From: rick.rans@canada.com
Robert
I think I would go with your first thought with the following additions.
1. If your form doesn't exist as an open form, then open it and give it a
different name.
2. Next, since your open form has a different name, change the check of the
enumerated list and for the new form name and if it exists, then the form is
open.
3. Since the open form has a different name than the form you are trying to
open, you can do a bring to top the form you want on top and close the form
that is opening.
Just a WAG, but hope it helps. - Rick
"Robert Wiltshire" wrote in message
news:488aad74$1@pnews.thedbcommunity.com...
>
> I have a form that assists me with programming tasks,
> and I would like to make sure it does not open a second time.
>
> Using a script,
> I am familiar with doing something like the following
> ( I am typing this off the top of head, so it is not syntax checked )
>
> stFormname=":ztools:\\coding\\pickfields.fsl"
> stTitle = "Pick Field Utility"
> if not f.attach(stTitleOfForm) then
> f.open(stFormname)
> endif
>
> And that would be fine,
> except, as part of my issue,
> I would like the code to be *inside* the form itself,
> not in an external script.
>
> I ended up figuring out 2 ways to do this,
> and I wanted to share this experience,
> but I welcome any input from others on how to do this.
> This post gets a little long, so proceed with caution. =)
>
> Remember, I want the prevention code to be inside the form,
> not in an external script, form, or library.
>
>
> Solution 1 :
>
> I decided to start in the init section of the form,
> and I am using either pdox 10 sp3 or pdox X3.
>
> Inside the form, I found the following useful :
>
> f.attach()
> stTitleThisForm = f.getTitle()
>
> This allows me to fetch the title on the fly, as the form that is opening,
> and eliminates the need to hard code the form title.
> ( which I think is a huge plus )
>
> I then used enumFormnames(arForms) to list all open forms to an array,
> and I can step through that array to see that the form is in there twice.
> If I find that arForms contains stTitleThisForm more than once,
> I simply exited the form that was loading as follows :
>
> eventInfo.setErrorCode(canNotArrive)
> close()
> return
>
> This closes the form, and only leaves one instance of the form open on the
> desktop.
> But, that form is not guaranteed to be on top,
> and even though I did not want this form open 2 times,
> I did want the open copy of this form to come to the top of the pile.
>
> So as many programming tasks happen,
> the main idea was fairly easy, but the last touch was a pita.
>
>
> If I had a form handle, I could use f.bringToTop(),
> but.........I dont see any way to get a handle to the first instance of
> the form,
> from the code in that form as it is opening the second time.
>
> The problem is, the title of the 1st instance is the same title as the 2nd
> instance,
> and we are now talking about the code that is running in the 2nd instance
> of the form.
>
> If you call enumFormnames(arForms)
> and then call ( or somethign similar, depending on what forms open)
> if arForms[1] = arForms[2] then
> msgInfo("Note","2 titles are the same")
> endif
> So, this proves that pdox thinks both instances of the form have the same
> name.
> Obviously the above indexes to the array need to be correct,
> to reflect where they are ni the array.
> I simply used arForms.view() to look at array and determine necessary
> index.
>
> Trying
> f.attach(arForms[1]) and f.attach(arForms[2])
> always returned a form handle to the 2nd instance of the form,
> which makes sense , since it was the same exact title.
>
> Without the form handle,
> I was unable to call the pdox form method bringToTop.
>
>
> I did find that there was a windows api call,
> and the uses statement looks like
>
> "USER32"
> BringWindowToTop(hWnd CLONG) CLONG
>
> This requires a windows handle for the form,
> not a paradox form handle.
> This ended up being fairly easy to get,
> using the paradox procedure : enumDesktopWindowHandles,
> which returns all paradox form handles in a dynarray,
> with the index of the dynarray being the handle,
> and the value being the window name.
>
> enumDesktopWindowHandles(dyHandles)
>
> We get the handle for the currently executing 2nd instance of the form
> rather easily as follows :
> ;This gets handle of the current instance of the form
> liHandleThisForm = f.windowHandle()
>
> ;init handle of the 1st instance we are looking for
> liHandleOtherForm = 0
>
> Now step thru dynarray, and find title
> but remember title is in the dynarray 2 times
> and we want the handle for the one that is different from the current form
>
> foreach stHandle in dyHandles
> stTitle = dyHandles[stHandle]
>
> if stTitle = stTitleThisForm then
> liHandle = longint(stHandle)
> if liHandle <> liHandleThisForm then
> liHandleOtherForm = liHandle
> quitloop
> endif
> endif
>
> endforeach
>
> ;If for some reason, we didnt find it, do not call windows api function
> if liHandleOtherForm = 0 then
> return(false)
> endif
>
> ; call api function, to bring 1st instance to the top of the pile
> liRet = BringWindowToTop(liHandleOtherForm)
>
> and then exit and close self as mentioned before
>
>
>
> Second Solution
>
> I had mentioned before,
> the issue to get pdox form handle is difficult
> because both instances have the same exact title.
>
> I went and manually entered the form title to be
> stTitle = "Pick Field Utilityx"
>
> My idea was to modify the title of the open form,
> so that it had a slightly differnt value than the form in the init stage.
> This worked rather well.
>
> So the init method looks like
>
> method init(var eventInfo Event)
>
> var
> fThis,fOrig form
> stTitleThisForm,stNewTitle string
> endvar
>
> ; attach to current form, and get its title
> fThis.attach()
> stTitleThisForm = fThis.getTitle()
>
> ; for new title, removes last char from orig title
> stNewTitle = stTitleThisForm.substr(1,stTitleThisForm.sizeEx()-1)
>
> ; if possible, attach to corrected title, bring to top, and close down
> if fOrig.attach(stNewTitle) then
> fOrig.bringtotop()
> eventInfo.setErrorCode(canNotArrive)
> close()
> return
> endif
>
> ; form was not open, so change this form title
> fThis.setTitle(stNewTitle)
>
> endMethod
>
> Thats it.
> It seems to work ok.
>
>
> I added this to the close method of this form,
>
> ;fix up title to original
> f.attach()
> f.setTitle(f.getTitle() + "x")
>
> I was thinking of putting a box object on the form,
> and putting all relevant code inside it,
> so that I could simply plop it on any form that needed this code,
> but I did not get around to that yet.
>
> Perhaps there are easier ways to do this.
> Comments, suggestions, and discussion always welcome.
>
>
> Robert Wiltshire
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