/*

     File: OverlayView.m

 Abstract: The OverlayView class is a subclass of NSView which will be drawn on top of other views.

  Version: 1.2

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#import "OverlayView.h"

#import "DimensionLineDrawing.h"

#define HIGHLIGHT_THICKNESS 3.0

@implementation OverlayView

@synthesize overlaidView;

- (id)initWithFrame:(NSRect)frameRect {

    self = [super initWithFrame:frameRect];

    if (self) {

        // Create a tracking area that will give our view mouseMoved events.

        NSTrackingArea *trackingArea = [[NSTrackingArea alloc] initWithRect:NSZeroRect

                                                                    options:NSTrackingMouseMoved | NSTrackingInVisibleRect | NSTrackingActiveInKeyWindow

                                                                      owner:self

                                                                   userInfo:nil];

        [self addTrackingArea:trackingArea];

        [trackingArea release];

    }

    return self;

}

- (BOOL)acceptsFirstResponder {

    return YES; // We want to be able to receive mouseMoved: events when we're the firstResponder view.

}

- (void)setSelectionHighlightNeedsDisplay {

    if (selectedView != nil) {

        NSView *superviewOfSelectedView = [selectedView superview];

        if (superviewOfSelectedView != nil) {

            // We could invalidate several rectangles that more tightly bound the area we

            // actually need to redraw, if that proved to yield a worthwhile performance benefit,

            // but since we're drawing dimension lines to all four edges of the selectedView's

            // superview, we'll just invalidate the superview's bounds for simplicity.

            //

            NSRect superviewRect = [self convertRect:[superviewOfSelectedView bounds] fromView:superviewOfSelectedView];    

            [self setNeedsDisplayInRect:superviewRect];

            // Make sure we'll also draw the entire box rectangle, in case half its stroke thickness exceeds the margin to the superview's bounds.

            NSRect boundingRect = NSInsetRect([self convertRect:[selectedView bounds] fromView:selectedView], -0.5 * HIGHLIGHT_THICKNESS, -0.5 * HIGHLIGHT_THICKNESS); // Outset by half of stroke width.

            [self setNeedsDisplayInRect:boundingRect];

        }

    }

}

- (NSView *)selectedView {

    return selectedView;

}

- (void)setSelectedView:(NSView *)newSelectedView {

    if (selectedView != newSelectedView) {

        // Schedule to erase highlight of previously selected view (if any).

        [self setSelectionHighlightNeedsDisplay];

        // Remember new selected view.

        [selectedView release];

        selectedView = [newSelectedView retain];

        // Schedule to draw highlight of newly selected view (if any).

        [self setSelectionHighlightNeedsDisplay];

    }

}

- (void)selectViewForEvent:(NSEvent *)theEvent {

    // Find out which view in the overlaid view this event would be associated with by using hitTest.

    // Be sure to convert the point into the correct coordinate space.

    //

    NSView *hitView = [overlaidView hitTest:[[overlaidView superview] convertPoint:[theEvent locationInWindow] fromView:nil]];

    if (hitView) {

        // Choose the immediately enclosing NSBox instead, if the hitView is the NSBox's contentView, or the immediately enclosing NSScrollView, if the hitView is its documentView.

        NSView *parent = [hitView superview];

        if (parent && [parent isKindOfClass:[NSBox class]] && hitView == [(NSBox *)parent contentView]) {

            hitView = parent;

        } else {

            NSScrollView *enclosingScrollView = [hitView enclosingScrollView];

            if (enclosingScrollView && hitView == [enclosingScrollView documentView]) {

                hitView = enclosingScrollView;

            }

        }

    }

    [self setSelectedView:hitView];

}

- (void)drawRect:(NSRect)rect {

    // Fill with a mostly transparent tint color to make the presence of the OverlayView

    // more obvious for demo purposes.  There's no other need to do this; you may draw

    // whatever you like in an overlay view.

    //

    [[NSColor colorWithCalibratedRed:0.0 green:1.0 blue:0.0 alpha:0.2] set];

    [NSBezierPath fillRect:rect];

    // Draw around/atop the selectedView to show the user that it's selected.

    if (selectedView != nil) {

        // Enforce cliping to the selectedView's superview's bounds.

        NSView *superviewOfSelectedView = [selectedView superview];

        NSRectClip([self convertRect:[superviewOfSelectedView bounds] fromView:superviewOfSelectedView]);

        NSRect selectionRect = [self convertRect:[selectedView bounds] fromView:selectedView];

        NSRect enclosingRect = [self convertRect:[superviewOfSelectedView bounds] fromView:superviewOfSelectedView];

        // Stroke a rect surrounding the view.

        [[NSColor redColor] set];

        NSBezierPath *path = [NSBezierPath bezierPathWithRect:selectionRect];

        [path setLineWidth:HIGHLIGHT_THICKNESS];

        [path stroke];

        // Draw dimension lines.

        DrawHorizontalDimensionLine(NSMinX(enclosingRect), NSMinX(selectionRect), NSMidY(selectionRect)); // -x line

        DrawHorizontalDimensionLine(NSMaxX(selectionRect), NSMaxX(enclosingRect), NSMidY(selectionRect)); // +x line

        DrawVerticalDimensionLine(NSMinY(enclosingRect), NSMinY(selectionRect), NSMidX(selectionRect)); // -y line

        DrawVerticalDimensionLine(NSMaxY(selectionRect), NSMaxY(enclosingRect), NSMidX(selectionRect)); // -y line

    }

}

- (void)mouseMoved:(NSEvent *)theEvent {

    // Figure out which view (if any) was clicked, and select it.

    [self selectViewForEvent:theEvent];

}

- (void)mouseDown:(NSEvent *)theEvent {

    // Figure out which view (if any) was clicked, and make sure it's selected.

    [self selectViewForEvent:theEvent];

    // Remember start point for drag.

    lastWindowPoint = [theEvent locationInWindow];

}

- (void)mouseDragged:(NSEvent *)theEvent {

    // Let the user drag the selected view, if any.

    if (selectedView != nil) {

        // Calculate (dx,dy) for this mouse move, in the selected view's superview's coordinate space.

        NSView *superview = [selectedView superview];

        NSPoint windowPoint = [theEvent locationInWindow];

        NSPoint lastSuperviewPoint = [superview convertPoint:lastWindowPoint fromView:nil];

        NSPoint superviewPoint = [superview convertPoint:windowPoint fromView:nil];

        CGFloat dx = superviewPoint.x - lastSuperviewPoint.x;

        CGFloat dy = superviewPoint.y - lastSuperviewPoint.y;

        // Move view's frameOrigin by (dx,dy).

        NSRect frame = [selectedView frame];

        frame.origin.x += dx;

        frame.origin.y += dy;

        [self setSelectionHighlightNeedsDisplay]; // Schedule erase of selection highlight for old position.

        [selectedView setFrameOrigin:frame.origin];

        [self setSelectionHighlightNeedsDisplay]; // Schedule erase of selection highlight for new position.

        // Save windowPoint as the lastWindowPoint for the next drag increment.

        lastWindowPoint = windowPoint;

    }

}

- (void)dealloc {

    [selectedView release];

    [super dealloc];

}

@end