/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "ViewRegion.h"
#import <Cocoa/Cocoa.h>

#include "nsChildView.h"

using namespace mozilla;

ViewRegion::~ViewRegion() {
  for (size_t i = 0; i < mViews.Length(); i++) {
    [mViews[i] removeFromSuperview];
  }
}

bool ViewRegion::UpdateRegion(const LayoutDeviceIntRegion& aRegion,
                              const nsChildView& aCoordinateConverter, NSView* aContainerView,
                              NSView* (^aViewCreationCallback)()) {
  if (mRegion == aRegion) {
    return false;
  }

  // We need to construct the required region using as many EffectViews
  // as necessary. We try to update the geometry of existing views if
  // possible, or create new ones or remove old ones if the number of
  // rects in the region has changed.

  nsTArray<NSView*> viewsToRecycle = std::move(mViews);
  // The mViews array is now empty.

  size_t i = 0;
  for (auto iter = aRegion.RectIter(); !iter.Done() || i < viewsToRecycle.Length(); i++) {
    if (!iter.Done()) {
      NSView* view = nil;
      NSRect rect = aCoordinateConverter.DevPixelsToCocoaPoints(iter.Get());
      if (i < viewsToRecycle.Length()) {
        view = viewsToRecycle[i];
      } else {
        view = aViewCreationCallback();
        [aContainerView addSubview:view];

        // Now that the view is in the view hierarchy, it'll be kept alive by
        // its superview, so we can drop our reference.
        [view release];
      }
      if (!NSEqualRects(rect, [view frame])) {
        [view setFrame:rect];
      }
      [view setNeedsDisplay:YES];
      mViews.AppendElement(view);
      iter.Next();
    } else {
      // Our new region is made of fewer rects than the old region, so we can
      // remove this view. We only have a weak reference to it, so removing it
      // from the view hierarchy will release it.
      [viewsToRecycle[i] removeFromSuperview];
    }
  }

  mRegion = aRegion;
  return true;
}