LibWeb+WebContent+WebWorker: Move backing store allocation in Navigable

Making navigables responsible for backing store allocation will allow us to have separate backing stores for iframes and run paint updates for them independently, which is a step toward isolating them into separate processes. Another nice side effect is that now Skia backend context is ready by the time backing stores are allocated, so we will be able to get rid of BackingStore class in the upcoming changes and allocate PaintingSurface directly.
Author: https://github.com/kalenikaliaksandr Commit: 082053d781 Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5259 Reviewed-by: https://github.com/gmta ✅
2025-07-24 09:52:31 +00:00 · 2025-06-26 22:33:58 +02:00 · 2025-06-26 22:33:58 +02:00 · 082053d781 · 2025-07-04 14:14:12 +00:00
commit 082053d781
parent b73525ba0e
23 changed files with 265 additions and 262 deletions
--- a/Libraries/LibWeb/Painting/BackingStoreManager.cpp
+++ b/Libraries/LibWeb/Painting/BackingStoreManager.cpp
@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2024, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibCore/Timer.h>
+#include <LibWeb/HTML/TraversableNavigable.h>
+#include <LibWeb/Painting/BackingStoreManager.h>
+#include <WebContent/PageClient.h>
+
+#ifdef AK_OS_MACOS
+#    include <LibCore/IOSurface.h>
+#    include <LibCore/MachPort.h>
+#    include <LibCore/Platform/MachMessageTypes.h>
+#endif
+
+namespace Web::Painting {
+
+GC_DEFINE_ALLOCATOR(BackingStoreManager);
+
+#ifdef AK_OS_MACOS
+static Optional<Core::MachPort> s_browser_mach_port;
+void BackingStoreManager::set_browser_mach_port(Core::MachPort&& port)
+{
+    s_browser_mach_port = move(port);
+}
+#endif
+
+BackingStoreManager::BackingStoreManager(HTML::Navigable& navigable)
+    : m_navigable(navigable)
+{
+    m_backing_store_shrink_timer = Core::Timer::create_single_shot(3000, [this] {
+        resize_backing_stores_if_needed(WindowResizingInProgress::No);
+    });
+}
+
+void BackingStoreManager::visit_edges(Cell::Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(m_navigable);
+}
+
+void BackingStoreManager::restart_resize_timer()
+{
+    m_backing_store_shrink_timer->restart();
+}
+
+void BackingStoreManager::reallocate_backing_stores(Gfx::IntSize size)
+{
+#ifdef AK_OS_MACOS
+    if (m_navigable->is_top_level_traversable() && s_browser_mach_port.has_value()) {
+        auto back_iosurface = Core::IOSurfaceHandle::create(size.width(), size.height());
+        auto back_iosurface_port = back_iosurface.create_mach_port();
+
+        auto front_iosurface = Core::IOSurfaceHandle::create(size.width(), size.height());
+        auto front_iosurface_port = front_iosurface.create_mach_port();
+
+        m_front_bitmap_id = m_next_bitmap_id++;
+        m_back_bitmap_id = m_next_bitmap_id++;
+
+        auto& page_client = m_navigable->top_level_traversable()->page().client();
+
+        Core::Platform::BackingStoreMetadata metadata;
+        metadata.page_id = page_client.id();
+        metadata.front_backing_store_id = m_front_bitmap_id;
+        metadata.back_backing_store_id = m_back_bitmap_id;
+
+        Core::Platform::MessageWithBackingStores message;
+
+        message.header.msgh_remote_port = s_browser_mach_port->port();
+        message.header.msgh_local_port = MACH_PORT_NULL;
+        message.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0) | MACH_MSGH_BITS_COMPLEX;
+        message.header.msgh_size = sizeof(message);
+        message.header.msgh_id = Core::Platform::BACKING_STORE_IOSURFACES_MESSAGE_ID;
+
+        message.body.msgh_descriptor_count = 2;
+
+        message.front_descriptor.name = front_iosurface_port.release();
+        message.front_descriptor.disposition = MACH_MSG_TYPE_MOVE_SEND;
+        message.front_descriptor.type = MACH_MSG_PORT_DESCRIPTOR;
+
+        message.back_descriptor.name = back_iosurface_port.release();
+        message.back_descriptor.disposition = MACH_MSG_TYPE_MOVE_SEND;
+        message.back_descriptor.type = MACH_MSG_PORT_DESCRIPTOR;
+
+        message.metadata = metadata;
+
+        mach_msg_timeout_t const timeout = 100; // milliseconds
+        auto const send_result = mach_msg(&message.header, MACH_SEND_MSG | MACH_SEND_TIMEOUT, message.header.msgh_size, 0, MACH_PORT_NULL, timeout, MACH_PORT_NULL);
+        if (send_result != KERN_SUCCESS) {
+            dbgln("Failed to send message to server: {}", mach_error_string(send_result));
+            VERIFY_NOT_REACHED();
+        }
+
+        m_front_store = IOSurfaceBackingStore::create(move(front_iosurface));
+        m_back_store = IOSurfaceBackingStore::create(move(back_iosurface));
+
+        return;
+    }
+#endif
+
+    m_front_bitmap_id = m_next_bitmap_id++;
+    m_back_bitmap_id = m_next_bitmap_id++;
+
+    auto front_bitmap = Gfx::Bitmap::create_shareable(Gfx::BitmapFormat::BGRA8888, Gfx::AlphaType::Premultiplied, size).release_value();
+    auto back_bitmap = Gfx::Bitmap::create_shareable(Gfx::BitmapFormat::BGRA8888, Gfx::AlphaType::Premultiplied, size).release_value();
+
+    m_front_store = BitmapBackingStore::create(front_bitmap);
+    m_back_store = BitmapBackingStore::create(back_bitmap);
+
+    if (m_navigable->is_top_level_traversable()) {
+        auto& page_client = m_navigable->top_level_traversable()->page().client();
+        page_client.page_did_allocate_backing_stores(m_front_bitmap_id, front_bitmap->to_shareable_bitmap(), m_back_bitmap_id, back_bitmap->to_shareable_bitmap());
+    }
+}
+
+void BackingStoreManager::resize_backing_stores_if_needed(WindowResizingInProgress window_resize_in_progress)
+{
+    auto viewport_size = m_navigable->page().css_to_device_rect(m_navigable->viewport_rect()).size();
+    if (viewport_size.is_empty())
+        return;
+
+    Web::DevicePixelSize minimum_needed_size;
+    if (window_resize_in_progress == WindowResizingInProgress::Yes) {
+        // Pad the minimum needed size so that we don't have to keep reallocating backing stores while the window is being resized.
+        minimum_needed_size = { viewport_size.width() + 256, viewport_size.height() + 256 };
+    } else {
+        // If we're not in the middle of a resize, we can shrink the backing store size to match the viewport size.
+        minimum_needed_size = viewport_size;
+        m_front_store.clear();
+        m_back_store.clear();
+    }
+
+    if (!m_front_store || !m_back_store || !m_front_store->size().contains(minimum_needed_size.to_type<int>())) {
+        reallocate_backing_stores(minimum_needed_size.to_type<int>());
+    }
+}
+
+void BackingStoreManager::swap_back_and_front()
+{
+    swap(m_front_store, m_back_store);
+    swap(m_front_bitmap_id, m_back_bitmap_id);
+}
+
+}