Speaks english for 21 years and still has no idea how to spell

Remedy #6

backend.go

@@ -17,18 +17,33 @@ type Backend interface {
 	NewSurfaceBox   () (SurfaceBox, error)
 	NewContainerBox () ContainerBox
 
-	// NewWindow creates a normal MainWindow and returns it.
-	NewWindow (image.Rectangle) (MainWindow, error)
+	// NewWindow creates a normal Window and returns it.
+	NewWindow (image.Rectangle) (Window, error)
 
 	// NewPlainWindow creates an undecorated window that does not appear in
 	// window lists and returns it. This is intended for making things like
 	// panels, docks, etc.
-	NewPlainWindow (image.Rectangle) (MainWindow, error)
+	NewPlainWindow (image.Rectangle) (Window, error)
 
 	// NewTexture creates a new texture from an image. The backend must
 	// reject any texture that was not made by it.
 	NewTexture (image.Image) canvas.TextureCloser
 
+	// NewCanvas creates a new canvas with the specified bounds. The backend
+	// must reject any canvas that was not made by it.
+	NewCanvas (image.Rectangle) canvas.CanvasCloser
+
+	// SetStyle sets the style that will be used on objects. The backend is
+	// in charge of applying the style to objects. When this method is
+	// called, it must propagate a StyleChange event to all boxes it is
+	// keeping track of.
+	SetStyle (Style)
+
+	// SetIcons sets the icon set that icons will be pulled from. When this
+	// method is called, it must propagate an IconChange event to all boxes
+	// it is keeping track of.
+	SetIcons (Icons)
+
 	// Run runs the event loop until Stop() is called, or the backend
 	// experiences a fatal error.
 	Run () error

canvas/canvas.go

@@ -2,6 +2,7 @@
 // primitives.
 package canvas
 
+import "io"
 import "image"
 import "image/draw"
 import "image/color"
@@ -77,6 +78,13 @@ type Canvas interface {
 	SubCanvas (image.Rectangle) Canvas
 }
 
+// CanvasCloser is a canvas that can be closed. Anything that receives a
+// CanvasCloser must close it after use.
+type CanvasCloser interface {
+	Canvas
+	io.Closer
+}
+
 // Drawer can draw to a canvas.
 type Drawer interface {
 	// Draw draws to the given canvas.

go.sum

@@ -1,8 +1,6 @@
 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 v0.8.0 h1:agUcRXV/+w6L9ryntYYsF2x9fQTMd4T8fiiYXAVW6Jg=
-golang.org/x/image v0.8.0/go.mod h1:PwLxp3opCYg4WR2WO9P0L6ESnsD6bLTWcw8zanLMVFM=
 golang.org/x/image v0.11.0 h1:ds2RoQvBvYTiJkwpSFDwCcDFNX7DqjL2WsUgTNk0Ooo=
 golang.org/x/image v0.11.0/go.mod h1:bglhjqbqVuEb9e9+eNR45Jfu7D+T4Qan+NhQk8Ck2P8=
 golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
@@ -27,7 +25,6 @@ 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 v0.10.0/go.mod h1:TvPlkZtksWOMsz7fbANvkp4WM8x/WCo/om8BMLbz+aE=
 golang.org/x/text v0.12.0/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=

icon.go

@@ -35,19 +35,9 @@ const (
 	IconCallStart                    Icon = "CallStart"
 	IconCallStop                     Icon = "CallStop"
 	IconContactNew                   Icon = "ContactNew"
-	// actions: file
-	IconFileNew                      Icon = "FileNew"
-	IconDirectoryNew                 Icon = "DirectoryNew"
-	IconFileOpen                     Icon = "FileOpen"
-	IconFileOpenRecent               Icon = "FileOpenRecent"
-	IconFilePageSetup                Icon = "FilePageSetup"
-	IconFilePrint                    Icon = "FilePrint"
-	IconFilePrintPreview             Icon = "FilePrintPreview"
-	IconFileProperties               Icon = "FileProperties"
-	IconFileRevert                   Icon = "FileRevert"
-	IconFileSave                     Icon = "FileSave"
-	IconFileSaveAs                   Icon = "FileSaveAs"
-	IconFileSend                     Icon = "FileSend"
+	// actions: dialog
+	IconDialogOkay                   Icon = "DialogOkay"
+	IconDialogCancel                 Icon = "DialogCancel"
 	// actions: edit
 	IconEditClear                    Icon = "EditClear"
 	IconEditCopy                     Icon = "EditCopy"
@@ -59,6 +49,21 @@ const (
 	IconEditRedo                     Icon = "EditRedo"
 	IconEditSelectAll                Icon = "EditSelectAll"
 	IconEditUndo                     Icon = "EditUndo"
+	// actions: file
+	IconFileNew                      Icon = "FileNew"
+	IconDirectoryNew                 Icon = "DirectoryNew"
+	IconFileOpen                     Icon = "FileOpen"
+	IconFileOpenRecent               Icon = "FileOpenRecent"
+	IconFilePageSetup                Icon = "FilePageSetup"
+	IconFilePrint                    Icon = "FilePrint"
+	IconFilePrintPreview             Icon = "FilePrintPreview"
+	IconFilePermissions              Icon = "FilePermissions"
+	IconFileProperties               Icon = "FileProperties"
+	IconFileRename                   Icon = "FileRename"
+	IconFileRevert                   Icon = "FileRevert"
+	IconFileSave                     Icon = "FileSave"
+	IconFileSaveAs                   Icon = "FileSaveAs"
+	IconFileSend                     Icon = "FileSend"
 	// actions: format
 	IconFormatIndentLess             Icon = "FormatIndentLess"
 	IconFormatIndentMore             Icon = "FormatIndentMore"
@@ -73,7 +78,6 @@ const (
 	IconFormatTextUnderline          Icon = "FormatTextUnderline"
 	IconFormatTextStrikethrough      Icon = "FormatTextStrikethrough"
 	// actions: go
-	IconGo                           Icon = "Go"
 	IconGoBottom                     Icon = "GoBottom"
 	IconGoDown                       Icon = "GoDown"
 	IconGoFirst                      Icon = "GoFirst"
@@ -134,6 +138,10 @@ const (
 	IconSystemShutdown               Icon = "SystemShutdown"
 	// actions: tools
 	IconToolsCheckSpelling           Icon = "ToolsCheckSpelling"
+	// actions: value
+	IconValueIncrement               Icon = "ValueIncrement"
+	IconValueDecrement               Icon = "ValueDecrement"
+	IconValueReset                   Icon = "ValueReset"
 	// actions: view
 	IconViewFullscreen               Icon = "ViewFullscreen"
 	IconViewRefresh                  Icon = "ViewRefresh"
@@ -192,7 +200,6 @@ const (
 	IconApplicationsSystem           Icon = "ApplicationsSystem"
 	IconApplicationsUtilities        Icon = "ApplicationsUtilities"
 	// categories: preferences
-	
 	IconPreferences                  Icon = "Preferences"
 	IconPreferencesDesktop           Icon = "PreferencesDesktop"
 	IconPreferencesPeripherals       Icon = "PreferencesPeripherals"
@@ -224,6 +231,7 @@ const (
 	IconPowerBattery                 Icon = "PowerBattery"
 	// devices: storage
 	IconStorageHardDisk              Icon = "StorageHardDisk"
+	IconStorageFloppyDisk            Icon = "StorageFloppyDisk"
 	IconStorageSolidState            Icon = "StorageSolidState"
 	IconStorageOptical               Icon = "StorageOptical"
 	IconStorageFlashStick            Icon = "StorageFlashStick"
@@ -277,6 +285,9 @@ const (
 	IconPlaceHistory                 Icon = "PlaceHistory"
 	IconPlacePreferences             Icon = "PlacePreferences"
 
+	// status: checkbox
+	IconCheckboxChecked              Icon = "CheckboxChecked"
+	IconCheckboxUnchecked            Icon = "CheckboxUnchecked"
 	// status: appointments
 	IconAppointmentMissed            Icon = "AppointmentMissed"
 	IconAppointmentSoon              Icon = "AppointmentSoon"
@@ -371,12 +382,44 @@ const (
 
 // Texture returns a texture of the corresponding icon ID.
 func (id Icon) Texture (size IconSize) canvas.Texture {
-	if theme == nil { return nil }
-	return theme.Icon(id, size)
+	if icons == nil { return nil }
+	return icons.Icon(id, size)
 }
 
 // MimeIcon returns an icon corresponding to a MIME type.
 func MimeIcon (mime data.Mime, size IconSize) canvas.Texture {
-	if theme == nil { return nil }
-	return theme.MimeIcon(mime, size)
+	if icons == nil { return nil }
+	return icons.MimeIcon(mime, size)
+}
+
+// Icons holds a set of icon textures.
+type Icons interface {
+	// A word on textures:
+	//
+	// Because textures can be linked to some resource that is outside of
+	// the control of Go's garbage collector, methods of Icons must not
+	// allocate new copies of a texture each time they are called. It is
+	// fine to lazily load textures and save them for later use, but the
+	// same texture must never be allocated multiple times as this could
+	// cause a memory leak.
+	//
+	// As such, textures returned by these methods must be protected.
+	
+	// Icon returns a texture of the corresponding icon ID. If there is no
+	// suitable option, it should return nil.
+	Icon (Icon, IconSize) canvas.Texture
+
+	// MimeIcon returns a texture of an icon corresponding to a MIME type.
+	// If there is no suitable specific option, it should return a more
+	// generic icon or a plain file icon.
+	MimeIcon (data.Mime, IconSize) canvas.Texture
+}
+
+var icons Icons
+
+// SetIcons sets the icon set.
+func SetIcons (icns Icons) {
+	assertBackend()
+	icons = icns
+	backend.SetIcons(icns)
 }

object.go

@@ -9,98 +9,6 @@ import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/input"
 import "git.tebibyte.media/tomo/tomo/canvas"
 
-// Side represents one side of a rectangle.
-type Side int; const (
-	SideTop Side = iota
-	SideRight
-	SideBottom
-	SideLeft
-)
-
-// Inset represents a rectangle inset that can have a different value for each
-// side.
-type Inset [4]int
-
-// I allows you to create an inset in a CSS-ish way:
-//
-//   - One argument: all sides are set to this value
-//   - Two arguments: the top and bottom sides are set to the first value, and
-//     the left and right sides are set to the second value.
-//   - Three arguments: the top side is set by the first value, the left and
-//     right sides are set by the second vaue, and the bottom side is set by the
-//     third value.
-//   - Four arguments: each value corresponds to a side.
-//
-// This function will panic if an argument count that isn't one of these is
-// given.
-func I (sides ...int) Inset {
-	switch len(sides) {
-	case 1: return Inset { sides[0], sides[0], sides[0], sides[0] }
-	case 2: return Inset { sides[0], sides[1], sides[0], sides[1] }
-	case 3: return Inset { sides[0], sides[1], sides[2], sides[1] }
-	case 4: return Inset { sides[0], sides[1], sides[2], sides[3] }
-	default: panic("I: illegal argument count.")
-	}
-}
-
-// Apply returns the given rectangle, shrunk on all four sides by the given
-// inset. If a measurment of the inset is negative, that side will instead be
-// expanded outward. If the rectangle's dimensions cannot be reduced any
-// further, an empty rectangle near its center will be returned.
-func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) {
-	smaller = bigger
-	if smaller.Dx() < inset[3] + inset[1] {
-		smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2
-		smaller.Max.X = smaller.Min.X
-	} else {
-		smaller.Min.X += inset[3]
-		smaller.Max.X -= inset[1]
-	}
-
-	if smaller.Dy() < inset[0] + inset[2] {
-		smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2
-		smaller.Max.Y = smaller.Min.Y
-	} else {
-		smaller.Min.Y += inset[0]
-		smaller.Max.Y -= inset[2]
-	}
-	return
-}
-
-// Inverse returns a negated version of the inset.
-func (inset Inset) Inverse () (prime Inset) {
-	return Inset {
-		inset[0] * -1,
-		inset[1] * -1,
-		inset[2] * -1,
-		inset[3] * -1,
-	}
-}
-
-// Horizontal returns the sum of SideRight and SideLeft.
-func (inset Inset) Horizontal () int {
-	return inset[SideRight] + inset[SideLeft]
-}
-
-// Vertical returns the sum of SideTop and SideBottom.
-func (inset Inset) Vertical () int {
-	return inset[SideTop] + inset[SideBottom]
-}
-
-// Border represents a single border of a box.
-type Border struct {
-	Width Inset
-	Color [4]color.Color
-}
-
-// Align lists basic alignment types.
-type Align int; const (
-	AlignStart Align = iota // similar to left-aligned text
-	AlignMiddle             // similar to center-aligned text
-	AlignEnd                // similar to right-aligned text
-	AlignEven               // similar to justified text
-)
-
 // Object is any onscreen object that is linked to a box (or is that box).
 // Unlike the Box interface and associated interfaces, Object implementations
 // may originate from anywhere.
@@ -144,6 +52,8 @@ type Box interface {
 	//     internal content that does not overflow, the size of that is also
 	//     taken into account here.
 	MinimumSize () image.Point
+	// Role returns this Box's role as set by SetRole.
+	Role () Role
 	// SetBounds sets the bounding rectangle of this Box relative to the
 	// Window.
 	SetBounds (image.Rectangle)
@@ -168,12 +78,9 @@ type Box interface {
 	// SetPadding sets the padding between the Box's innermost Border and
 	// its content.
 	SetPadding (Inset)
-	// SetVisible sets whether or not this box is visible. If invisible,
-	// it will not be drawn and no space will be created for it in the
-	// layout. Boxes are visible by default.
-	SetVisible (bool)
-	// Visible returns whether or not this box is visible.
-	Visible () bool
+	// SetRole sets what role this Box takes on. It is used to apply styling
+	// from a theme.
+	SetRole (Role)
 
 	// SetDNDData sets the data that will be picked up if this Box is
 	// dragged. If this is nil (which is the default), this Box will not be
@@ -217,6 +124,8 @@ type Box interface {
 	OnScroll      (func (deltaX, deltaY float64)) event.Cookie
 	OnKeyDown     (func (key input.Key, numberPad bool)) event.Cookie
 	OnKeyUp       (func (key input.Key, numberPad bool)) event.Cookie
+	OnStyleChange (func ()) event.Cookie
+	OnIconsChange (func ()) event.Cookie
 }
 
 // CanvasBox is a box that can be drawn to.
@@ -250,9 +159,16 @@ type SurfaceBox interface {
 	// expected type was not found.
 	Surface () any
 	
-	// Invalidate causes the Box's area to be redrawn at the end of the
-	// event cycle, even if it wouldn't be otherwise.
+	// Invalidate causes the data within the surface to be pushed to the
+	// screen at the end of the event cycle, even if it wouldn't be
+	// otherwise.
 	Invalidate ()
+
+	// OnSizeChange specifies a function to be called when the size of the
+	// Box is changed, or the surface is re-allocated. The application must
+	// call Surface() each time this event fires in order to not draw to a
+	// closed surface.
+	OnSizeChange (func ())
 }
 
 // ContentBox is a box that has some kind of content.
@@ -269,6 +185,14 @@ type ContentBox interface {
 	// ContentBounds returns the bounds of the inner content of the Box
 	// relative to the Box's InnerBounds.
 	ContentBounds () image.Rectangle
+	// RecommendedHeight returns the recommended height for a given width,
+	// if supported by the current content or layout. Otherwise, it should
+	// just return the minimum height.
+	RecommendedHeight(width int) int
+	// RecommendedWidth returns the recommended width for a given height, if
+	// supported by the current content or layout. Otherwise, it should just
+	// return the minimum width.
+	RecommendedWidth(height int) int
 	// ScrollTo shifts the origin of the Box's content to the origin of the
 	// Box's InnerBounds, offset by the given point.
 	ScrollTo (image.Point)
@@ -365,9 +289,21 @@ type Layout interface {
 	MinimumSize (LayoutHints, []Box) image.Point
 	// Arrange arranges child boxes according to the given LayoutHints.
 	Arrange (LayoutHints, []Box)
+	// RecommendedHeight returns the recommended height for a given width,
+	// if supported. Otherwise, it should just return the minimum height.
+	// The result of this behavior may or may not be respected, depending on
+	// the situation.
+	RecommendedHeight (width int) int
+	// RecommendedWidth returns the recommended width for a given height, if
+	// supported. Otherwise, it should just return the minimum width. The
+	// result of this behavior may or may not be respected, depending on the
+	// situation.
+	RecommendedWidth (height int) int
 }
 
-// Window is an operating system window. It can contain one object.
+// Window is an operating system window. It can contain one object. Windows
+// themselves are completely transparent, and become opaque once an opaque
+// object is added as their root.
 type Window interface {
 	// SetRoot sets the root child of the window. There can only be one at
 	// a time, and setting it will remove the current child if there is one.
@@ -376,12 +312,24 @@ type Window interface {
 	SetTitle (string)
 	// SetIcon sets the icon of the window. When multiple icon sizes are
 	// provided, the best fitting one is chosen for display.
-	SetIcon (... image.Image)
+	SetIcon (... canvas.Texture)
+	// SetResizable sets whether the window can be resized by the user in
+	// the X and Y directions. If one or both axes are false, the ones that
+	// are will be shrunk to the window's minimum size.
+	SetResizable (x, y bool)
+	// SetBounds sets this window's bounds. This may or may not have any
+	// effect on the window's position on screen depending on the platform.
+	SetBounds (image.Rectangle)
 	// Widget returns a window representing a smaller iconified form of this
 	// window. How exactly this window is used depends on the platform.
 	// Subsequent calls to this method on the same window will return the
 	// same window object.
 	Widget () (Window, error)
+	// NewChild creates a new window that is semantically a child of this
+	// window. It does not actually reside within this window, but it may be
+	// linked to it via some other means. This is intended for things like
+	// toolboxes and tear-off menus.
+	NewChild (image.Rectangle) (Window, error)
 	// NewMenu creates a new menu window. This window is undecorated and
 	// will close once the user clicks outside of it.
 	NewMenu (image.Rectangle) (Window, error)
@@ -403,14 +351,3 @@ type Window interface {
 	// OnClose specifies a function to be called when the window is closed.
 	OnClose (func ()) event.Cookie
 }
-
-// MainWindow is a top-level operating system window.
-type MainWindow interface {
-	Window
-
-	// NewChild creates a new window that is semantically a child of this
-	// window. It does not actually reside within this window, but it may be
-	// linked to it via some other means. This is intended for things like
-	// toolboxes and tear-off menus.
-	NewChild (image.Rectangle) (Window, error)
-}

style.go

@@ -1,9 +1,7 @@
 package tomo
 
 import "fmt"
-import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/event"
-import "git.tebibyte.media/tomo/tomo/canvas"
 
 // Role describes the role of an object.
 type Role struct {
@@ -60,49 +58,26 @@ func (c Color) String () string {
 
 // RGBA satisfies the color.Color interface.
 func (id Color) RGBA () (r, g, b, a uint32) {
-	if theme == nil { return }
-	return theme.RGBA(id)
+	if style == nil { return }
+	return style.RGBA(id)
 }
 
-// Theme can apply a visual style to different objects.
-type Theme interface {
-	// A word on textures:
-	//
-	// Because textures can be linked to some resource that is outside of
-	// the control of Go's garbage collector, methods of Theme must not
-	// allocate new copies of a texture each time they are called. It is
-	// fine to lazily load textures and save them for later use, but the
-	// same texture must never be allocated multiple times as this could
-	// cause a memory leak.
-	//
-	// As such, textures returned by these methods must be protected.
-	
-	// Apply applies the theme to the given object, according to the given
-	// role. This may register event listeners with the given object;
-	// closing the returned cookie must remove them.
-	Apply (Object, Role) event.Cookie
+// Style can apply a visual style to different objects.
+type Style interface {
+	// Apply applies the theme to the given object, according to its role.
+	// This may register event listeners with the given object; closing the
+	// returned cookie must remove them.
+	Apply (Object) event.Cookie
 
 	// RGBA returns the RGBA values of the corresponding color ID.
 	RGBA (Color) (r, g, b, a uint32)
-
-	// Icon returns a texture of the corresponding icon ID.
-	Icon (Icon, IconSize) canvas.Texture
-
-	// MimeIcon returns an icon corresponding to a MIME type.
-	MimeIcon (data.Mime, IconSize) canvas.Texture
 }
 
-var theme Theme
+var style Style
 
-// SetTheme sets the theme.
-func SetTheme (them Theme) {
-	theme = them
-}
-
-// Apply applies the current theme to the given object, according to the given
-// role. This may register event listeners with the given object; closing the
-// returned cookie will remove them.
-func Apply (object Object, role Role) event.Cookie {
-	if theme == nil { return event.NoCookie { } }
-	return theme.Apply(object, role)
+// SetStyle sets the style.
+func SetStyle (sty Style) {
+	assertBackend()
+	style = sty
+	backend.SetStyle(sty)
 }

tomo.go

@@ -50,7 +50,7 @@ func Do (callback func ()) {
 }
 
 // NewWindow creates and returns a window within the specified bounds on screen.
-func NewWindow (bounds image.Rectangle) (MainWindow, error) {
+func NewWindow (bounds image.Rectangle) (Window, error) {
 	assertBackend()
 	return backend.NewWindow(bounds)
 }
@@ -58,7 +58,7 @@ func NewWindow (bounds image.Rectangle) (MainWindow, error) {
 // NewPlainWindow is like NewWindow, but it creates an undecorated window that
 // does not appear in window lists. It is intended for creating things like
 // docks, panels, etc.
-func NewPlainWindow (bounds image.Rectangle) (MainWindow, error) {
+func NewPlainWindow (bounds image.Rectangle) (Window, error) {
 	assertBackend()
 	return backend.NewPlainWindow(bounds)
 }
@@ -93,3 +93,10 @@ func NewTexture (source image.Image) canvas.TextureCloser {
 	assertBackend()
 	return backend.NewTexture(source)
 }
+
+// NewCanvas creates a new canvas with the specified bounds. When no longer in
+// use, it must be freed using Close().
+func NewCanvas (bounds image.Rectangle) canvas.CanvasCloser {
+	assertBackend()
+	return backend.NewCanvas(bounds)
+}

unit.go

@@ -0,0 +1,96 @@
+package tomo
+
+import "image"
+import "image/color"
+
+// Side represents one side of a rectangle.
+type Side int; const (
+	SideTop Side = iota
+	SideRight
+	SideBottom
+	SideLeft
+)
+
+// Inset represents a rectangle inset that can have a different value for each
+// side.
+type Inset [4]int
+
+// I allows you to create an inset in a CSS-ish way:
+//
+//   - One argument: all sides are set to this value
+//   - Two arguments: the top and bottom sides are set to the first value, and
+//     the left and right sides are set to the second value.
+//   - Three arguments: the top side is set by the first value, the left and
+//     right sides are set by the second vaue, and the bottom side is set by the
+//     third value.
+//   - Four arguments: each value corresponds to a side.
+//
+// This function will panic if an argument count that isn't one of these is
+// given.
+func I (sides ...int) Inset {
+	switch len(sides) {
+	case 1: return Inset { sides[0], sides[0], sides[0], sides[0] }
+	case 2: return Inset { sides[0], sides[1], sides[0], sides[1] }
+	case 3: return Inset { sides[0], sides[1], sides[2], sides[1] }
+	case 4: return Inset { sides[0], sides[1], sides[2], sides[3] }
+	default: panic("I: illegal argument count.")
+	}
+}
+
+// Apply returns the given rectangle, shrunk on all four sides by the given
+// inset. If a measurment of the inset is negative, that side will instead be
+// expanded outward. If the rectangle's dimensions cannot be reduced any
+// further, an empty rectangle near its center will be returned.
+func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) {
+	smaller = bigger
+	if smaller.Dx() < inset[3] + inset[1] {
+		smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2
+		smaller.Max.X = smaller.Min.X
+	} else {
+		smaller.Min.X += inset[3]
+		smaller.Max.X -= inset[1]
+	}
+
+	if smaller.Dy() < inset[0] + inset[2] {
+		smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2
+		smaller.Max.Y = smaller.Min.Y
+	} else {
+		smaller.Min.Y += inset[0]
+		smaller.Max.Y -= inset[2]
+	}
+	return
+}
+
+// Inverse returns a negated version of the inset.
+func (inset Inset) Inverse () (prime Inset) {
+	return Inset {
+		inset[0] * -1,
+		inset[1] * -1,
+		inset[2] * -1,
+		inset[3] * -1,
+	}
+}
+
+// Horizontal returns the sum of SideRight and SideLeft.
+func (inset Inset) Horizontal () int {
+	return inset[SideRight] + inset[SideLeft]
+}
+
+// Vertical returns the sum of SideTop and SideBottom.
+func (inset Inset) Vertical () int {
+	return inset[SideTop] + inset[SideBottom]
+}
+
+// Border represents a single border of a box.
+type Border struct {
+	Width Inset
+	Color [4]color.Color
+}
+
+// Align lists basic alignment types.
+type Align int; const (
+	AlignStart Align = iota // similar to left-aligned text
+	AlignMiddle             // similar to center-aligned text
+	AlignEnd                // similar to right-aligned text
+	AlignEven               // similar to justified text
+)