Enumerating Properties of Controls

[Doogle]

I've been playing with Typelib Information (TBLINF32.DLL) to enumerate the Properties of all the Controls on a Form and determine whether specific ones are Read only.

Basic code is

    Dim TypeLib As TLI.InterfaceInfo
    Dim Prop As TLI.MemberInfo
    Debug.Print pObject.Name
    Set TypeLib = TLI.InterfaceInfoFromObject(pObject)
    For Each Prop In TypeLib.Members
        Debug.Print , Prop.Name & " " & Prop.InvokeKind
    Next

where pObject is the Control in question
The output from a ComboBox looks something like this

Combo1
              _DEFAULT 2
              _DEFAULT 4
              NAME 2
              STYLE 2
              INDEX 2
              BACKCOLOR 2
              BACKCOLOR 4
              FORECOLOR 2
              FORECOLOR 4
              LEFT 2
              LEFT 4
              TOP 2
              TOP 4
              WIDTH 2
              WIDTH 4
              HEIGHT 2
              HEIGHT 4
              ENABLED 2
              ENABLED 4
              VISIBLE 2
              VISIBLE 4
              MOUSEPOINTER 2
              MOUSEPOINTER 4
              TEXT 2
              TEXT 4
              FONTNAME 2
              FONTNAME 4
              FONTBOLD 2
              FONTBOLD 4
              FONTITALIC 2
              FONTITALIC 4
              FONTSTRIKETHRU 2
              FONTSTRIKETHRU 4
              FONTUNDERLINE 2
              FONTUNDERLINE 4
              FONTSIZE 2
              FONTSIZE 4
              TABINDEX 2
              TABINDEX 4
              LISTCOUNT 2
              LISTINDEX 2
              LISTINDEX 4
              LIST 2
              LIST 4
              SORTED 2
              SELSTART 2
              SELSTART 4
              SELLENGTH 2
              SELLENGTH 4
              SELTEXT 2
              SELTEXT 4
              PARENT 2
              DRAGMODE 2
              DRAGMODE 4
              DRAGICON 2
              DRAGICON 4
              DRAGICON 8
              TABSTOP 2
              TABSTOP 4
              TAG 2
              TAG 4
              HWND 2
              ITEMDATA 2
              ITEMDATA 4
              NEWINDEX 2
              HELPCONTEXTID 2
              HELPCONTEXTID 4
              MOUSEICON 2
              MOUSEICON 4
              MOUSEICON 8
              FONT 2
              FONT 8
              DATAFIELD 2
              DATAFIELD 4
              DATACHANGED 2
              DATACHANGED 4
              WHATSTHISHELPID 2
              WHATSTHISHELPID 4
              APPEARANCE 2
              APPEARANCE 4
              CONTAINER 2
              CONTAINER 8
              INTEGRALHEIGHT 2
              RIGHTTOLEFT 2
              RIGHTTOLEFT 4
              TOOLTIPTEXT 2
              TOOLTIPTEXT 4
              OLEDRAGMODE 2
              OLEDRAGMODE 4
              OLEDROPMODE 2
              OLEDROPMODE 4
              LOCKED 2
              LOCKED 4
              TOPINDEX 2
              TOPINDEX 4
              CAUSESVALIDATION 2
              CAUSESVALIDATION 4
              DATAMEMBER 2
              DATAMEMBER 4
              DATAFORMAT 2
              DATAFORMAT 8
              DATASOURCE 2
              DATASOURCE 8
              CLEAR 1
              ADDITEM 1
              REMOVEITEM 1
              SETFOCUS 1
              REFRESH 1
              ZORDER 1
              DRAG 1
              MOVE 1
              SHOWWHATSTHIS 1
              OLEDRAG 1

From what I curently understand, a Prop.InvokeKind of 2 (INVOKE_PROPERTYGET) means it's a Readable property and a Prop.InvokeKind of 4 (INVOKE_PROPERTYPUT) means it's Writeable.

The issue is that, for example, the 'Height' property of a ComboBox is read only, yet the results above suggest it's Read/ Write. If you note, the ListIndex Property does not have a Prop.InvokeKind of INVOKE_PROPERTYPUT which is what I would expect.

Am I missing something or is there a 'better' way to achieve the objective? (apart from attempting to assign a value to the Property and using in-line Error Handling to trap errors)

BTW The overall objective is to attempt to build a 'generic' Form Resize Class / Module (yes,I know it's been done a thousand times before, but I've never done it- this is an exercise for me rather than anything 'useful') and in order to do so it's required to be able to identify whether a particular Property exists (e.g.Height) and whether it's writable.

[HanneSThEGreaT]

The InvokeKind enumeration is only responsible for how the function is to be invoked, according to this :

http://msdn.microsoft.com/en-us/library/aa911289.aspx

INVOKE_FUNC

Indicates that the member is called using standard function invocation syntax.

INVOKE_PROPERTYGET

Indicates that the function is invoked using standard property-access syntax.

INVOKE_PROPERTYPUT

Indicates that the function is invoked using property value assignment syntax. Syntactically, a typical programming language might represent changing a property in the same way as assignment, for example, object.property : = value

INVOKE_PROPERTYPUTREF

Indicates that the function is invoked using property reference assignment syntax.

So, it seems as if you're understanding it a bit wrong

This may also be helpful :

http://www.xtremevbtalk.com/showthread.php?t=78324

It just takes your code a step further.

[Zvoni]

I've been playing with Typelib Information (TBLINF32.DLL) to enumerate the Properties of all the Controls on a Form and determine whether specific ones are Read only.

From what I curently understand, a Prop.InvokeKind of 2 (INVOKE_PROPERTYGET) means it's a Readable property and a Prop.InvokeKind of 4 (INVOKE_PROPERTYPUT) means it's Writeable.

The issue is that, for example, the 'Height' property of a ComboBox is read only, yet the results above suggest it's Read/ Write. If you note, the ListIndex Property does not have a Prop.InvokeKind of INVOKE_PROPERTYPUT which is what I would expect.

Am I missing something or is there a 'better' way to achieve the objective? (apart from attempting to assign a value to the Property and using in-line Error Handling to trap errors)

BTW The overall objective is to attempt to build a 'generic' Form Resize Class / Module (yes,I know it's been done a thousand times before, but I've never done it- this is an exercise for me rather than anything 'useful') and in order to do so it's required to be able to identify whether a particular Property exists (e.g.Height) and whether it's writable.

How do you figure, that Height would be read-only for a combobox? Or that you would expect that ListIndex is read-only, since in your example above i can clearly see a LISTINDEX 4, which suggests writable. Or did you mean ListCount?
I've been setting Height and ListIndex for a ComboBox during Runtime since Adam & Eve...

[Doogle]

I've been setting Height and ListIndex for a ComboBox during Runtime since Adam & Eve...

I meant ListCount.

I get a Run-time error if I try to set a ComboBox Height property at run time. Error 383 'Height' property is read only

Perhaps the Serpent in the Garden of Eden is playing around again

[Zvoni]

I just did a test with a ComboBox, but in Excel (since i don't have the VB-IDE at work).
No difference by setting different Styles (Combo vs. DropDown, Plain vs. Options etc.)
I could change the height at runtime.
Maybe you have set some weird property which needs a read-only-height.

EDIT: I think my problem is, that in Excel-VBA you can change the height at Runtime

I've found something on codeguru: http://forums.codeguru.com/showthrea...omboBox-Height

[Doogle]

I just did a test with a ComboBox, but in Excel

You'll note that we are in the VB 6 Froum as opposed to VBA or Office.

I can assure you that no 'wierd property' has been set. Try it with VB6 when you have a chance

Private Sub Form_Load()
Combo1.Height = 3000
End Sub

[Zvoni]

You're right. After some research i found out, that in VB6 it's really read-only.
It seems the only "official" way to change the height of a ComboBox is to change its Font-Size, if you don't want to use the hack with the MoveWindow-API
Since changing a combobox's Fontsize also changes its height, you could argue, that Height as such has to be "writable" hence the INVOKE_PROPERTYPUT even if you cannot access it directly.

At least that's my conclusion

[Doogle]

Yes, I think I've concluded that there's a PROPERTYPUT for the Height Property because it can be set at Design-time and it's at run-time that the error occurrs. If I try to set a value for ListCount I get a compile error. It begs the question: "How does VB run-time work out that the Property is Read Only?" - more Googling I suppose.

[Zvoni]

The funny thing is, if you set a combobox to "simple combo" (like a textbox) you can change its height at run time.
at least that is what i could find

[Zvoni]

*snip* It begs the question: "How does VB run-time work out that the Property is Read Only?" - more Googling I suppose.

http://msdn.microsoft.com/en-us/libr...=vs.60%29.aspx

It's not the vb-runtime, it's the design of the control!