Animation: Difference between revisions

=={{header|Nim}}==

<lang Nim>import gintro/[glib, gobject, gdk, gtk, gio]

type

# Scrolling direction.

ScrollDirection = enum toLeft, toRight

# Data transmitted to update callback.

UpdateData = ref object

label: Label

scrollDir: ScrollDirection

#---------------------------------------------------------------------------------------------------

proc update(data: UpdateData): gboolean =

## Update the text, scrolling to the right or to the left according to "data.scrollDir".

data.label.setText(if data.scrollDir == toRight: data.label.text[^1] & data.label.text[0..^2]

else: data.label.text[1..^1] & data.label.text[0])

result = gboolean(1)

#---------------------------------------------------------------------------------------------------

proc changeScrollingDir(evtBox: EventBox; event: EventButton; data: UpdateData): bool =

## Change scrolling direction.

data.scrollDir = ScrollDirection(1 - ord(data.scrollDir))

#---------------------------------------------------------------------------------------------------

proc activate(app: Application) =

## Activate the application.

let window = app.newApplicationWindow()

window.setSizeRequest(150, 50)

window.setTitle("Animation")

# Create an event box to catch the button press event.

let evtBox = newEventBox()

window.add(evtBox)

# Create the label and add it to the event box.

let label = newLabel("Hello World! ")

evtBox.add(label)

# Create the update data.

let data = UpdateData(label: label, scrollDir: toRight)

# Connect the "button-press-event" to the callback to change scrolling direction.

discard evtBox.connect("button-press-event", changeScrollingDir, data)

# Create a timer to update the label and simulate scrolling.

timeoutAdd(100, update, data)

window.showAll()

#———————————————————————————————————————————————————————————————————————————————————————————————————

let app = newApplication(Application, "Rosetta.animation")

discard app.connect("activate", activate)

discard app.run()</lang>