NSTableView, file promises, and the message queue
-
OK, I've searched the archives and found this,
<http://cocoa.mamasam.com/COCOADEV/2003/03/1/57866.php>, which
describes my problem exactly, but no one answered.
I've set up an NSTableView to do drag-and-drop, and it's done by using
file promises. Since there isn't any way currently to create a file
promise pasteboard, I'm using the workaround I read about, which is to
manually call -dragPromisedFilesOfType: within the data source's
-tableView:writeRows:toPasteboard: method.
Things work fine, but now I'm having yet another weird problem:
Drag-and-drop works, but after the drop, the application just "sticks".
That is, the message queue just stops until the user clicks somewhere
in the application, and then it magically restarts.
Is there any workaround or fix for this? I'm using something similar
(but not the same) as this:
- (BOOL)tableView:(NSTableView *)tableView writeRows:(NSArray *)rows
toPasteboard:(NSPasteboard *)pboard
{
NSPoint dragPosition = [tableView convertPoint:[window
convertScreenToBase:[NSEvent mouseLocation]] fromView:nil];
NSRect imageLocation;
long i;
// This code sets up the "image" so that it appears directly in the
center of the cursor.
dragPosition.x -= 16;
dragPosition.y -= 16;
imageLocation.origin = dragPosition;
imageLocation.size = NSMakeSize(32,32);
[tableView dragPromisedFilesOfTypes:[NSArray arrayWithObject:@""]
fromRect:imageLocation source:tableView slideBack:YES event:[NSApp
currentEvent]];
return NO;
}
Any ideas would be appreciated...
Nick Zitzmann
AIM/iChat: dragonsdontsleep
Check out my software page: http://dreamless.home.attbi.com/
"Great spirits have always encountered violent opposition from mediocre
minds." - Albert Einstein
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I have the same problem too...I've tried many methods of working around
it, but all lead to quirks such as stalls or odd table view selection
behaviour...
Has anyone on the list successfully implemented promise drags for a
TableView / OutlineView? I think it is an oversight on Apple's part not
to provide a method for manually adding the promise drag sources to the
dragging pasteboard, since that would have allowed us to use the
default method for starting drags from table views.
/ Rgds, David
On Tuesday, May 13, 2003, at 03:08 PM, Nick Zitzmann wrote:> OK, I've searched the archives and found this,_______________________________________________
> <http://cocoa.mamasam.com/COCOADEV/2003/03/1/57866.php>, which
> describes my problem exactly, but no one answered.
>
> I've set up an NSTableView to do drag-and-drop, and it's done by using
> file promises. Since there isn't any way currently to create a file
> promise pasteboard, I'm using the workaround I read about, which is to
> manually call -dragPromisedFilesOfType: within the data source's
> -tableView:writeRows:toPasteboard: method.
>
> Things work fine, but now I'm having yet another weird problem:
> Drag-and-drop works, but after the drop, the application just
> "sticks". That is, the message queue just stops until the user clicks
> somewhere in the application, and then it magically restarts.
>
> Is there any workaround or fix for this? I'm using something similar
> (but not the same) as this:
>
> - (BOOL)tableView:(NSTableView *)tableView writeRows:(NSArray *)rows
> toPasteboard:(NSPasteboard *)pboard
> {
> NSPoint dragPosition = [tableView convertPoint:[window
> convertScreenToBase:[NSEvent mouseLocation]] fromView:nil];
> NSRect imageLocation;
> long i;
>
> // This code sets up the "image" so that it appears directly in
> the center of the cursor.
> dragPosition.x -= 16;
> dragPosition.y -= 16;
> imageLocation.origin = dragPosition;
> imageLocation.size = NSMakeSize(32,32);
>
> [tableView dragPromisedFilesOfTypes:[NSArray arrayWithObject:@""]
> fromRect:imageLocation source:tableView slideBack:YES event:[NSApp
> currentEvent]];
> return NO;
> }
>
> Any ideas would be appreciated...
>
> Nick Zitzmann
> AIM/iChat: dragonsdontsleep
> Check out my software page: http://dreamless.home.attbi.com/
>
> "Great spirits have always encountered violent opposition from
> mediocre minds." - Albert Einstein
> _______________________________________________
> cocoa-dev mailing list | <cocoa-dev...>
> Help/Unsubscribe/Archives:
> http://www.lists.apple.com/mailman/listinfo/cocoa-dev
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I have promised file drag&drop working (it was a joyous
occasion when that happened :-) ), no application sticking.
It looks like you are trying to fit promised files around the
more normal drag&drop API, I don't think you can do that,
I think you have to subclass NSTableView (see below) and
overload some methods. Don't rely on the Jaguar developer
CD Cocoa documentation to cover promised files properly,
it doesn't (well mine doesn't), you have to look at the Apple
on-line documentation. That is where my code came from.
There are a couple of slight anomalies in its behaviour, which
if someone knows how to fix then I'd be glad to hear:
1. You can't start a drag until your app is at the front, which
is different to normal drag&drop.
2. The drag starts immediately rather after a slight mouse
movement with the button down, i.e. all you have to do is
click.
Otherwise it works great, the Finder responds with the path
of the folder the drag was dropped onto perfectly and (after
some initial struggling to get it to work) no application sticking.
Tim.
@implementation MyTableView
- (NSDragOperation)draggingSourceOperationMaskForLocal:(BOOL)isLocal {
if (isLocal) return NSDragOperationNone;
else return NSDragOperationCopy;
}
- (void)mouseDown:(NSEvent *)theEvent
{
NSPoint dragPosition;
NSRect imageLocation;
int row;
dragPosition = [self convertPoint:[theEvent locationInWindow]
fromView:nil];
row = [self rowAtPoint:dragPosition];
if ( (row != -1) && (row < [[self delegate] nRows]) ) {
[self selectRow:row byExtendingSelection:NO];
dragPosition.x -= 16;
dragPosition.y -= 16;
imageLocation.origin = dragPosition;
imageLocation.size = NSMakeSize( 32, 32 );
printf ( "mouseDown: called (x: %f, y:%f, row:%d)\n", dragPosition.x,
dragPosition.y, row );
[self dragPromisedFilesOfTypes:[NSArray arrayWithObject:@""]
fromRect:imageLocation source:self slideBack:YES event:theEvent];
}
}
- (NSArray *)namesOfPromisedFilesDroppedAtDestination:(NSURL *)url
{
printf( "Dropped to: %s\n", [[url path] cString] );
return nil;
}
@end
On Tuesday, May 13, 2003, at 15:53 Europe/London,
<cocoa-dev-request...> wrote:> OK, I've searched the archives and found this,_______________________________________________
> <http://cocoa.mamasam.com/COCOADEV/2003/03/1/57866.php>, which
> describes my problem exactly, but no one answered.
>
> I've set up an NSTableView to do drag-and-drop, and it's done by using
> file promises. Since there isn't any way currently to create a file
> promise pasteboard, I'm using the workaround I read about, which is to
> manually call -dragPromisedFilesOfType: within the data source's
> -tableView:writeRows:toPasteboard: method.
>
> Things work fine, but now I'm having yet another weird problem:
> Drag-and-drop works, but after the drop, the application just "sticks".
> That is, the message queue just stops until the user clicks somewhere
> in the application, and then it magically restarts.
>
> Is there any workaround or fix for this? I'm using something similar
> (but not the same) as this:
>
> - (BOOL)tableView:(NSTableView *)tableView writeRows:(NSArray *)rows
> toPasteboard:(NSPasteboard *)pboard
> {
> NSPoint dragPosition = [tableView convertPoint:[window
> convertScreenToBase:[NSEvent mouseLocation]] fromView:nil];
> NSRect imageLocation;
> long i;
>
> // This code sets up the "image" so that it appears directly in
> the
> center of the cursor.
> dragPosition.x -= 16;
> dragPosition.y -= 16;
> imageLocation.origin = dragPosition;
> imageLocation.size = NSMakeSize(32,32);
>
> [tableView dragPromisedFilesOfTypes:[NSArray arrayWithObject:@""]
> fromRect:imageLocation source:tableView slideBack:YES event:[NSApp
> currentEvent]];
> return NO;
> }
>
> Any ideas would be appreciated...
>
> Nick Zitzmann
> AIM/iChat: dragonsdontsleep
> Check out my software page: http://dreamless.home.attbi.com/
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On Tuesday, May 13, 2003, at 09:41 AM, Tim Hewett wrote:> I have promised file drag&drop working (it was a joyous
> occasion when that happened :-) ), no application sticking.
> It looks like you are trying to fit promised files around the
> more normal drag&drop API, I don't think you can do that,
> I think you have to subclass NSTableView (see below) and
> overload some methods. Don't rely on the Jaguar developer
> CD Cocoa documentation to cover promised files properly,
> it doesn't (well mine doesn't), you have to look at the Apple
> on-line documentation. That is where my code came from.
I tried your approach and it didn't work.
First of all, subclassing -mouseDown: and adding the drag stuff makes
the program assume I'm dragging something as soon as the mouse is down.
Also, it completely breaks the table view action and double-click
action, both of which I need to preserve.
So, I tried subclassing -mouseDragged: and for some reason, the
subclass method is never called.
Then, I tried capturing the next event using NSApplication, and that
appears to block unless I set the expiration date to be [NSDate date],
which doesn't work.
So I'm all out of ideas. Has anyone made this work flawlessly? As I
said before, my solution worked, but I end up with a stalled message
queue...
Nick Zitzmann
AIM/iChat: dragonsdontsleep
Check out my software page: http://dreamless.home.attbi.com/
"Great spirits have always encountered violent opposition from mediocre
minds." - Albert Einstein
_______________________________________________
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On Wednesday, May 14, 2003, at 02:06 PM, Nick Zitzmann wrote:> On Tuesday, May 13, 2003, at 09:41 AM, Tim Hewett wrote:
>
>> I have promised file drag&drop working (it was a joyous
>> occasion when that happened :-) ), no application sticking.
>> It looks like you are trying to fit promised files around the
>> more normal drag&drop API, I don't think you can do that,
>> I think you have to subclass NSTableView (see below) and
>> overload some methods. Don't rely on the Jaguar developer
>> CD Cocoa documentation to cover promised files properly,
>> it doesn't (well mine doesn't), you have to look at the Apple
>> on-line documentation. That is where my code came from.
>
> I tried your approach and it didn't work.
>
> First of all, subclassing -mouseDown: and adding the drag stuff makes
> the program assume I'm dragging something as soon as the mouse is
> down. Also, it completely breaks the table view action and
> double-click action, both of which I need to preserve.
>
> So, I tried subclassing -mouseDragged: and for some reason, the
> subclass method is never called.
The reason for that is that NSTableView starts event tracking in
mouseDown: and doesn't stop tracking until the mouse button is
released. That makes it difficult to overload - since you would have to
figure out exactly what mouseDown: does except for catching drags.> Then, I tried capturing the next event using NSApplication, and that
> appears to block unless I set the expiration date to be [NSDate date],
> which doesn't work.
>
> So I'm all out of ideas. Has anyone made this work flawlessly? As I
> said before, my solution worked, but I end up with a stalled message
> queue...
I've tried both your approach and the subclassing method, without
success...Could someone who managed to do it please post some sample
code?
/ Rgds, David
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For the problem of the event queue sticking when dragging from the
datasource: just return YES to the method writeCell... I seem to
remember that i had to do a few trick after that to keep everything
working as expected, but that should get rid of the sticking. The only
problem left is that when dragging, it will behave as if you did two
drags, one for the promise, one for the regular so you'll sometimes get
a slide back effect (minor annoyance in my case).
As for overriding mouse down, you have to set a periodic event so
you'll know if you need to start a drag or just select or anything else.
NSEvent startPeriodicEventsAfterDelay: 0.3 withPeriod: 0];
NSEvent *newEvent = [[self window] nextEventMatchingMask:
NSLeftMouseUpMask | NSLeftMouseDraggedMask |
NSPeriodicMask];
switch ([newEvent type]) {
case NSLeftMouseUp:
break;
case NSPeriodic:
[self doPromiseDrag: theEvent];
break;
case NSLeftMouseDragged:
break;
default:
break;
hope this helps.
Olivier
On Wednesday, May 14, 2003, at 07:23 AM, David Remahl wrote:> On Wednesday, May 14, 2003, at 02:06 PM, Nick Zitzmann wrote:_______________________________________________
>
>> On Tuesday, May 13, 2003, at 09:41 AM, Tim Hewett wrote:
>>
>>> I have promised file drag&drop working (it was a joyous
>>> occasion when that happened :-) ), no application sticking.
>>> It looks like you are trying to fit promised files around the
>>> more normal drag&drop API, I don't think you can do that,
>>> I think you have to subclass NSTableView (see below) and
>>> overload some methods. Don't rely on the Jaguar developer
>>> CD Cocoa documentation to cover promised files properly,
>>> it doesn't (well mine doesn't), you have to look at the Apple
>>> on-line documentation. That is where my code came from.
>>
>> I tried your approach and it didn't work.
>>
>> First of all, subclassing -mouseDown: and adding the drag stuff makes
>> the program assume I'm dragging something as soon as the mouse is
>> down. Also, it completely breaks the table view action and
>> double-click action, both of which I need to preserve.
>>
>> So, I tried subclassing -mouseDragged: and for some reason, the
>> subclass method is never called.
>
> The reason for that is that NSTableView starts event tracking in
> mouseDown: and doesn't stop tracking until the mouse button is
> released. That makes it difficult to overload - since you would have
> to figure out exactly what mouseDown: does except for catching drags.
>
>> Then, I tried capturing the next event using NSApplication, and that
>> appears to block unless I set the expiration date to be [NSDate
>> date], which doesn't work.
>>
>> So I'm all out of ideas. Has anyone made this work flawlessly? As I
>> said before, my solution worked, but I end up with a stalled message
>> queue...
>
> I've tried both your approach and the subclassing method, without
> success...Could someone who managed to do it please post some sample
> code?
>
> / Rgds, David
> _______________________________________________
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On Wednesday, May 14, 2003, at 07:00 AM, olivier wrote:> For the problem of the event queue sticking when dragging from the
> datasource: just return YES to the method writeCell... I seem to
> remember that i had to do a few trick after that to keep everything
> working as expected, but that should get rid of the sticking.
Hmm, which writeCell: method might this be? We're talking about
NSTableView, and after searching through the documentation and headers,
I can only find a writeCell: method for NSTextView. Is there some sort
of undocumented method I need to implement here?
Nick Zitzmann
AIM/iChat: dragonsdontsleep
Check out my software page: http://dreamless.home.attbi.com/
"Great spirits have always encountered violent opposition from mediocre
minds." - Albert Einstein
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sorry for the imprecision:
- (BOOL)tableView:(NSTableView *)tableView writeRows:(NSArray*)rows
toPasteboard:(NSPasteboard*)pboard
- (BOOL)outlineView:(NSOutlineView *)outlineView
writeItems:(NSArray*)items toPasteboard:(NSPasteboard*)pboard
Olivier
On Thursday, May 15, 2003, at 06:58 AM, Nick Zitzmann wrote:>_______________________________________________
> On Wednesday, May 14, 2003, at 07:00 AM, olivier wrote:
>
>> For the problem of the event queue sticking when dragging from the
>> datasource: just return YES to the method writeCell... I seem to
>> remember that i had to do a few trick after that to keep everything
>> working as expected, but that should get rid of the sticking.
>
> Hmm, which writeCell: method might this be? We're talking about
> NSTableView, and after searching through the documentation and
> headers, I can only find a writeCell: method for NSTextView. Is there
> some sort of undocumented method I need to implement here?
>
> Nick Zitzmann
> AIM/iChat: dragonsdontsleep
> Check out my software page: http://dreamless.home.attbi.com/
>
> "Great spirits have always encountered violent opposition from
> mediocre minds." - Albert Einstein
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