Scrolled lists

A scrolled list is a CwList widget with scrolling capability. All resources and callbacks associated with lists can be applied to scrolled lists. The scrolling mechanism is handled automatically.

Creating a scrolled list inserts a CwScrolledWindow parent between the list and the receiver of the creation message. In other words, createScrolledList:argBlock: returns an instance of CwList (the child of a CwScrolledWindow); however, the CwScrolledWindow is the child of the form. Form attachment messages must therefore be sent to the CwList's parent.

In the following example, a scrolled list widget is created as a child of a form. The list selection policy is set to XmSINGLESELECT. A singleSelection callback is added, corresponding to the selection policy.

| items shell form list |

items := OrderedCollection new.

"20 items are initialized as the list contents."

1 to: 20 do: [:i |

items add: 'Item ', i printString].

shell := CwTopLevelShell

createApplicationShell: 'shell'

argBlock: [:w | w title: 'Scrolled List Example'].

form := shell

createForm: 'form'

argBlock: nil.

form manageChild.

list := form

"Create the scrolled list. The list widget is answered, not the scrolled window."

createScrolledList: 'list'

argBlock: [:w |

w

"Set the scrolling policy to single selection, the number of visible items

to one-half of the number of items, and the list's items to items."

selectionPolicy: XmSINGLESELECT;

visibleItemCount: items size // 2;

items: items].

list

addCallback: XmNsingleSelectionCallback

receiver: self

selector: #singleSelect:clientData:callData:

clientData: nil.

list manageChild.

"Note that the attachments are set on the parent of the list (which

is a CwScrolledWindow). The scrolled window is the child of the form,

not the list widget."

list parent setValuesBlock: [:w |

w

topAttachment: XmATTACHFORM;

topOffset: 10;

bottomAttachment: XmATTACHFORM;

bottomOffset: 10;

leftAttachment: XmATTACHFORM;

leftOffset: 10;

rightAttachment: XmATTACHFORM;

rightOffset: 10].

shell realizeWidget

 

Tip:

If other children of a form are to be attached to a scrolled list, which is a child of the form, using XmATTACHWIDGET, they must be attached to the scrolled list's parent.