| /* |
| * Copyright (C) 2020-2021 Apple Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, |
| * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS |
| * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF |
| * THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #pragma once |
| |
| #include "DisplayListItemBufferIdentifier.h" |
| #include "DisplayListItemType.h" |
| #include "DisplayListItems.h" |
| #include "SharedBuffer.h" |
| #include <wtf/FastMalloc.h> |
| #include <wtf/ObjectIdentifier.h> |
| |
| namespace WebCore { |
| |
| class GraphicsContext; |
| |
| namespace DisplayList { |
| |
| class DisplayList; |
| |
| // An ItemBufferHandle wraps a pointer to a buffer that contains display list item data. |
| struct ItemBufferHandle { |
| ItemBufferIdentifier identifier; |
| uint8_t* data { nullptr }; |
| size_t capacity { 0 }; |
| |
| operator bool() const { return !!(*this); } |
| bool operator!() const { return !data; } |
| }; |
| |
| using ItemBufferHandles = Vector<ItemBufferHandle, 2>; |
| |
| // An ItemHandle wraps a pointer to an ItemType followed immediately by an item of that type. |
| // Each item handle data pointer is aligned to 8 bytes, and the item itself is also aligned |
| // to 8 bytes. To ensure this, the item type consists of 8 bytes (1 byte for the type and 7 |
| // bytes of padding). |
| struct ItemHandle { |
| uint8_t* data { nullptr }; |
| |
| void apply(GraphicsContext&); |
| WEBCORE_EXPORT void destroy(); |
| bool isDrawingItem() const { return WebCore::DisplayList::isDrawingItem(type()); } |
| |
| operator bool() const { return !!(*this); } |
| bool operator!() const { return !data; } |
| |
| #if !defined(NDEBUG) || !LOG_DISABLED |
| CString description() const; |
| #endif |
| |
| ItemType type() const { return static_cast<ItemType>(data[0]); } |
| |
| template<typename T> bool is() const { return type() == T::itemType; } |
| template<typename T> T& get() const |
| { |
| ASSERT(is<T>()); |
| return *reinterpret_cast<T*>(data + sizeof(uint64_t)); |
| } |
| |
| bool safeCopy(ItemType, ItemHandle destination) const; |
| }; |
| |
| bool safeCopy(ItemHandle destination, const DisplayListItem& source); |
| |
| enum class DidChangeItemBuffer : bool { No, Yes }; |
| |
| class ItemBufferWritingClient { |
| public: |
| virtual ~ItemBufferWritingClient() |
| { |
| } |
| |
| virtual ItemBufferHandle createItemBuffer(size_t) |
| { |
| return { }; |
| } |
| |
| virtual std::optional<std::size_t> requiredSizeForItem(const DisplayListItem&) const |
| { |
| return std::nullopt; |
| } |
| |
| virtual RefPtr<FragmentedSharedBuffer> encodeItemOutOfLine(const DisplayListItem&) const |
| { |
| return nullptr; |
| } |
| |
| virtual void encodeItemInline(const DisplayListItem&, uint8_t*) const |
| { |
| } |
| |
| virtual void didAppendData(const ItemBufferHandle&, size_t numberOfBytes, DidChangeItemBuffer) |
| { |
| UNUSED_PARAM(numberOfBytes); |
| } |
| }; |
| |
| class ItemBufferReadingClient { |
| public: |
| virtual ~ItemBufferReadingClient() |
| { |
| } |
| |
| virtual std::optional<ItemHandle> WARN_UNUSED_RETURN decodeItem(const uint8_t* data, size_t dataLength, ItemType, uint8_t* handleLocation) = 0; |
| }; |
| |
| // An ItemBuffer contains display list item data, and consists of a readwrite ItemBufferHandle (to which display |
| // list items are appended) as well as a number of readonly ItemBufferHandles. Items are appended to the readwrite |
| // buffer until all available capacity is exhausted, at which point we will move this writable handle to the list |
| // of readonly handles. |
| class ItemBuffer { |
| WTF_MAKE_NONCOPYABLE(ItemBuffer); WTF_MAKE_FAST_ALLOCATED; |
| public: |
| friend class DisplayList; |
| |
| WEBCORE_EXPORT ItemBuffer(); |
| WEBCORE_EXPORT ~ItemBuffer(); |
| ItemBuffer(ItemBufferHandles&&); |
| |
| WEBCORE_EXPORT ItemBuffer(ItemBuffer&&); |
| WEBCORE_EXPORT ItemBuffer& operator=(ItemBuffer&&); |
| |
| size_t sizeInBytes() const |
| { |
| size_t result = 0; |
| for (auto buffer : m_readOnlyBuffers) |
| result += buffer.capacity; |
| result += m_writtenNumberOfBytes; |
| return result; |
| } |
| |
| void clear(); |
| void shrinkToFit(); |
| |
| bool isEmpty() const |
| { |
| return !m_writtenNumberOfBytes && m_readOnlyBuffers.isEmpty(); |
| } |
| |
| WEBCORE_EXPORT ItemBufferHandle createItemBuffer(size_t); |
| |
| // ItemBuffer::append<T>(...) appends a display list item of type T to the end of the current |
| // writable buffer handle; if remaining buffer capacity is insufficient to store the item, a |
| // new buffer will be allocated (either by the ItemBufferWritingClient, if set, or by the item |
| // buffer itself if there is no client). Items are placed back-to-back in these item buffers, |
| // with padding between each item to ensure that all items are aligned to 8 bytes. |
| // |
| // If a writing client is present and requires custom encoding for the given item type T, the |
| // item buffer will ask the client for an opaque FragmentedSharedBuffer containing encoded data for the |
| // item. This encoded data is then appended to the item buffer, with padding to ensure that |
| // the start and end of this data are aligned to 8 bytes, if necessary. When consuming encoded |
| // item data, a corresponding ItemBufferReadingClient will be required to convert this encoded |
| // data back into an item of type T. |
| template<typename T, class... Args> void append(Args&&... args) |
| { |
| static_assert(std::is_trivially_destructible<T>::value == T::isInlineItem); |
| |
| if constexpr (!T::isInlineItem) { |
| RELEASE_ASSERT(m_writingClient); |
| append(DisplayListItem(T(std::forward<Args>(args)...))); |
| return; |
| } |
| |
| auto bufferChanged = swapWritableBufferIfNeeded(paddedSizeOfTypeAndItemInBytes(T::itemType)); |
| |
| uncheckedAppend<T>(bufferChanged, std::forward<Args>(args)...); |
| } |
| |
| void setClient(ItemBufferWritingClient* client) { m_writingClient = client; } |
| void setClient(ItemBufferReadingClient* client) { m_readingClient = client; } |
| void prepareToAppend(ItemBufferHandle&&); |
| |
| private: |
| const ItemBufferHandles& readOnlyBuffers() const { return m_readOnlyBuffers; } |
| void forEachItemBuffer(Function<void(const ItemBufferHandle&)>&&) const; |
| WEBCORE_EXPORT void didAppendData(size_t numberOfBytes, DidChangeItemBuffer); |
| |
| WEBCORE_EXPORT DidChangeItemBuffer swapWritableBufferIfNeeded(size_t numberOfBytes); |
| WEBCORE_EXPORT void append(const DisplayListItem&); |
| template<typename T, class... Args> void uncheckedAppend(DidChangeItemBuffer didChangeItemBuffer, Args&&... args) |
| { |
| auto* startOfItem = &m_writableBuffer.data[m_writtenNumberOfBytes]; |
| startOfItem[0] = static_cast<uint8_t>(T::itemType); |
| new (startOfItem + sizeof(uint64_t)) T(std::forward<Args>(args)...); |
| didAppendData(paddedSizeOfTypeAndItemInBytes(T::itemType), didChangeItemBuffer); |
| } |
| |
| ItemBufferReadingClient* m_readingClient { nullptr }; |
| ItemBufferWritingClient* m_writingClient { nullptr }; |
| Vector<uint8_t*> m_allocatedBuffers; |
| ItemBufferHandles m_readOnlyBuffers; |
| ItemBufferHandle m_writableBuffer; |
| size_t m_writtenNumberOfBytes { 0 }; |
| }; |
| |
| } // namespace DisplayList |
| } // namespace WebCore |