Graphics.Rendering.TrueType.STB

This is a wrapper around Sean Barrett's TrueType font rasterizer code. The original can be found at http://nothings.org/stb/stb_truetype.h. The version of stb-truetype used here is 0.2.

Documentation

data TrueType

A TrueType font file (containing maybe multiple font sets) loaded into memory.

data Offset

A font offset inside a TrueType font file.

Instances

Show Offset

data FontInfo

data Glyph

A glyph inside a font.

Instances

Show Glyph

loadTTF :: FilePath -> IO TrueType

withTTF :: FilePath -> (TrueType -> IO a) -> IO a

enumerateFonts :: TrueType -> IO [Offset]

Enumerates the fonts found in a TrueType file.

initFont :: TrueType -> Offset -> IO FontInfo

findGlyphIndex :: FontInfo -> Char -> IO (Maybe Glyph)

type Unscaled = Int

data HorizontalMetrics

Constructors

HMetrics

Fields

advanceWidth :: Unscaled

leftSideBearing :: Unscaled

Instances

Show HorizontalMetrics

data VerticalMetrics

ascent is the coordinate above the baseline the font extends; descent is the coordinate below the baseline the font extends (i.e. it is typically negative) lineGap is the spacing between one row's descent and the next row's ascent... so you should advance the vertical position by ascent - descent + lineGap

Constructors

VMetrics

Fields

ascent :: Unscaled

descent :: Unscaled

lineGap :: Unscaled

Instances

Show VerticalMetrics

data BoundingBox a

The convention is BBox (x0,y0) (x1,y1).

Constructors

BBox (a, a) (a, a)

Instances

Show a => Show (BoundingBox a)

lineAdvance :: VerticalMetrics -> Unscaled

As calculated by (ascent - descent + lineGap).

verticalSize :: VerticalMetrics -> Unscaled

As calculated by (ascent - descent).

scaleForPixelHeight :: VerticalMetrics -> Float -> Float

getFontVerticalMetrics :: FontInfo -> IO VerticalMetrics

getGlyphHorizontalMetrics :: FontInfo -> Glyph -> IO HorizontalMetrics

getGlyphKernAdvance :: FontInfo -> Glyph -> Glyph -> IO Unscaled

This is not yet implemented in stb_truetype; it always returns 0.

getGlyphBoundingBox :: FontInfo -> Glyph -> IO (BoundingBox Unscaled)

type Scaling = (Float, Float)

data Bitmap

A 8-bit grayscale bitmap.

Constructors

Bitmap

Fields

bitmapSize :: (Int, Int)

bitmapPtr :: ForeignPtr Word8

newBitmap :: (Int, Int) -> IO Bitmap

withBitmap :: Bitmap -> (Int -> Int -> Ptr Word8 -> IO a) -> IO a

type BitmapOfs = (Int, Int)

An offset (for example the pivot of the glyph)

getGlyphBitmapBox :: FontInfo -> Glyph -> Scaling -> IO (BoundingBox Int)

Returns the size of the bitmap (in pixels) needed to render the glyph with the given scaling.

The box is centered around the glyph origin; so the bitmap width is x1-x0, height is y1-y0, and location to place the bitmap top left is (leftSideBearing*scale,y0). Note that the bitmap uses y-increases-down, but the shape uses y-increases-up, so the results of getGlyphBitmapBox and getGlyphBoundingBox are inverted.

newGlyphBitmap :: FontInfo -> Glyph -> Scaling -> IO (Bitmap, BitmapOfs)

Creates a new bitmap just enough to fit the glyph with the given scaling, and renders the glyph into it. The offset returned is the offset of the glyph origin within the bitmap.

renderGlyphIntoBitmap' :: FontInfo -> Glyph -> Scaling -> Bitmap -> BitmapOfs -> IO ()

The offset is the top-left corner of the bounding box of the glyph, and must be nonnegative (otherwise nothing will happen).

renderGlyphIntoBitmap :: FontInfo -> Glyph -> Scaling -> Bitmap -> BitmapOfs -> IO ()

The offset is the origin of the glyph. If the glyph extends from the bitmap in the positive direction, it is clipped; however, if it extends in the negative direction, no drawing will happen!

bitmapArray :: Bitmap -> IO (UArray (Int, Int) Word8)

NOTE: because of the way Haskell indexes rectangular arrays, the resulting array is indexed with (y,x), as opposed to what you would expect.

bitmapFloatArray :: Bitmap -> IO (UArray (Int, Int) Float)