/* -*- 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 MOZILLA_GFX_COMPOSITORHITTESTINFO_H_
#define MOZILLA_GFX_COMPOSITORHITTESTINFO_H_

#include "mozilla/EnumSet.h"
#include "mozilla/EnumTypeTraits.h"

namespace mozilla {
namespace gfx {

// This set of flags is used to figure out what information a frame has
// that is relevant to hit-testing in the compositor. The flags are
// intentionally set up so that if all of them are 0 the item is effectively
// invisible to hit-testing, and no information for this frame needs to be
// sent to the compositor.
// Each enumerator is annotated with the value it contributes to an
// EnumSet (2 ^ <value of enumerator>), in hexadecimal.
enum class CompositorHitTestFlags : uint8_t {
  // The frame participates in hit-testing
  eVisibleToHitTest = 0,  // 0x0001

  // The frame may have odd shapes that requires the main thread to do accurate
  // hit-testing.
  eIrregularArea,  // 0x0002
  // The frame has APZ-aware listeners and so inputs targeted at this area
  // need to be handled by the main thread before APZ can use them, as they
  // might be prevent-defaulted.
  eApzAwareListeners,  // 0x0004
  // This is an inactive scrollframe or unlayerized scrollthumb. In this state
  // it cannot be used by APZ for async scrolling, so APZ will defer to the main
  // thread.
  eInactiveScrollframe,  // 0x0008

  // The touch action flags are set up so that the default of
  // touch-action:auto on an element leaves all the flags as 0.
  eTouchActionPanXDisabled,           // 0x0010
  eTouchActionPanYDisabled,           // 0x0020
  eTouchActionPinchZoomDisabled,      // 0x0040
  eTouchActionDoubleTapZoomDisabled,  // 0x0080

  // The frame is a scrollbar or a subframe inside a scrollbar (including
  // scroll thumbs)
  eScrollbar,  // 0x0100
  // The frame is a scrollthumb. If this is set then eScrollbar will also be
  // set, unless gecko somehow generates a scroll thumb without a containing
  // scrollbar.
  eScrollbarThumb,  // 0x0200
  // If eScrollbar is set, this flag indicates if the scrollbar is a vertical
  // one (if set) or a horizontal one (if not set)
  eScrollbarVertical,  // 0x0400

  // Events targeting this frame should only be processed if a target
  // confirmation is received from the main thread. If no such confirmation
  // is received within a timeout period, the event may be dropped.
  // Only meaningful in combination with eDispatchToContent.
  eRequiresTargetConfirmation,  // 0x0800

  // Bits 0x1000, 0x2000, 0x4000, and 0x8000 are used by SideBitsPacked in
  // WebRenderAPI.cpp when we pack SideBits and CompositorHitTestInfo into a
  // uint16_t and pass in into webrender to store in the item tag.

};

using CompositorHitTestInfo = EnumSet<CompositorHitTestFlags, uint32_t>;

// A CompositorHitTestInfo with none of the flags set
constexpr CompositorHitTestInfo CompositorHitTestInvisibleToHit;

// Mask to check for all the touch-action flags at once
constexpr CompositorHitTestInfo CompositorHitTestTouchActionMask(
    CompositorHitTestFlags::eTouchActionPanXDisabled,
    CompositorHitTestFlags::eTouchActionPanYDisabled,
    CompositorHitTestFlags::eTouchActionPinchZoomDisabled,
    CompositorHitTestFlags::eTouchActionDoubleTapZoomDisabled);

// Mask to check all the flags that involve APZ waiting for results from the
// main thread
constexpr CompositorHitTestInfo CompositorHitTestDispatchToContent(
    CompositorHitTestFlags::eIrregularArea,
    CompositorHitTestFlags::eApzAwareListeners,
    CompositorHitTestFlags::eInactiveScrollframe);

}  // namespace gfx

// Used for IPDL serialization. The 'value' have to be the biggest enum from
// CompositorHitTestFlags.
template <>
struct MaxEnumValue<::mozilla::gfx::CompositorHitTestFlags> {
  static constexpr unsigned int value = static_cast<unsigned int>(
      gfx::CompositorHitTestFlags::eRequiresTargetConfirmation);
};

namespace gfx {

// Checks if the CompositorHitTestFlags max enum value is less than N.
template <int N>
static constexpr bool DoesCompositorHitTestInfoFitIntoBits() {
  if (MaxEnumValue<CompositorHitTestInfo::valueType>::value < N) {
    return true;
  }

  return false;
}
}  // namespace gfx

}  // namespace mozilla

#endif /* MOZILLA_GFX_COMPOSITORHITTESTINFO_H_ */