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Diffstat (limited to 'Godeps/_workspace/src/golang.org/x/image/font/font.go')
| -rw-r--r-- | Godeps/_workspace/src/golang.org/x/image/font/font.go | 202 |
1 files changed, 0 insertions, 202 deletions
diff --git a/Godeps/_workspace/src/golang.org/x/image/font/font.go b/Godeps/_workspace/src/golang.org/x/image/font/font.go deleted file mode 100644 index de8802fcc..000000000 --- a/Godeps/_workspace/src/golang.org/x/image/font/font.go +++ /dev/null @@ -1,202 +0,0 @@ -// Copyright 2015 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// Package font defines an interface for font faces, for drawing text on an -// image. -// -// Other packages provide font face implementations. For example, a truetype -// package would provide one based on .ttf font files. -package font - -import ( - "image" - "image/draw" - "io" - - "golang.org/x/image/math/fixed" -) - -// TODO: who is responsible for caches (glyph images, glyph indices, kerns)? -// The Drawer or the Face? - -// Face is a font face. Its glyphs are often derived from a font file, such as -// "Comic_Sans_MS.ttf", but a face has a specific size, style, weight and -// hinting. For example, the 12pt and 18pt versions of Comic Sans are two -// different faces, even if derived from the same font file. -// -// A Face is not safe for concurrent use by multiple goroutines, as its methods -// may re-use implementation-specific caches and mask image buffers. -// -// To create a Face, look to other packages that implement specific font file -// formats. -type Face interface { - io.Closer - - // Glyph returns the draw.DrawMask parameters (dr, mask, maskp) to draw r's - // glyph at the sub-pixel destination location dot, and that glyph's - // advance width. - // - // It returns !ok if the face does not contain a glyph for r. - // - // The contents of the mask image returned by one Glyph call may change - // after the next Glyph call. Callers that want to cache the mask must make - // a copy. - Glyph(dot fixed.Point26_6, r rune) ( - dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) - - // GlyphBounds returns the bounding box of r's glyph, drawn at a dot equal - // to the origin, and that glyph's advance width. - // - // It returns !ok if the face does not contain a glyph for r. - // - // The glyph's ascent and descent equal -bounds.Min.Y and +bounds.Max.Y. A - // visual depiction of what these metrics are is at - // https://developer.apple.com/library/mac/documentation/TextFonts/Conceptual/CocoaTextArchitecture/Art/glyph_metrics_2x.png - GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) - - // GlyphAdvance returns the advance width of r's glyph. - // - // It returns !ok if the face does not contain a glyph for r. - GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) - - // Kern returns the horizontal adjustment for the kerning pair (r0, r1). A - // positive kern means to move the glyphs further apart. - Kern(r0, r1 rune) fixed.Int26_6 - - // TODO: per-font Metrics. - // TODO: ColoredGlyph for various emoji? - // TODO: Ligatures? Shaping? -} - -// TODO: Drawer.Layout or Drawer.Measure methods to measure text without -// drawing? - -// Drawer draws text on a destination image. -// -// A Drawer is not safe for concurrent use by multiple goroutines, since its -// Face is not. -type Drawer struct { - // Dst is the destination image. - Dst draw.Image - // Src is the source image. - Src image.Image - // Face provides the glyph mask images. - Face Face - // Dot is the baseline location to draw the next glyph. The majority of the - // affected pixels will be above and to the right of the dot, but some may - // be below or to the left. For example, drawing a 'j' in an italic face - // may affect pixels below and to the left of the dot. - Dot fixed.Point26_6 - - // TODO: Clip image.Image? - // TODO: SrcP image.Point for Src images other than *image.Uniform? How - // does it get updated during DrawString? -} - -// TODO: should DrawString return the last rune drawn, so the next DrawString -// call can kern beforehand? Or should that be the responsibility of the caller -// if they really want to do that, since they have to explicitly shift d.Dot -// anyway? -// -// In general, we'd have a DrawBytes([]byte) and DrawRuneReader(io.RuneReader) -// and the last case can't assume that you can rewind the stream. -// -// TODO: how does this work with line breaking: drawing text up until a -// vertical line? Should DrawString return the number of runes drawn? - -// DrawString draws s at the dot and advances the dot's location. -func (d *Drawer) DrawString(s string) { - var prevC rune - for i, c := range s { - if i != 0 { - d.Dot.X += d.Face.Kern(prevC, c) - } - dr, mask, maskp, advance, ok := d.Face.Glyph(d.Dot, c) - if !ok { - // TODO: is falling back on the U+FFFD glyph the responsibility of - // the Drawer or the Face? - // TODO: set prevC = '\ufffd'? - continue - } - draw.DrawMask(d.Dst, dr, d.Src, image.Point{}, mask, maskp, draw.Over) - d.Dot.X += advance - prevC = c - } -} - -// MeasureString returns how far dot would advance by drawing s. -func (d *Drawer) MeasureString(s string) (advance fixed.Int26_6) { - var prevC rune - for i, c := range s { - if i != 0 { - advance += d.Face.Kern(prevC, c) - } - a, ok := d.Face.GlyphAdvance(c) - if !ok { - // TODO: is falling back on the U+FFFD glyph the responsibility of - // the Drawer or the Face? - // TODO: set prevC = '\ufffd'? - continue - } - advance += a - prevC = c - } - return advance -} - -// Hinting selects how to quantize a vector font's glyph nodes. -// -// Not all fonts support hinting. -type Hinting int - -const ( - HintingNone Hinting = iota - HintingVertical - HintingFull -) - -// Stretch selects a normal, condensed, or expanded face. -// -// Not all fonts support stretches. -type Stretch int - -const ( - StretchUltraCondensed Stretch = -4 - StretchExtraCondensed Stretch = -3 - StretchCondensed Stretch = -2 - StretchSemiCondensed Stretch = -1 - StretchNormal Stretch = +0 - StretchSemiExpanded Stretch = +1 - StretchExpanded Stretch = +2 - StretchExtraExpanded Stretch = +3 - StretchUltraExpanded Stretch = +4 -) - -// Style selects a normal, italic, or oblique face. -// -// Not all fonts support styles. -type Style int - -const ( - StyleNormal Style = iota - StyleItalic - StyleOblique -) - -// Weight selects a normal, light or bold face. -// -// Not all fonts support weights. -type Weight int - -const ( - WeightThin Weight = 100 - WeightExtraLight Weight = 200 - WeightLight Weight = 300 - WeightNormal Weight = 400 - WeightMedium Weight = 500 - WeightSemiBold Weight = 600 - WeightBold Weight = 700 - WeightExtraBold Weight = 800 - WeightBlack Weight = 900 -) |