layout/base/nsDisplayItemTypes.h

   1 // IWYU pragma: private, include "nsDisplayList.h"
   2 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   3  * vim: set ts=2 sw=2 et tw=78:
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   7  */
   8
   9 /**
  10  * It's useful to be able to dynamically check the type of certain items.
  11  * Every subclass of nsDisplayItem must have a new type added here for the purposes
  12  * of easy comparison and matching of items in different display lists.
  13  *
  14  * This is #included inside nsDisplayItem.
  15  */
  16
  17
  18 enum Type {
  19   TYPE_ZERO = 0, /** Spacer so that the first item starts at 1 */
  20
  21 #define DECLARE_DISPLAY_ITEM_TYPE(name) TYPE_##name,
  22 #define DECLARE_DISPLAY_ITEM_TYPE_FLAGS(name,flags) TYPE_##name,
  23 #include "nsDisplayItemTypesList.h"
  24 #undef DECLARE_DISPLAY_ITEM_TYPE
  25 #undef DECLARE_DISPLAY_ITEM_TYPE_FLAGS
  26
  27   TYPE_MAX
  28 };
  29
  30 enum {
  31   // Number of bits needed to represent all types
  32   TYPE_BITS = 8
  33 };
  34
  35 enum DisplayItemFlags {
  36   TYPE_RENDERS_NO_IMAGES = 1 << 0
  37 };
  38
  39 static const char* DisplayItemTypeName(Type aType)
  40 {
  41   switch (aType) {
  42 #define DECLARE_DISPLAY_ITEM_TYPE(name) case TYPE_##name: return #name;
  43 #define DECLARE_DISPLAY_ITEM_TYPE_FLAGS(name,flags) case TYPE_##name: return #name;
  44 #include "nsDisplayItemTypesList.h"
  45 #undef DECLARE_DISPLAY_ITEM_TYPE
  46 #undef DECLARE_DISPLAY_ITEM_TYPE_FLAGS
  47
  48     default: return "TYPE_UNKNOWN";
  49   }
  50 }
  51
  52 static uint8_t GetDisplayItemFlagsForType(Type aType)
  53 {
  54   static const uint8_t flags[TYPE_MAX] = {
  55     0
  56 #define DECLARE_DISPLAY_ITEM_TYPE(name) ,0
  57 #define DECLARE_DISPLAY_ITEM_TYPE_FLAGS(name,flags) ,flags
  58 #include "nsDisplayItemTypesList.h"
  59 #undef DECLARE_DISPLAY_ITEM_TYPE
  60 #undef DECLARE_DISPLAY_ITEM_TYPE_FLAGS
  61   };
  62
  63   return flags[aType];
  64 }
  65
  66 static Type GetDisplayItemTypeFromKey(uint32_t aDisplayItemKey)
  67 {
  68   static const uint32_t typeMask = (1 << TYPE_BITS) - 1;
  69   Type type = static_cast<Type>(aDisplayItemKey & typeMask);
  70   NS_ASSERTION(type > TYPE_ZERO && type < TYPE_MAX, "Invalid display item type!");
  71   return type;
  72 }