[Drawkit] Introductory demo ??

[Graham Cox]

Ah - you've run into a little issue that I fixed after the last beta  
drop.

NSUndoManager indeed does not implement -changeCount, though  
DKUndoManager does. So I added a respondsToSelector: check in the one  
place I use it, with DKObjectDrawingLayer. The better solution would  
be to swap the NSUndoManager for a DKUndoManager, but when the app  
isn't document based, it's not clear how to do that. I've asked about  
this on cocoa-dev.

For now you could add the check yourself to the code in DrawKit:


- (void)	recordSelectionForUndo
{
	if ( m_selectionUndo )
	{
		[m_selectionUndo release];
		m_selectionUndo = nil;
	}
	
	// keep a note of the undo count at this point - if it hasn't changed  
when the
	// selection is committed, then don't record the selection change  
unless the flag forces it.
	
	if([[self undoManager] respondsToSelector:@selector(changeCount)])		// 
<------------------------------------------ +
		mUndoCount = [(DKUndoManager*)[self undoManager] changeCount];
	
	m_selectionUndo = [[self selection] retain];
	
	LogEvent_( kReactiveEvent, @"recorded selection for possible undo,  
count = %d", mUndoCount );
}


- (void)	commitSelectionUndoWithActionName:(NSString*) actionName
{
	// sends the recorded selection to the undo manager. If sel changes  
are not undoable on their own, the sel change is only
	// added to the undo stack if some other operation has also occurred,  
and then only if the selection actually
	// changed. If the flag is to record all changes, unaccompanied sel  
changes are recorded regardless.
	
	unsigned cc;
	
	
	if([[self undoManager]  
respondsToSelector:@selector(changeCount)])		//  
<------------------------------------------ +
		cc = [(DKUndoManager*)[self undoManager] changeCount];
	else
		cc = mUndoCount + 1;
	
	if (([self selectionChangesAreUndoable] || cc > mUndoCount) &&  
m_selectionUndo != nil )
	{
		// if selection hasn't changed, do nothing
		
		if([self selectionHasChangedFromRecorded])
		{
			LogEvent_( kStateEvent, @"selection changed - recording for undo");
			
			[[self undoManager] registerUndoWithTarget:self  
selector:@selector(setSelection:) object:m_selectionUndo];
			
			// use the passed action name if there is one, otherwise any stored  
action name
			
			if ( actionName != nil )
				[[self undoManager] setActionName:actionName];
		}
	}
	else
	{
		// here, the selection is the only change, and it's not meant to be  
undone, so
		// do not set the action name
		
		actionName = nil;
	}
	
	if ( actionName != nil )
		[[self undoManager] setActionName:actionName];
	
	// done with the recorded selection, so get rid of it
	
	[m_selectionUndo release];
	m_selectionUndo = nil;
}


cheers, Graham




On 19 Jun 2008, at 3:23 pm, Troy Rollins wrote:

>
> On Jun 19, 2008, at 12:46 AM, Graham Cox wrote:
>
>> I'll attach the project file to this message, but I'll also put the  
>> project and executable up on the website so you can download it.  
>> The single controller class is: a) the controller between the UI  
>> shown here and DK, b) the application's delegate (to get a few  
>> things set up at launch) c) the table's delegate and datasource and  
>> d) the window's delegate. So it wears a few hats which also add a  
>> little to its complexity, but overall it's extremely lightweight.  
>> You can also get to a number of features by right-clicking objects  
>> in the drawing (that's just default DK behaviour).
>
> Compiling doesn't seem to raise any issues, however I've been unable  
> so far to actually create a drawing object.
>
> Mouse actions give me -
>
> 2008-06-19 01:18:57.257 DK Mini Demo[4380:10b] *** -[NSUndoManager  
> changeCount]: unrecognized selector sent to instance 0x475610
> 2008-06-19 01:18:57.258 DK Mini Demo[4380:10b] *** -[NSUndoManager  
> changeCount]: unrecognized selector sent to instance 0x475610
> 2008-06-19 01:18:57.407 DK Mini Demo[4380:10b]  
> enableUndoRegistration: NSUndoManager 0x475610 is in invalid state,  
> enableUndoRegistration may only be invoked with matching call to  
> disableUndoRegistration
>
>
>
>
> --
> Troy
> RPSystems, Ltd.
> http://www.rpsystems.net
>
>
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