adjusting_view_for_nsscrollview.m

- (void) updateToolOptionsView
{
  ToolOptionsViewController* optionsController = tool.optionsViewController;
  
  // Stretch view frame according to autoresizing rules
  // If the view is not stretched, there will be autosurprising
  NSView* optionsView = [optionsController view];
  NSSize optionsSize = [optionsView frame].size;
  NSSize targetSize = [[self.scrollView contentView] frame].size;
  NSSize newOptionsSize = optionsSize;
  NSUInteger autoresizingMask = [optionsView autoresizingMask];
  if (autoresizingMask & NSViewWidthSizable)
  {
    newOptionsSize.width = targetSize.width;
  }
  if (autoresizingMask & NSViewHeightSizable)
  {
    newOptionsSize.height = targetSize.height;
  }
  [optionsView setFrameSize:newOptionsSize];
  
  // Wrap the options view into a flipped view so that NSScrollView
  // renders view from top to bottom as expected.
  [self patchViewControllerWithFlippedViewIfNeeded:optionsController];
  [self.scrollView setDocumentView:[optionsController view]];
}


- (void) patchViewControllerWithFlippedViewIfNeeded:(NSViewController*) controller
{
  NSView* myView = [controller view];
  
  // The view is already good or was already patched - do nothing.
  if  ([myView isFlipped]) return;
  
  // MyViewFlipped is a subclass of NSView with a single method isFlipped returning YES
  NSView* flippedWrapper = [[[MyViewFlipped alloc] initWithFrame:[myView frame]] autorelease];
  
  // Clone the existing autoresizingMask
  [flippedWrapper setAutoresizingMask:[myView autoresizingMask]];
  [flippedWrapper setAutoresizesSubviews:YES];
  
  // And autoresize myView inside the wrapper
  [myView setAutoresizingMask:
   NSViewWidthSizable | 
   NSViewHeightSizable | 
   NSViewMinXMargin | 
   NSViewMaxXMargin |
   NSViewMinYMargin |
   NSViewMaxYMargin ];
  [myView setFrameOrigin:NSZeroPoint];
  
  // Replace the view
  [flippedWrapper addSubview:myView];
  [controller setView:flippedWrapper];
}