1-DragItemAround/DraggableItemView.m

/*
     File: DraggableItemView.m 
 Abstract: Part of the DraggableItemView project referenced in the 
 View Programming Guide for Cocoa documentation.
  
  Version: 1.1 
  
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 */
 
#import "DraggableItemView.h"
 
 
@implementation DraggableItemView
 
// -----------------------------------
// Initialize the View
// -----------------------------------
 
- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
    // setup the starting location of the 
    // draggable item
    [self setItemPropertiesToDefault:self];
    }
    return self;
}
 
// -----------------------------------
// Release the View
// -----------------------------------
 
- (void)dealloc
{
    // release the color items and set
    // the instance variables to nil
    [itemColor release];
    itemColor=nil;
    
    [backgroundColor release];
    backgroundColor=nil;
    
    // call super
    [super dealloc];  
}
 
// -----------------------------------
// Draw the View Content
// -----------------------------------
 
- (void)drawRect:(NSRect)rect
{
    // erase the background by drawing white
    [[NSColor whiteColor] set];
    [NSBezierPath fillRect:rect];
    
    // set the current color for the draggable item
    [[self itemColor] set];
    
    // draw the draggable item
    [NSBezierPath fillRect:[self calculatedItemBounds]];
}
 
- (BOOL)isOpaque
{
    // If the background color is opaque, return YES
    // otherwise, return NO
    return [[self backgroundColor] alphaComponent] >= 1.0 ? YES : NO;
}
 
 
// -----------------------------------
// Modify the item location 
// -----------------------------------
 
- (void)offsetLocationByX:(float)x andY:(float)y
{
    // tell the display to redraw the old rect
    [self setNeedsDisplayInRect:[self calculatedItemBounds]];
 
    // since the offset can be generated by both mouse moves
    // and moveUp:, moveDown:, etc.. actions, we'll invert
    // the deltaY amount based on if the view is flipped or 
    // not.
    int invertDeltaY = [self isFlipped] ? -1: 1;
    
    location.x=location.x+x;
    location.y=location.y+y*invertDeltaY;
    
    // invalidate the new rect location so that it'll
    // be redrawn
    [self setNeedsDisplayInRect:[self calculatedItemBounds]];
    
}
 
// -----------------------------------
// Hit test the item
// -----------------------------------
 
- (BOOL)isPointInItem:(NSPoint)testPoint
{
    BOOL itemHit=NO;
    
    // test first if we're in the rough bounds
    itemHit = NSPointInRect(testPoint,[self calculatedItemBounds]);
    
    // yes, lets further refine the testing
    if (itemHit) {
    
    }
   
    return itemHit;
}
 
// -----------------------------------
// Handle Mouse Events 
// -----------------------------------
 
-(void)mouseDown:(NSEvent *)event
{
    NSPoint clickLocation;
    BOOL itemHit=NO;
    
    // convert the click location into the view coords
    clickLocation = [self convertPoint:[event locationInWindow]
                  fromView:nil];
    
    // did the click occur in the item?
    itemHit = [self isPointInItem:clickLocation];
    
    // Yes it did, note that we're starting to drag
    if (itemHit) {
    // flag the instance variable that indicates 
    // a drag was actually started
    dragging=YES;
    
    // store the starting click location;
    lastDragLocation=clickLocation;
    
    // set the cursor to the closed hand cursor
    // for the duration of the drag
    [[NSCursor closedHandCursor] push];
    }
}
 
-(void)mouseDragged:(NSEvent *)event
{
    if (dragging) {
    NSPoint newDragLocation=[self convertPoint:[event locationInWindow]
                      fromView:nil];
    
    
    // offset the pill by the change in mouse movement
    // in the event
    [self offsetLocationByX:(newDragLocation.x-lastDragLocation.x)
               andY:(newDragLocation.y-lastDragLocation.y)];
    
    // save the new drag location for the next drag event
    lastDragLocation=newDragLocation;
    
    // support automatic scrolling during a drag
    // by calling NSView's autoscroll: method
    [self autoscroll:event];
    }
}
 
-(void)mouseUp:(NSEvent *)event
{
    dragging=NO;
    
    // finished dragging, restore the cursor
    [NSCursor pop];
    
    // the item has moved, we need to reset our cursor
    // rectangle
    [[self window] invalidateCursorRectsForView:self];
}
 
 
 
 
// -----------------------------------
// First Responder Methods
// -----------------------------------
 
- (BOOL)acceptsFirstResponder
{
    return YES;
}
 
 
 
// -----------------------------------
// Handle KeyDown Events 
// -----------------------------------
 
 
- (void)keyDown:(NSEvent *)event
{
    BOOL handled = NO;
    NSString  *characters;
    
    // get the pressed key
    characters = [event charactersIgnoringModifiers];
    
    // is the "r" key pressed?
    if ([characters isEqual:@"r"]) {
    // Yes, it is
    handled = YES;
    
    // set the rectangle properties
    [self setItemPropertiesToDefault:self];
    }
    if (!handled)
    [super keyDown:event];
    
}
 
// -----------------------------------
// Handle NSResponder Actions 
// -----------------------------------
 
-(IBAction)moveUp:(id)sender
{
    [self offsetLocationByX:0.0f andY: 10.0f];
    [[self window] invalidateCursorRectsForView:self];
}
 
-(IBAction)moveDown:(id)sender
{
    [self offsetLocationByX:0.0f andY:-10.0f];
    [[self window] invalidateCursorRectsForView:self];
}
 
-(IBAction)moveLeft:(id)sender
{
    [self offsetLocationByX:-10.0f andY:0.0f];
    [[self window] invalidateCursorRectsForView:self];
}
 
-(IBAction)moveRight:(id)sender
{
    [self offsetLocationByX:10.0f andY:0.0f];
    [[self window] invalidateCursorRectsForView:self];
}
 
- (IBAction)setItemPropertiesToDefault:(id)sender
{
    [self setLocation:NSMakePoint(0.0f,0.0f)];
    [self setItemColor:[NSColor redColor]];
    [self setBackgroundColor:[NSColor whiteColor]];
}
 
 
 
// -----------------------------------
// Handle color changes via first responder 
// -----------------------------------
 
- (void)changeColor:(id)sender
{
    // Set the color in response
    // to the color changing in the color panel.
    // get the new color by asking the sender, the color panel
    [self setItemColor:[sender color]];
}
 
 
 
 
// -----------------------------------
// Reset Cursor Rects 
// -----------------------------------
 
-(void)resetCursorRects
{
    // remove the existing cursor rects
    [self discardCursorRects];
    
    // add the draggable item's bounds as a cursor rect
    [self addCursorRect:[self calculatedItemBounds] cursor:[NSCursor openHandCursor]];
    
}
 
// -----------------------------------
//  Accessor Methods
// -----------------------------------
 
- (void)setItemColor:(NSColor *)aColor
{
    if (![itemColor isEqual:aColor]) {
        [itemColor release];
        itemColor = [aColor retain];
        
        // if the colors are not equal, mark the
        // draggable rect as needing display
        [self setNeedsDisplayInRect:[self calculatedItemBounds]];
    }
}
 
 
- (NSColor *)itemColor
{
    return [[itemColor retain] autorelease];
}
 
- (void)setBackgroundColor:(NSColor *)aColor
{
    if (![backgroundColor isEqual:aColor]) {
        [backgroundColor release];
        backgroundColor = [aColor retain];
        
        // if the colors are not equal, mark the
        // draggable rect as needing display
        [self setNeedsDisplayInRect:[self calculatedItemBounds]];
    }
}
 
 
- (NSColor *)backgroundColor
{
    return [[backgroundColor retain] autorelease];
}
 
 
- (void)setLocation:(NSPoint)point
{
    // test to see if the point actually changed
    if (!NSEqualPoints(point,location)) {
        // tell the display to redraw the old rect
    [self setNeedsDisplayInRect:[self calculatedItemBounds]];
    
        // reassign the rect
    location=point;
    
        // display the new rect
    [self setNeedsDisplayInRect:[self calculatedItemBounds]];
    
        // invalidate the cursor rects 
    [[self window] invalidateCursorRectsForView:self];
    }
}
 
- (NSPoint)location {
    return location;
}
 
 
- (NSRect)calculatedItemBounds
{
    NSRect calculatedRect;
    
    // calculate the bounds of the draggable item
    // relative to the location
    calculatedRect.origin=location;
    
    // the example assumes that the width and height
    // are fixed values
    calculatedRect.size.width=60.0f;
    calculatedRect.size.height=20.0f;
    
    return calculatedRect;
}
 
 
 
 
 
@end