PackagedDocument/AttachmentView.m

/*
 Copyright (C) 2017 Apple Inc. All Rights Reserved.
 See LICENSE.txt for this sample’s licensing information
 
 Abstract:
 Custom view holding the image to attach to our document.
 */
 
#import "AttachmentView.h"
#import "ViewController.h"
 
@interface AttachmentView ()
 
@property BOOL highlightForDragAcceptence;
 
@end
 
 
#pragma mark -
 
@implementation AttachmentView
 
- (void)commonInit
{
    // Register for all the image types we can display - include NSFilenamesPboardType for Finder drags.
    NSMutableArray *dragTypes = [[NSImage imageTypes] mutableCopy];
    [dragTypes addObject:NSFilenamesPboardType];
    [self registerForDraggedTypes:dragTypes];
    
    [self setKeyboardFocusRingNeedsDisplayInRect:self.bounds];
    
    self.highlightForDragAcceptence = NO;
}
 
- (instancetype)initWithCoder:(NSCoder *)coder
{
    // Init method called for Interface Builder objects.
    self = [super initWithCoder:coder];
    if (self)
    {
        [self commonInit];
    }
    return self;
}
 
- (instancetype)initWithFrame:(NSRect)frame
{
    self = [super initWithFrame:frame];
    if (self)
    {
        [self commonInit];
    }
    
    return self;
}
 
- (void)drawRect:(NSRect)rect
{
    [super drawRect:rect];
 
    // Draw the focus frame if necessary.
    if (self.highlightForDragAcceptence)
    {
        [NSGraphicsContext saveGraphicsState];
        NSSetFocusRingStyle(NSFocusRingOnly);
        [[NSBezierPath bezierPathWithRect: NSInsetRect(self.bounds,3,3)] fill];
        [NSGraphicsContext restoreGraphicsState];
    }
}
 
- (void)dealloc
{
    [self unregisterDraggedTypes];
}
 
- (NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
{
    NSDragOperation dragOperation = NSDragOperationNone;
    
    if ((NSDragOperationCopy & [sender draggingSourceOperationMask]) == NSDragOperationCopy)
    {
        self.highlightForDragAcceptence = YES;
        [self setNeedsDisplay:YES];
        
        // The sender is offering the type of operation we want,
        // return that we want the NSDragOperationCopy (cursor has a + image).
        //
        dragOperation = NSDragOperationCopy;
    }
    
    return dragOperation;
}
 
- (void)draggingExited:(id <NSDraggingInfo>)sender
{
    // User has left our drag area, erase our focus frame.
    self.highlightForDragAcceptence = NO;
    [self setNeedsDisplay:YES];
}
 
- (NSDragOperation)draggingUpdated:(id <NSDraggingInfo>)sender
{
    NSDragOperation dragOperation = NSDragOperationNone;
    
    if ((NSDragOperationCopy & [sender draggingSourceOperationMask]) == NSDragOperationCopy)
    {
        // The sender is offering the type of operation we want,
        // return that we want the NSDragOperationCopy (cursor has a + image).
        //
        dragOperation = NSDragOperationCopy;
    }
    
    return dragOperation;
}
 
- (void)draggingEnded:(id <NSDraggingInfo>)sender
{
    //..
}
 
- (BOOL)prepareForDragOperation:(id <NSDraggingInfo>)sender
{
    return YES;
}
 
- (BOOL)performDragOperation:(id <NSDraggingInfo>)sender
{
    NSPasteboard *paste = [sender draggingPasteboard];
    
    // Gets the dragging-specific pasteboard from the sender.
    NSArray *types = @[NSTIFFPboardType, NSFilenamesPboardType];
    
    // A list of types that we can accept.
    NSString *desiredType = [paste availableTypeFromArray:types];
    NSData *carriedData = [paste dataForType:desiredType];
    
    if (carriedData == nil)
    {
        // The drag operation failed.
        return NO;
    }
    else
    {
        // the pasteboard was able to give us some meaningful data.
        if ([desiredType isEqualToString:NSTIFFPboardType])
        {
            // We have TIFF bitmap data in the NSData object.
            // Keep a reference to the image for drawing.
            self.image = [[NSImage alloc] initWithData:carriedData];
            
        }
        else if ([desiredType isEqualToString:NSFilenamesPboardType])
        {
            // We have a list of file names in an NSData object.
            NSArray *fileArray = [paste propertyListForType:@"NSFilenamesPboardType"];
 
            NSString *path = fileArray[0];
            
            // Assume that we can ignore all but the first path in the list.
            NSImage *newImage = [[NSImage alloc] initWithContentsOfFile:path];
            if (newImage == nil)
            {
                // Failed to open the file.
                return NO;
            }
            else
            {
                // Keep a reference to the image for drawing.
                self.image = newImage;
                
                // Tell our window controller that a new image was dragged in by the user.
                ViewController *viewController = (ViewController *)self.window.contentViewController;
                [viewController updateImage:newImage];
            }
        }
        else
        {
            return NO;
        }
    }
    
    // Erase the drag acceptance highlight, and draws the new image.
    self.highlightForDragAcceptence = NO;
    [self setNeedsDisplay:YES];
 
    return YES;
}
 
@end


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