rendered to the image bitmap

• pcf_text_width :: Int

  Width of the rendered bitmap image

• pcf_text_height :: Int

  Height of the rendered bitmap image

• pcf_text_image :: Vector Word8

  Text rendered as a bitmap image where 0 is opaque and 255 is empty in each cell

data Metrics

Container of glyph dimension and position metrics.

Constructors

Metrics

Fields

• metrics_left_sided_bearings :: Int16
• metrics_right_sided_bearings :: Int16
• metrics_character_width :: Int16
• metrics_character_ascent :: Int16
• metrics_character_descent :: Int16
• metrics_character_attributes :: Int16

Instances

Eq Metrics

Methods

(==) :: Metrics -> Metrics -> Bool

(/=) :: Metrics -> Metrics -> Bool

Show Metrics

Methods

showsPrec :: Int -> Metrics -> ShowS

show :: Metrics -> String

showList :: [Metrics] -> ShowS