drag and drop issue...

If I use software like OpenOffice and try to drag text I could notice that
1. when I drag inside the document I'm moving the text
2. when I drag outside the document I'm copying the text

Yet it all looks like one smooth operation. With correct cursor feedback
(the little + marker next to the icon).
My problem is, once I call DoDragDrop() it's blocking, I have no other
opportunities to change the AllowedEffect to only Copy if I drag over, say,
an other control

And QueryContinueDrag:
1. don't allow me to change the efect
2. don't inform me about the current drop target

How could I do that?
(i.e. how could I modify the allowed efffect depending on the target (i.e.
wether it's me or not))

CiaranODonnell
Fri Nov 24 03:42:01 CST 2006

The DragDropEffects enum is a Flags enum so when DoDrapDrop'ing at the
source, if the data can be moved or copied then you set the effect to
DragDropEffects.Copy | DragDropEffects.Move
The when the destination handles drag enter, that can decide whether it
should be copied or moved to it.
I generally like to make a struct or class to hold more information that the
dragdrop'd data like the source object and anythign else used in the
descision. Then if dragging to another part of my app then i can handle it
easily.

HTH

Ciaran O'Donnell

"Lloyd Dupont" wrote:

> If I use software like OpenOffice and try to drag text I could notice that
> 1. when I drag inside the document I'm moving the text
> 2. when I drag outside the document I'm copying the text
>
> Yet it all looks like one smooth operation. With correct cursor feedback
> (the little + marker next to the icon).
> My problem is, once I call DoDragDrop() it's blocking, I have no other
> opportunities to change the AllowedEffect to only Copy if I drag over, say,
> an other control
>
> And QueryContinueDrag:
> 1. don't allow me to change the efect
> 2. don't inform me about the current drop target
>
> How could I do that?
> (i.e. how could I modify the allowed efffect depending on the target (i.e.
> wether it's me or not))
>
>
>

Lloyd
Fri Nov 24 07:31:47 CST 2006

No, it didn't H!

Perhaps I was not clear enough?
I'm trying to do something which looks impossible with the public .NET API,
yet Word and OpenOffice manage it.


In pseudo code it will look like that:

if(target == this)
AllowedEffect = Copy | Move;
else
AllowedEffect = Copy;

Of course the source should update the AllowedEffect every time the target
change. Which is not possible with the API, yet Word manage to do it.
So I wonder how it does it...


"Ciaran O''Donnell" <CiaranODonnell@discussions.microsoft.com> wrote in
message news:793E0F3F-DABF-44DC-B1AF-400EAD5376D5@microsoft.com...
> The DragDropEffects enum is a Flags enum so when DoDrapDrop'ing at the
> source, if the data can be moved or copied then you set the effect to
> DragDropEffects.Copy | DragDropEffects.Move
> The when the destination handles drag enter, that can decide whether it
> should be copied or moved to it.
> I generally like to make a struct or class to hold more information that
> the
> dragdrop'd data like the source object and anythign else used in the
> descision. Then if dragging to another part of my app then i can handle it
> easily.
>
> HTH
>
> Ciaran O'Donnell
>
> "Lloyd Dupont" wrote:
>
>> If I use software like OpenOffice and try to drag text I could notice
>> that
>> 1. when I drag inside the document I'm moving the text
>> 2. when I drag outside the document I'm copying the text
>>
>> Yet it all looks like one smooth operation. With correct cursor feedback
>> (the little + marker next to the icon).
>> My problem is, once I call DoDragDrop() it's blocking, I have no other
>> opportunities to change the AllowedEffect to only Copy if I drag over,
>> say,
>> an other control
>>
>> And QueryContinueDrag:
>> 1. don't allow me to change the efect
>> 2. don't inform me about the current drop target
>>
>> How could I do that?
>> (i.e. how could I modify the allowed efffect depending on the target
>> (i.e.
>> wether it's me or not))
>>
>>
>>

Jeff
Fri Nov 24 09:18:23 CST 2006

On 24/11/2006 in message <##xYcz8DHHA.3520@TK2MSFTNGP04.phx.gbl> Lloyd
Dupont wrote:

>No, it didn't H!
>
>Perhaps I was not clear enough?
>I'm trying to do something which looks impossible with the public .NET
>API, yet Word and OpenOffice manage it.

I do that with a TreeView as follows:

private void tvFav_DragOver(object sender, DragEventArgs e)
{
// Control key moves
if (e.Data.GetDataPresent(typeof(JExLVItem)))
{
if ((e.KeyState & 8) == 8)
e.Effect = DragDropEffects.Move;
else
e.Effect = DragDropEffects.Copy;
}
else
e.Effect = DragDropEffects.None;
}

Can you trap DragOver in whatever control you are dropping on? You could
then test for the type of data.


--
Jeff Gaines

Dave
Sat Nov 25 23:53:37 CST 2006

Hi Lloyd,

The key is that your drop targets must be aware of the source, not the other
way around.

You may want to read the following article:

"Performing Drag and Drop Operations"
http://msdn2.microsoft.com/en-gb/library/ms973845.aspx

(The article uses VB.NET; sorry :)

--
Dave Sexton

"Lloyd Dupont" <net.galador@ld> wrote in message
news:%23%23xYcz8DHHA.3520@TK2MSFTNGP04.phx.gbl...
> No, it didn't H!
>
> Perhaps I was not clear enough?
> I'm trying to do something which looks impossible with the public .NET
> API, yet Word and OpenOffice manage it.
>
>
> In pseudo code it will look like that:
>
> if(target == this)
> AllowedEffect = Copy | Move;
> else
> AllowedEffect = Copy;
>
> Of course the source should update the AllowedEffect every time the target
> change. Which is not possible with the API, yet Word manage to do it.
> So I wonder how it does it...
>
>
> "Ciaran O''Donnell" <CiaranODonnell@discussions.microsoft.com> wrote in
> message news:793E0F3F-DABF-44DC-B1AF-400EAD5376D5@microsoft.com...
>> The DragDropEffects enum is a Flags enum so when DoDrapDrop'ing at the
>> source, if the data can be moved or copied then you set the effect to
>> DragDropEffects.Copy | DragDropEffects.Move
>> The when the destination handles drag enter, that can decide whether it
>> should be copied or moved to it.
>> I generally like to make a struct or class to hold more information that
>> the
>> dragdrop'd data like the source object and anythign else used in the
>> descision. Then if dragging to another part of my app then i can handle
>> it
>> easily.
>>
>> HTH
>>
>> Ciaran O'Donnell
>>
>> "Lloyd Dupont" wrote:
>>
>>> If I use software like OpenOffice and try to drag text I could notice
>>> that
>>> 1. when I drag inside the document I'm moving the text
>>> 2. when I drag outside the document I'm copying the text
>>>
>>> Yet it all looks like one smooth operation. With correct cursor feedback
>>> (the little + marker next to the icon).
>>> My problem is, once I call DoDragDrop() it's blocking, I have no other
>>> opportunities to change the AllowedEffect to only Copy if I drag over,
>>> say,
>>> an other control
>>>
>>> And QueryContinueDrag:
>>> 1. don't allow me to change the efect
>>> 2. don't inform me about the current drop target
>>>
>>> How could I do that?
>>> (i.e. how could I modify the allowed efffect depending on the target
>>> (i.e.
>>> wether it's me or not))
>>>
>>>
>>>
>
>