TransactionsController_Dragging.m

/*
     File: TransactionsController_Dragging.m
 Abstract: This category implements tableView data source methods to support dragging.
  Version: 1.2
 
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 */
 
#import "TransactionsController.h"
#import "MyDocument_Pasteboard.h"
 
@implementation TransactionsController(Dragging)
 
/* Preliminary registration */
 
- (void)awakeFromNib {
    [_transactionTable registerForDraggedTypes:[_document readablePasteboardTypes]];
    [_transactionTable setDraggingSourceOperationMask:(NSDragOperationCopy|NSDragOperationGeneric) forLocal:YES];
    [_transactionTable setDraggingSourceOperationMask:(NSDragOperationCopy|NSDragOperationGeneric) forLocal:NO];
}
 
 
/* Data source methods for dragging out */
 
- (BOOL)tableView:(NSTableView *)tv writeRowsWithIndexes:(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard *)pboard {
    // This method will be called before the start of a drag out
    BOOL result = NO;
    if (NSNotFound != [rowIndexes firstIndex]) {
        // We ask the document to write out the selected transactions plus a file promise to the pasteboard
        [self setSelectionIndexes:rowIndexes];
        result = [_document writeSelectionToPasteboard:pboard types:[_document writablePasteboardTypes]];
    }
    return result;
}
 
- (NSArray *)tableView:(NSTableView *)tv namesOfPromisedFilesDroppedAtDestination:(NSURL *)dropDestination forDraggedRowsWithIndexes:(NSIndexSet *)rowIndexes {
    // This method will be called if we need to redeem our file promise
    NSURL *fileURL = nil;
    if (dropDestination && NSNotFound != [rowIndexes firstIndex]) {
        // We ask the document to write out the selected transactions to a file in the specified directory
        [self setSelectionIndexes:rowIndexes];
        fileURL = [_document writeSelectionToDestination:dropDestination];
    }
    return (fileURL ? [NSArray arrayWithObject:[[fileURL path] lastPathComponent]] : nil);
}
 
 
/* Data source methods for dragging in */
 
- (NSDragOperation)tableView:(NSTableView *)tv validateDrop:(id <NSDraggingInfo>)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)op {
    // This method will be called repeatedly during a drag in, to validate it and to determine the operation type and drop location
    NSDragOperation result = NSDragOperationNone, mask = [info draggingSourceOperationMask];
    NSArray *availableTypes = [[info draggingPasteboard] types], *readableTypes = [_document readablePasteboardTypes];
    NSEnumerator *enumerator = [readableTypes objectEnumerator];
    NSString *type;
 
    // We always copy, but if source and destination are the same, then we do not accept the drag unless the user explicitly chooses copy
    if (tv != [info draggingSource] || 0 == (mask & NSDragOperationGeneric)) {
        while (result == NSDragOperationNone && (type = [enumerator nextObject])) {
            // In any case, we accept the drag only if the pasteboard contains one of our desired types
            if ([availableTypes containsObject:type]) {
                // We always place the drop after the last existing row
                [tv setDropRow:[tv numberOfRows] dropOperation:NSTableViewDropAbove];
                result = NSDragOperationCopy;
            }
        }
    }
    return result;
}
 
- (BOOL)tableView:(NSTableView *)tv acceptDrop:(id <NSDraggingInfo>)info row:(NSInteger)row dropOperation:(NSTableViewDropOperation)op {
    // This method will be called when a drag in is finally dropped on our table view
    return [_document readSelectionFromPasteboard:[info draggingPasteboard]];
}
 
@end