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eventssmalltalkpharo

Event system in pharo

I am trying to make a simple user interface in Pharo 3.0. At a certain place I need a color picker, so I thought about using ColorSelectorDialogWindow.

My problem is that I am not sure how to actually get a color out of it. I have seen that it has a selectedColor message, but I miss a way to actually catch the event when the user clicks on the ok button.

I have tried on: send: to: but it does not seem to help and in any case I don't know the event name. I have also seen that on confirmation, the message applyChanges gets sent to self, so I tried subclassing ColorSelectorDialogWindow just to add

applyChanges
    super applyChanges.
    self triggerEvent: 'selectedColor' with: self selectedColor.

but it seems that I cannot catch my own selectedColor event using on: send: to:.

What is the right way to hook into the dialog ok, and more generally to send events between components?

Solution

  • There are Announcements, a currently not very well documented part of Pharo. Try this in a workspace:

    | colorPicker |
colorPicker := ColorSelectorDialogWindow new.
colorPicker announcer when: ColorChanged do: [ :announcement | UIManager inform: 'Selected color: ' , announcement newColor asString ].
colorPicker open.

    This is the example that can be found in the ColorChanged announcement class comment.
    You get the selected color by sending newColor to the ColorChanged announcement.