Wrapping OCXs with extended widgets

The Common Widgets Extended Widgets framework can be used to wrapper an OleControl so it can be used in a more familiar way. That is, Smalltalk accesssors are used to wrap the OleControl property messages (propertyAt: and propertyAt:put:) and invoke message (invoke:withArguments:), and the Common Widgets callback style is used for all the OLE events of interest.

For a reference on building Extended Widgets, see the Extended Widgets. The main approach is to:

1.	Make a subclass CwExtentedPrimitive.

2.	Create an instance of OleControl in the Extended Widgets createPrimaryWidget:parent:argBlock: method and register an ambient-property handler. For example:

createPrimaryWidget: theName parent: parent argBlock: argBlock

"Private - Create and answer the basic widget that is the root

of the widget hierarchy for the receiver's widget system."

^self parent

createOleControl: 'the control'

argBlock: :w | w

clientName: 'TRACKBAR.TrackbarCtrl.1';

ambientPropertyReceiver: self;

ambientPropertySelector: #dispidAmbientPropertyAt:].

3.	Register OLE event handlers and associate them with Common Widgets callbacks in the initializeAfterCreate method. For example:

initializeAfterCreate

"Private - Perform any widget-specific post-create initialization."

super initializeAfterCreate.

self primaryWidget

addOleEventHandler: 'Change'

receiver: self

selector: #callValueChangedCallback

Implement widget-specific methods, such as:

clearSelection

"Clears the slider's selection range."

^self primaryWidget

invoke: 'ClearSelection'

withArguments: #()

Implement accessors for resources, such as:

lineSize: resourceValue

"Set the value of the XmNlineSize resource.

Resource type: Integer

Default setting: 10

Resource access: CSG

Description: Specifies the line size. This is the amount

that the slider moves when receiving a key press."

self primaryWidget propertyAt: 'LineSize' put: resourceValue

lineSize

"Answer the value of the XmNlineSize resource.

Resource type: Integer

Default setting: 10

Resource access: CSG

Description: Specifies the line size. This is the amount

that the slider moves when receiving a key press."

self primaryWidget propertyAt: 'LineSize'