Change clip behaviors to sub behaviors

Remedies #4

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+indent_style = tab
+indent_size = 8
+charset = utf-8
+
+[*.md]
+indent_style = space
+indent_size = 2

README.md

@@ -1,6 +1,8 @@
 # tomo
 
-WIP rewrite of tomo.
+[![Go Reference](https://pkg.go.dev/badge/git.tebibyte.media/tomo/tomo.svg)](https://pkg.go.dev/git.tebibyte.media/tomo/tomo)
 
-This module will serve as a wafer-thin collection of interfaces and glue code so
-that plugins will be an actual viable concept.
+Tomo is a lightweight GUI toolkit written in pure Go. This repository defines
+the API that other components of the toolkit agree on. In order to use Tomo in
+an application, use [Nasin](https://git.tebibyte.media/tomo/nasin), which builds
+an application framework on top of Tomo.

backend.go

@@ -3,19 +3,39 @@ package tomo
 import "sort"
 import "image"
 import "errors"
+import "git.tebibyte.media/tomo/tomo/canvas"
 
+// Backend is any Tomo implementation. Backends handle window creation, layout,
+// rendering, and events so that there can be as many platform-specific
+// optimizations as possible.
 type Backend interface {
-	NewWindow       (image.Rectangle) (MainWindow, error)
+	// These methods create new objects. The backend must reject any object
+	// that was not made by it.
 	NewBox          () Box
 	NewTextBox      () TextBox
 	NewCanvasBox    () CanvasBox
 	NewContainerBox () ContainerBox
 
+	// NewWindow creates a normal MainWindow and returns it.
+	NewWindow (image.Rectangle) (MainWindow, 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)
+
+	// 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
+
+	// Run runs the event loop until Stop() is called, or the backend
+	// experiences a fatal error.
+	Run () error
+	
 	// Stop must unblock run.
-	Run  () error
 	Stop ()
 
-	// Do performs a callback function in the main thread as soon as
+	// Do performs a callback function in the event loop thread as soon as
 	// possible. This method must be safe to call concurrently.
 	Do (func ())
 }

canvas/canvas.go

@@ -8,45 +8,60 @@ import "image/color"
 
 // Cap represents a stroke cap type.
 type Cap int; const (
-	CapButt Cap = iota
-	CapRound
-	CapSquare
+	CapRound Cap = iota // Round cap that surrounds the point
+	CapSquare           // Square cap that surrounds the point
+	CapButt             // Square cap that ends at the point
 )
 
 // Joint represents a stroke joint type.
 type Joint int; const (
-	JointRount Joint = iota
-	JointSharp
-	JointMiter
+	JointRount Joint = iota // Rounded joint
+	JointSharp              // Sharp joint
+	JointMiter              // Clipped/beveled joint
 )
 
 // StrokeAlign determines whether a stroke is drawn inside, outside, or on a
 // path.
 type StrokeAlign int; const (
-	StrokeAlignCenter StrokeAlign = iota
-	StrokeAlignInner
-	StrokeAlignOuter
+	StrokeAlignCenter StrokeAlign = iota // Centered on the path
+	StrokeAlignInner                     // Inset into the path
+	StrokeAlignOuter                     // Outset around the path
 )
 
 // Pen represents a drawing context that is linked to a canvas. Each canvas can
 // have multiple pens associated with it, each maintaining their own drawing
-// context.
+// state.
 type Pen interface {
-	// Rectangle draws a rectangle
+	// Rectangle draws a rectangle.
 	Rectangle (image.Rectangle)
 
-	// Path draws a path
+	// Path draws a path, which is a series of connected points.
 	Path (points ...image.Point)
 
-	Closed       (bool)        // if the path is closed
-	Cap          (Cap)         // line cap stype
-	Joint        (Joint)       // line joint style
-	StrokeWeight (int)         // how thick the stroke is
-	StrokeAlign  (StrokeAlign) // where the stroke is drawn
+	// StrokeWeight sets how thick the stroke is. The default value is zero.
+	StrokeWeight (int)
+	// SetClosed sets whether the path is a closed shape, or has an open
+	// side. This only applies if the stroke weight is greater than zero.
+	Closed (bool)
+	// Cap sets how the ends of the stroke look. This only applies if the
+	// stroke weight is greater than zero, and if the path is not closed.
+	// The default value is CapRound.
+	Cap (Cap)
+	// Joint sets how bend points in the stroke look. This only applies if
+	// the stroke weight is greater than zero. The default value is
+	// JointRound.
+	Joint (Joint)
+	// StrokeAlign sets where the stroke is drawn in relation to the path.
+	// This only applies if the stroke weight is greater than zero. The
+	// default value is StrokeAlignCenter.
+	StrokeAlign (StrokeAlign)
 
-	// set the stroke/fill to a solid color
+	// Stroke sets the stroke to a solid color.
 	Stroke (color.Color)
-	Fill   (color.Color)
+	// Fill sets the fill to a solid color.
+	Fill (color.Color)
+	// Texture overlaps a texture onto the fill color.
+	Texture (Texture)
 }
 
 // Canvas is an image that supports drawing paths.
@@ -56,12 +71,15 @@ type Canvas interface {
 	// Pen returns a new pen for this canvas.
 	Pen () Pen
 
-	// Clip returns a new canvas that points to a specific area of this one.
-	Clip (image.Rectangle) Canvas
+	// SubCanvas returns a returns a Canvas representing the portion of this
+	// Canvas visible and drawable through a rectangle. The returned value
+	// shares pixels with the original Canvas.
+	SubCanvas (image.Rectangle) Canvas
 }
 
 // Drawer is an object that can draw to a canvas.
 type Drawer interface {
+	// Draw draws to the given canvas.
 	Draw (Canvas)
 }
 

canvas/texture.go

@@ -0,0 +1,21 @@
+package canvas
+
+import "io"
+import "image"
+
+// Texture is a handle that points to a 2D raster image managed by the backend.
+type Texture interface {
+	image.Image
+
+	// SubTexture returns a returns a Texture representing the portion of
+	// this Texture visible through a rectangle. The returned value shares
+	// pixels with the original Texture.
+	SubTexture (image.Rectangle) Texture
+}
+
+// TextureCloser is a texture that can be closed. Anything that receives a
+// TextureCloser must close it after use.
+type TextureCloser interface {
+	Texture
+	io.Closer
+}

data/data.go

@@ -27,7 +27,10 @@ func (mime Mime) String () string {
 	return mime.Type + "/" + mime.Subtype
 }
 
+// MimePlain returns the MIME type of plain text.
 func MimePlain () Mime { return Mime { "text", "plain"    } }
+
+// MimeFile returns the MIME type of a file path/URI.
 func MimeFile  () Mime { return Mime { "text", "uri-list" } }
 
 type byteReadCloser struct { *bytes.Reader }

event/event.go

@@ -45,6 +45,10 @@ func (broadcaster *Broadcaster[L]) ensure () {
 	}
 }
 
+// NoCookie is a cookie that does nothing when closed.
+type NoCookie struct { }
+func (NoCookie) Close () { }
+
 type cookie[L any] struct {
 	id int
 	broadcaster *Broadcaster[L]
@@ -65,3 +69,17 @@ func (broadcaster *FuncBroadcaster) Broadcast () {
 		listener()
 	}
 }
+
+type multiCookie []Cookie
+
+// MultiCookie creates a single cookie that, when closed, closes a list of other
+// cookies.
+func MultiCookie (cookies ...Cookie) Cookie {
+	return multiCookie(cookies)
+}
+
+func (cookies multiCookie) Close () {
+	for _, cookie := range cookies {
+		cookie.Close()
+	}
+}

go.mod

@@ -2,4 +2,4 @@ module git.tebibyte.media/tomo/tomo
 
 go 1.20
 
-require golang.org/x/image v0.8.0
+require golang.org/x/image v0.11.0

go.sum

@@ -3,6 +3,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 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=
 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=
@@ -26,6 +28,7 @@ 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=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=

input/input.go

@@ -59,6 +59,18 @@ const (
 	KeyF10 Key = 138
 	KeyF11 Key = 139
 	KeyF12 Key = 140
+	KeyF13 Key = 141
+	KeyF14 Key = 142
+	KeyF15 Key = 143
+	KeyF16 Key = 144
+	KeyF17 Key = 145
+	KeyF18 Key = 146
+	KeyF19 Key = 147
+	KeyF20 Key = 148
+	KeyF21 Key = 149
+	KeyF22 Key = 150
+	KeyF23 Key = 151
+	KeyF24 Key = 152
 )
 
 // Button represents a mouse button.

object.go

@@ -3,6 +3,7 @@ package tomo
 import "image"
 import "image/color"
 import "golang.org/x/image/font"
+import "git.tebibyte.media/tomo/tomo/text"
 import "git.tebibyte.media/tomo/tomo/data"
 import "git.tebibyte.media/tomo/tomo/event"
 import "git.tebibyte.media/tomo/tomo/input"
@@ -16,6 +17,8 @@ type Side int; const (
 	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:
@@ -84,11 +87,13 @@ 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
@@ -96,35 +101,86 @@ type Align int; const (
 	AlignEven               // similar to justified text
 )
 
-// Object is any obscreen object. Each object must be linked to a box, even if
+// Object is any onscreen object. Each object must be linked to a box, even if
 // it is that box.
 type Object interface {
-	Box () Box
+	GetBox () Box
 }
 
 // Box is a basic styled box.
 type Box interface {
 	Object
 
-	Window         () Window
-	Bounds         () image.Rectangle
-	InnerBounds    () image.Rectangle
-	MinimumSize    () image.Point
-	SetBounds      (image.Rectangle)
-	SetColor       (color.Color)
-	SetBorder      (...Border)
+	// Window returns the Window this Box is a part of.
+	Window () Window
+	// Bounds returns the outer bounding rectangle of the Box relative to
+	// the Window.
+	Bounds () image.Rectangle
+	// InnerBounds returns the inner bounding rectangle of the box. It is
+	// the value of Bounds inset by the Box's border and padding.
+	InnerBounds () image.Rectangle
+	// MinimumSize returns the minimum width and height this Box's bounds
+	// can be set to. This will return the value of whichever of these is
+	// greater:
+	//   - The size as set by SetMinimumSize
+	//   - The size taken up by the Box's border and padding. If there is
+	//     internal content that does not overflow, the size of that is also
+	//     taken into account here.
+	MinimumSize () image.Point
+	// SetBounds sets the bounding rectangle of this Box relative to the
+	// Window.
+	SetBounds (image.Rectangle)
+	// SetColor sets the background color of this Box.
+	SetColor (color.Color)
+	// SetTexture sets a repeating background texture. If the texture is
+	// transparent, it will be overlayed atop the color specified by
+	// SetColor().
+	SetTexture (canvas.Texture)
+	// SetBorder sets the Border(s) of the box. The first Border will be the
+	// most outset, and the last Border will be the most inset.
+	SetBorder (...Border)
+	// SetMinimumSize sets the minimum width and height of the box, as
+	// described in MinimumSize.
 	SetMinimumSize (image.Point)
-	SetPadding     (Inset)
+	// 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
 
-	SetDNDData   (data.Data)
+	// 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
+	// picked up.
+	SetDNDData (data.Data)
+	// SetDNDAccept sets the type of data that can be dropped onto this Box.
+	// If this is nil (which is the default), this Box will reject all
+	// drops.
 	SetDNDAccept (...data.Mime)
-	SetFocused   (bool)
+	// SetFocused sets whether or not this Box has keyboard focus. If set to
+	// true, this method will steal focus away from whichever Object
+	// currently has focus.
+	SetFocused (bool)
+	// SetFocusable sets whether or not this Box can receive keyboard focus.
+	// If set to false and the Box is already focused. the focus is removed.
 	SetFocusable (bool)
-	
-	Focused       () bool
-	Modifiers     () input.Modifiers
+
+	// Focused returns whether or not this Box has keyboard focus.
+	Focused () bool
+	// Modifiers returns which modifier keys on the keyboard are currently
+	// being held down.
+	Modifiers () input.Modifiers
+	// MousePosition returns the position of the mouse pointer relative to
+	// the Window.
 	MousePosition () image.Point
 
+	// These are event subscription functions that allow callbacks to be
+	// connected to particular events. Multiple callbacks may be connected
+	// to the same event at once. Callbacks can be removed by closing the
+	// returned cookie.
 	OnFocusEnter  (func ()) event.Cookie
 	OnFocusLeave  (func ()) event.Cookie
 	OnDNDEnter    (func ()) event.Cookie
@@ -143,7 +199,18 @@ type Box interface {
 // CanvasBox is a box that can be drawn to.
 type CanvasBox interface {
 	Box
-	SetDrawer  (canvas.Drawer)
+
+	// SetDrawer sets the Drawer that will be called upon to draw the Box's
+	// content when it is invalidated. The Canvas passed to the drawer will
+	// have these properties:
+	//   - It will have the same origin (0, 0) as the window which contains
+	//     the CanvasBox
+	//   - The Canvas bounds will describe the portion of the CanvasBox
+	//     visible on screen
+	SetDrawer (canvas.Drawer)
+
+	// Invalidate causes the Box's area to be redrawn at the end of the
+	// event cycle, even if it wouldn't be otherwise.
 	Invalidate ()
 }
 
@@ -151,9 +218,22 @@ type CanvasBox interface {
 // is to be embedded into TextBox and ContainerBox.
 type ContentBox interface {
 	Box
-	SetOverflow           (horizontal, vertical bool)
-	ContentBounds         () image.Rectangle
-	ScrollTo              (image.Point)
+
+	// SetOverflow sets whether or not the Box's content overflows
+	// horizontally and vertically. Overflowing content is clipped to the
+	// bounds of the Box inset by all Borders (but not padding).
+	SetOverflow (horizontal, vertical bool)
+	// SetAlign sets how the Box's content is distributed horizontally and
+	// vertically.
+	SetAlign (x, y Align)
+	// ContentBounds returns the bounds of the inner content of the Box
+	// relative to the Box's InnerBounds.
+	ContentBounds () image.Rectangle
+	// 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)
+	// OnContentBoundsChange specifies a function to be called when the
+	// Box's ContentBounds or InnerBounds changes.
 	OnContentBoundsChange (func ()) event.Cookie
 }
 
@@ -161,59 +241,136 @@ type ContentBox interface {
 type TextBox interface {
 	ContentBox
 
-	SetText      (string)
+	// SetText sets the text content of the Box.
+	SetText (string)
+	// SetTextColor sets the text color.
 	SetTextColor (color.Color)
-	SetFace      (font.Face)
-	SetHAlign    (Align)
-	SetVAlign    (Align)
+	// SetFace sets the font face text is rendered in.
+	SetFace (font.Face)
+	// SetWrap sets whether or not the text wraps.
+	SetWrap (bool)
+
+	// SetSelectable sets whether or not the text content can be
+	// highlighted/selected.
+	SetSelectable (bool)
+	// SetDotColor sets the highlight color of selected text.
+	SetDotColor (color.Color)
+	// Select sets the text cursor or selection.
+	Select (text.Dot)
+	// Dot returns the text cursor or selection.
+	Dot () text.Dot
+	// OnDotChange specifies a function to be called when the text cursor or
+	// selection changes.
+	OnDotChange (func ()) event.Cookie
 }
 
-// ContentBox is a box that can contain child objects. It arranges them
+// ContentBox is a box that can contain child Objects. It arranges them
 // according to a layout rule.
 type ContainerBox interface {
 	ContentBox
-	SetGap    (image.Point)
-	Add       (Object)
-	Delete    (Object)
-	Insert    (child Object, before Object)
-	Clear     ()
-	Length    () int
-	At        (int) Object
+
+	// SetGap sets the gap between child Objects.
+	SetGap (image.Point)
+	// Add appends a child Object. If the object is already a child of
+	// another object, it will be removed from that object first.
+	Add (Object)
+	// Remove removes a child Object, if it is a child of this Box.
+	Remove (Object)
+	// Insert inserts a child Object before a specified Object. If the
+	// before Object is nil or is not contained within this Box, the
+	// inserted Object is appended.
+	Insert (child Object, before Object)
+	// Clear removes all child Objects.
+	Clear ()
+	// Length returns the amount of child Objects.
+	Length () int
+	// At returns the child Object at the specified index.
+	At (int) Object
+	// SetLayout sets the layout of this Box. Child Objects will be
+	// positioned according to it.
 	SetLayout (Layout)
+
+	// These methods control whether certain user input events get
+	// propagated to child Objects. If set to true, the relevant events will
+	// be sent to this container. If set to false (which is the default),
+	// the events will be sent to the appropriate child Object.
+	CaptureDND      (bool)
+	CaptureMouse    (bool)
+	CaptureScroll   (bool)
+	CaptureKeyboard (bool)
 }
 
 // LayoutHints are passed to a layout to tell it how to arrange child boxes.
 type LayoutHints struct {
+	// Bounds is the bounding rectangle that children should be placed
+	// within. Any padding values are already applied.
 	Bounds image.Rectangle
+	// OverflowX and OverflowY control whether child Boxes may be positioned
+	// outside of Bounds.
 	OverflowX bool
 	OverflowY bool
+	// AlignX and AlignY control how child Boxes are aligned horizontally
+	// and vertically. The effect of this may vary depending on the Layout.
+	AlignX Align
+	AlignY Align
+	// Gap controls the amount of horizontal and vertical spacing in-between
+	// child Boxes.
 	Gap image.Point
 }
 
-// Layout can be given to a ContainerBox to arrange child objects.
+// A Layout can be given to a ContainerBox to arrange child objects.
 type Layout interface {
+	// MinimumSize returns the minimum width and height of
+	// LayoutHints.Bounds needed to properly lay out all child Boxes.
 	MinimumSize (LayoutHints, []Box) image.Point
-	Arrange     (LayoutHints, []Box)
+	// Arrange arranges child boxes according to the given LayoutHints.
+	Arrange (LayoutHints, []Box)
 }
 
 // Window is an operating system window. It can contain one object.
 type Window interface {
-	SetRoot  (Object)
+	// 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.
+	SetRoot (Object)
+	// SetTitle sets the title of the window.
 	SetTitle (string)
-	SetIcon  (sizes []image.Image)
-	NewMenu  (image.Rectangle) (Window, error)
+	// SetIcon sets the icon of the window. When multiple icon sizes are
+	// provided, the best fitting one is chosen for display.
+	SetIcon (... image.Image)
+	// 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)
+	// 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)
+	// NewModal creates a new modal window that blocks all input to this
+	// window until it is closed.
 	NewModal (image.Rectangle) (Window, error)
-	Widget   () (Window, error)
-	Copy     (data.Data)
-	Paste    (callback func (data.Data, error), accept ...data.Mime)
-	Show     ()
-	Hide     ()
-	Close    ()
-	OnClose  (func ()) event.Cookie
+	// Copy copies data to the clipboard.
+	Copy (data.Data)
+	// Paste reads data from the clipboard. When the data is available or an
+	// error has occurred, the provided function will be called.
+	Paste (callback func (data.Data, error), accept ...data.Mime)
+	// SetVisible sets whether or not this window is visible. Windows are
+	// invisible by default.
+	SetVisible (bool)
+	// Visible returns whether or not this window is visible.
+	Visible () bool
+	// Close closes the window.
+	Close ()
+	// 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)
 }

plugin.go

@@ -1,55 +0,0 @@
-package tomo
-
-import "os"
-import "plugin"
-import "path/filepath"
-
-var pluginPaths []string
-
-func loadPlugins () {
-	for _, dir := range pluginPaths {
-		if dir != "" {
-			loadPluginsFrom(dir)
-		}
-	}
-}
-
-func loadPluginsFrom (dir string) {
-	entries, err := os.ReadDir(dir)
-	// its no big deal if one of the dirs doesn't exist
-	if err != nil { return }
-
-	for _, entry := range entries {
-		if entry.IsDir() { continue }
-		if filepath.Ext(entry.Name()) != ".so" { continue }
-		pluginPath := filepath.Join(dir, entry.Name())
-		loadPlugin(pluginPath)
-	}
-}
-
-func loadPlugin (path string) {
-	die := func (reason string) {
-		println("tomo: could not load plugin at", path + ":", reason)
-	}
-
-	plugin, err := plugin.Open(path)
-	if err != nil {
-		die(err.Error())
-		return
-	}
-
-	// check for and obtain basic plugin functions
-	name, ok := extract[func () string](plugin, "Name")
-	if !ok { die("does not implement Name() string"); return }
-	_, ok = extract[func () string](plugin, "Description")
-	if !ok { die("does not implement Description() string"); return }
-
-	println("tomo: loaded plugin", name())
-}
-
-func extract[T any] (plugin *plugin.Plugin, name string) (value T, ok bool) {
-	symbol, err := plugin.Lookup(name)
-	if err != nil { return }
-	value, ok = symbol.(T)
-	return
-}

text/text.go

@@ -0,0 +1,248 @@
+package text
+
+import "unicode"
+
+// Dot represents a cursor or text selection. It has a start and end position,
+// referring to where the user began and ended the selection respectively.
+type Dot struct { Start, End int }
+
+// EmptyDot returns a zero-width dot at the specified position.
+func EmptyDot (position int) Dot {
+	return Dot { position, position }
+}
+
+// Canon places the lesser value at the start, and the greater value at the end.
+// Note that a canonized dot does not in all cases correspond directly to the
+// original, because there is a semantic value to the start and end positions.
+func (dot Dot) Canon () Dot {
+	if dot.Start > dot.End {
+		return Dot { dot.End, dot.Start }
+	} else {
+		return dot
+	}
+}
+
+// Empty returns whether or not the 
+func (dot Dot) Empty () bool {
+	return dot.Start == dot.End
+}
+
+// Add shifts the dot to the right by the specified amount.
+func (dot Dot) Add (delta int) Dot {
+	return Dot {
+		dot.Start + delta,
+		dot.End   + delta,
+	}
+}
+
+// Sub shifts the dot to the left by the specified amount.
+func (dot Dot) Sub (delta int) Dot {
+	return Dot {
+		dot.Start - delta,
+		dot.End   - delta,
+	}
+}
+
+// Constrain constrains the dot's start and end from zero to length (inclusive).
+func (dot Dot) Constrain (length int) Dot {
+	if dot.Start < 0      { dot.Start = 0      }
+	if dot.Start > length { dot.Start = length }
+	if dot.End   < 0      { dot.End   = 0      }
+	if dot.End   > length { dot.End   = length }
+	return dot
+}
+
+// Width returns how many runes the dot spans.
+func (dot Dot) Width () int {
+	dot = dot.Canon()
+	return dot.End - dot.Start
+}
+
+// Slice returns the subset of text that the dot covers.
+func (dot Dot) Slice (text []rune) []rune {
+	dot = dot.Canon().Constrain(len(text))
+	return text[dot.Start:dot.End]
+}
+
+// WordToLeft returns how far away to the left the next word boundary is from a
+// given position.
+func WordToLeft (text []rune, position int) (length int) {
+	if position < 1 { return }
+	if position > len(text) { position = len(text) }
+
+	index := position - 1
+	for index >= 0 && unicode.IsSpace(text[index]) {
+		length ++
+		index --
+	}
+	for index >= 0 && !unicode.IsSpace(text[index]) {
+		length ++
+		index --
+	}
+	return
+}
+
+// WordToRight returns how far away to the right the next word boundary is from
+// a given position.
+func WordToRight (text []rune, position int) (length int) {
+	if position < 0 { return }
+	if position > len(text) { position = len(text) }
+
+	index := position
+	for index < len(text) && unicode.IsSpace(text[index]) {
+		length ++
+		index ++
+	}
+	for index < len(text) && !unicode.IsSpace(text[index]) {
+		length ++
+		index ++
+	}
+	return
+}
+
+// WordAround returns a dot that surrounds the word at the specified position.
+func WordAround (text []rune, position int) (around Dot) {
+	return Dot {
+		position - WordToLeft(text, position),
+		position + WordToRight(text, position),
+	}
+}
+
+// Backspace deletes the rune to the left of the dot. If word is true, it
+// deletes up until the next word boundary on the left. If the dot is non-empty,
+// it deletes the text inside of the dot.
+func Backspace (text []rune, dot Dot, word bool) (result []rune, moved Dot) {
+	dot = dot.Constrain(len(text))
+	if dot.Empty() {
+		distance := 1
+		if word {
+			distance = WordToLeft(text, dot.End)
+		}
+		result = append (
+			result,
+			text[:dot.Sub(distance).Constrain(len(text)).End]...)
+		result = append(result, text[dot.End:]...)
+		moved = EmptyDot(dot.Sub(distance).Start)
+		return
+	} else {
+		return Delete(text, dot, word)
+	}
+}
+
+// Delete deletes the rune to the right of the dot. If word is true, it deletes
+// up until the next word boundary on the right. If the dot is non-empty, it
+// deletes the text inside of the dot.
+func Delete (text []rune, dot Dot, word bool) (result []rune, moved Dot) {
+	dot = dot.Constrain(len(text))
+	if dot.Empty() {
+		distance := 1
+		if word {
+			distance = WordToRight(text, dot.End)
+		}
+		result = append(result, text[:dot.End]...)
+		result = append (
+			result,
+			text[dot.Add(distance).Constrain(len(text)).End:]...)
+		moved = dot
+		return	
+	} else {
+		dot = dot.Canon()
+		result = append(result, text[:dot.Start]...)
+		result = append(result, text[dot.End:]...)
+		moved = EmptyDot(dot.Start)
+		return
+	}
+}
+
+// Lift removes the section of text inside of the dot, and returns a copy of it.
+func Lift (text []rune, dot Dot) (result []rune, moved Dot, lifted []rune) {
+	dot = dot.Constrain(len(text))
+	if dot.Empty() {
+		moved = dot
+		return
+	}
+
+	dot = dot.Canon()
+	lifted = make([]rune, dot.Width())
+	copy(lifted, dot.Slice(text))
+	result = append(result, text[:dot.Start]...)
+	result = append(result, text[dot.End:]...)
+	moved = EmptyDot(dot.Start)
+	return
+}
+
+// Type inserts one of more runes into the text at the dot position. If the dot
+// is non-empty, it replaces the text inside of the dot with the new runes.
+func Type (text []rune, dot Dot, characters ...rune) (result []rune, moved Dot) {
+	dot = dot.Constrain(len(text))
+	if dot.Empty() {
+		result = append(result, text[:dot.End]...)
+		result = append(result, characters...)
+		if dot.End < len(text) {
+			result = append(result, text[dot.End:]...)
+		}
+		moved = EmptyDot(dot.Add(len(characters)).End)
+		return
+	} else {
+		dot = dot.Canon()
+		result = append(result, text[:dot.Start]...)
+		result = append(result, characters...)
+		result = append(result, text[dot.End:]...)
+		moved = EmptyDot(dot.Add(len(characters)).Start)
+		return
+	}
+}
+
+// MoveLeft moves the dot left one rune. If word is true, it moves the dot to
+// the next word boundary on the left.
+func MoveLeft (text []rune, dot Dot, word bool) (moved Dot) {
+	dot = dot.Canon().Constrain(len(text))
+	distance := 0
+	if dot.Empty() {
+		distance = 1
+	}
+	if word {
+		distance = WordToLeft(text, dot.Start)
+	}
+	moved = EmptyDot(dot.Sub(distance).Start)
+	return
+}
+
+// MoveRight moves the dot right one rune. If word is true, it moves the dot to
+// the next word boundary on the right.
+func MoveRight (text []rune, dot Dot, word bool) (moved Dot) {
+	dot = dot.Canon().Constrain(len(text))
+	distance := 0
+	if dot.Empty() {
+		distance = 1
+	}
+	if word {
+		distance = WordToRight(text, dot.End)
+	}
+	moved = EmptyDot(dot.Add(distance).End)
+	return
+}
+
+// SelectLeft moves the end of the dot left one rune. If word is true, it moves
+// the end of the dot to the next word boundary on the left.
+func SelectLeft (text []rune, dot Dot, word bool) (moved Dot) {
+	dot = dot.Constrain(len(text))
+	distance := 1
+	if word {
+		distance = WordToLeft(text, dot.End)
+	}
+	dot.End -= distance
+	return dot
+}
+
+// SelectRight moves the end of the dot right one rune. If word is true, it
+// moves the end of the dot to the next word boundary on the right.
+func SelectRight (text []rune, dot Dot, word bool) (moved Dot) {
+	dot = dot.Constrain(len(text))
+	distance := 1
+	if word {
+		distance = WordToRight(text, dot.End)
+	}
+	dot.End += distance
+	return dot
+}

theme/icon.go

@@ -0,0 +1,278 @@
+package theme
+
+import "git.tebibyte.media/tomo/tomo/data"
+import "git.tebibyte.media/tomo/tomo/canvas"
+
+// IconSize represents the size of an icon.
+type IconSize int; const (
+	IconSizeSmall IconSize = iota;
+	IconSizeMedium
+	IconSizeLarge
+)
+
+// String satisfies the fmt.Stringer interface.
+func (size IconSize) String () string {
+	switch size {
+	case IconSizeSmall:  return "small"
+	case IconSizeMedium: return "medium"
+	case IconSizeLarge:  return "large"
+	default:             return "unknown"
+	}
+}
+
+// Icon represents an icon ID.
+type Icon string
+
+// A list of standard icon IDs.
+const (
+	IconUnknown                      Icon = ""
+
+	// objects: files
+	IconFile                         Icon = "File" // generic
+	IconDirectory                    Icon = "Directory"
+	IconDirectoryFull                Icon = "DirectoryFull"
+
+	// objects: places
+	IconPlaceHome                    Icon = "PlaceHome"
+	IconPlaceDownloads               Icon = "PlaceDownloads"
+	IconPlacePhotos                  Icon = "PlacePhotos"
+	IconPlaceBooks                   Icon = "PlaceBooks"
+	IconPlaceDocuments               Icon = "PlaceDocuments"
+	IconPlaceRepositories            Icon = "PlaceRepositories"
+	IconPlaceMusic                   Icon = "PlaceMusic"
+	IconPlaceArchives                Icon = "PlaceArchives"
+	IconPlaceFonts                   Icon = "PlaceFonts"
+	IconPlaceBinaries                Icon = "PlaceBinaries"
+	IconPlaceVideos                  Icon = "PlaceVideos"
+	IconPlace3DObjects               Icon = "Place3DObjects"
+	IconPlaceHistory                 Icon = "PlaceHistory"
+	IconPlacePreferences             Icon = "PlacePreferences"
+
+	// objects: storage
+	IconStorage                      Icon = "Storage" // generic
+	IconStorageMagneticTape          Icon = "StorageMagneticTape"
+	IconStorageFloppyDisk            Icon = "StorageFloppyDisk"
+	IconStorageHardDisk              Icon = "StorageHardDisk"
+	IconStorageSolidStateDisk        Icon = "StorageSolidState"
+	IconStorageFlashStick            Icon = "StorageFlashStick"
+	IconStorageFlashCard             Icon = "StorageFlashCard"
+	IconStorageROM                   Icon = "StorageROM"
+	IconStorageRAM                   Icon = "StorageRAM"
+	IconStorageCD                    Icon = "StorageCD"
+	IconStorageDVD                   Icon = "StorageDVD"
+
+	// objects: applications
+	// Keep these in sync with nasin.ApplicationRole!
+	IconApplication                  Icon = "Application" // generic
+	IconApplicationWebBrowser        Icon = "ApplicationWebBrowser"
+	IconApplicationMesssanger        Icon = "ApplicationMesssanger"
+	IconApplicationPhone             Icon = "ApplicationPhone"
+	IconApplicationMail              Icon = "ApplicationMail"
+	IconApplicationTerminalEmulator  Icon = "ApplicationTerminalEmulator"
+	IconApplicationFileBrowser       Icon = "ApplicationFileBrowser"
+	IconApplicationTextEditor        Icon = "ApplicationTextEditor"
+	IconApplicationDocumentViewer    Icon = "ApplicationDocumentViewer"
+	IconApplicationWordProcessor     Icon = "ApplicationWordProcessor"
+	IconApplicationSpreadsheet       Icon = "ApplicationSpreadsheet"
+	IconApplicationSlideshow         Icon = "ApplicationSlideshow"
+	IconApplicationCalculator        Icon = "ApplicationCalculator"
+	IconApplicationPreferences       Icon = "ApplicationPreferences"
+	IconApplicationProcessManager    Icon = "ApplicationProcessManager"
+	IconApplicationSystemInformation Icon = "ApplicationSystemInformation"
+	IconApplicationManual            Icon = "ApplicationManual"
+	IconApplicationCamera            Icon = "ApplicationCamera"
+	IconApplicationImageViewer       Icon = "ApplicationImageViewer"
+	IconApplicationMediaPlayer       Icon = "ApplicationMediaPlayer"
+	IconApplicationImageEditor       Icon = "ApplicationImageEditor"
+	IconApplicationAudioEditor       Icon = "ApplicationAudioEditor"
+	IconApplicationVideoEditor       Icon = "ApplicationVideoEditor"
+	IconApplicationClock             Icon = "ApplicationClock"
+	IconApplicationCalendar          Icon = "ApplicationCalendar"
+	IconApplicationChecklist         Icon = "ApplicationChecklist"
+
+	// objects: networks
+	IconNetwork                      Icon = "Network" // generic
+	IconNetworkLocal                 Icon = "NetworkLocal"
+	IconNetworkInternet              Icon = "NetworkInternet"
+	IconNetworkEthernet              Icon = "NetworkEthernet"
+	IconNetworkWireless              Icon = "NetworkWireless"
+	IconNetworkCell                  Icon = "NetworkCell"
+	IconNetworkBluetooth             Icon = "NetworkBluetooth"
+	IconNetworkRadio                 Icon = "NetworkRadio"
+
+	// objects: devices
+	IconDevice                       Icon = "Device" // generic
+	IconDeviceRouter                 Icon = "DeviceRouter"
+	IconDeviceServer                 Icon = "DeviceServer"
+	IconDeviceDesktop                Icon = "DeviceDesktop"
+	IconDeviceLaptop                 Icon = "DeviceLaptop"
+	IconDeviceTablet                 Icon = "DeviceTablet"
+	IconDevicePhone                  Icon = "DevicePhone"
+	IconDeviceWatch                  Icon = "DeviceWatch"
+	IconDeviceCamera                 Icon = "DeviceCamera"
+
+	// objects: peripherals
+	IconPeripheral                   Icon = "Peripheral" // generic
+	IconPeripheralKeyboard           Icon = "PeripheralKeyboard"
+	IconPeripheralMouse              Icon = "PeripheralMouse"
+	IconPeripheralMonitor            Icon = "PeripheralMonitor"
+	IconPeripheralWebcam             Icon = "PeripheralWebcam"
+	IconPeripheralMicrophone         Icon = "PeripheralMicrophone"
+	IconPeripheralSpeaker            Icon = "PeripheralSpeaker"
+	IconPeripheralPenTablet          Icon = "PeripheralPenTablet"
+	IconPeripheralTrackpad           Icon = "PeripheralTrackpad"
+	IconPeripheralController         Icon = "PeripheralController"
+
+	// objects: i/o
+	IconPort                         Icon = "Port" // generic
+	IconPortEthernet                 Icon = "PortEthernet"
+	IconPortUSB                      Icon = "PortUSB"
+	IconPortParallel                 Icon = "PortParallel"
+	IconPortSerial                   Icon = "PortSerial"
+	IconPortPS2                      Icon = "PortPS2"
+	IconPortDisplay                  Icon = "PortDisplay"
+	IconPortCGA                      Icon = "PortCGA"
+	IconPortVGA                      Icon = "PortVGA"
+	IconPortHDMI                     Icon = "PortHDMI"
+	IconPortDisplayPort              Icon = "PortDisplayPort"
+	IconPortInfrared                 Icon = "PortInfrared"
+
+	// actions: files
+	IconActionOpen                   Icon = "ActionOpen"
+	IconActionOpenIn                 Icon = "ActionOpenIn"
+	IconActionSave                   Icon = "ActionSave"
+	IconActionSaveAs                 Icon = "ActionSaveAs"
+	IconActionPrint                  Icon = "ActionPrint"
+	IconActionNew                    Icon = "ActionNew"
+	IconActionNewDirectory           Icon = "ActionNewDirectory"
+	IconActionDelete                 Icon = "ActionDelete"
+	IconActionRename                 Icon = "ActionRename"
+	IconActionGetInformation         Icon = "ActionGetInformation"
+	IconActionChangePermissions      Icon = "ActionChangePermissions"
+	IconActionRevert                 Icon = "ActionRevert"
+
+	// actions: list management
+	IconActionAdd                    Icon = "ActionAdd"
+	IconActionRemove                 Icon = "ActionRemove"
+	IconActionAddBookmark            Icon = "ActionAddBookmark"
+	IconActionRemoveBookmark         Icon = "ActionRemoveBookmark"
+	IconActionAddFavorite            Icon = "ActionAddFavorite"
+	IconActionRemoveFavorite         Icon = "ActionRemoveFavorite"
+
+	// actions: media
+	IconActionPlay                   Icon = "ActionPlay"
+	IconActionPause                  Icon = "ActionPause"
+	IconActionStop                   Icon = "ActionStop"
+	IconActionFastForward            Icon = "ActionFastForward"
+	IconActionRewind                 Icon = "ActionRewind"
+	IconActionToBeginning            Icon = "ActionToBeginning"
+	IconActionToEnd                  Icon = "ActionToEnd"
+	IconActionRecord                 Icon = "ActionRecord"
+	IconActionVolumeUp               Icon = "ActionVolumeUp"
+	IconActionVolumeDown             Icon = "ActionVolumeDown"
+	IconActionMute                   Icon = "ActionMute"
+
+	// actions: editing
+	IconActionUndo                   Icon = "ActionUndo"
+	IconActionRedo                   Icon = "ActionRedo"
+	IconActionCut                    Icon = "ActionCut"
+	IconActionCopy                   Icon = "ActionCopy"
+	IconActionPaste                  Icon = "ActionPaste"
+	IconActionFind                   Icon = "ActionFind"
+	IconActionReplace                Icon = "ActionReplace"
+	IconActionSelectAll              Icon = "ActionSelectAll"
+	IconActionSelectNone             Icon = "ActionSelectNone"
+	IconActionIncrement              Icon = "ActionIncrement"
+	IconActionDecrement              Icon = "ActionDecrement"
+
+	// actions: window management
+	IconActionClose                  Icon = "ActionClose"
+	IconActionQuit                   Icon = "ActionQuit"
+	IconActionIconify                Icon = "ActionIconify"
+	IconActionShade                  Icon = "ActionShade"
+	IconActionMaximize               Icon = "ActionMaximize"
+	IconActionFullScreen             Icon = "ActionFullScreen"
+	IconActionRestore                Icon = "ActionRestore"
+
+	// actions: view
+	IconActionExpand                 Icon = "ActionExpand"
+	IconActionContract               Icon = "ActionContract"
+	IconActionBack                   Icon = "ActionBack"
+	IconActionForward                Icon = "ActionForward"
+	IconActionUp                     Icon = "ActionUp"
+	IconActionDown                   Icon = "ActionDown"
+	IconActionReload                 Icon = "ActionReload"
+	IconActionZoomIn                 Icon = "ActionZoomIn"
+	IconActionZoomOut                Icon = "ActionZoomOut"
+	IconActionZoomReset              Icon = "ActionZoomReset"
+	IconActionMove                   Icon = "ActionMove"
+	IconActionResize                 Icon = "ActionResize"
+	IconActionGoTo                   Icon = "ActionGoTo"
+
+	// actions: tools
+	IconActionTransform              Icon = "ActionTransform"
+	IconActionTranslate              Icon = "ActionTranslate"
+	IconActionRotate                 Icon = "ActionRotate"
+	IconActionScale                  Icon = "ActionScale"
+	IconActionWarp                   Icon = "ActionWarp"
+	IconActionCornerPin              Icon = "ActionCornerPin"
+	IconActionSelectRectangle        Icon = "ActionSelectRectangle"
+	IconActionSelectEllipse          Icon = "ActionSelectEllipse"
+	IconActionSelectLasso            Icon = "ActionSelectLasso"
+	IconActionSelectGeometric        Icon = "ActionSelectGeometric"
+	IconActionSelectAuto             Icon = "ActionSelectAuto"
+	IconActionCrop                   Icon = "ActionCrop"
+	IconActionFill                   Icon = "ActionFill"
+	IconActionGradient               Icon = "ActionGradient"
+	IconActionPencil                 Icon = "ActionPencil"
+	IconActionBrush                  Icon = "ActionBrush"
+	IconActionEraser                 Icon = "ActionEraser"
+	IconActionText                   Icon = "ActionText"
+	IconActionEyedropper             Icon = "ActionEyedropper"
+
+	// status: dialog
+	IconStatusInformation            Icon = "StatusInformation"
+	IconStatusQuestion               Icon = "StatusQuestion"
+	IconStatusWarning                Icon = "StatusWarning"
+	IconStatusError                  Icon = "StatusError"
+	IconStatusCancel                 Icon = "StatusCancel"
+	IconStatusOkay                   Icon = "StatusOkay"
+
+	// status: network
+	IconStatusCellSignal0            Icon = "StatusCellSignal0"
+	IconStatusCellSignal1            Icon = "StatusCellSignal1"
+	IconStatusCellSignal2            Icon = "StatusCellSignal2"
+	IconStatusCellSignal3            Icon = "StatusCellSignal3"
+	IconStatusWirelessSignal0        Icon = "StatusWirelessSignal0"
+	IconStatusWirelessSignal1        Icon = "StatusWirelessSignal1"
+	IconStatusWirelessSignal2        Icon = "StatusWirelessSignal2"
+	IconStatusWirelessSignal3        Icon = "StatusWirelessSignal3"
+
+	// status: power
+	IconStatusBattery0               Icon = "StatusBattery0"
+	IconStatusBattery1               Icon = "StatusBattery1"
+	IconStatusBattery2               Icon = "StatusBattery2"
+	IconStatusBattery3               Icon = "StatusBattery3"
+	IconStatusBrightness0            Icon = "StatusBrightness0"
+	IconStatusBrightness1            Icon = "StatusBrightness1"
+	IconStatusBrightness2            Icon = "StatusBrightness2"
+	IconStatusBrightness3            Icon = "StatusBrightness3"
+
+	// status: media
+	IconStatusVolume0                Icon = "StatusVolume0"
+	IconStatusVolume1                Icon = "StatusVolume1"
+	IconStatusVolume2                Icon = "StatusVolume2"
+	IconStatusVolume3                Icon = "StatusVolume3"
+)
+
+// Texture returns a texture of the corresponding icon ID.
+func (id Icon) Texture (size IconSize) canvas.Texture {
+	if current == nil { return nil }
+	return current.Icon(id, size)
+}
+
+// MimeIcon returns an icon corresponding to a MIME type.
+func MimeIcon (mime data.Mime, size IconSize) canvas.Texture {
+	if current == nil { return nil }
+	return current.MimeIcon(mime, size)
+}

theme/theme.go

@@ -0,0 +1,109 @@
+package theme
+
+import "fmt"
+import "git.tebibyte.media/tomo/tomo"
+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 {
+	// Package is an optional namespace field. If specified, it should be
+	// the package name or module name the object is from.
+	Package string
+
+	// Object specifies what type of object it is. For example:
+	//   - TextInput
+	//   - Table
+	//   - Label
+	//   - Dial
+	// This should correspond directly to the type name of the object.
+	Object string
+
+	// Variant is an optional field to be used when an object has one or
+	// more soft variants under one type. For example, an object "Slider"
+	// may have variations "horizontal" and "vertical".
+	Variant string
+}
+
+// String satisfies the fmt.Stringer interface.
+// It follows the format of:
+// Package.Object[Variant]
+func (r Role) String () string {
+	return fmt.Sprintf("%s.%s[%s]", r.Package, r.Object, r.Variant)
+}
+
+// R is shorthand for creating a Role structure.
+func R (pack, object, variant string) Role {
+	return Role { Package: pack, Object: object, Variant: variant }
+}
+
+// Color represents a color ID.
+type Color int; const (
+	ColorBackground Color = iota
+	ColorForeground
+	ColorRaised
+	ColorSunken
+	ColorAccent
+)
+
+// String satisfies the fmt.Stringer interface.
+func (c Color) String () string {
+	switch c {
+	case ColorBackground: return "background"
+	case ColorForeground: return "foreground"
+	case ColorRaised:     return "raised"
+	case ColorSunken:     return "sunken"
+	case ColorAccent:     return "accent"
+	default:              return "unknown"
+	}
+}
+
+// RGBA satisfies the color.Color interface.
+func (id Color) RGBA () (r, g, b, a uint32) {
+	if current == nil { return }
+	return current.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 (tomo.Object, Role) 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 current Theme
+
+// SetTheme sets the theme.
+func SetTheme (theme Theme) {
+	current = theme
+}
+
+// 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 tomo.Object, role Role) event.Cookie {
+	if current == nil { return event.NoCookie { } }
+	return current.Apply(object, role)
+}

tomo.go

@@ -1,23 +1,27 @@
 package tomo
 
+import "sync"
 import "image"
 import "errors"
+import "git.tebibyte.media/tomo/tomo/canvas"
 
+var backendLock sync.Mutex
 var backend Backend
 
 // Run initializes a backend, runs the specified callback function, and runs the
 // event loop in that order. This function blocks until Stop is called, or the
 // backend experiences a fatal error.
 func Run (callback func ()) error {
-	loadPlugins()
-
 	if backend != nil {
 		return errors.New("there is already a backend running")
 	}
 
 	back, err := Initialize()
 	if err != nil { return err }
+	
+	backendLock.Lock()
 	backend = back
+	backendLock.Unlock()
 
 	callback()
 	return backend.Run()
@@ -32,30 +36,60 @@ func assertBackend () {
 func Stop () {
 	assertBackend()
 	backend.Stop()
+	
+	backendLock.Lock()
 	backend = nil
+	backendLock.Unlock()
 }
 
+// Do performs a callback function in the event loop thread as soon as possible.
+func Do (callback func ()) {
+	backendLock.Lock()
+	if backend != nil { backend.Do(callback) }
+	backendLock.Unlock()
+}
+
+// NewWindow creates and returns a window within the specified bounds on screen.
 func NewWindow (bounds image.Rectangle) (MainWindow, error) {
 	assertBackend()
 	return backend.NewWindow(bounds)
 }
 
+// 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) {
+	assertBackend()
+	return backend.NewPlainWindow(bounds)
+}
+
+// NewBox creates and returns a basic Box.
 func NewBox () Box {
 	assertBackend()
 	return backend.NewBox()
 }
 
+// NewTextBox creates and returns a Box that can display text.
 func NewTextBox () TextBox {
 	assertBackend()
 	return backend.NewTextBox()
 }
 
+// NewCanvasBox creates and returns a Box that can display custom graphics.
 func NewCanvasBox () CanvasBox {
 	assertBackend()
 	return backend.NewCanvasBox()
 }
 
+// NewContainerBox creates and returns a Box that can contain other boxes.
 func NewContainerBox () ContainerBox {
 	assertBackend()
 	return backend.NewContainerBox()
 }
+
+// NewTexture creates a new texture from an image. When no longer in use, it
+// must be freed using Close().
+func NewTexture (source image.Image) canvas.TextureCloser {
+	assertBackend()
+	return backend.NewTexture(source)
+}

unix.go

@@ -1,22 +0,0 @@
-//go:build linux || darwin || freebsd
-
-package tomo
-
-import "os"
-import "strings"
-import "path/filepath"
-
-func init () {
-	pathVariable := os.Getenv("TOMO_PLUGIN_PATH")
-	pluginPaths = strings.Split(pathVariable, ":")
-	pluginPaths = append (
-		pluginPaths,
-		"/usr/lib/tomo/plugins",
-		"/usr/local/lib/tomo/plugins")
-	homeDir, err := os.UserHomeDir()
-	if err == nil {
-		pluginPaths = append (
-			pluginPaths,
-			filepath.Join(homeDir, ".local/lib/tomo/plugins"))
-	}
-}