DMKArrayController.m

/*
     File: DMKArrayController.m
 Abstract: An array controller subclass to manage a collection of text snippets, including support for drag and drop.
 
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 */

#import "DMKArrayController.h"
#import "EditController.h"
#import "MyDocument.h"
#import "Step.h"


NSString *MovedRowsUTI = @"com.yourcompany.demomonkey.movedrows";

@implementation DMKArrayController


@synthesize tableView, windowController;


#pragma mark -
#pragma mark Pasteboard / drag and drop support

- (void)awakeFromNib {
    // Register the table view for drag and drop.
    [tableView registerForDraggedTypes:[NSArray arrayWithObjects:StepUTI, MovedRowsUTI, NSStringPboardType, nil]];
    [tableView setAllowsMultipleSelection:YES];
    [tableView setDraggingSourceOperationMask:NSDragOperationCopy forLocal:NO];
}


- (BOOL)tableView:(NSTableView *)tv writeRowsWithIndexes:(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard*)pboard {
    /*
     Take ownership of the pasteboard, then:
     * Write the currently-selected steps directly;
     * Archive the selection index set and write the archive to the pasteboard as the data for the moved rows type.  The index set is used in tableView:acceptDrop:row:dropOperation: if there is a reorder operation within a table view.
     */
    [pboard clearContents];
    
    // Write the current steps.
    [pboard writeObjects:[[self arrangedObjects] objectsAtIndexes:rowIndexes]];

    // Add rows array for a local move.
    [pboard addTypes:[NSArray arrayWithObject:MovedRowsUTI] owner:self];        
    NSData *rowIndexesData = [NSArchiver archivedDataWithRootObject:rowIndexes];
    [pboard setData:rowIndexesData forType:MovedRowsUTI];        
    
    return YES;
}



- (NSDragOperation)tableView:(NSTableView *)aTableView validateDrop:(id < NSDraggingInfo >)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)operation {
    
    NSDragOperation dragOp = NSDragOperationCopy;
    
    // If drag source is self, it's a move.
    if ([info draggingSource] == tableView) {
        dragOp =  NSDragOperationMove;
    }
    
    // Put the object at, not over, the current row (contrast NSTableViewDropOn).
    if ([[self arrangedObjects] count] > 0) {
        [aTableView setDropRow:row dropOperation:NSTableViewDropAbove];
    }
    return dragOp;
}


- (BOOL)tableView:(NSTableView *)aTableView acceptDrop:(id < NSDraggingInfo >)info row:(NSInteger)row dropOperation:(NSTableViewDropOperation)operation {
    
    if (row < 0) {
        row = 0;
    }
    /*
     If the dragging source is our table view, look for the moved rows type for a reorder operation.
     */
    if ([info draggingSource] == tableView) {
        
        NSData *rowsData = [[info draggingPasteboard] dataForType:MovedRowsUTI];
        NSIndexSet  *indexSet = [NSUnarchiver unarchiveObjectWithData:rowsData];        
        [self moveObjectsInArrangedObjectsFromIndexes:indexSet toIndex:row];
        
        /*
         Set the selected rows to those that were just moved.  Work out what moved where to determine proper selection.
         */
        NSInteger rowsAbove = [self rowsAboveRow:row inIndexSet:indexSet];
        NSRange range = NSMakeRange(row - rowsAbove, [indexSet count]);
        indexSet = [NSIndexSet indexSetWithIndexesInRange:range];
        [self setSelectionIndexes:indexSet];
        
        return YES;
    }
    
    /*
     If the dragging source is something other than our table view, create new steps from whatever's on the pasteboard and add them.
     */
    NSDictionary *options = [NSDictionary dictionary];
    NSArray *newSteps = [[info draggingPasteboard] readObjectsForClasses:[NSArray arrayWithObject:[Step class]] options:options];
    if (newSteps == nil) {
        return NO;
    }

    NSRange insertionRange = NSMakeRange(row, [newSteps count]);
    NSIndexSet *insertionIndexes = [NSIndexSet indexSetWithIndexesInRange:insertionRange];
    [self insertObjects:newSteps atArrangedObjectIndexes:insertionIndexes];
    return YES;
}


#pragma mark -
#pragma mark New objects

- (id)newObject {
    // Configure a new object.
    Step *newObject = [super newObject];
    NSUInteger row = [[self arrangedObjects] count];
    newObject.tableSummary = [NSString stringWithFormat:@"Step %d", (row +1)];
    newObject.undoManager = [[windowController document] undoManager];
    return newObject;
}


- (void)add:sender {
    // Add a new object, then select its row.
    Step *newObject = [super newObject];
    NSUInteger row = [[self arrangedObjects] count];
    [self insertObject:newObject atArrangedObjectIndex:row];
    [tableView selectRowIndexes:[NSIndexSet indexSetWithIndex:row] byExtendingSelection:NO];
    [tableView editColumn:0 row:row withEvent:nil select:YES];
    [newObject release];
}


#pragma mark -
#pragma mark Reorder operation

-(void) moveObjectsInArrangedObjectsFromIndexes:(NSIndexSet*)indexSet toIndex:(NSUInteger)insertIndex {
    
    NSArray *objects = [self arrangedObjects];
    NSInteger idx = [indexSet lastIndex];
    
    NSInteger aboveInsertIndexCount = 0;
    id object = nil;
    NSInteger removeIndex;
    
    while (NSNotFound != idx) {
        if (idx >= insertIndex) {
            removeIndex = idx + aboveInsertIndexCount;
            aboveInsertIndexCount += 1;
        }
        else {
            removeIndex = idx;
            insertIndex -= 1;
        }
        object = [[objects objectAtIndex:removeIndex] retain];
        [self removeObjectAtArrangedObjectIndex:removeIndex];
        [self insertObject:object atArrangedObjectIndex:insertIndex];
        [object release];
        idx = [indexSet indexLessThanIndex:idx];
    }
}


- (NSInteger)rowsAboveRow:(NSInteger)row inIndexSet:(NSIndexSet *)indexSet {
    
    NSUInteger currentIndex = [indexSet firstIndex];
    NSInteger i = 0;
    while (currentIndex != NSNotFound) {
        if (currentIndex < row) { i++; }
        currentIndex = [indexSet indexGreaterThanIndex:currentIndex];
    }
    return i;
}


@end