Re: Out-of-order Undos and NSTextField [SOLVED, well sort of]

FROM : Ken Victor
DATE : Tue Jul 11 21:37:49 2006

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ken


At 12:05 PM -0700 7/11/06, James Bucanek wrote:
>After messing around with this problem, I found an almost acceptable
>solution. This is a bit hacky, and I fear there are unpredicatble
>side-effect, but it seems to be working in my application OK.
>
>The hack is to sub-class NSTextField, then intercept one of the
>delegate messages sent to NSTextField from the NSTextView that gets
>created as the field's editor. I wish there was a
>textViewWillBeginEditing:, but I settled for
>textView:shouldChangeTextInRange:replacementString: which gets
>invoked whenever the user tries to add/remove/replace any text.
>Before the message is passed on to the real NSTextField, I simply
>turn off undo support in the field editor.
>
>Hopefully this will solve someone else's problem, or at least
>encourage someone to find a better solution.
>
>
>------------- /Users/james/Desktop/UndoableTextField.h
>
>//
>//  UndoableTextField.h
>//  QRecall
>//
>//  Created by James Bucanek on 7/11/06.
>//
>
>#import <Cocoa/Cocoa.h>
>
>//
>//  An NSTextField that does not use the undo manager.
>//
>// NSTextField/NSTextView has this nasty habid of registering undo
>actions out of order.
>// This is used in windows where the text field is bound to a
>property that is already
>//  registering undo actions based on the changes in its value and
>we don't need the field
>//  editor registering superfluous text edit changes at the same time.
>//
>// Notes:
>// The object works by intercepting the
>textView:shouldChangeTextInRange:replacementString:
>//  delegate message sent to the text field whenever the user tries
>to change the text.
>//  Before passing the message on, it disables undo on the
>NSTextView that is being used
>//  as the field editor.
>// This won't work for more complex cases where the user changes the font or
>//  other attributes of the text first. It also might mess up other
>fields that reuse
>//  the NSTextView object.
>
>
>@interface UndoableTextField : NSTextField
>
>- (BOOL)textView:(NSTextView*)textView
>shouldChangeTextInRange:(NSRange)affectedCharRange
>replacementString:(NSString*)replacementString;
>
>@end
>
>
>------------- /Users/james/Desktop/UndoableTextField.m
>
>//
>//  UndoableTextField.m
>//  QRecall
>//
>//  Created by James Bucanek on 7/11/06.
>//
>
>#import "UndoableTextField.h"
>
>
>@implementation UndoableTextField
>
>- (BOOL)textView:(NSTextView*)textView
>shouldChangeTextInRange:(NSRange)affectedCharRange
>replacementString:(NSString*)replacementString
>{
>    [textView setAllowsUndo:NO];    // turn off Undo before the user
>changes anything
>    // NSTextField should implement
>textView:shouldChangeTextInRange:replacementString:, but just to be
>on the safe side...
>    if ([super
>respondsToSelector:@selector(textView:shouldChangeTextInRange:replacementString:)])
>        return ([super textView:textView
>shouldChangeTextInRange:affectedCharRange
>replacementString:replacementString]);
>    return (YES);
>}
>
>@end
>--
>James Bucanek