Events

日本語

UIng applications respond to native events with callback blocks. Register callbacks while building the interface, before calling UIng.main. This excerpt uses the window created in First Steps.

entry = UIng::Entry.new
button = UIng::Button.new("Greet")
status = UIng::Label.new("Enter your name")

button.on_clicked do
  name = entry.text || ""
  window.msg_box("Greeting", "Hello, #{name}!")
end

entry.on_changed do |text|
  status.text = "#{text.size} characters"
end

Callbacks expose values when useful. For example, Entry#on_changed yields the current text and Slider#on_changed yields the current integer value.

Updating the interface

Native controls should be read and changed on the UI thread. If work performed elsewhere needs to update the interface, schedule only the UI update with UIng.queue_main:

UIng.queue_main do
  status.text = "Finished"
end

Keep referenced controls and application data alive for as long as a callback may use them. Callback exceptions are logged by UIng instead of crossing the native callback boundary.