commit d037503b38d56fd6e5b1914d6841228d517b7e15 Author: Sasha Koshka Date: Fri Jul 7 01:49:32 2023 -0400 Initial commit diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..f288702 --- /dev/null +++ b/LICENSE @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. By contrast, +the GNU General Public License is intended to guarantee your freedom to +share and change all versions of a program--to make sure it remains free +software for all its users. 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If not, see . + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + Copyright (C) + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/README.md b/README.md new file mode 100644 index 0000000..50c9b14 --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +# typeset + +Typeset provides utilities for text layout, wrapping, and rendering. diff --git a/drawer.go b/drawer.go new file mode 100644 index 0000000..0b835d7 --- /dev/null +++ b/drawer.go @@ -0,0 +1,50 @@ +package textdraw + +import "image" +import "unicode" +import "image/draw" +import "image/color" +import "golang.org/x/image/math/fixed" + +// Drawer is an extended TypeSetter that is able to draw text. Much like +// TypeSetter, It has no constructor and its zero value can be used safely. +type Drawer struct { TypeSetter } + +// Draw draws the drawer's text onto the specified canvas at the given offset. +func (drawer Drawer) Draw ( + destination draw.Image, + color color.RGBA, + offset image.Point, +) ( + updatedRegion image.Rectangle, +) { + drawer.For (func ( + index int, + char rune, + position fixed.Point26_6, + ) bool { + destinationRectangle, + mask, maskPoint, _, ok := drawer.face.Glyph ( + fixed.P ( + offset.X + position.X.Round(), + offset.Y + position.Y.Round()), + char) + if !ok || unicode.IsSpace(char) || char == 0 { + return true + } + + // FIXME:? clip destination rectangle if we are on the cusp of + // the maximum height. + + draw.DrawMask ( + destination, + destinationRectangle, + image.NewUniform(color), image.Point { }, + mask, maskPoint, + draw.Over) + + updatedRegion = updatedRegion.Union(destinationRectangle) + return true + }) + return +} diff --git a/go.mod b/go.mod new file mode 100644 index 0000000..46e1392 --- /dev/null +++ b/go.mod @@ -0,0 +1,5 @@ +module git.tebibyte.media/tomo/typeset + +go 1.20 + +require golang.org/x/image v0.9.0 diff --git a/go.sum b/go.sum new file mode 100644 index 0000000..e5f4e5d --- /dev/null +++ b/go.sum @@ -0,0 +1,33 @@ +github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY= +golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w= +golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc= +golang.org/x/image v0.9.0 h1:QrzfX26snvCM20hIhBwuHI/ThTg18b/+kcKdXHvnR+g= +golang.org/x/image v0.9.0/go.mod h1:jtrku+n79PfroUbvDdeUWMAI+heR786BofxrbiSF+J0= +golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4= +golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs= +golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s= +golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg= +golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c= +golang.org/x/net v0.6.0/go.mod h1:2Tu9+aMcznHK/AK1HMvgo6xiTLG5rD5rZLDS+rp2Bjs= +golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM= +golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY= +golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs= +golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg= +golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo= +golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8= +golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k= +golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ= +golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ= +golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ= +golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8= +golang.org/x/text v0.11.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE= +golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ= +golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo= +golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc= +golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU= +golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0= diff --git a/layout.go b/layout.go new file mode 100644 index 0000000..9b847f0 --- /dev/null +++ b/layout.go @@ -0,0 +1,208 @@ +package textdraw + +import "unicode" +import "golang.org/x/image/font" +import "golang.org/x/image/math/fixed" + +// Align specifies a text alignment method. +type Align int + +const ( + // AlignLeft aligns the start of each line to the beginning point + // of each dot. + AlignLeft Align = iota + AlignRight + AlignCenter + AlignJustify +) + +// RuneLayout contains layout information for a single rune relative to its +// word. +type RuneLayout struct { + X fixed.Int26_6 + Width fixed.Int26_6 + Rune rune +} + +// WordLayout contains layout information for a single word relative to its +// line. +type WordLayout struct { + X fixed.Int26_6 + Width fixed.Int26_6 + SpaceAfter fixed.Int26_6 + Runes []RuneLayout +} + +// DoWord consumes exactly one word from the given string, and produces a word +// layout according to the given font. It returns the remaining text as well. +func DoWord (text []rune, face font.Face) (word WordLayout, remaining []rune) { + remaining = text + gettingSpace := false + x := fixed.Int26_6(0) + lastRune := rune(-1) + for _, char := range text { + // if we run into a line break, we must break out immediately + // because it is not DoWord's job to handle that. + if char == '\n' { break } + + // if we suddenly run into spaces, and then run into a word + // again, we must break out immediately. + if unicode.IsSpace(char) { + gettingSpace = true + } else if gettingSpace { + break + } + + // apply kerning + if lastRune >= 0 { x += face.Kern(lastRune, char) } + lastRune = char + + // consume and process the rune + remaining = remaining[1:] + _, advance, ok := face.GlyphBounds(char) + if !ok { continue } + word.Runes = append (word.Runes, RuneLayout { + X: x, + Width: advance, + Rune: char, + }) + + // advance + if gettingSpace { + word.SpaceAfter += advance + } else { + word.Width += advance + } + x += advance + } + return +} + +// LastRune returns the last rune in the word. +func (word WordLayout) LastRune () rune { + if word.Runes == nil { + return -1 + } else { + return word.Runes[len(word.Runes) - 1].Rune + } +} + +// FirstRune returns the last rune in the word. +func (word WordLayout) FirstRune () rune { + if word.Runes == nil { + return -1 + } else { + return word.Runes[0].Rune + } +} + +// LineLayout contains layout information for a single line. +type LineLayout struct { + Y fixed.Int26_6 + Width fixed.Int26_6 + ContentWidth fixed.Int26_6 + SpaceAfter fixed.Int26_6 + Words []WordLayout + BreakAfter bool +} + +// DoLine consumes exactly one line from the given string, and produces a line +// layout according to the given font. It returns the remaining text as well. If +// maxWidth is greater than zero, this function will stop processing words once +// the limit is crossed. The word which would have crossed over the limit will +// not be processed. +func DoLine (text []rune, face font.Face, maxWidth fixed.Int26_6) (line LineLayout, remaining []rune) { + remaining = text + x := fixed.Int26_6(0) + lastWord := WordLayout { } + isFirstWord := true + for { + // process one word + word, remainingFromWord := DoWord(remaining, face) + word.X = x + x += word.Width + + // if we have gone over the maximum width, stop processing + // words (if maxWidth is even specified) + if !isFirstWord && maxWidth > 0 && x > maxWidth { + break + } + + x += word.SpaceAfter + remaining = remainingFromWord + + // if the word actually has contents, add it + if word.Runes != nil { + lastWord = word + line.Words = append(line.Words, word) + } + + // if we have hit the end of the line, stop processing words + if len(remaining) == 0 { break } + if remaining[0] == '\n' { + line.BreakAfter = true + remaining = remaining[1:] + break + } + + isFirstWord = false + } + + // set the width of the line's content. + line.ContentWidth = lastWord.X + lastWord.Width + + // set the line's width. this is subject to be overridden by the + // TypeSetter to match the longest line. + if maxWidth > 0 { + line.Width = maxWidth + } else { + line.Width = line.ContentWidth + line.SpaceAfter = lastWord.SpaceAfter + } + return +} + +// Align aligns the text in the line according to the specified alignment +// method. +func (line *LineLayout) Align (align Align) { + if len(line.Words) == 0 { return } + + if align == AlignJustify { + line.justify() + return + } + + leftOffset := -line.Words[0].X + + if align == AlignCenter { + leftOffset += (line.Width - line.ContentWidth) / 2 + } else if align == AlignRight { + leftOffset += line.Width - line.ContentWidth + } + + for index := range line.Words { + line.Words[index].X += leftOffset + } +} + +func (line *LineLayout) justify () { + if len(line.Words) < 2 { + line.Align(AlignLeft) + return + } + + // We are going to be moving the words, so we can't take SpaceAfter into + // account. + trueContentWidth := fixed.Int26_6(0) + for _, word := range line.Words { + trueContentWidth += word.Width + } + + spaceCount := fixed.Int26_6(len(line.Words) - 1) + spacePerWord := (line.Width - trueContentWidth) / spaceCount + x := fixed.Int26_6(0) + for index, word := range line.Words { + line.Words[index].X = x + x += spacePerWord + word.Width + } +} diff --git a/setter.go b/setter.go new file mode 100644 index 0000000..8932682 --- /dev/null +++ b/setter.go @@ -0,0 +1,329 @@ +package textdraw + +import "image" +import "golang.org/x/image/font" +import "golang.org/x/image/math/fixed" + +// TypeSetter manages several lines of text, and can perform layout operations +// on them. It automatically avoids performing redundant work. It has no +// constructor and its zero value can be used safely. +type TypeSetter struct { + lines []LineLayout + text []rune + + layoutClean bool + alignClean bool + + align Align + face font.Face + maxWidth int + maxHeight int + + layoutBounds image.Rectangle + layoutBoundsSpace image.Rectangle +} + +func (setter *TypeSetter) needLayout () { + if setter.layoutClean { return } + setter.layoutClean = true + setter.alignClean = false + + // we need to have a font and some text to do anything + setter.lines = nil + setter.layoutBounds = image.Rectangle { } + setter.layoutBoundsSpace = image.Rectangle { } + if len(setter.text) == 0 { return } + if setter.face == nil { return } + + horizontalExtent := fixed.Int26_6(0) + horizontalExtentSpace := fixed.Int26_6(0) + + metrics := setter.face.Metrics() + remaining := setter.text + y := fixed.Int26_6(0) + for len(remaining) > 0 { + // process one line + line, remainingFromLine := DoLine ( + remaining, setter.face, fixed.I(setter.maxWidth)) + remaining = remainingFromLine + + // add the line + line.Y = y + y += metrics.Height + if line.Width > horizontalExtent { + horizontalExtent = line.Width + } + lineWidthSpace := line.Width + line.SpaceAfter + if lineWidthSpace > horizontalExtentSpace { + horizontalExtentSpace = lineWidthSpace + } + setter.lines = append(setter.lines, line) + } + + // set all line widths to horizontalExtent if we don't have a specified + // maximum width + if setter.maxWidth == 0 { + for index := range setter.lines { + setter.lines[index].Width = horizontalExtent + } + setter.layoutBounds.Max.X = horizontalExtent.Round() + setter.layoutBoundsSpace.Max.X = horizontalExtentSpace.Round() + } else { + setter.layoutBounds.Max.X = setter.maxWidth + setter.layoutBoundsSpace.Max.X = setter.maxWidth + } + + y -= metrics.Height + if setter.maxHeight == 0 { + setter.layoutBounds.Min.Y = -metrics.Ascent.Round() + setter.layoutBounds.Max.Y = + y.Round() + + metrics.Descent.Round() + } else { + setter.layoutBounds.Min.Y = -metrics.Ascent.Round() + setter.layoutBounds.Max.Y = + setter.maxHeight - + metrics.Ascent.Round() + } + setter.layoutBoundsSpace.Min.Y = setter.layoutBounds.Min.Y + setter.layoutBoundsSpace.Max.Y = setter.layoutBounds.Max.Y +} + +func (setter *TypeSetter) needAlignedLayout () { + if setter.alignClean && setter.layoutClean { return } + setter.needLayout() + setter.alignClean = true + + for index := range setter.lines { + align := setter.align + if index == len(setter.lines) - 1 && align == AlignJustify { + align = AlignLeft + } + setter.lines[index].Align(align) + } +} + +// SetAlign sets the alignment method of the typesetter. +func (setter *TypeSetter) SetAlign (align Align) { + if setter.align == align { return } + setter.alignClean = false + setter.align = align +} + +// SetText sets the text content of the typesetter. +func (setter *TypeSetter) SetText (text []rune) { + setter.layoutClean = false + setter.alignClean = false + setter.text = text +} + +// SetFace sets the font face of the typesetter. +func (setter *TypeSetter) SetFace (face font.Face) { + if setter.face == face { return } + setter.layoutClean = false + setter.alignClean = false + setter.face = face +} + +// SetMaxWidth sets the maximum width of the typesetter. If the maximum width +// is greater than zero, the text will wrap to that width. If the maximum width +// is zero, the text will not wrap and instead extend as far as it needs to. +func (setter *TypeSetter) SetMaxWidth (width int) { + if setter.maxWidth == width { return } + setter.layoutClean = false + setter.alignClean = false + setter.maxWidth = width +} + +// SetMaxHeight sets the maximum height of the typesetter. If the maximum height +// is greater than zero, no lines will be laid out past that point. If the +// maximum height is zero, the text's maximum height will not be constrained. +func (setter *TypeSetter) SetMaxHeight (heignt int) { + if setter.maxHeight == heignt { return } + setter.layoutClean = false + setter.alignClean = false + setter.maxHeight = heignt +} + +// Em returns the width of one emspace according to the typesetter's font, which +// is the width of the capital letter 'M'. +func (setter *TypeSetter) Em () (width fixed.Int26_6) { + if setter.face == nil { return 0 } + width, _ = setter.face.GlyphAdvance('M') + return +} + +// LineHeight returns the height of one line according to the typesetter's font. +func (setter *TypeSetter) LineHeight () fixed.Int26_6 { + if setter.face == nil { return 0 } + return setter.face.Metrics().Height +} + +// MaxWidth returns the maximum width of the typesetter as set by SetMaxWidth. +func (setter *TypeSetter) MaxWidth () int { + return setter.maxWidth +} + +// MaxHeight returns the maximum height of the typesetter as set by +// SetMaxHeight. +func (setter *TypeSetter) MaxHeight () int { + return setter.maxHeight +} + +// Face returns the TypeSetter's font face as set by SetFace. +func (setter *TypeSetter) Face () font.Face { + return setter.face +} + +// Length returns the amount of runes in the typesetter. +func (setter *TypeSetter) Length () int { + return len(setter.text) +} + +// RuneIterator is a function that can iterate accross a typesetter's runes. +type RuneIterator func ( + index int, + char rune, + position fixed.Point26_6, +) ( + keepGoing bool, +) + +// For calls the specified iterator for every rune in the typesetter. If the +// iterator returns false, the loop will immediately stop. +func (setter *TypeSetter) For (iterator RuneIterator) { + setter.needAlignedLayout() + + index := 0 + lastLineY := fixed.Int26_6(0) + lastCharRightBound := fixed.Int26_6(0) + for _, line := range setter.lines { + lastLineY = line.Y + for _, word := range line.Words { + for _, char := range word.Runes { + lastCharRightBound = word.X + char.X + char.Width + keepGoing := iterator (index, char.Rune, fixed.Point26_6 { + X: word.X + char.X, + Y: line.Y, + }) + if !keepGoing { return } + index ++ + }} + + if line.BreakAfter { + keepGoing := iterator (index, '\n', fixed.Point26_6 { + X: lastCharRightBound, + Y: line.Y, + }) + if !keepGoing { return } + index ++ + } + } + + keepGoing := iterator (index, '\000', fixed.Point26_6 { + X: lastCharRightBound, + Y: lastLineY, + }) + if !keepGoing { return } + index ++ +} + +// AtPosition returns the index of the rune at the specified position. +func (setter *TypeSetter) AtPosition (position fixed.Point26_6) (index int) { + setter.needAlignedLayout() + + if setter.lines == nil { return } + if setter.face == nil { return } + + // find the first line who's bottom bound is greater than position.Y. if + // we haven't found it, then dont set the line variable (defaults to the + // last line) + metrics := setter.face.Metrics() + line := setter.lines[len(setter.lines) - 1] + lineSize := 0 + for _, curLine := range setter.lines { + for _, curWord := range curLine.Words { + lineSize += len(curWord.Runes) + } + if curLine.BreakAfter { lineSize ++ } + index += lineSize + + if curLine.Y + metrics.Descent > position.Y { + line = curLine + break + } + } + index -= lineSize + + if line.Words == nil { return } + + // find the first rune who's right bound is greater than position.X. + for _, curWord := range line.Words { + for _, curChar := range curWord.Runes { + x := curWord.X + curChar.X + curChar.Width + if x > position.X { goto foundRune } + index ++ + } + } + foundRune: + return +} + +// PositionAt returns the position of the rune at the specified index. +func (setter *TypeSetter) PositionAt (index int) (position fixed.Point26_6) { + setter.needAlignedLayout() + + setter.For (func (i int, r rune, p fixed.Point26_6) bool { + position = p + return i < index + }) + return +} + +// LayoutBounds returns the semantic bounding box of the text. The origin point +// (0, 0) of the rectangle corresponds to the origin of the first line's +// baseline. +func (setter *TypeSetter) LayoutBounds () (image.Rectangle) { + setter.needLayout() + return setter.layoutBounds + +} + +// LayoutBoundsSpace is like LayoutBounds, but it also takes into account the +// trailing whitespace at the end of each line (if it exists). +func (setter *TypeSetter) LayoutBoundsSpace () (image.Rectangle) { + setter.needLayout() + return setter.layoutBoundsSpace +} + +// ReccomendedHeightFor returns the reccomended max height if the text were to +// have its maximum width set to the given width. This does not alter the +// typesetter's state. +func (setter *TypeSetter) ReccomendedHeightFor (width int) (height int) { + setter.needLayout() + + if setter.lines == nil { return } + if setter.face == nil { return } + + metrics := setter.face.Metrics() + dot := fixed.Point26_6 { X: 0, Y: metrics.Height } + firstWord := true + for _, line := range setter.lines { + for _, word := range line.Words { + if word.Width + dot.X > fixed.I(width) && !firstWord { + dot.Y += metrics.Height + dot.X = 0 + firstWord = true + } + dot.X += word.Width + word.SpaceAfter + firstWord = false + } + if line.BreakAfter { + dot.Y += metrics.Height + dot.X = 0 + firstWord = true + } + } + + return dot.Y.Round() +}