gistfile1.h

@interface HostView : NSView {
  NSView *_docView;
  CGFloat _scale;
}

@property (assign) CGFloat scale;

@end



@implementation HostView

@synthesize scale=_scale;

- (void)updateFrame {
  NSRect frame = _docView.frame;

  // When in landscape mode, flip around the width/height.
  if ([_docView frameRotation] == 90.) {
    CGFloat t = frame.size.width;
    frame.size.width = frame.size.height;
    frame.size.height = t;
  }

  frame.size.width = frame.size.width * _scale;
  frame.size.height = frame.size.height * _scale;
  self.frame = frame;
}

- (void)setScale:(CGFloat)f {
  CGFloat s = f / _scale;
  [docView scaleUnitSquareToSize:NSMakeSize(s, s)];
  _scale = f;
  [self updateFrame];
}

- (void)setOrientation:(BOOL)landscape {
  CGFloat rotationDegrees = 0.;

  // When asked for landscape orientation, rotate counter-clockwise 90 degrees.
  if (landscape) {
    rotationDegrees = 90.;
  }

  // Rotate the document view.  This will generate a frame changed notification
  // that comes back to this object.  The updateFrame: selector will get run to
  // change the document frame.  This will eventually allow the scroll view in
  // which this view is hosted to recalculate its scroll extents.
  [_docView setFrameCenterRotation:rotationDegrees];

  // Oddly, rotation adjusts the frame but not by enough to accommodate a scroll
  // view correctly.  Adjust the frame ourselves.
  NSRect frame = _docView.frame;
  frame.origin = NSZeroPoint;
  if (rotationDegrees == 90.) {
    frame.origin.x = frame.size.height;
  }
  _docView.frame = frame;

  [self setNeedsDisplay:YES];
}

- (void)documentFrameChanged:(NSNotification *)n {
  [self updateFrame];
}

- (void)initWithDocumentView:(NSView *)docView {
  _scale = 1.0;
  _docView = [docView retain];
  
  [self addSubview:_docView];
  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(documentFrameChanged:) name:NSViewFrameDidChangeNotification object:_docView];
  
  [self updateFrame];
}

- (void)dealloc {
  [_docView release];
  [super dealloc];
}

@end