/* -*- 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/. */

#ifndef VibrancyManager_h
#define VibrancyManager_h

#include "mozilla/Assertions.h"
#include "nsClassHashtable.h"
#include "nsRegion.h"
#include "nsTArray.h"

#import <Foundation/NSGeometry.h>

@class NSColor;
@class NSView;
class nsChildView;

namespace mozilla {

enum class VibrancyType {
  LIGHT,
  DARK,
  TOOLTIP,
  MENU,
  HIGHLIGHTED_MENUITEM,
  SHEET
};

/**
 * VibrancyManager takes care of updating the vibrant regions of a window.
 * Vibrancy is a visual look that was introduced on OS X starting with 10.10.
 * An app declares vibrant window regions to the window server, and the window
 * server will display a blurred rendering of the screen contents from behind
 * the window in these areas, behind the actual window contents. Consequently,
 * the effect is only visible in areas where the window contents are not
 * completely opaque. Usually this is achieved by clearing the background of
 * the window prior to drawing in the vibrant areas. This is possible even if
 * the window is declared as opaque.
 */
class VibrancyManager {
public:
  /**
   * Create a new VibrancyManager instance and provide it with an NSView
   * to attach NSVisualEffectViews to.
   *
   * @param aCoordinateConverter  The nsChildView to use for converting
   *   nsIntRect device pixel coordinates into Cocoa NSRect coordinates. Must
   *   outlive this VibrancyManager instance.
   * @param aContainerView  The view that's going to be the superview of the
   *   NSVisualEffectViews which will be created for vibrant regions.
   */
  VibrancyManager(const nsChildView& aCoordinateConverter,
                  NSView* aContainerView)
    : mCoordinateConverter(aCoordinateConverter)
    , mContainerView(aContainerView)
  {
    MOZ_ASSERT(SystemSupportsVibrancy(),
               "Don't instantiate this if !SystemSupportsVibrancy()");
  }

  /**
   * Update the placement of the NSVisualEffectViews inside the container
   * NSView so that they cover aRegion, and create new NSVisualEffectViews
   * or remove existing ones as needed.
   * @param aType   The vibrancy type to use in the region.
   * @param aRegion The vibrant area, in device pixels.
   */
  void UpdateVibrantRegion(VibrancyType aType,
                           const LayoutDeviceIntRegion& aRegion);

  /**
   * Clear the vibrant areas that we know about.
   * The clearing happens in the current NSGraphicsContext. If you call this
   * from within an -[NSView drawRect:] implementation, the currrent
   * NSGraphicsContext is already correctly set to the window drawing context.
   */
  void ClearVibrantAreas() const;

  /**
   * Return the fill color that should be drawn on top of the cleared window
   * parts. Usually this would be drawn by -[NSVisualEffectView drawRect:].
   * The returned color is opaque if the system-wide "Reduce transparency"
   * preference is set.
   */
  NSColor* VibrancyFillColorForType(VibrancyType aType);

  /**
   * Return the font smoothing background color that should be used for text
   * drawn on top of the vibrant window parts.
   */
  NSColor* VibrancyFontSmoothingBackgroundColorForType(VibrancyType aType);

  /**
   * Check whether the operating system supports vibrancy at all.
   * You may only create a VibrancyManager instance if this returns true.
   * @return Whether VibrancyManager can be used on this OS.
   */
  static bool SystemSupportsVibrancy();

  // The following are only public because otherwise ClearVibrantRegionFunc
  // can't see them.
  struct VibrantRegion {
    LayoutDeviceIntRegion region;
    nsTArray<NSView*> effectViews;
  };
  void ClearVibrantRegion(const VibrantRegion& aVibrantRegion) const;

protected:
  NSView* CreateEffectView(VibrancyType aType, NSRect aRect);

  const nsChildView& mCoordinateConverter;
  NSView* mContainerView;
  nsClassHashtable<nsUint32HashKey, VibrantRegion> mVibrantRegions;
};

} // namespace mozilla

#endif // VibrancyManager_h