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Using Object Controls |
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Both Object Enhanced and Object Defined Controls have the property 'ObjectID, which is set to the object that will handle the requests to the control. A value in this property distinguishes an Object Control from a regular control.
See Object Enhanced Controls and Object Defined Controls.
Whenever an Object Control's property is referenced, the system will first check its associated object to see if it has that property. If so, the system will use the property from the object instead of property in the control. This allows the object to intercept all property accesses external of the application program.
In the case of an Object Defined Control (ODC), all properties for the control must exist within the object, as there is not related system control.
In the case of an Object Enhanced Control (OEC), should the object itself make references to the properties of the control, the reference will be sent directly to the control, not the object itself. This means that should an OEC want to return a modified 'Value$ property for a control, internally it could read the control's 'Value$ property and then pass back the modified version.
Whenever the application issues a standard graphical control directive against an Object Control, the system will attempt to map the directive to a method within the object. For example, when the directive LIST_BOX DISABLE is issued against an object control, the system will first attempt to execute a 'Disable( ) method in the object should it exist.
For Enhanced controls, if the method does not exist, the system will apply the directive to the actual control as it would normally. For Defined controls, the method must exist; otherwise, the directive will fail.
The full list of the directive mappings is displayed below.
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Directive |
Object Method |
Purpose |
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control GOTO nn |
Focus( ) |
Set Focus to control |
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control REMOVE nn |
Remove( ) |
Remove control |
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control LOCK nn |
Lock( ) |
Lock the control |
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control UNLOCK nn |
UnLock( ) |
Unlock the control |
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control AUTO nn |
Auto( ) |
Set Automatic mode (Signal All Changes) |
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control ENABLE nn |
Enable( ) |
Enable the control |
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control DISABLE nn |
Disable( ) |
Disable the control |
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control FIND nn,a$ |
Find(a$) |
Find element in list |
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control FIND nn,c,r |
Find(c,r,a$) |
Find element in grid |
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control READ nn,a$,e$ |
Read(a$,e$) |
Read value from control |
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control WRITE nn,v$ |
Write(v$) |
Write value to control |
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control LOAD nn,i,v$ |
Load(i,v$) |
Load specific value to control |
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control LOAD nn,l$ |
Load(l$) |
Load list of values to control |
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control LOAD nn,i,* |
Delete(i) |
Delete entry from list |
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control SET_FOCUS nn,fctl |
SetFocus(fctl) |
Set On Focus CTL value |
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control ON nn |
SetOn( ) |
Set control to ON state |
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control OFF nn |
SetOff( ) |
Set control to OFF state |
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control HIDE nn |
Hide( ) |
Hide the control |
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control SHOW nn |
Show( ) |
Show the control |
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GRID Specific Functions | ||
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GRID CLEAR nn,c,r [,w,h] |
Clear(c,r [,w,h ]) |
Clear range of grid type control |
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GRID WRITE nn,c,r,v$ |
Write(c,r,v$) |
Write value to grid |
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GRID READ nn,c,r,a$,e$ |
Read(c,r,a$,e$) |
Read value from grid |
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GRID DELETE nn,c,r |
Delete(c,r) |
Delete columns/rows |
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GRID ADD nn,c,r |
Add(c,r) |
Add rows/columns |
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GRID SELECT nn,c,r [,w,h] |
Select(c,r [,w,h]) |
Select range |
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GRID SELECT READ nn,c,r |
SelectRead(c,r) |
Read first selected cell |
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GRID SELECT NEXT nn,c,r |
SelectNext(c,r) |
Read next selected cell |
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GRID SELECT RESET nn,c,r |
SelectReset(c,r) |
Read next selected cell |
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control will vary depending on the type of control being enhanced/defined | ||