Connecting Builder signals

signals in UI definitions

User interfaces may be defined by in XML documents. Such documents are typically edited with Glade.

Signals, along with a named handler, maybe appear in a definition.

<interface>
  ...
    <object class="GtkButton" id="ok_button">
      <signal name="clicked" handler="ok_button_clicked"/>
    </object>
  ...
</interface>

The handler attribute value provides a name that can be used to associate the signal with a handler function.

connecting

To connect signals from a UI definition, call Builder’s ConnectSignals method. The single argument is a map of handler names to handler functions

The map keys should match handler attribute values in the UI definition.

The handler function signatures must match the signal’s equivalent Connect... function.

example

builder := gtk.BuilderNewFromString(`
    <interface>
      <object class="GtkButton" id="ok_button">
        <signal name="clicked" handler="ok_button_clicked"/>
        <signal name="draw" handler="draw"/>
      </object>
    </interface>
`)

err := builder.ConnectSignals(map[string]interface{}{
    "ok_button_clicked": func(button *gtk.Button) {
        // handle the click
    },
    "draw": func(widget *gtk.Widget, cr *cairo.Context) bool {
        // draw something in the context
        return false
    },
})

See the tests in gtkbuilder-connect-signals_test.go for more examples including some error scenarios.

errors

There are a number of errors that may occur while connecting signals. * A key in the map passed to ConnectSignals may not match any handler attribute value in the UI definition. * A handler function’s signature may be incorrect. * A signal name may be valid, but the signal may not be supported by gobbi.

Any of these will result in an error being returned.