Update backend

application.go

@@ -8,7 +8,6 @@ import "strings"
 import "net/url"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/objects"
-import "git.tebibyte.media/tomo/tomo/canvas"
 import "git.tebibyte.media/tomo/nasin/internal/registrar"
 
 // Application represents an application object.
@@ -66,6 +65,15 @@ type ApplicationDescription struct {
 	Role ApplicationRole
 }
 
+// GlobalApplicationDescription returns the global application description which
+// points to cache, data, config, etc. used by Nasin itself.
+func GlobalApplicationDescription () ApplicationDescription {
+	return ApplicationDescription {
+		Name: "Nasin",
+		ID:   "xyz.holanet.Nasin",
+	}
+}
+
 // String satisfies the fmt.Stringer interface.
 func (application ApplicationDescription) String () string {
 	if application.Name == "" {
@@ -120,8 +128,9 @@ func (role ApplicationRole) Icon () tomo.Icon {
 	}
 }
 
-// RunApplication is like tomo.Run, but runs an application. If something fails
-// to initialize, an error is written to the standard logger.
+// RunApplication is like tomo.Run, but runs an application. It automatically
+// sets up a backend. If something fails to initialize, an error is written to
+// the standard logger.
 func RunApplication (application Application) {
 	// TODO: see #4
 
@@ -130,18 +139,22 @@ func RunApplication (application Application) {
 	}
 	flag.Parse()
 
-	err := registrar.RegisterBackend()
+	reg := new(registrar.Registrar)
+	backend, err := reg.SetBackend()
 	if err != nil { log.Fatalln("nasin: could not register backend:", err) }
-	err = tomo.Run(func () {
-		err := registrar.SetTheme()
-		if err != nil { log.Fatalln("nasin: could not set theme:", err) }
-		err = application.Init()
-		if err != nil { log.Fatalln("nasin: could not run application:", err) }
+	err = reg.SetTheme()
+	if err != nil { log.Fatalln("nasin: could not set theme:", err) }
+	err = reg.SetIconSet()
+	if err != nil { log.Fatalln("nasin: could not set icon set:", err) }
+	err = reg.SetFaceSet()
+	if err != nil { log.Fatalln("nasin: could not set face set:", err) }
+	err = application.Init()
+	if err != nil { log.Fatalln("nasin: could not run application:", err) }
 
-		// open URLs
-		args := flag.Args()
-		applicationOpenUrls(application, args...)
-	})
+	// open URLs
+	args := flag.Args()
+	applicationOpenUrls(application, args...)
+	err = backend.Run()
 	if err != nil { log.Fatalln("nasin: could not run application:", err) }
 }
 
@@ -202,22 +215,16 @@ func applicationOpenUrls (application Application, args ...string) {
 }
 
 func setApplicationWindowIcon (window tomo.Window, description ApplicationDescription) {
-	allSizes := func (icon tomo.Icon) (sizes []canvas.Texture) {
-		small  := icon.Texture(tomo.IconSizeSmall)
-		medium := icon.Texture(tomo.IconSizeMedium)
-		large  := icon.Texture(tomo.IconSizeLarge)
-		if small  != nil { sizes = append(sizes,  small) }
-		if medium != nil { sizes = append(sizes, medium) }
-		if large  != nil { sizes = append(sizes,  large) }
-		return sizes
+	iconExists := func (icon tomo.Icon) bool {
+		return icon.Texture(tomo.IconSizeMedium) != nil
 	}
 
-	if sizes := allSizes(tomo.Icon(description.ID)); len(sizes) > 0 {
-		window.SetIcon(sizes...)
+	if iconExists(tomo.Icon(description.ID)) {
+		window.SetIcon(tomo.Icon(description.ID))
 		return
 	}
-	if sizes := allSizes(description.Role.Icon()); len(sizes) > 0 {
-		window.SetIcon(sizes...)
+	if iconExists(description.Role.Icon()) {
+		window.SetIcon(description.Role.Icon())
 		return
 	}
 }

go.mod

@@ -1,11 +1,12 @@
 module git.tebibyte.media/tomo/nasin
 
-go 1.20
+go 1.22.2
 
 require (
-	git.tebibyte.media/tomo/backend v0.5.0
-	git.tebibyte.media/tomo/objects v0.20.0
-	git.tebibyte.media/tomo/tomo v0.41.0
+	git.tebibyte.media/sashakoshka/goparse v0.2.0
+	git.tebibyte.media/tomo/backend v0.6.1
+	git.tebibyte.media/tomo/objects v0.21.0
+	git.tebibyte.media/tomo/tomo v0.45.0
 	git.tebibyte.media/tomo/xdg v0.1.0
 	golang.org/x/image v0.11.0
 )

go.sum

@@ -1,10 +1,12 @@
+git.tebibyte.media/sashakoshka/goparse v0.2.0 h1:uQmKvOCV2AOlCHEDjg9uclZCXQZzq2PxaXfZ1aIMiQI=
+git.tebibyte.media/sashakoshka/goparse v0.2.0/go.mod h1:tSQwfuD+EujRoKr6Y1oaRy74ZynatzkRLxjE3sbpCmk=
 git.tebibyte.media/sashakoshka/xgbkb v1.0.0/go.mod h1:pNcE6TRO93vHd6q42SdwLSTTj25L0Yzggz7yLe0JV6Q=
-git.tebibyte.media/tomo/backend v0.5.0 h1:Byrz1yjhYKnMXljIHgEdwW5/41gWtRm3xHYZ18lBUbg=
-git.tebibyte.media/tomo/backend v0.5.0/go.mod h1:1Ne0h4nsRYy8GudBia7um+qaqzME0wDrOAjpHvySqRA=
-git.tebibyte.media/tomo/objects v0.20.0 h1:HK6aWxBfRe0sgqvfIZnvfW0c8jSYP7F5Od/rWvi5DAM=
-git.tebibyte.media/tomo/objects v0.20.0/go.mod h1:DNTKSU9u126XF4usZG0ax9b20So4UpBZ+wAwRiA7XOQ=
-git.tebibyte.media/tomo/tomo v0.41.0 h1:Z+7FHhbGiKjs+kQNvuJOfz47xIct5qxvSJqyDuoNIOs=
-git.tebibyte.media/tomo/tomo v0.41.0/go.mod h1:C9EzepS9wjkTJjnZaPBh22YvVPyA4hbBAJVU20Rdmps=
+git.tebibyte.media/tomo/backend v0.6.1 h1:TVbvfbcMrF8YAVGsXPQNQLCam3xuOWJmZA0B+op0ig0=
+git.tebibyte.media/tomo/backend v0.6.1/go.mod h1:7gl0Z1V8Vcns41pXIpQt1FYlANrQf5bCboxMjTCCrgc=
+git.tebibyte.media/tomo/objects v0.21.0 h1:exFbzQPQhGIVQK5BCDg69ZV96zMamV50G4GRsnK+yfA=
+git.tebibyte.media/tomo/objects v0.21.0/go.mod h1:ljnNcCuNfvcYLHmQrEU7LuG0OvQiAVDCXU+ajspq+TI=
+git.tebibyte.media/tomo/tomo v0.45.0 h1:fQH0WIPidW275hOq9dE6R7p064xG1RGx2QU68Avlr84=
+git.tebibyte.media/tomo/tomo v0.45.0/go.mod h1:WrtilgKB1y8O2Yu7X4mYcRiqOlPR8NuUnoA/ynkQWrs=
 git.tebibyte.media/tomo/typeset v0.7.1 h1:aZrsHwCG5ZB4f5CruRFsxLv5ezJUCFUFsQJJso2sXQ8=
 git.tebibyte.media/tomo/typeset v0.7.1/go.mod h1:PwDpSdBF3l/EzoIsa2ME7QffVVajnTHZN6l3MHEGe1g=
 git.tebibyte.media/tomo/xdg v0.1.0 h1:6G2WYPPiM2IXleCpKKHuJA34BxumwNWuLsUoX3yu5zA=

internal/faces/fallback/face.go

@@ -0,0 +1,35 @@
+package fallbackFaces
+
+import "golang.org/x/image/font"
+import "git.tebibyte.media/tomo/tomo"
+import "golang.org/x/image/font/basicfont"
+import "git.tebibyte.media/tomo/backend/style"
+
+type faceSet struct {
+	regular    font.Face
+	bold       font.Face
+	italic     font.Face
+	boldItalic font.Face
+}
+
+// New creates a new fallback face set.
+func New () style.FaceSet {
+	// TODO maybe pre-generate different variations of this face
+	return &faceSet {
+		regular:    basicfont.Face7x13,
+		bold:       basicfont.Face7x13,
+		italic:     basicfont.Face7x13,
+		boldItalic: basicfont.Face7x13,
+	}
+}
+
+func (this *faceSet) Face (face tomo.Face) font.Face {
+	bold   := face.Weight >= 500
+	italic := face.Italic >= 0.1 || face.Slant >= 0.1
+	switch {
+	case bold && italic: return this.boldItalic
+	case bold:           return this.bold
+	case italic:         return this.italic
+	default:             return this.regular
+	}
+}

internal/icons/fallback/icon.go

@@ -7,6 +7,7 @@ import _ "image/png"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
 
 //go:embed assets/icons-small.png
 var atlasSmallBytes []byte
@@ -411,23 +412,23 @@ func generateSource (data []byte, width int) map[tomo.Icon] canvas.Texture {
 	return source
 }
 
-type iconTheme struct {
+type iconSet struct {
 	texturesSmall map[tomo.Icon] canvas.Texture
 	texturesLarge map[tomo.Icon] canvas.Texture
 }
 
-// New creates a new fallback icon theme.
-func New () tomo.IconSet {
-	return new(iconTheme)
+// New creates a new fallback icon set.
+func New () style.IconSet {
+	return new(iconSet)
 }
 
-func (this *iconTheme) ensure () {
+func (this *iconSet) ensure () {
 	if this.texturesSmall != nil { return }
 	this.texturesSmall = generateSource(atlasSmallBytes, 16)
 	this.texturesLarge = generateSource(atlasLargeBytes, 32)
 }
 
-func (this *iconTheme) selectSource (size tomo.IconSize) map[tomo.Icon] canvas.Texture {
+func (this *iconSet) selectSource (size tomo.IconSize) map[tomo.Icon] canvas.Texture {
 	if size == tomo.IconSizeSmall {
 		return this.texturesSmall
 	} else {
@@ -435,7 +436,7 @@ func (this *iconTheme) selectSource (size tomo.IconSize) map[tomo.Icon] canvas.T
 	}
 }
 
-func (this *iconTheme) Icon (icon tomo.Icon, size tomo.IconSize) canvas.Texture {
+func (this *iconSet) Icon (icon tomo.Icon, size tomo.IconSize) canvas.Texture {
 	this.ensure()
 	source := this.selectSource(size)
 	if texture, ok := source[icon]; ok {
@@ -444,7 +445,7 @@ func (this *iconTheme) Icon (icon tomo.Icon, size tomo.IconSize) canvas.Texture
 	return nil
 }
 
-func (this *iconTheme) MimeIcon (mime data.Mime, size tomo.IconSize) canvas.Texture {
+func (this *iconSet) MimeIcon (mime data.Mime, size tomo.IconSize) canvas.Texture {
 	this.ensure()
 	source := this.selectSource(size)
 	if mime == data.M("inode", "directory") {

internal/icons/xdg/icon.go

@@ -8,19 +8,20 @@ import "regexp"
 import "strings"
 import _ "image/png"
 import "git.tebibyte.media/tomo/tomo"
-import xdgIconTheme "git.tebibyte.media/tomo/xdg/icon-theme"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
+import xdgIconTheme "git.tebibyte.media/tomo/xdg/icon-theme"
 
 type iconTheme struct {
 	xdg xdgIconTheme.Theme
-	fallback       tomo.IconSet
+	fallback       style.IconSet
 	texturesSmall  map[tomo.Icon] canvas.Texture
 	texturesMedium map[tomo.Icon] canvas.Texture
 	texturesLarge  map[tomo.Icon] canvas.Texture
 }
 
-func FindThemeWarn (name string, fallback tomo.IconSet, path ...string) (tomo.IconSet, error) {
+func FindThemeWarn (name string, fallback style.IconSet, path ...string) (style.IconSet, error) {
 	this := &iconTheme {
 		fallback:       fallback,
 		texturesLarge:  make(map[tomo.Icon] canvas.Texture),

internal/registrar/registrar_unix.go

@@ -5,39 +5,64 @@ import "os"
 import "log"
 import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/backend/x"
+import "git.tebibyte.media/sashakoshka/goparse"
 import "git.tebibyte.media/tomo/nasin/internal/icons/xdg"
+import "git.tebibyte.media/tomo/nasin/internal/styles/tss"
 import "git.tebibyte.media/tomo/nasin/internal/icons/fallback"
-import "git.tebibyte.media/tomo/nasin/internal/style/fallback"
-// import "git.tebibyte.media/tomo/nasin/internal/style/aluminum"
+import "git.tebibyte.media/tomo/nasin/internal/styles/fallback"
+import "git.tebibyte.media/tomo/nasin/internal/faces/fallback"
 
-func RegisterBackend () error {
-	tomo.Register(1, x.New)
-	return nil
+type Registrar struct {
+	backend *x.Backend
 }
 
-func SetTheme () error {
-	var styl *tomo.Style
-	// TODO eventually get rid of this when we make a file format for
-	// storing visual styles
-	// TODO migrate aluminum
-	// if os.Getenv("TOMO_USE_ALUMINUM_STYLE") != "" {
-		// styl = aluminumStyle.New()
-	// } else {
-		styl = fallbackStyle.New()
-	// }
-	icons := fallbackIcons.New()
-	
-	iconThemeName := os.Getenv("TOMO_XDG_ICON_THEME")
-	if iconThemeName != "" {
-		xdgIconTheme, err := xdgIcons.FindThemeWarn(iconThemeName, icons)
+func (this *Registrar) SetBackend () (tomo.Backend, error) {
+	backend, err := x.New()
+	if err != nil { return nil, err }
+	this.backend = backend.(*x.Backend)
+	tomo.SetBackend(backend)
+	return backend, nil
+}
+
+func (this *Registrar) SetTheme () error {
+	styleSheetName := os.Getenv("TOMO_STYLE_SHEET")
+	if styleSheetName != "" {
+		styl, _, err := tss.LoadFile(styleSheetName)
 		if err == nil {
-			icons = xdgIconTheme
+			this.backend.SetStyle(styl)
+			return nil
 		} else {
-			log.Printf("nasin: could not load icon theme '%s': %v", iconThemeName, err)
+			log.Printf (
+				"nasin: could not load style sheet '%s'\n%v",
+				styleSheetName, parse.Format(err))
 		}
 	}
 	
-	tomo.SetStyle(styl)
-	tomo.SetIconSet(icons)
-	return nil	
+	styl, _ := fallbackStyle.New()
+	this.backend.SetStyle(styl)
+	return nil
+}
+
+func (this *Registrar) SetIconSet () error {
+	iconSet := fallbackIcons.New()
+	iconSetName := os.Getenv("TOMO_XDG_ICON_THEME")
+	if iconSetName != "" {
+		xdgIconSet, err := xdgIcons.FindThemeWarn(iconSetName, iconSet)
+		if err == nil {
+			iconSet = xdgIconSet
+		} else {
+			log.Printf("nasin: could not load icon theme '%s': %v", iconSetName, err)
+		}
+	}
+	
+	this.backend.SetIconSet(iconSet)
+	return nil
+}
+
+func (this *Registrar) SetFaceSet () error {
+	// TODO replace this with something that uses findfont, and caches and
+	// refcounts the faces
+	faceSet := fallbackFaces.New()
+	this.backend.SetFaceSet(faceSet)
+	return nil
 }

internal/style/fallback/wintergreen.go

@@ -1,19 +0,0 @@
-package fallbackStyle
-
-import "image/color"
-import "git.tebibyte.media/tomo/tomo"
-
-// New returns Wintergreen, the default Tomo style. It is neutral-gray with
-// green and turquoise accents.
-func New () *tomo.Style {
-	return &tomo.Style {
-		Rules: rules,
-		Colors: map[tomo.Color] color.Color {
-			tomo.ColorBackground: colorBackground,
-			tomo.ColorForeground: colorForeground,
-			tomo.ColorRaised:     colorCarved,
-			tomo.ColorSunken:     colorCarved,
-			tomo.ColorAccent:     colorFocus,
-		},
-	}
-}

internal/style/styleconcept.tss

@@ -1,21 +0,0 @@
-$colorBlack    = #000000FF
-$borderOutline = $black / 1
-
-*.Slider {
-	Border:  $borderOutline, $borderColorFocused / 1
-	Color:   $colorGutter
-	Padding: 0 1 1 0
-}
-
-*.Slider[focused] {
-	Border:  $borderOutline
-	Padding: 0
-}
-
-*.Slider[horizontal] {
-	MinimumSize: 48 0
-}
-
-*.Slider[vertical] {
-	MinimumSize: 0 48
-}

internal/styles/aluminum/aluminum.tss

@@ -0,0 +1,215 @@
+// Colors
+$ColorDot                   = #7391c080;
+$ColorAccent                = #5f8bc4;
+$ColorHighlight             = #5f8bc4;
+$ColorBackground            = #d4d4d4;
+$ColorForeground            = #000;
+$ColorOutline               = $ColorForeground;
+$ColorGutter                = #bfc6d1;
+$ColorGutterHovered         = #c5cbd6;
+$ColorRaised                = #e9eaea;
+$ColorRaisedPressed         = #ccd4dd;
+$ColorRaisedFocused         = #cfd6dd;
+$ColorRaisedHovered         = #f1f3f5;
+$ColorSunken                = #e9eaea;
+$ColorSunkenFocused         = #e0e6ee;
+$ColorSunkenPressed         = #e0e6ee;
+$ColorCalendarWeekdayHeader = #d3cac2;
+$ColorCalendarWeekend       = #c2d3c4;
+$ColorCalendarDay           = #d6dae2;
+
+// Borders
+$BorderOutline        = $ColorOutline                   / 1;
+$BorderEngraved       = #c3c3c5 #e3e3e3 #e9e9e9 #c2c2c2 / 1;
+$BorderGap            = #697c7c #566767 #566767 #697c7c / 1;
+$BorderLifted         = #f9fafc #c2c8d3 #a4afc0 #f5f6f8 / 1;
+$BorderLiftedFocused  = #f0f4f9 #b1baca #9aa6b7 #e4e9ee / 1;
+$BorderFocused        = #5f8bc4 #5f8bc4 #5f8bc4 #5f8bc4 / 1;
+$BorderTear           = $BorderEngraved;
+$BorderTearFocused    = #7f94b5 #ced7e4 #ced7e4 #7f94b5 / 1;
+$BorderTearPad        = #0000                           / 3;
+$BorderTearPadFocused = #7391c080                       / 3;
+$BorderInnerShadow    = #a4afc0                         / 1 0 0 1;
+$BorderOuterShadow    = #a4afc0                         / 0 1 1 0;
+
+*.* {
+	TextColor: $ColorForeground;
+	DotColor:  $ColorDot;
+	Gap:       8;
+}
+
+*.Button {
+	Border:  $BorderEngraved, $BorderGap, $BorderLifted;
+	Padding: 4 8;
+	Color:   $ColorRaised;
+}
+
+*.Button[focused] {
+	Border:  $BorderEngraved, $BorderGap, $BorderLiftedFocused;
+	Padding: 4 8;
+	Color:   $ColorRaisedFocused;
+}
+
+*.Button[hovered] {
+	Color: $ColorRaisedHovered;
+}
+
+*.Button[pressed] {
+	Border:  $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Padding: 5 8 4 9;
+	Color:   $ColorRaisedPressed;
+}
+
+*.TextInput {
+	Border:  $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Padding: 5 4 4 5;
+	Color:   $ColorSunken;
+}
+
+*.TextInput[focused] {
+	Border: $BorderEngraved, $BorderFocused, $BorderInnerShadow;
+}
+
+*.TextView {
+	Border:  $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Padding: 5 4 4 5;
+	Color:   $ColorSunken;
+}
+
+*.NumberInput {
+	Gap: 0;
+}
+
+*.Container[sunken] {
+	Border:  $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Padding: 5 4 4 5;
+	Color:   $ColorSunken;
+}
+
+*.Container[outer] {
+	Color:   $ColorBackground;
+	Padding: 8;
+}
+
+*.Container[menu] {
+	Border: $BorderGap, $BorderLifted;
+	Color:  $ColorBackground;
+	Gap:    0;
+}
+
+*.Heading {
+	Align: middle middle;
+}
+
+*.Separator {
+	Border: $BorderEngraved;
+}
+
+*.Slider {
+	Border: $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Color:  $ColorGutter;
+}
+
+*.Slider[focused] {
+	Border: $BorderEngraved, $BorderFocused, $BorderInnerShadow;
+}
+
+*.Slider[hovered] {
+	Color: $ColorGutterHovered;
+}
+
+*.Slider[horizontal] {
+	MinimumSize: 48 0;
+}
+
+*.Slider[vertical] {
+	MinimumSize: 0 48;
+}
+
+*.SliderHandle {
+	Border:      $BorderOuterShadow, $BorderGap, $BorderLifted;
+	Color:       $ColorRaised;
+	MinimumSize: 12;
+}
+
+*.ScrollContainer {
+	Gap: 0;
+}
+
+*.Checkbox {
+	Border:      $BorderEngraved, $BorderGap, $BorderInnerShadow;
+	Color:       $ColorSunken;
+	Padding:     0 1 1 0;
+	MinimumSize: 19;
+}
+
+*.Checkbox[focused] {
+	Border:  $BorderEngraved, $BorderFocused, $BorderInnerShadow;
+	Color:   $ColorSunkenFocused;
+	Padding: 0;
+}
+
+*.Checkbox[checked] {
+	Texture:     "assets/checkbox-checked.png";
+	TextureMode: center;
+}
+
+*.MenuItem {
+	Padding: 4;
+	Gap:     4;
+	Color:   #0000;
+}
+
+*.MenuItem[hovered] {
+	Color: $ColorDot;
+}
+
+*.MenuItem[focused] {
+	Color: $ColorDot;
+}
+
+*.File {
+	Color: #0000;
+}
+
+*.File[focused] {
+	Color: $ColorDot;
+}
+
+*.TearLine {
+	Border: $BorderTearPad, $BorderTear;
+}
+
+*.TearLine[hovered] {
+	Border: $BorderTearPadFocused, $BorderTearFocused;
+}
+
+*.TearLine[focused] {
+	Border: $BorderTearPadFocused, $BorderTearFocused;
+}
+
+*.Calendar {
+	Border:  $BorderOuterShadow, $BorderGap;
+	Color:   $ColorRaised;
+	Padding: 2;
+	Gap:     2;
+}
+
+*.CalendarGrid {
+	Gap: 2 2;
+}
+
+*.CalendarWeekdayHeader {
+	Color:   $ColorCalendarWeekdayHeader;
+	Padding: 2;
+}
+
+*.CalendarDay {
+	Color:       $ColorCalendarDay;
+	Padding:     2;
+	MinimumSize: 32;
+}
+
+*.CalendarDay[weekend] {
+	Color: $ColorCalendarWeekend;
+}

internal/styles/fallback/wintergreen.go

@@ -1,8 +1,14 @@
 package fallbackStyle
 
+import "io"
+import "bytes"
+import "image"
+import _ "embed"
+import _ "image/png"
 import "image/color"
 import "git.tebibyte.media/tomo/tomo"
-import "golang.org/x/image/font/basicfont"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/backend/style"
 
 var colorFocus                 = color.RGBA { R:  61, G: 128, B: 143, A: 255 }
 var colorInput                 = color.RGBA { R: 208, G: 203, B: 150, A: 255 }
@@ -38,17 +44,40 @@ var borderColorInput    = [4]color.Color { colorInputShadow, colorInput,     col
 var borderColorFocused  = [4]color.Color { colorFocus,       colorFocus,     colorFocus,     colorFocus       }
 var borderColorShade    = [4]color.Color { colorShade,       colorShade,     colorShade,     colorShade       }
 
-var rules = []tomo.Rule {
+//go:embed assets/atlas.png
+var atlasBytes []byte
+
+type closerCookie struct { io.Closer }
+func (cookie closerCookie) Close () { cookie.Closer.Close() }
+func newCloserCookie (closer io.Closer) event.Cookie {
+	return closerCookie { Closer: closer }
+}
+
+// New returns Wintergreen, the default Tomo style. It is neutral-gray with
+// green and turquoise accents.
+func New () (*style.Style, event.Cookie) {
+	atlasImage, _, err := image.Decode(bytes.NewReader(atlasBytes))
+	if err != nil { panic(err) }
+	atlasTexture := tomo.NewTexture(atlasImage)
+	
+	textureCheckboxChecked  := atlasTexture.SubTexture(image.Rect( 0,  0, 12, 11))
+	textureCorkboard        := atlasTexture.SubTexture(image.Rect(16,  0, 28, 12))
+	textureTearLine         := atlasTexture.SubTexture(image.Rect(16, 12, 18, 13))
+	textureHandleVertical   := atlasTexture.SubTexture(image.Rect(28,  0, 29,  2))
+	textureHandleHorizontal := atlasTexture.SubTexture(image.Rect(28,  0, 30,  1))
+
+	cookie := event.MultiCookie(newCloserCookie(atlasTexture))
+
+rules := []style.Rule {
 	// *.*
-	tomo.Ru(tomo.AS (
-		tomo.AFace      (basicfont.Face7x13  ),
+	style.Ru(style.AS (
 		tomo.ATextColor (tomo.ColorForeground),
 		tomo.ADotColor  (tomo.ColorAccent    ),
 		tomo.AGap       (8, 8                ),
 	), tomo.R("", "")),
 
 	// *.Button
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -61,7 +90,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Button")),
 
 	// *.Button[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -69,11 +98,10 @@ var rules = []tomo.Rule {
 				Color: borderColorFocused,
 			},
 		},
-		tomo.AttrPadding(tomo.I(4, 8)),
 	), tomo.R("", "Button"), "focused"),
 	
 	// *.Button[pressed]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -86,7 +114,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Button"), "pressed"),
 
 	// *.TextInput
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.ABorder (
 			outline,
 			tomo.Border {
@@ -98,7 +126,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TextInput")),
 
 	// *.TextInput[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.ABorder (
 			outline,
 			tomo.Border {
@@ -108,7 +136,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TextInput"), "focused"),
 	
 	// *.TextView
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.ABorder (
 			outline,
 			tomo.Border {
@@ -120,31 +148,31 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TextView")),
 	
 	// *.NumberInput
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AGap(0, 0),
 	), tomo.R("", "NumberInput")),
 
 	// *.Container[sunken]
-	tomo.Ru(tomo.AS (
-		tomo.AttrBorder {
+	style.Ru(style.AS (
+		tomo.ABorder (
 			outline,
 			tomo.Border {
 				Width: tomo.I(1, 0, 0, 1),
 				Color: borderColorEngraved,
-			},
-		},
-		tomo.AttrColor { Color: tomo.ColorSunken },
-		tomo.AttrPadding(tomo.I(8)),
+			}),
+		tomo.AColor(nil),
+		tomo.ATexture(textureCorkboard),
+		tomo.APadding(8),
 	), tomo.R("", "Container"), "sunken"),
 
 	// *.Container[outer]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrColor { Color: tomo.ColorBackground },
 		tomo.AttrPadding(tomo.I(8)),
 	), tomo.R("", "Container"), "outer"),
 
 	// *.Container[menu]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -157,12 +185,12 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Container"), "menu"),
 
 	// *.Heading
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AAlign(tomo.AlignMiddle, tomo.AlignMiddle),
 	), tomo.R("", "Heading")),
 
 	// *.Separator
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(1),
@@ -172,7 +200,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Separator")),
 
 	// *.Slider
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -185,42 +213,58 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Slider")),
 	
 	// *.Slider[focused]
-	tomo.Ru(tomo.AS (
-			tomo.AttrBorder {
-				outline,
-				tomo.Border {
-					Width: tomo.I(1),
-					Color: borderColorFocused,
-				},
-			},
-			tomo.AttrPadding(tomo.I(0)),
+	style.Ru(style.AS (
+		tomo.ABorder (
+			outline,
+			tomo.Border {
+				Width: tomo.I(1),
+				Color: borderColorFocused,
+			}),
+		tomo.APadding(0),
 	), tomo.R("", "Slider"), "focused"),
 	
 	// *.Slider[horizontal]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AMinimumSize(48, 0),
 	), tomo.R("", "Slider"), "horizontal"),
 	
 	// *.Slider[vertical]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AMinimumSize(0, 48),
 	), tomo.R("", "Slider"), "vertical"),
 
 	// *.SliderHandle
-	tomo.Ru(tomo.AS (
-		tomo.AttrBorder {
+	style.Ru(style.AS (
+		tomo.ABorder (
 			outline,
 			tomo.Border {
 				Width: tomo.I(1),
 				Color: borderColorLifted,
 			},
-		},
-		tomo.AttrColor { Color: tomo.ColorRaised },
-		tomo.AttrMinimumSize { X: 12, Y: 12, },
+			tomo.Border {
+				Width: tomo.I(1),
+				Color: [4]color.Color {
+					tomo.ColorRaised, tomo.ColorRaised,
+					tomo.ColorRaised, tomo.ColorRaised,
+				},
+			}),
+		tomo.AColor(nil),
+		tomo.ATexture(textureHandleVertical),
+		tomo.AMinimumSize(12, 12),
 	), tomo.R("", "SliderHandle")),
 
+	// *.SliderHandle[horizontal]
+	style.Ru(style.AS (
+		tomo.ATexture(textureHandleHorizontal),
+	), tomo.R("", "SliderHandle"), "horizontal"),
+
+	// *.ScrollContainer
+	style.Ru(style.AS (
+		tomo.AGap(0, 0),
+	), tomo.R("", "ScrollContainer")),
+
 	// *.Checkbox
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.ABorder (
 			outline,
 			tomo.Border {
@@ -235,7 +279,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Checkbox")),
 
 	// *.Checkbox[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.ABorder (
 			outline,
 			tomo.Border {
@@ -246,40 +290,40 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Checkbox"), "focused"),
 
 	// *.Checkbox[checked]
-	tomo.Ru(tomo.AS (
-		tomo.ATexture(nil), // TODO: checked texture
+	style.Ru(style.AS (
+		tomo.ATexture(textureCheckboxChecked),
 	), tomo.R("", "Checkbox"), "checked"),
 
 	// *.MenuItem
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrPadding(tomo.I(4)),
 		tomo.AttrGap { X: 4, Y: 4 },
 		tomo.AttrColor { Color: color.Transparent },
 	), tomo.R("", "MenuItem")),
 
 	// *MenuItem[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrColor { Color: tomo.ColorAccent },
 	), tomo.R("", "MenuItem"), "focused"),
 	
 	// *.MenuItem[hovered]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrColor { Color: tomo.ColorAccent },
 	), tomo.R("", "MenuItem"), "hovered"),
 
 	// *.File
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrColor { Color: color.Transparent },
 	), tomo.R("", "File")),
 
 	// *.File[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrColor { Color: tomo.ColorAccent },
 	), tomo.R("", "File"), "focused"),
 
 	// *.TearLine
-	tomo.Ru(tomo.AS (
-		tomo.AttrBorder {
+	style.Ru(style.AS (
+		tomo.ABorder (
 			tomo.Border {
 				Width: tomo.I(3),
 				Color: [4]color.Color {
@@ -288,14 +332,13 @@ var rules = []tomo.Rule {
 					color.Transparent,
 					color.Transparent,
 				},
-			},
-		},
-		tomo.AttrColor { Color: tomo.ColorForeground },
-		tomo.AttrPadding(tomo.I(1, 0, 0, 1)),
+			}),
+		tomo.ATexture(textureTearLine),
+		tomo.APadding(1, 0, 0, 1),
 	), tomo.R("", "TearLine")),
 
 	// *.TearLine[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(3),
@@ -305,7 +348,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TearLine"), "focused"),
 
 	// *.TearLine[hovered]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(3),
@@ -315,7 +358,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TearLine"), "hovered"),
 	
 	// *.Calendar
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(0, 1, 1, 0),
@@ -329,37 +372,37 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Calendar")),
 	
 	// *.CalendarGrid
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrGap { X: 2, Y: 2 },
 	), tomo.R("", "CalendarGrid")),
 	
 	// *.CalendarWeekdayHeader
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrPadding(tomo.I(2)),
 		tomo.AttrColor { Color: colorCalendarWeekdayHeader },
 	), tomo.R("", "CalendarWeekdayHeader")),
 	
 	// *.CalendarDay[weekday]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrPadding(tomo.I(2)),
 		tomo.AttrMinimumSize { X: 32, Y: 32 },
 		tomo.AttrColor { Color: colorCalendarDay },
 	), tomo.R("", "CalendarDay"), "weekday"),
 
 	// *.CalendarDay[weekend]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrPadding(tomo.I(2)),
 		tomo.AttrMinimumSize { X: 32, Y: 32 },
 		tomo.AttrColor { Color: colorCalendarWeekend },
 	), tomo.R("", "CalendarDay"), "weekend"),
 	
 	// *.TabbedContainer
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AGap(0, 0),
 	), tomo.R("", "TabbedContainer")),
 	
 	// *.TabRow
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(1, 1, 0, 1),
@@ -376,7 +419,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TabRow")),
 	
 	// *.TabSpacer[left]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(0, 0, 1, 0),
@@ -391,7 +434,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TabSpacer")),
 	
 	// *.TabSpacer[right]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(1, 0, 0, 0),
@@ -417,7 +460,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "TabSpacer"), "right"),
 	
 	// *.Tab
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(1, 0, 0, 0),
@@ -444,7 +487,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Tab")),
 	
 	// *.Tab[active]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			tomo.Border {
 				Width: tomo.I(1, 0, 0, 1),
@@ -460,7 +503,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Tab"), "active"),
 
 	// *.Swatch
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 		},
@@ -468,7 +511,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Swatch")),
 
 	// *.Swatch[focused]
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -479,7 +522,7 @@ var rules = []tomo.Rule {
 	), tomo.R("", "Swatch"), "focused"),
 
 	// *.ColorPickerMap
-	tomo.Ru(tomo.AS (
+	style.Ru(style.AS (
 		tomo.AttrBorder {
 			outline,
 			tomo.Border {
@@ -491,3 +534,15 @@ var rules = []tomo.Rule {
 		tomo.AttrMinimumSize { X: 128, Y: 128 },
 	), tomo.R("", "ColorPickerMap")),
 }
+
+	return &style.Style {
+		Rules: rules,
+		Colors: map[tomo.Color] color.Color {
+			tomo.ColorBackground: colorBackground,
+			tomo.ColorForeground: colorForeground,
+			tomo.ColorRaised:     colorCarved,
+			tomo.ColorSunken:     colorCarved,
+			tomo.ColorAccent:     colorFocus,
+		},
+	}, cookie
+}

internal/styles/misc/styleconcept.tss

@@ -0,0 +1,21 @@
+$colorBlack    = #000000FF;
+$borderOutline = $black 1;
+
+*.Slider {
+	Border:  $borderOutline, $borderColorFocused 1;
+	Color:   $colorGutter;
+	Padding: 0 1 1 0;
+}
+
+*.Slider[focused] {
+	Border:  $borderOutline;
+	Padding: 0;
+}
+
+*.Slider[horizontal] {
+	MinimumSize: 48 0;
+}
+
+*.Slider[vertical] {
+	MinimumSize: 0 48;
+}

internal/styles/misc/styleminimal.tss

@@ -0,0 +1,14 @@
+$ColorBackground = #FFF;
+$ColorForeground = #000;
+$ColorRaised     = #AAA;
+$ColorSunken     = #888;
+$ColorAccent     = #0FF;
+
+*.* {
+	Color:     $ColorBackground;
+	Border:    $ColorForeground / 1;
+	TextColor: $ColorForeground;
+	DotColor:  $ColorAccent;
+	Padding:   2;
+}
+

internal/styles/tss/build.go

@@ -0,0 +1,407 @@
+package tss
+
+import "os"
+import "io"
+import "fmt"
+import "image"
+import "errors"
+import "image/color"
+import _ "image/png"
+import "path/filepath"
+import "git.tebibyte.media/tomo/tomo"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/tomo/canvas"
+import "git.tebibyte.media/tomo/backend/style"
+
+type styleBuilder struct {
+	sheet      Sheet
+	workingDir string
+	textures   map[string] canvas.TextureCloser
+}
+
+// BuildStyle builds a Tomo style from the specified sheet. Resources associated
+// with it (such as textures) can be freed by closing the returned cookie.
+func BuildStyle (sheet Sheet) (*style.Style, event.Cookie, error) {
+	builder := &styleBuilder {
+		sheet:      sheet,
+		workingDir: filepath.Dir(sheet.Path),
+	}
+	return builder.build()
+}
+
+func (this *styleBuilder) build () (*style.Style, event.Cookie, error) {
+	// ensure the sheet is flattened (all vars are resolved)
+	err := this.sheet.Flatten()
+	if err != nil { return nil, nil, err }
+	
+	getColor := func (name string) color.Color {
+		if list, ok := this.sheet.Variables[name]; ok {
+			if len(list) > 0 {
+				if col, ok := list[0].(ValueColor); ok {
+					return col				
+				}
+			}
+		}
+		return color.RGBA { R: 255, B: 255, A: 255 }
+	}
+
+	// construct style and get colors
+	cookies := []event.Cookie { }
+	sty := &style.Style {
+		Rules: make([]style.Rule, len(this.sheet.Rules)),
+		Colors: map[tomo.Color] color.Color {
+			tomo.ColorBackground: getColor("ColorBackground"),
+			tomo.ColorForeground: getColor("ColorForeground"),
+			tomo.ColorRaised:     getColor("ColorRaised"),
+			tomo.ColorSunken:     getColor("ColorSunken"),
+			tomo.ColorAccent:     getColor("ColorAccent"),
+		},
+	}
+
+	// build style rules from the sheet's rule slice
+	for index, rule := range this.sheet.Rules {
+		styleRule := style.Rule {
+			Role: tomo.Role {
+				Package: rule.Selector.Package,
+				Object:  rule.Selector.Object,
+			},
+			Tags: rule.Selector.Tags,
+			Set:  make(style.AttrSet),
+		}
+		for name, attr := range rule.Attrs {
+			styleAttr, cookie, err := this.buildAttr(name, attr)
+			if err != nil { return nil, nil, err }
+			styleRule.Set.Add(styleAttr)
+			if cookie != nil {
+				cookies = append(cookies, cookie)
+			}
+		}
+		sty.Rules[index] = styleRule
+	}
+
+	// add each texture to the cookies list
+	for _, texture := range this.textures {
+		cookies = append(cookies, closerCookie { Closer: texture })
+	}
+	
+	return sty, event.MultiCookie(cookies...), nil
+}
+
+func (this *styleBuilder) buildAttr (name string, attr []ValueList) (tomo.Attr, event.Cookie, error) {
+	errWrongType := func () error {
+		return errors.New(fmt.Sprintf("wrong type for %s attribute", name))
+	}
+	expectSingle := func () error {
+		if len(attr) != 1 {
+			return errors.New(fmt.Sprintf (
+				"%s attribute requires exactly one value list",
+				name))
+		}
+		return nil
+	}
+	expectSingleSingle := func () error {
+		err := expectSingle()
+		if err != nil { return err }
+		if len(attr[0]) != 1 {
+			return errors.New(fmt.Sprintf (
+				"%s attribute requires exactly one value",
+				name))
+		}
+		return nil
+	}
+	expectNumbers := func (list ValueList) error {
+		for _, value := range list {
+			if _, ok := value.(ValueNumber); ok { continue }
+			return errWrongType()
+		}
+		return nil
+	}
+	numbers := func (list ValueList) ([]int, error) {
+		nums := make([]int, len(list))
+		for index, value := range list {
+			if value, ok := value.(ValueNumber); ok {
+				nums[index] = int(value)
+				continue
+			}
+			return nil, errWrongType()
+		}
+		return nums, nil
+	}
+	bools := func (list ValueList) ([]bool, error) {
+		bools := make([]bool, len(list))
+		for index, value := range list {
+			if value, ok := value.(ValueKeyword); ok {
+				switch value {
+				case "true":
+					bools[index] = true
+					continue
+				case "false":
+					bools[index] = false
+					continue
+				}
+			}
+			return nil, errWrongType()
+		}
+		return bools, nil
+	}
+	point := func (list ValueList) (image.Point, error) {
+		err := expectNumbers(list)
+		if err != nil { return image.Point { }, err }
+		
+		vector := image.Point { }
+		switch len(attr[0]) {
+		case 1:
+			vector.X = int(list[0].(ValueNumber))
+			vector.Y = int(list[0].(ValueNumber))
+		case 2:
+			vector.X = int(list[0].(ValueNumber))
+			vector.Y = int(list[1].(ValueNumber))
+		default:
+			return image.Point { }, errors.New(fmt.Sprintf (
+				"%s attribute requires exactly one or two values",
+				name))
+		}
+		return vector, nil
+	}
+	
+	switch name {
+	case "Color":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if col, ok := attr[0][0].(ValueColor); ok {
+			return tomo.AColor(col), nil, nil
+		}
+		return nil, nil, errWrongType()
+		
+	case "Texture":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if name, ok := attr[0][0].(ValueString); ok {
+			texture, err := this.texture(string(name))
+			if err != nil { return nil, nil, err }
+			return tomo.ATexture(texture), nil, nil
+		}
+		return nil, nil, errWrongType()
+	
+	case "TextureMode":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if keyword, ok := attr[0][0].(ValueKeyword); ok {
+			switch keyword {
+			case "tile":   return tomo.ATextureMode(tomo.TextureModeCenter), nil, nil
+			case "center": return tomo.ATextureMode(tomo.TextureModeCenter), nil, nil
+			}
+			return nil, nil, errors.New(fmt.Sprintf (
+				"unknown texture mode: %s",
+				keyword))
+		}
+		return nil, nil, errWrongType()
+	
+	case "Border":
+		attrBorder, err := buildAttrBorder(attr)
+		if err != nil { return nil, nil, err }
+		return attrBorder, nil, nil
+	
+	case "MinimumSize":
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		vector, err := point(attr[0])
+		if err != nil { return nil, nil, err }
+		return tomo.AttrMinimumSize(vector), nil, nil
+	
+	case "Padding":
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		numbers, err := numbers(attr[0])
+		if err != nil { return nil, nil, err }
+		inset := tomo.Inset { }
+		if !copyBorderValue(inset[:], numbers) {
+			return nil, nil, errors.New(fmt.Sprintf (
+				"%s attribute requires exactly one, two, or four values",
+				name))
+		}
+		return tomo.AttrPadding(inset), nil, nil
+		
+	case "Gap":
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		vector, err := point(attr[0])
+		if err != nil { return nil, nil, err }
+		return tomo.AttrGap(vector), nil, nil
+	
+	case "TextColor":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if col, ok := attr[0][0].(ValueColor); ok {
+			return tomo.ATextColor(col), nil, nil
+		}
+		return nil, nil, errWrongType()
+			
+	case "DotColor":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if col, ok := attr[0][0].(ValueColor); ok {
+			return tomo.ADotColor(col), nil, nil
+		}
+		return nil, nil, errWrongType()
+			
+	case "Face":
+		// TODO support weight, italic, slant
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		list := attr[0]
+		if len(list) != 2 {
+			return nil, nil, errors.New(fmt.Sprintf (
+				"%s attribute requires exactly two values",
+				name))
+		}
+		name, ok := list[0].(ValueString)
+		if !ok { return nil, nil, errWrongType() }
+		size, ok := list[1].(ValueNumber)
+		if !ok { return nil, nil, errWrongType() }
+		return tomo.AFace(tomo.Face {
+			Font: string(name),
+			Size: float64(size),
+		}), nil, nil
+		
+	case "Wrap":
+		err := expectSingleSingle()
+		if err != nil { return nil, nil, err }
+		if value, ok := attr[0][0].(ValueKeyword); ok {
+			switch value {
+			case "true":  return tomo.AWrap(true),  nil, nil
+			case "false": return tomo.AWrap(false), nil, nil
+			}
+		}
+		return nil, nil, errWrongType()
+		
+	case "Align":
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		list := attr[0]
+		if len(list) != 2 {
+			return nil, nil, errors.New(fmt.Sprintf (
+				"%s attribute requires exactly two values",
+				name))
+		}
+		aligns := [2]tomo.Align { }
+		for index, value := range list {
+			if keyword, ok := value.(ValueKeyword); ok {
+				switch keyword {
+				case "start":  aligns[index] = tomo.AlignStart;  continue
+				case "middle": aligns[index] = tomo.AlignMiddle; continue
+				case "end":    aligns[index] = tomo.AlignEnd;    continue
+				case "even":   aligns[index] = tomo.AlignEven;   continue
+				default: return nil, nil, errors.New(fmt.Sprintf (
+					"unknown texture mode: %s",
+					keyword))					
+				}
+			}
+			return nil, nil, errWrongType()
+		}
+		return tomo.AAlign(aligns[0], aligns[1]), nil, nil
+		
+	case "Overflow":
+		err := expectSingle()
+		if err != nil { return nil, nil, err }
+		bools, err := bools(attr[0])
+		if err != nil { return nil, nil, err }
+		if len(bools) != 2 {
+			return nil, nil, errors.New(fmt.Sprintf (
+				"%s attribute requires exactly two values",
+				name))
+		}
+		return tomo.AOverflow(bools[0], bools[1]), nil, nil
+		
+	case "Layout":
+		// TODO allow use of some layouts in the objects package
+		
+	default: return nil, nil, errors.New(fmt.Sprintf("unknown attribute name %s", name))
+	}
+	return nil, nil, errors.New(fmt.Sprintf("unimplemented attribute name %s", name))
+}
+
+func (this *styleBuilder) texture (path string) (canvas.TextureCloser, error) {
+	path = filepath.Join(this.workingDir, path)
+	if texture, ok := this.textures[path]; ok {
+		return texture, nil
+	}
+	file, err := os.Open(path)
+	if err != nil { return nil, err }
+	defer file.Close()
+	rawImage, _, err := image.Decode(file)
+	if err != nil { return nil, err }
+	return tomo.NewTexture(rawImage), nil
+}
+
+func buildAttrBorder (attr []ValueList) (tomo.Attr, error) {
+	borders := make([]tomo.Border, len(attr))
+	for index, list := range attr {
+		colors := make([]color.Color, 0, len(list))
+		sizes  := make([]int, 0, len(list))
+		
+		capturingSize := false
+		for _, value := range list {
+			if capturingSize {
+				if value, ok := value.(ValueNumber); ok {
+					sizes = append(sizes, int(value))
+					continue
+				}
+			} else {
+				if _, ok := value.(ValueCut); ok {
+					capturingSize = true
+					continue
+				}
+				if value, ok := value.(ValueColor); ok {
+					colors = append(colors, value)
+					continue
+				}
+			}
+			return nil, errors.New("malformed Border attribute value list")
+		}
+		
+		border := tomo.Border { }
+		if !copyBorderValue(border.Width[:], sizes) {
+			return nil, errors.New("malformed Border attribute width list")
+		}
+		if !copyBorderValue(border.Color[:], colors) {
+			return nil, errors.New("malformed Border attribute color list")
+		}
+		borders[index] = border
+	}
+	
+	return tomo.ABorder(borders...), nil
+}
+
+func copyBorderValue[T any, U ~[]T] (destination, source U) bool {
+	if len(source) > len(destination) { return false } 
+	switch len(source) {
+	case 1:
+		destination[0] = source[0]
+		destination[1] = source[0]
+		destination[2] = source[0]
+		destination[3] = source[0]
+		return true
+	case 2:
+		destination[0] = source[0]
+		destination[1] = source[1]
+		destination[2] = source[0]
+		destination[3] = source[1]
+		return true
+	case 4:
+		destination[0] = source[0]
+		destination[1] = source[1]
+		destination[2] = source[2]
+		destination[3] = source[3]
+		return true
+	default:
+		return false
+	}
+}
+
+type closerCookie struct {
+	io.Closer
+}
+func (cookie closerCookie) Close () {
+	cookie.Closer.Close()
+}

internal/styles/tss/color_test.go

@@ -0,0 +1,17 @@
+package tss
+
+import "testing"
+
+func TestValueColor (test *testing.T) {
+	testValueColorRGBA(test, 0xFB380CFF, 0xFBFB, 0x3838, 0x0C0C, 0xFFFF)
+	testValueColorRGBA(test, 0xFB380C00, 0x0000, 0x0000, 0x0000, 0x0000)
+}
+
+func testValueColorRGBA (test *testing.T, col ValueColor, r, g, b, a uint32) {
+	gr, gg, gb, ga := col.RGBA()
+	test.Logf("testing RGBA for color #%08X", col)
+	if gr != r { test.Errorf("r component inequal (%04X != %04X)", gr, r) }
+	if gg != g { test.Errorf("g component inequal (%04X != %04X)", gg, g) }
+	if gb != b { test.Errorf("b component inequal (%04X != %04X)", gb, b) }
+	if ga != a { test.Errorf("a component inequal (%04X != %04X)", ga, a) }
+}

internal/styles/tss/flatten.go

@@ -0,0 +1,53 @@
+package tss
+
+import "fmt"
+import "errors"
+
+// Flatten evaluates all variables recursively, thereby eliminating all
+// instances of ValueVariable.
+func (this *Sheet) Flatten () error {
+	if this.flat { return nil }
+	this.flat = true
+	
+	for name, variable := range this.Variables {
+		variable, err := this.eval(variable)
+		if err != nil { return err }
+		this.Variables[name] = variable
+	}
+	
+	for index, rule := range this.Rules {
+		for name, attr := range rule.Attrs {
+			for index, list := range attr {
+				list, err := this.eval(list)
+				if err != nil { return err }
+				attr[index] = list
+			}
+			rule.Attrs[name] = attr
+		}
+		this.Rules[index] = rule
+	}
+	
+	return nil
+}
+
+func (this *Sheet) eval (source ValueList) (ValueList, error) {
+	destination := make(ValueList, 0, len(source))
+	for _, value := range source {
+		if name, ok := value.(ValueVariable); ok {
+			variable, ok := this.Variables[string(name)]
+			if !ok {
+				return nil, errors.New(fmt.Sprintf(
+					"variable $%s does not exist",
+					value))
+			}
+			variable, err := this.eval(variable)
+			if err != nil { return nil, err }
+			destination = append(destination, variable...)
+			continue
+		} else {
+			destination = append(destination, value)
+		}
+	}
+	
+	return destination, nil
+}

internal/styles/tss/lex.go

@@ -0,0 +1,363 @@
+package tss
+
+import "io"
+import "bufio"
+import "unicode"
+import "unicode/utf8"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+const (
+	Comment parse.TokenKind = iota
+	LBrace
+	RBrace
+	LBracket
+	RBracket
+	Equals
+	Colon
+	Comma
+	Semicolon
+	Star
+	Dot
+	Dollar
+	Slash
+	Color
+	Ident
+	Number
+	String
+)
+
+var tokenNames = map[parse.TokenKind] string {
+	parse.EOF: "EOF",
+	Comment: "Comment",
+	LBrace: "LBrace",
+	RBrace: "RBrace",
+	LBracket: "LBracket",
+	RBracket: "RBracket",
+	Equals: "Equals",
+	Colon: "Colon",
+	Comma: "Comma",
+	Semicolon: "Semicolon",
+	Star: "Star",
+	Dot: "Dot",
+	Dollar: "Dollar",
+	Slash: "Slash",
+	Color: "Color",
+	Ident: "Ident",
+	Number: "Number",
+	String: "String",
+}
+
+type lexer struct {
+	filename    string
+	lineScanner *bufio.Scanner
+	rune        rune
+	line        string
+	lineFood    string
+
+	offset   int
+	row      int
+	column   int
+
+	eof bool
+}
+
+func Lex (filename string, reader io.Reader) parse.Lexer {
+	lex := &lexer {
+		filename:    filename,
+		lineScanner: bufio.NewScanner(reader),
+	}
+	lex.nextRune()
+	return lex
+}
+
+func (this *lexer) Next () (parse.Token, error) {
+	for {
+		token, err := this.next()
+		if err == io.EOF { return token, this.errUnexpectedEOF() }
+		if err != nil    { return token, err                     }
+
+		if !token.Is(Comment) {
+			return token, err
+		}
+	}
+}
+
+func (this *lexer) next () (token parse.Token, err error) {
+	err = this.skipWhitespace()
+	token.Position = this.pos()
+	if this.eof {
+		token.Kind = parse.EOF
+		err = nil
+		return
+	}
+	if err != nil { return }
+
+	appendRune := func () {
+		token.Value += string(this.rune)
+		err = this.nextRune()
+	}
+
+	skipRune := func () {
+		err = this.nextRune()
+	}
+
+	defer func () {
+		newPos := this.pos()
+		newPos.End --
+		token.Position = token.Position.Union(newPos)
+	} ()
+
+	switch {
+	case this.rune == '/':
+		token.Kind = Comment
+		skipRune()
+		if err != nil { return }
+		if this.rune == '/' {
+			for this.rune != '\n' {
+				skipRune()
+				if err != nil { return }
+			}
+		} else {
+			token.Kind = Slash
+		}
+		if this.eof { err = nil; return }
+
+	case this.rune == '{':
+		token.Kind = LBrace
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '}':
+		token.Kind = RBrace
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '[':
+		token.Kind = LBracket
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == ']':
+		token.Kind = RBracket
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '=':
+		token.Kind = Equals
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == ':':
+		token.Kind = Colon
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == ',':
+		token.Kind = Comma
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == ';':
+		token.Kind = Semicolon
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '*':
+		token.Kind = Star
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '.':
+		token.Kind = Dot
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '$':
+		token.Kind = Dollar
+		appendRune()
+		if this.eof { err = nil; return }
+
+	case this.rune == '#':
+		token.Kind = Color
+		skipRune()
+		if err != nil { return }
+		for isHexDigit(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+		}
+		if this.eof { err = nil; return }
+
+	case unicode.IsLetter(this.rune):
+		token.Kind = Ident
+		for unicode.IsLetter(this.rune) || unicode.IsNumber(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+		}
+		if this.eof { err = nil; return }
+
+	case this.rune == '-':
+		token.Kind = Number
+		appendRune()
+		for isDigit(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+		}
+		if this.eof { err = nil; return }
+		
+	case isDigit(this.rune):
+		token.Kind = Number
+		for isDigit(this.rune) {
+			appendRune()
+			if this.eof { err = nil; return }
+		}
+		if this.eof { err = nil; return }
+		
+	case this.rune == '\'', this.rune == '"':
+		stringDelimiter := this.rune
+		token.Kind = String
+		err = this.nextRune()
+		if err != nil { return }
+
+		for this.rune != stringDelimiter {
+			if this.rune == '\\' {
+				var result rune
+				result, err = this.escapeSequence(stringDelimiter)
+				if err != nil { return }
+				token.Value += string(result)
+			} else {
+				appendRune()
+				if this.eof { err = nil; return }
+				if err != nil { return }
+			}
+		}
+		err = this.nextRune()
+		if this.eof { err = nil; return }
+		if err != nil { return }
+
+	default:
+		err = parse.Errorf (
+			this.pos(), "unexpected rune %U",
+			this.rune)
+	}
+
+	return
+}
+
+func (this *lexer) nextRune () error {
+	if this.lineFood == "" {
+		ok := this.lineScanner.Scan()
+		if ok {
+			this.line     = this.lineScanner.Text()
+			this.lineFood = this.line
+			this.rune     = '\n'
+			this.column   = 0
+			this.row      ++
+		} else {
+			err := this.lineScanner.Err()
+			if err == nil {
+				this.eof = true
+				return io.EOF
+			} else {
+				return err
+			}
+		}
+	} else {
+		var ch   rune
+		var size int
+		for ch == 0 && this.lineFood != "" {
+			ch, size = utf8.DecodeRuneInString(this.lineFood)
+			this.lineFood = this.lineFood[size:]
+		}
+		this.rune = ch
+		this.column ++
+	}
+
+	return nil
+}
+
+func (this *lexer) escapeSequence (stringDelimiter rune) (rune, error) {
+	err := this.nextRune()
+	if err != nil { return 0, err }
+
+	if isDigit(this.rune) {
+		var number rune
+		for index := 0; index < 3; index ++ {
+			if !isDigit(this.rune) { break }
+		
+			number *= 8
+			number += this.rune - '0'
+
+			err = this.nextRune()
+			if err != nil { return 0, err }
+		}
+		return number, nil
+	}
+
+	defer this.nextRune()
+	switch this.rune {
+	case '\\', '\n', stringDelimiter:
+		return this.rune, nil
+	case 'a': return '\a', nil
+	case 'b': return '\b', nil
+	case 't': return '\t', nil
+	case 'n': return '\n', nil
+	case 'v': return '\v', nil
+	case 'f': return '\f', nil
+	case 'r': return '\r', nil
+	default: return 0, this.errBadEscapeSequence()
+	}
+}
+
+func (this *lexer) skipWhitespace () error {
+	for isWhitespace(this.rune) {
+		err := this.nextRune()
+		if err != nil { return err }
+	}
+	return nil
+}
+
+func (this *lexer) pos () parse.Position {
+	return parse.Position {
+		File:   this.filename,
+		Line:   this.lineScanner.Text(),
+		Row:    this.row    - 1,
+		Start:  this.column - 1,
+		End:    this.column,
+	}
+}
+
+func (this *lexer) errUnexpectedEOF () error {
+	return parse.Errorf(this.pos(), "unexpected EOF")
+}
+
+func (this *lexer) errBadEscapeSequence () error {
+	return parse.Errorf(this.pos(), "bad escape sequence")
+}
+
+func isWhitespace (char rune) bool {
+	switch char {
+	case ' ', '\t', '\r', '\n': return true
+	default: return false
+	}
+}
+
+func isSymbol (char rune) bool {
+	switch char {
+	case
+		'~', '!', '@', '#', '$', '%', '^', '&', '-', '_', '=', '+',
+		'\\', '|', ';', ',', '<', '>', '/', '?':
+		return true
+	default:
+		return false
+	}
+}
+
+func isDigit (char rune) bool {
+	return char >= '0' && char <= '9'
+}
+
+func isHexDigit (char rune) bool {
+	return isDigit(char) ||
+		char >= 'a' && char <= 'f' ||
+		char >= 'A' && char <= 'F'
+}

internal/styles/tss/lex_test.go

@@ -0,0 +1,66 @@
+package tss
+
+import "fmt"
+import "strings"
+import "testing"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+func TestLexSimple (test *testing.T) {
+testString(test,
+`hello #BABE {#Beef}, 384920 #0ab3fc840`,
+tok(Ident, "hello"),
+tok(Color, "BABE"),
+tok(LBrace, "{"),
+tok(Color, "Beef"),
+tok(RBrace, "}"),
+tok(Comma, ","),
+tok(Number, "384920"),
+tok(Color, "0ab3fc840"),
+tok(parse.EOF, ""),
+)}
+
+func testString (test *testing.T, input string, correct ...parse.Token) {
+	lexer := Lex("test.tss", strings.NewReader(input))
+	index := 0
+	for {
+		token, err := lexer.Next()
+		if err != nil { test.Fatalf("lexer returned error:\n%v", parse.Format(err)) }
+		if index >= len(correct) {
+			test.Logf("%d:\t%-16s | !", index, tokStr(token))
+			test.Fatalf("index %d greater than %d", index, len(correct))
+		}
+		correctToken := correct[index]
+		test.Logf (
+			"%d:\t%-16s | %s",
+			index,
+			tokStr(token),
+			tokStr(correctToken))
+		if correctToken.Kind != token.Kind || correctToken.Value != token.Value {
+			test.Fatalf("tokens at %d do not match up", index)
+		}
+		if token.Is(parse.EOF) { break }
+		index ++
+	}
+	if index < len(correct) - 1 {
+		test.Fatalf("index %d less than %d", index, len(correct) - 1)
+	}
+}
+
+func tokStr (token parse.Token) string {
+	name, ok := tokenNames[token.Kind]
+	if !ok {
+		name = fmt.Sprintf("Token(%d)", token.Kind)
+	}
+	if token.Value == "" {
+		return name
+	} else {
+		return fmt.Sprintf("%s:\"%s\"", name, token.Value)
+	}
+}
+
+func tok (kind parse.TokenKind, value string) parse.Token {
+	return parse.Token {
+		Kind:  kind,
+		Value: value,
+	}
+}

internal/styles/tss/parse.go

@@ -0,0 +1,253 @@
+package tss
+
+import "io"
+import "strconv"
+import "git.tebibyte.media/sashakoshka/goparse"
+
+type parser struct {
+	parse.Parser
+	sheet Sheet
+	lexer parse.Lexer
+}
+
+func newParser (lexer parse.Lexer) *parser {
+	return &parser {
+		sheet: Sheet {
+			Variables: make(map[string] ValueList),
+		},
+		Parser: parse.Parser {
+			Lexer:      lexer,
+			TokenNames: tokenNames,
+		},
+	}
+}
+
+func Parse (lexer parse.Lexer) (Sheet, error) {
+	parser := newParser(lexer)
+	err := parser.parse()
+	if err == io.EOF { err = nil }
+	if err != nil { return Sheet { }, err }
+	return parser.sheet, nil
+}
+
+func (this *parser) parse () error {
+	err := this.Next()
+	if err != nil { return err }
+	for this.Token.Kind != parse.EOF {
+		err = this.parseTopLevel()
+		if err != nil { return err }
+	}
+	return nil
+}
+
+func (this *parser) parseTopLevel () error {
+	err := this.ExpectDesc("variable or rule", Dollar, Ident, Star)
+	if err != nil { return err }
+	if this.EOF() { return nil }
+	pos := this.Pos()
+	
+	switch this.Kind() {
+	case Dollar:
+		name, variable, err := this.parseVariable()
+		if err != nil { return err }
+		if _, exists := this.sheet.Variables[name]; exists {
+			return parse.Errorf(pos, "variable %s already declared", name)
+		}
+		this.sheet.Variables[name] = variable
+		
+	case Ident, Star:
+		rule, err := this.parseRule()
+		if err != nil { return err }
+		this.sheet.Rules = append(this.sheet.Rules, rule)
+	}
+	return nil
+}
+
+func (this *parser) parseVariable () (string, ValueList, error) {
+	err := this.Expect(Dollar)
+	if err != nil { return "", nil, err }
+	err = this.ExpectNext(Ident)
+	if err != nil { return "", nil, err }
+	name := this.Value()
+	err = this.ExpectNext(Equals)
+	if err != nil { return "", nil, err }
+	this.Next()
+	values, err := this.parseValueList()
+	if err != nil { return "", nil, err }
+	err = this.Expect(Semicolon)
+	if err != nil { return "", nil, err }
+	return name, values, this.Next()
+}
+
+func (this *parser) parseRule () (Rule, error) {
+	rule := Rule {
+		Attrs: make(map[string] []ValueList),
+	}
+	
+	selector, err := this.parseSelector()
+	if err != nil { return Rule { }, err }
+	rule.Selector = selector
+	err = this.Expect(LBrace)
+	if err != nil { return Rule { }, err }
+	
+	for {
+		this.Next()
+		if this.Is(RBrace) { break }
+		pos := this.Pos()
+		name, attr, err := this.parseAttr()
+		if err != nil { return Rule { }, err }
+		err = this.Expect(Semicolon)
+		if err != nil { return Rule { }, err }
+		if _, exists := rule.Attrs[name]; exists {
+			return Rule { }, parse.Errorf (
+				pos,
+				"attribute %s already declared in this rule",
+				name)
+		}
+		rule.Attrs[name] = attr
+	}
+	
+	return rule, this.Next()
+}
+
+func (this *parser) parseSelector () (Selector, error) {
+	selector := Selector { }
+
+	// package
+	err := this.ExpectDesc("selector", Ident, Star)
+	if err != nil { return Selector { }, err }
+	if this.Is(Ident) {
+		selector.Package = this.Value()
+	}
+	
+	err = this.ExpectNext(Dot)
+	if err != nil { return Selector { }, err }
+
+	// object
+	err = this.ExpectNext(Ident, Star)
+	if err != nil { return Selector { }, err }
+	if this.Is(Ident) {
+		selector.Object = this.Value()
+	}
+
+	// tags
+	err = this.ExpectNext(LBracket)
+	if err == nil {
+		this.Next()
+		for {
+			err := this.Expect(Ident, String, RBracket)
+			if err != nil { return Selector { }, err }
+			if this.Is(RBracket) { break       }
+			if this.Is(Comma)    { this.Next() }
+			selector.Tags = append(selector.Tags, this.Value())
+			err = this.ExpectNext(Comma, RBracket)
+			if err != nil { return Selector { }, err }
+		}
+		this.Next()
+	}
+	
+	return selector, nil
+}
+
+func (this *parser) parseAttr () (string, []ValueList, error) {
+	err := this.ExpectDesc("attr", Ident)
+	if err != nil { return "", nil, err }
+	name := this.Value()
+
+	err = this.ExpectNext(Colon)
+	if err != nil { return "", nil, err }
+
+	attr := []ValueList { }
+	this.Next()
+	for {
+		err := this.ExpectDesc (
+			"value, Comma, or Semicolon",
+			Number, Color, String, Ident, Dollar, Slash,
+			Comma, Semicolon)
+		if err != nil { return "", nil, err }
+		if this.Is(Semicolon) { break       }
+		if this.Is(Comma)     { this.Next() }
+		valueList, err := this.parseValueList()
+		if err != nil { return "", nil, err }
+		attr = append(attr, valueList)
+		err = this.Expect(Comma, Semicolon)
+		if err != nil { return "", nil, err }
+	}
+	
+	return name, attr, nil
+}
+
+func (this *parser) parseValueList () (ValueList, error) {
+	list := ValueList { }
+	for {
+		err := this.ExpectDesc (
+			"value",
+			Number, Color, String, Ident, Dollar, Slash)
+		if err != nil { break }
+		switch this.Kind() {
+		case Number:
+			number, err := strconv.Atoi(this.Value())
+			if err != nil { return nil, err }
+			list = append(list, ValueNumber(number))
+		case Color:
+			color, ok := parseColor([]rune(this.Value()))
+			if !ok {
+				return nil, parse.Errorf (
+					this.Pos(),
+					"malformed color literal")
+			}
+			list = append(list, ValueColor(color))
+		case String:
+			list = append(list, ValueString(this.Value()))
+		case Ident:
+			list = append(list, ValueKeyword(this.Value()))
+		case Dollar:
+			err := this.ExpectNext(Ident)
+			if err != nil { return nil, err }
+			list = append(list, ValueVariable(this.Value()))
+		case Slash:
+			list = append(list, ValueCut { })
+		}
+		this.Next()
+	}
+	return list, nil
+}
+
+func parseColor (runes []rune) (uint32, bool) {
+	digits := make([]uint32, len(runes))
+	for index, run := range runes {
+		digit := hexDigit(run)
+		if digit < 0 { return 0, false }
+		digits[index] = uint32(digit)
+	}
+	switch len(runes) {
+	case 3:
+		return  digits[0] << 28 | digits[0] << 24 |
+			digits[1] << 20 | digits[1] << 16 |
+			digits[2] << 12 | digits[2] <<  8 | 0xFF, true
+	case 6:
+		return  digits[0] << 28 | digits[1] << 24 |
+			digits[2] << 20 | digits[3] << 16 |
+			digits[4] << 12 | digits[5] <<  8 | 0xFF, true
+	case 4:
+		return  digits[0] << 28 | digits[0] << 24 |
+			digits[1] << 20 | digits[1] << 16 |
+			digits[2] << 12 | digits[2] <<  8 |
+			digits[3] <<  4 | digits[3] <<  0, true
+	case 8:
+		return  digits[0] << 28 | digits[1] << 24 |
+			digits[2] << 20 | digits[3] << 16 |
+			digits[4] << 12 | digits[5] <<  8 |
+			digits[6] <<  4 | digits[7] <<  0, true
+	default: return 0, false
+	}
+}
+
+func hexDigit (digit rune) int {
+	switch {
+	case digit >= '0' && digit <= '9': return int(digit - '0')
+	case digit >= 'a' && digit <= 'f': return int(digit - 'a') + 10
+	case digit >= 'A' && digit <= 'F': return int(digit - 'A') + 10
+	default: return -1
+	}
+}

internal/styles/tss/tss.go

@@ -0,0 +1,81 @@
+package tss
+
+import "os"
+import "git.tebibyte.media/tomo/tomo/event"
+import "git.tebibyte.media/tomo/backend/style"
+
+type Sheet struct {
+	Path      string
+	Variables map[string] ValueList
+	Rules     []Rule
+	flat      bool
+}
+
+type Rule struct {
+	Selector Selector
+	Attrs    map[string] []ValueList
+}
+
+type Selector struct {
+	Package string
+	Object  string
+	Tags    []string
+}
+
+type ValueList []Value
+
+type Value interface {
+	value ()
+}
+
+type ValueNumber int
+func (ValueNumber) value () { }
+
+type ValueColor uint32
+func (ValueColor) value () { }
+func (value ValueColor) RGBA () (r, g, b, a uint32) {
+	// extract components
+	bits := uint32(value)
+	r = (bits & 0xFF000000) >> 24
+	g = (bits & 0x00FF0000) >> 16
+	b = (bits & 0x0000FF00) >> 8
+	a = (bits & 0x000000FF)
+	// extend to 16 bits per channel
+	r = r << 8 | r
+	g = g << 8 | g
+	b = b << 8 | b
+	a = a << 8 | a
+	// alpha premultiply
+	r = (r * a) / 0xFFFF
+	g = (g * a) / 0xFFFF
+	b = (b * a) / 0xFFFF
+	return
+}
+
+type ValueString string
+func (ValueString) value () { }
+
+type ValueKeyword string
+func (ValueKeyword) value () { }
+
+type ValueVariable string
+func (ValueVariable) value () { }
+
+type ValueCut struct { }
+func (ValueCut) value () { }
+
+// LoadFile loads the stylesheet from the specified file. This may return a
+// parse.Error, so use parse.Format to print it.
+func LoadFile (name string) (*style.Style, event.Cookie, error) {
+	// TODO check cache for gobbed sheet. if the cache is nonexistent or
+	// invalid, then open/load/cache.
+	
+	file, err := os.Open(name)
+	if err != nil { return nil, nil, err }
+	defer file.Close()
+
+	sheet, err := Parse(Lex(name, file))
+	if err != nil { return nil, nil, err }
+	sheet.Path = name
+	return BuildStyle(sheet)
+}

internal/styles/tss/tss.yaml

@@ -0,0 +1,35 @@
+# Happen to use Micro to edit text?
+# Drop this in ~/.config/micro/syntax and get syntax highlighting for TSS files!
+
+filetype: tss
+
+detect:
+        filename: "\\.tss$"
+
+rules:
+        - type: "\\b([A-Z][a-zA-Z0-9]*).*:"
+        - identifier.var: "\\$[a-zA-Z0-9]*\\b"
+        - identifier.class: "(\\*|[a-z][a-zA-Z0-9]*)\\.(\\*|[A-Z][a-zA-Z0-9]*)"
+        - constant: "\\b(tile|center)\\b"
+        - constant: "\\b(start|middle|end|even)\\b"
+        - constant.bool: "\\b(true|false)\\b"
+        - special: "(\\/|,|\\;|:|\\.)"
+        - symbol.operator: "(=|\\*)"
+        - symbol.brackets: "(\\{\\[|\\}\\])"
+
+        - comment:
+                start: "//"
+                end: "$"
+                rules:
+                        - todo: "(TODO|XXX|FIXME|BUG):?"
+        
+        - constant.string:
+                start: "\""
+                end: "\""
+                skip: "\\\\."
+                rules:
+                        - constant.specialChar: "\\\\[abfnrtv'\\\"\\\\]"
+                        - constant.specialChar: "\\\\([0-7]{3})"
+
+        - constant.number: "\\b[0-9][0-9.]*\\b"
+        - constant.string: "\\B#[0-9a-fA-F]*"