backend.go

@@ -1,7 +1,6 @@
 package tomo
 
 import "errors"
-import "git.tebibyte.media/sashakoshka/tomo/data"
 import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/elements"
@@ -24,12 +23,6 @@ type Backend interface {
 	// and returns a struct representing it that fulfills the MainWindow
 	// interface.
 	NewWindow (width, height int) (window elements.MainWindow, err error)
-
-	// Copy puts data into the clipboard.
-	Copy (data.Data)
-
-	// Paste returns the data currently in the clipboard.
-	Paste (accept []data.Mime) (data.Data)
 	
 	// SetTheme sets the theme of all open windows.
 	SetTheme (theme.Theme)

backends/x/event.go

@@ -235,6 +235,39 @@ func (window *window) handleMotionNotify (
 	}
 }
 
+func (window *window) handleSelectionNotify (
+	connection *xgbutil.XUtil,
+	event xevent.SelectionNotifyEvent,
+) {
+	if window.selectionRequest == nil { return }
+	window.selectionRequest.handleSelectionNotify(connection, event)
+	if !window.selectionRequest.open() { window.selectionRequest = nil }
+}
+
+func (window *window) handlePropertyNotify (
+	connection *xgbutil.XUtil,
+	event xevent.PropertyNotifyEvent,
+) {
+	if window.selectionRequest == nil { return }
+	window.selectionRequest.handlePropertyNotify(connection, event)
+	if !window.selectionRequest.open() { window.selectionRequest = nil }
+}
+
+func (window *window) handleSelectionClear (
+	connection *xgbutil.XUtil,
+	event xevent.SelectionClearEvent,
+) {
+	window.selectionClaim = nil
+}
+
+func (window *window) handleSelectionRequest (
+	connection *xgbutil.XUtil,
+	event xevent.SelectionRequestEvent,
+) {
+	if window.selectionClaim == nil { return }
+	window.selectionClaim.handleSelectionRequest(connection, event)
+}
+
 func (window *window) compressExpose (
 	firstEvent xproto.ExposeEvent,
 ) (

backends/x/selection.go

@@ -0,0 +1,363 @@
+package x
+
+import "errors"
+import "strings"
+import "github.com/jezek/xgb"
+import "github.com/jezek/xgbutil"
+import "github.com/jezek/xgb/xproto"
+import "github.com/jezek/xgbutil/xprop"
+import "github.com/jezek/xgbutil/xevent"
+import "git.tebibyte.media/sashakoshka/tomo/data"
+
+const clipboardName = "CLIPBOARD"
+
+type selReqState int; const (
+	selReqStateClosed selReqState = iota
+	selReqStateAwaitTargets
+	selReqStateAwaitValue
+	selReqStateAwaitChunk
+)
+
+type selectionRequest struct {
+	state       selReqState
+	window      *window
+	source      xproto.Atom
+	destination xproto.Atom
+	accept      []data.Mime
+	incrBuffer  []byte
+	incrMime    data.Mime
+	callback func (data.Data, error)
+}
+
+func (window *window) newSelectionRequest (
+	source, destination xproto.Atom,
+	callback func (data.Data, error),
+	accept ...data.Mime,
+) (
+	request *selectionRequest,
+) {
+	request = &selectionRequest {
+		source:      source,
+		destination: destination,
+		window:      window,
+		accept:      accept,
+		callback:    callback,
+	}
+
+	targets, err := xprop.Atm(window.backend.connection, "TARGETS")
+	if err != nil { request.die(err); return }
+	request.convertSelection(targets, selReqStateAwaitTargets)
+	return
+}
+
+func (request *selectionRequest) convertSelection (
+	target xproto.Atom, switchTo selReqState,
+) {
+	// The requestor should set the property argument to the name of a
+	// property that the owner can use to report the value of the selection.
+	// Requestors should ensure that the named property does not exist on
+	// the window before issuing the ConvertSelection. The exception to this
+	// rule is when the requestor intends to pass parameters with the
+	// request. Some targets may be defined such that requestors can pass
+	// parameters along with the request. If the requestor wishes to provide
+	// parameters to a request, they should be placed in the specified
+	// property on the requestor window before the requestor issues the
+	// ConvertSelection request, and this property should be named in the
+	// request.
+	err := xproto.DeletePropertyChecked (
+		request.window.backend.connection.Conn(),
+		request.window.xWindow.Id,
+		request.destination).Check()
+	if err != nil { request.die(err); return }
+
+	// The selection argument specifies the particular selection involved,
+	// and the target argument specifies the required form of the
+	// information. For information about the choice of suitable atoms to
+	// use, see section 2.6. The requestor should set the requestor argument
+	// to a window that it created; the owner will place the reply property
+	// there. The requestor should set the time argument to the timestamp on
+	// the event that triggered the request for the selection value. Note
+	// that clients should not specify CurrentTime*.
+	err = xproto.ConvertSelectionChecked (
+		request.window.backend.connection.Conn(),
+		request.window.xWindow.Id,
+		request.source,
+		target,
+		request.destination,
+		// TODO: *possibly replace this zero with an actual timestamp
+		// received from the server. this is non-trivial as we cannot
+		// rely on the timestamp of the last received event, because
+		// there is a possibility that this method is invoked
+		// asynchronously from within tomo.Do().
+		0).Check()
+	if err != nil { request.die(err); return }
+	
+	request.state = switchTo
+}
+
+func (request *selectionRequest) die (err error) {
+	request.callback(nil, err)
+	request.state = selReqStateClosed
+}
+
+func (request *selectionRequest) finalize (data data.Data) {
+	request.callback(data, nil)
+	request.state = selReqStateClosed
+}
+
+func (request *selectionRequest) open () bool {
+	return request.state != selReqStateClosed
+}
+
+type confidence int; const (
+	confidenceNone confidence = iota
+	confidencePartial
+	confidenceFull
+)
+
+func targetToMime (name string) (data.Mime, confidence) {
+	// TODO: add other stuff. reference this table:
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.6.2
+	// perhaps we should also have parameters for mime types so we can
+	// return an encoding here for things like STRING?
+	switch name {
+	case "ADOBE_PORTABLE_DOCUMENT_FORMAT":
+		return data.M("application", "pdf"), confidenceFull
+	case "APPLE_PICT":
+		return data.M("image", "pict"), confidenceFull
+	case
+		"POSTSCRIPT",
+		"ENCAPSULATED_POSTSCRIPT",
+		"ENCAPSULATED_POSTSCRIPT_INTERCHANGE":
+		return data.M("application", "postscript"), confidenceFull
+	case "FILE_NAME":
+		return data.MimeFile, confidenceFull
+	case "UTF8_STRING":
+		return data.MimePlain, confidenceFull
+	case "TEXT":
+		return data.MimePlain, confidencePartial
+	case "STRING":
+		return data.MimePlain, confidencePartial
+	default:
+		if strings.Count(name, "/") == 1 {
+			ty, subtype, _ := strings.Cut(name, "/")
+			return data.M(ty, subtype), confidenceFull
+		} else {
+			return data.Mime { }, confidenceNone
+		}
+	}
+}
+
+func mimeToTargets (mime data.Mime) (names []string) {
+	names = append(names, mime.String())
+	switch mime {
+	case data.M("application", "pdf"):
+		names = append(names, "ADOBE_PORTABLE_DOCUMENT_FORMAT")
+	case data.M("image", "pict"):
+		names = append(names, "APPLE_PICT")
+	case data.M("application", "postscript"):
+		names = append(names, "POSTSCRIPT")
+	case data.MimeFile:
+		names = append(names, "FILE_NAME")
+	case data.MimePlain:
+		names = append(names, "UTF8_STRING", "TEXT", "STRING")
+	}
+	return
+}
+
+func (request *selectionRequest) handleSelectionNotify (
+	connection *xgbutil.XUtil,
+	event xevent.SelectionNotifyEvent,
+) {
+	// the only valid states that we can process a SelectionNotify event in
+	invalidState :=
+		request.state != selReqStateAwaitValue &&
+		request.state != selReqStateAwaitTargets
+	if invalidState { return }
+	
+	// Follow:
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.4
+	
+	// If the property argument is None, the conversion has been refused.
+	// This can mean either that there is no owner for the selection, that
+	// the owner does not support the conversion implied by the target, or
+	// that the server did not have sufficient space to accommodate the
+	// data.
+	if event.Property == 0 { request.die(nil); return }
+
+	// When using GetProperty to retrieve the value of a selection, the
+	// property argument should be set to the corresponding value in the
+	// SelectionNotify event. Because the requestor has no way of knowing
+	// beforehand what type the selection owner will use, the type argument
+	// should be set to AnyPropertyType. Several GetProperty requests may be
+	// needed to retrieve all the data in the selection; each should set the
+	// long-offset argument to the amount of data received so far, and the
+	// size argument to some reasonable buffer size (see section 2.5). If
+	// the returned value of bytes-after is zero, the whole property has
+	// been transferred.
+	reply, err := xproto.GetProperty (
+		connection.Conn(), false, request.window.xWindow.Id,
+		event.Property, xproto.GetPropertyTypeAny,
+		0, (1 << 32) - 1).Reply()
+	if err != nil { request.die(err); return }
+	if reply.Format == 0 {
+		request.die(errors.New("x: missing selection property"))
+		return
+	}
+
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.7.2
+	// Requestors may receive a property of type INCR9 in response to any
+	// target that results in selection data. This indicates that the owner
+	// will send the actual data incrementally. The contents of the INCR
+	// property will be an integer, which represents a lower bound on the
+	// number of bytes of data in the selection. The requestor and the
+	// selection owner transfer the data in the selection in the following
+	// manner. The selection requestor starts the transfer process by
+	// deleting the (type==INCR) property forming the reply to the
+	// selection.
+	incr, err := xprop.Atm(request.window.backend.connection, "INCR")
+	if err != nil { request.die(err); return }
+	if reply.Type == incr {
+		// reply to the INCR selection
+		err = xproto.DeletePropertyChecked (
+			request.window.backend.connection.Conn(),
+			request.window.xWindow.Id,
+			request.destination).Check()
+		if err != nil { request.die(err); return }
+
+		// await the first chunk
+		request.state = selReqStateAwaitChunk
+		return
+	}
+
+	// Once all the data in the selection has been retrieved (which may
+	// require getting the values of several properties &emdash; see section
+	// 2.7), the requestor should delete the property in the SelectionNotify
+	// request by using a GetProperty request with the delete argument set
+	// to True. As previously discussed, the owner has no way of knowing
+	// when the data has been transferred to the requestor unless the
+	// property is removed.
+	err = xproto.DeletePropertyChecked (
+		request.window.backend.connection.Conn(),
+		request.window.xWindow.Id,
+		request.destination).Check()
+	if err != nil { request.die(err); return }
+
+	// depending on which state the selection request is in, do something
+	// different with the property's value
+	switch request.state {
+	case selReqStateAwaitValue:
+		// get the type from the property and convert that to the mime
+		// value to pass to the application.
+		targetName, err := xprop.AtomName (
+			request.window.backend.connection, reply.Type)
+		if err != nil { request.die(err); return }
+		mime, _ := targetToMime(targetName)
+		
+		// we now have the full selection data in the property, so we
+		// finalize the request and are done.
+		request.finalize(data.Bytes(mime, reply.Value))
+		
+	case selReqStateAwaitTargets:
+		// make a list of the atoms we got
+		buffer := reply.Value
+		atoms  := make([]xproto.Atom, len(buffer) / 4)
+		for index := range atoms {
+			atoms[index] = xproto.Atom(xgb.Get32(buffer[index * 4:]))
+		}
+
+		// choose the best match out of all targets using a confidence
+		// system
+		confidentMatchFound := false
+		var chosenTarget xproto.Atom
+		for _, atom := range atoms {
+			targetName, err := xprop.AtomName (
+				request.window.backend.connection, atom)
+			if err != nil { request.die(err); return }
+			
+			mime, confidence := targetToMime(targetName)
+			if confidence == confidenceNone { continue }
+
+			// if the accepted types list is nil, just choose this
+			// one. however, if we are not 100% confident that this
+			// target can be directly converted into a mime type,
+			// don't mark it as the final match. we still want the
+			// mime type we give to the application to be as
+			// accurate as possible.
+			if request.accept == nil {
+				chosenTarget = atom
+				if confidence == confidenceFull {
+					confidentMatchFound = true
+				}
+			}
+
+			// run through the accepted types list if it exists,
+			// looking for a match. if one is found, then choose
+			// this target. however, if we are not 100% confident
+			// that this target directly corresponds to the mime
+			// type, don't mark it as the final match, because there
+			// may be a better target in the list.
+			for _, accept := range request.accept {
+			if accept == mime {
+				chosenTarget = atom
+				if confidence == confidenceFull {
+					confidentMatchFound = true
+				}
+				break
+			}}
+			
+			if confidentMatchFound { break }
+		}
+
+		// if we didn't find a match, finalize the request with an empty
+		// data map to inform the application that, although there were
+		// no errors, there wasn't a suitable target to choose from.
+		if chosenTarget == 0 {
+			request.finalize(data.Data { })
+			return
+		}
+
+		// await the selection value
+		request.convertSelection(chosenTarget, selReqStateAwaitValue)
+	}
+}
+
+func (request *selectionRequest) handlePropertyNotify (
+	connection *xgbutil.XUtil,
+	event xevent.PropertyNotifyEvent,
+) {
+	// the only valid state that we can process a PropertyNotify event in
+	if request.state != selReqStateAwaitChunk { return }
+	if event.State != xproto.PropertyNewValue { return }
+
+	request.handleINCRProperty(event.Atom)
+}
+
+func (request *selectionRequest) handleINCRProperty (property xproto.Atom) {
+	// Retrieving data using GetProperty with the delete argument True.
+	reply, err := xproto.GetProperty (
+		request.window.backend.connection.Conn(), true,
+		request.window.xWindow.Id, property, xproto.GetPropertyTypeAny,
+		0, (1 << 32) - 1).Reply()
+	if err != nil { request.die(err); return }
+
+	if len(reply.Value) == 0 {
+		// a zero length property means the transfer has finished. we
+		// finalize the request with the data we have, and don't wait
+		// for more.
+		request.finalize(data.Bytes(request.incrMime, request.incrBuffer))
+
+		// we want to be extra sure we aren't holding onto this memory
+		request.incrBuffer = nil
+	} else {
+		// a property with content means the transfer is still ongoing.
+		// we append the data we got and wait for more.
+		request.state = selReqStateAwaitChunk
+		request.incrBuffer = append(request.incrBuffer, reply.Value...)
+		
+		targetName, err := xprop.AtomName (
+			request.window.backend.connection, reply.Type)
+		if err != nil { request.die(err); return }
+		request.incrMime, _ = targetToMime(targetName)
+	}
+}

backends/x/selectionclaim.go

@@ -0,0 +1,164 @@
+package x
+
+import "io"
+import "github.com/jezek/xgb"
+import "github.com/jezek/xgbutil"
+import "github.com/jezek/xgb/xproto"
+import "github.com/jezek/xgbutil/xprop"
+import "github.com/jezek/xgbutil/xevent"
+import "git.tebibyte.media/sashakoshka/tomo/data"
+
+type selectionClaim struct {
+	window *window
+	data data.Data
+	name xproto.Atom
+}
+
+func (window *window) claimSelection (name xproto.Atom, data data.Data) *selectionClaim {
+	// Follow:
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.1
+	
+	// A client wishing to acquire ownership of a particular selection
+	// should call SetSelectionOwner. The client should set the specified
+	// selection to the atom that represents the selection, set the
+	// specified owner to some window that the client created, and set the
+	// specified time to some time between the current last-change time of
+	// the selection concerned and the current server time. This time value
+	// usually will be obtained from the timestamp of the event that
+	// triggers the acquisition of the selection. Clients should not set the
+	// time value to CurrentTime, because if they do so, they have no way of
+	// finding when they gained ownership of the selection. Clients must use
+	// a window they created so that requestors can route events to the
+	// owner of the selection.
+	err := xproto.SetSelectionOwnerChecked (
+		window.backend.connection.Conn(),
+		window.xWindow.Id, name, 0).Check() // FIXME: should not be zero
+	if err != nil { return nil }
+
+	ownerReply, err := xproto.GetSelectionOwner (
+		window.backend.connection.Conn(), name).Reply()
+	if err != nil { return nil }
+	if ownerReply.Owner != window.xWindow.Id { return nil }
+
+	return &selectionClaim {
+		window: window,
+		data: data,
+		name: name,
+	}
+}
+
+func (window *window) refuseSelectionRequest (request xevent.SelectionRequestEvent) {
+	// ... refuse the SelectionRequest by sending the requestor window a
+	// SelectionNotify event with the property set to None (by means of a
+	// SendEvent request with an empty event mask).
+	event := xproto.SelectionNotifyEvent {
+		Requestor: request.Requestor,
+		Selection: request.Selection,
+		Target:    request.Target,
+		Property:  0,
+	}.Bytes()
+	xproto.SendEvent (
+		window.backend.connection.Conn(),
+		false, request.Requestor, 0, string(event))
+}
+
+func (window *window) fulfillSelectionRequest (
+	data    []byte,
+	format  byte,
+	ty      xproto.Atom,
+	request xevent.SelectionRequestEvent,
+) {
+	die := func () { window.refuseSelectionRequest(request) }
+	
+	// If the specified property is not None, the owner should place the
+	// data resulting from converting the selection into the specified
+	// property on the requestor window and should set the property's type
+	// to some appropriate value, which need not be the same as the
+	// specified target.
+	err := xproto.ChangePropertyChecked (
+		window.backend.connection.Conn(),
+		xproto.PropModeReplace, request.Requestor,
+		request.Property,
+		ty, format,
+		uint32(len(data) / (int(format) / 8)), data).Check()
+	if err != nil { die() }
+
+	// If the property is successfully stored, the owner should acknowledge
+	// the successful conversion by sending the requestor window a
+	// SelectionNotify event (by means of a SendEvent request with an empty
+	// mask).
+	event := xproto.SelectionNotifyEvent {
+		Requestor: request.Requestor,
+		Selection: request.Selection,
+		Target:    request.Target,
+		Property:  request.Property,
+	}.Bytes()
+	xproto.SendEvent (
+		window.backend.connection.Conn(),
+		false, request.Requestor, 0, string(event))
+}
+
+func (claim *selectionClaim) handleSelectionRequest (
+	connection *xgbutil.XUtil,
+	event xevent.SelectionRequestEvent,
+) {
+	// Follow:
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.2
+
+	die := func () { claim.window.refuseSelectionRequest(event) }
+
+	// When a requestor wants the value of a selection, the owner receives a
+	// SelectionRequest event. The specified owner and selection will be the
+	// values that were specified in the SetSelectionOwner request. The
+	// owner should compare the timestamp with the period it has owned the
+	// selection and, if the time is outside, refuse the SelectionRequest.
+	if event.Selection != claim.name { die(); return }
+
+	// If the specified property is None , the requestor is an obsolete
+	// client. Owners are encouraged to support these clients by using the
+	// specified target atom as the property name to be used for the reply.
+	if event.Property == 0 {
+		event.Property = event.Target
+	}
+
+	// Otherwise, the owner should use the target to decide the form into
+	// which the selection should be converted. Some targets may be defined
+	// such that requestors can pass parameters along with the request. The
+	// owner will find these parameters in the property named in the
+	// selection request. The type, format, and contents of this property
+	// are dependent upon the definition of the target. If the target is not
+	// defined to have parameters, the owner should ignore the property if
+	// it is present. If the selection cannot be converted into a form based
+	// on the target (and parameters, if any), the owner should refuse the
+	// SelectionRequest as previously described.
+	targetName, err := xprop.AtomName (
+		claim.window.backend.connection, event.Target)
+	if err != nil { die(); return }
+	
+	switch targetName {
+	case "TARGETS":
+		targetNames := []string { "TARGETS", }
+		for mime := range claim.data {
+			targetNames = append(targetNames, mimeToTargets(mime)...)
+		}
+		data := make([]byte, len(targetNames) * 4)
+		for index, name := range targetNames {
+			atom, err := xprop.Atm(claim.window.backend.connection, name)
+			if err != nil { die(); return }
+			xgb.Put32(data[(index) * 4:], uint32(atom))
+		}
+		atomAtom, err := xprop.Atm(claim.window.backend.connection, "ATOM")
+		if err != nil { die(); return }
+		claim.window.fulfillSelectionRequest(data, 32, atomAtom, event)
+
+	default:
+		mime, confidence := targetToMime(targetName)
+		if confidence == confidenceNone { die(); return }
+		reader, ok := claim.data[mime]
+		if !ok { die(); return }
+		reader.Seek(0, io.SeekStart)
+		data, err := io.ReadAll(reader)
+		if err != nil { die() }
+		claim.window.fulfillSelectionRequest(data, 8, event.Target, event)
+	}
+}

backends/x/window.go

@@ -1,12 +1,15 @@
 package x
 
 import "image"
+import "errors"
 import "github.com/jezek/xgb/xproto"
 import "github.com/jezek/xgbutil/ewmh"
 import "github.com/jezek/xgbutil/icccm"
+import "github.com/jezek/xgbutil/xprop"
 import "github.com/jezek/xgbutil/xevent"
 import "github.com/jezek/xgbutil/xwindow"
 import "github.com/jezek/xgbutil/xgraphics"
+import "git.tebibyte.media/sashakoshka/tomo/data"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
@@ -30,6 +33,9 @@ type window struct {
 	theme  theme.Theme
 	config config.Config
 
+	selectionRequest *selectionRequest
+	selectionClaim   *selectionClaim
+
 	metrics struct {
 		width  int
 		height int
@@ -64,6 +70,7 @@ func (backend *Backend) newWindow (
 	err = window.xWindow.Listen (
 		xproto.EventMaskExposure,
 		xproto.EventMaskStructureNotify,
+		xproto.EventMaskPropertyChange,
 		xproto.EventMaskPointerMotion,
 		xproto.EventMaskKeyPress,
 		xproto.EventMaskKeyRelease,
@@ -89,6 +96,14 @@ func (backend *Backend) newWindow (
 		Connect(backend.connection, window.xWindow.Id)
 	xevent.MotionNotifyFun(window.handleMotionNotify).
 		Connect(backend.connection, window.xWindow.Id)
+	xevent.SelectionNotifyFun(window.handleSelectionNotify).
+		Connect(backend.connection, window.xWindow.Id)
+	xevent.PropertyNotifyFun(window.handlePropertyNotify).
+		Connect(backend.connection, window.xWindow.Id)
+	xevent.SelectionClearFun(window.handleSelectionClear).
+		Connect(backend.connection, window.xWindow.Id)
+	xevent.SelectionRequestFun(window.handleSelectionRequest).
+		Connect(backend.connection, window.xWindow.Id)
 
 	window.SetTheme(backend.theme)
 	window.SetConfig(backend.config)
@@ -246,7 +261,6 @@ func (window *window) setType (ty string) error {
 }
 
 func (window *window) setClientLeader (leader *window) error {
-	// FIXME: doe not fucking work
 	hints, _ := icccm.WmHintsGet(window.backend.connection, window.xWindow.Id)
 	if hints == nil {
 		hints = &icccm.Hints { }
@@ -275,6 +289,35 @@ func (window *window) Hide () {
 	window.xWindow.Unmap()
 }
 
+func (window *window) Copy (data data.Data) {
+	selectionAtom, err := xprop.Atm(window.backend.connection, clipboardName)
+	if err != nil { return }
+	window.selectionClaim = window.claimSelection(selectionAtom, data)
+}
+
+func (window *window) Paste (callback func (data.Data, error), accept ...data.Mime) {
+	// Follow:
+	// https://tronche.com/gui/x/icccm/sec-2.html#s-2.4
+	die := func (err error) { callback(nil, err) }
+	if window.selectionRequest != nil {
+		// TODO: add the request to a queue and take care of it when the
+		// current selection has completed
+		die(errors.New("there is already a selection request"))
+		return
+	}
+
+	propertyName := "TOMO_SELECTION"
+	selectionAtom, err := xprop.Atm(window.backend.connection, clipboardName)
+	if err != nil { die(err); return }
+	propertyAtom, err := xprop.Atm(window.backend.connection, propertyName)
+	if err != nil { die(err); return }
+
+	window.selectionRequest = window.newSelectionRequest (
+		selectionAtom, propertyAtom, callback, accept...)
+	if !window.selectionRequest.open() { window.selectionRequest = nil }
+	return
+}
+
 func (window *window) Close () {
 	if window.onClose != nil { window.onClose() }
 	if window.modalParent != nil {

backends/x/x.go

@@ -1,7 +1,6 @@
 package x
 
 import "git.tebibyte.media/sashakoshka/tomo"
-import "git.tebibyte.media/sashakoshka/tomo/data"
 import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 
@@ -39,7 +38,7 @@ type Backend struct {
 func NewBackend () (output tomo.Backend, err error) {
 	backend := &Backend {
 		windows: map[xproto.Window] *window { },
-		doChannel: make(chan func (), 0),
+		doChannel: make(chan func (), 32),
 		theme:  theme.Default  { },
 		config: config.Default { },
 		open:   true,
@@ -97,22 +96,6 @@ func (backend *Backend) Do (callback func ()) {
 	backend.doChannel <- callback
 }
 
-// Copy puts data into the clipboard. This method is not yet implemented and
-// will do nothing!
-func (backend *Backend) Copy (data data.Data) {
-	backend.assert()
-	// TODO
-}
-
-// Paste returns the data currently in the clipboard. This method may
-// return nil. This method is not yet implemented and will do nothing!
-func (backend *Backend) Paste (accept []data.Mime) (data data.Data) {
-	backend.assert()
-	// TODO
-	return
-}
-
-
 // SetTheme sets the theme of all open windows.
 func (backend *Backend) SetTheme (theme theme.Theme) {
 	backend.assert()

data/data.go

@@ -1,10 +1,11 @@
 package data
 
 import "io"
+import "bytes"
 
 // Data represents arbitrary polymorphic data that can be used for data transfer
 // between applications.
-type Data map[Mime] io.ReadCloser
+type Data map[Mime] io.ReadSeekCloser
 
 // Mime represents a MIME type.
 type Mime struct {
@@ -15,6 +16,41 @@ type Mime struct {
 	Type, Subtype string
 }
 
+// M is shorthand for creating a MIME type.
+func M (ty, subtype string) Mime {
+	return Mime { ty, subtype }
+}
+
+// String returns the string representation of the MIME type.
+func (mime Mime) String () string {
+	return mime.Type + "/" + mime.Subtype
+}
+
 var MimePlain = Mime { "text", "plain" }
 
 var MimeFile = Mime { "text", "uri-list" }
+
+type byteReadCloser struct { *bytes.Reader }
+func (byteReadCloser) Close () error { return nil }
+
+// Text returns plain text Data given a string.
+func Text (text string) Data {
+	return Bytes(MimePlain, []byte(text))
+}
+
+// Bytes constructs a Data given a buffer and a mime type.
+func Bytes (mime Mime, buffer []byte) Data {
+	return Data {
+		mime: byteReadCloser { bytes.NewReader(buffer) },
+	}
+}
+
+// Merge combines several Datas together. If multiple Datas provide a reader for
+// the same mime type, the ones further on in the list will take precedence.
+func Merge (individual ...Data) (combined Data) {
+	for _, data := range individual {
+	for mime, reader := range data {
+		combined[mime] = reader
+	}}
+	return
+}

elements/window.go

@@ -1,13 +1,12 @@
 package elements
 
 import "image"
+import "git.tebibyte.media/sashakoshka/tomo/data"
 
 // Window represents a top-level container generated by the currently running
 // backend. It can contain a single element. It is hidden by default, and must
 // be explicitly shown with the Show() method.
 type Window interface {
-	Parent
-
 	// Adopt sets the root element of the window. There can only be one of
 	// these at one time.
 	Adopt (Element)
@@ -27,6 +26,15 @@ type Window interface {
 
 	// NewModal creates a new modal dialog window.
 	NewModal (width, height int) (window Window, err error)
+	
+	// Copy puts data into the clipboard.
+	Copy (data.Data)
+
+	// Paste requests the data currently in the clipboard. When the data is
+	// available, the callback is called with the clipboard data. If there
+	// was no data matching the requested mime type found, nil is passed to
+	// the callback instead.
+	Paste (callback func (data.Data, error), accept ...data.Mime)
 
 	// Show shows the window. The window starts off hidden, so this must be
 	// called after initial setup to make sure it is visible.

examples/clipboard/main.go

@@ -0,0 +1,136 @@
+package main
+
+import "io"
+import "image"
+import _ "image/png"
+import _ "image/gif"
+import _ "image/jpeg"
+import "git.tebibyte.media/sashakoshka/tomo"
+import "git.tebibyte.media/sashakoshka/tomo/data"
+import "git.tebibyte.media/sashakoshka/tomo/theme"
+import "git.tebibyte.media/sashakoshka/tomo/popups"
+import "git.tebibyte.media/sashakoshka/tomo/layouts/basic"
+import "git.tebibyte.media/sashakoshka/tomo/elements/basic"
+import _ "git.tebibyte.media/sashakoshka/tomo/backends/all"
+import "git.tebibyte.media/sashakoshka/tomo/elements/containers"
+
+func main () {
+	tomo.Run(run)
+}
+
+var validImageTypes = []data.Mime {
+	data.M("image", "png"),
+	data.M("image", "gif"),
+	data.M("image", "jpeg"),
+}
+
+func run () {
+	window, _ := tomo.NewWindow(256, 2)
+	window.SetTitle("Clipboard")
+
+	container := containers.NewContainer(basicLayouts.Vertical { true, true })
+	textInput := basicElements.NewTextBox("", "")
+	controlRow := containers.NewContainer(basicLayouts.Horizontal { true, false })
+	copyButton := basicElements.NewButton("Copy")
+	copyButton.SetIcon(theme.IconCopy)
+	pasteButton := basicElements.NewButton("Paste")
+	pasteButton.SetIcon(theme.IconPaste)
+	pasteImageButton := basicElements.NewButton("Image")
+	pasteImageButton.SetIcon(theme.IconPictures)
+
+	imageClipboardCallback := func (clipboard data.Data, err error) {
+		if err != nil {
+			popups.NewDialog (
+				popups.DialogKindError,
+				window,
+				"Error",
+				"Cannot get clipboard:\n" + err.Error())
+			return 
+		}
+
+		var imageData io.Reader
+		var ok bool
+		for mime, reader := range clipboard {
+		for _, mimeCheck := range validImageTypes {
+		if mime == mimeCheck {
+			imageData = reader
+			ok = true
+		}}}
+		
+		if !ok {
+			popups.NewDialog (
+				popups.DialogKindError,
+				window,
+				"Clipboard Empty",
+				"No image data in clipboard")
+			return 
+		}
+
+		img, _, err := image.Decode(imageData)
+		if err != nil {
+			popups.NewDialog (
+				popups.DialogKindError,
+				window,
+				"Error",
+				"Cannot decode image:\n" + err.Error())
+			return 
+		}
+		imageWindow(img)
+	}
+	clipboardCallback := func (clipboard data.Data, err error) {
+		if err != nil {
+			popups.NewDialog (
+				popups.DialogKindError,
+				window,
+				"Error",
+				"Cannot get clipboard:\n" + err.Error())
+			return 
+		}
+		
+		textData, ok := clipboard[data.MimePlain]
+		if !ok {
+			popups.NewDialog (
+				popups.DialogKindError,
+				window,
+				"Clipboard Empty",
+				"No text data in clipboard")
+			return 
+		}
+
+		text, _ := io.ReadAll(textData)
+		textInput.SetValue(string(text))
+	}
+	copyButton.OnClick (func () {
+		window.Copy(data.Text(textInput.Value()))
+	})
+	pasteButton.OnClick (func () {
+		window.Paste(clipboardCallback, data.MimePlain)
+	})
+	pasteImageButton.OnClick (func () {
+		window.Paste(imageClipboardCallback, validImageTypes...)
+	})
+	
+	container.Adopt(textInput, true)
+	controlRow.Adopt(copyButton, true)
+	controlRow.Adopt(pasteButton, true)
+	controlRow.Adopt(pasteImageButton, true)
+	container.Adopt(controlRow, false)
+	window.Adopt(container)
+		
+	window.OnClose(tomo.Stop)
+	window.Show()
+}
+
+func imageWindow (image image.Image) {
+	window, _ := tomo.NewWindow(2, 2)
+	window.SetTitle("Clipboard Image")
+	container := containers.NewContainer(basicLayouts.Vertical { true, true })
+	closeButton := basicElements.NewButton("Ok")
+	closeButton.SetIcon(theme.IconYes)
+	closeButton.OnClick(window.Close)
+	
+	container.Adopt(basicElements.NewImage(image), true)
+	container.Adopt(closeButton, false)
+	window.Adopt(container)
+	window.Show()
+}

examples/panels/main.go

@@ -13,7 +13,7 @@ func main () {
 }
 
 func run () {
-	window, _ := tomo.NewWindow(2, 2)
+	window, _ := tomo.NewWindow(256, 256)
 	window.SetTitle("Main")
 
 	container := containers.NewContainer(basicLayouts.Vertical { true, true })
@@ -24,9 +24,9 @@ func run () {
 	window.Show()
 
 	createPanel(window, 0)
-	// createPanel(window, 1)
-	// createPanel(window, 2)
-	// createPanel(window, 3)
+	createPanel(window, 1)
+	createPanel(window, 2)
+	createPanel(window, 3)
 }
 
 func createPanel (parent elements.MainWindow, id int) {

go.mod

@@ -22,3 +22,5 @@ require (
 	github.com/BurntSushi/graphics-go v0.0.0-20160129215708-b43f31a4a966 // indirect
 	github.com/jezek/xgb v1.1.0
 )
+
+replace github.com/jezek/xgbutil => github.com/sashakoshka/xgbutil v0.0.0-20230330215824-bebecf813e8b

go.sum

@@ -1,9 +1,3 @@
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309011813-4cd4374e3830 h1:McIAkTzD4y0tS7YprTOwRu8a8NTsMKtomQnvxnCdOmg=
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309011813-4cd4374e3830/go.mod h1:cpXX8SAUDEvZX5m7scoyruavUhEqQ1SByfWzPFHkTbg=
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309013013-f7ee80c8f908 h1:kFdch6JQ/gWESn/vLeKzImzf3Xx1it2MkZqBwrSnR1Q=
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309013013-f7ee80c8f908/go.mod h1:cpXX8SAUDEvZX5m7scoyruavUhEqQ1SByfWzPFHkTbg=
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309013201-fc0de8121523 h1:1KaoiGetWYIDQKts6yas1hW+4ObkuTm6+TkFpl6jZxg=
-git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309013201-fc0de8121523/go.mod h1:cpXX8SAUDEvZX5m7scoyruavUhEqQ1SByfWzPFHkTbg=
 git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309044548-401cba83602b h1:vPFKR7vjN1VrMdMtpATMrKQobz/cqbPiRrA1EbtG6PM=
 git.tebibyte.media/sashakoshka/ezprof v0.0.0-20230309044548-401cba83602b/go.mod h1:cpXX8SAUDEvZX5m7scoyruavUhEqQ1SByfWzPFHkTbg=
 github.com/BurntSushi/freetype-go v0.0.0-20160129220410-b763ddbfe298 h1:1qlsVAQJXZHsaM8b6OLVo6muQUQd4CwkH/D3fnnbHXA=
@@ -27,8 +21,6 @@ github.com/icza/bitio v1.0.0/go.mod h1:0jGnlLAx8MKMr9VGnn/4YrvZiprkvBelsVIbA9Jjr
 github.com/icza/mighty v0.0.0-20180919140131-cfd07d671de6/go.mod h1:xQig96I1VNBDIWGCdTt54nHt6EeI639SmHycLYL7FkA=
 github.com/jezek/xgb v1.1.0 h1:wnpxJzP1+rkbGclEkmwpVFQWpuE2PUGNUzP8SbfFobk=
 github.com/jezek/xgb v1.1.0/go.mod h1:nrhwO0FX/enq75I7Y7G8iN1ubpSGZEiA3v9e9GyRFlk=
-github.com/jezek/xgbutil v0.0.0-20210302171758-530099784e66 h1:+wPhoJD8EH0/bXipIq8Lc2z477jfox9zkXPCJdhvHj8=
-github.com/jezek/xgbutil v0.0.0-20210302171758-530099784e66/go.mod h1:KACeV+k6b+aoLTVrrurywEbu3UpqoQcQywj4qX8aQKM=
 github.com/jfreymuth/oggvorbis v1.0.1/go.mod h1:NqS+K+UXKje0FUYUPosyQ+XTVvjmVjps1aEZH1sumIk=
 github.com/jfreymuth/vorbis v1.0.0/go.mod h1:8zy3lUAm9K/rJJk223RKy6vjCZTWC61NA2QD06bfOE0=
 github.com/lucasb-eyer/go-colorful v1.0.2/go.mod h1:0MS4r+7BZKSJ5mw4/S5MPN+qHFF1fYclkSPilDOKW0s=
@@ -38,6 +30,8 @@ github.com/mewkiz/pkg v0.0.0-20190919212034-518ade7978e2/go.mod h1:3E2FUC/qYUfM8
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/sashakoshka/xgbutil v0.0.0-20230330215824-bebecf813e8b h1:jkUYWTFGCavJ5I4/lkireJ9KxOxEWKLHB9SPoieIHro=
+github.com/sashakoshka/xgbutil v0.0.0-20230330215824-bebecf813e8b/go.mod h1:AHecLyFNy6AN9f/+0AH/h1MI7X1+JL5bmCz4XlVZk7Y=
 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=

textmanip/textmanip.go

@@ -42,6 +42,15 @@ func (dot Dot) Constrain (length int) Dot {
 	return dot
 }
 
+func (dot Dot) Width () int {
+	dot = dot.Canon()
+	return dot.End - dot.Start
+}
+
+func (dot Dot) Slice (text []rune) []rune {
+	return text[dot.Start:dot.End]
+}
+
 func WordToLeft (text []rune, position int) (length int) {
 	if position < 1 { return }
 	if position > len(text) { position = len(text) }
@@ -121,6 +130,22 @@ func Delete (text []rune, dot Dot, word bool) (result []rune, moved Dot) {
 	}
 }
 
+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
+}
+
 func Type (text []rune, dot Dot, character rune) (result []rune, moved Dot) {
 	dot = dot.Constrain(len(text))
 	if dot.Empty() {

theme/theme.go

@@ -63,10 +63,12 @@ type Color int; const (
 )
 
 // Icon lists a number of cannonical icons, each with its own ID.
-type Icon int; const (
-	// IconNone specifies no icon.
-	IconNone = -1
+type Icon int
 
+// IconNone specifies no icon.
+const IconNone = -1
+
+const (
 	// Place icons
 	IconHome Icon = iota
 	Icon3DObjects

tomo.go

@@ -4,7 +4,6 @@ import "os"
 import "io"
 import "path/filepath"
 import "git.tebibyte.media/sashakoshka/tomo/dirs"
-import "git.tebibyte.media/sashakoshka/tomo/data"
 import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/elements"
@@ -47,19 +46,6 @@ func NewWindow (width, height int) (window elements.MainWindow, err error) {
 	return backend.NewWindow(width, height)
 }
 
-// Copy puts data into the clipboard.
-func Copy (data data.Data) {
-	assertBackend()
-	backend.Copy(data)
-}
-
-// Paste returns the data currently in the clipboard. This method may
-// return nil.
-func Paste (accept []data.Mime) (data.Data) {
-	assertBackend()
-	return backend.Paste(accept)
-}
-
 // SetTheme sets the theme of all open windows.
 func SetTheme (theme theme.Theme) {
 	backend.SetTheme(theme)