visual_properties.h | Explore in Territory

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_PUBLIC_COMMON_WIDGET_VISUAL_PROPERTIES_H_
#define THIRD_PARTY_BLINK_PUBLIC_COMMON_WIDGET_VISUAL_PROPERTIES_H_

#include <optional>

#include "cc/trees/browser_controls_params.h"
#include "components/viz/common/surfaces/local_surface_id.h"
#include "third_party/blink/public/common/common_export.h"
#include "third_party/blink/public/mojom/manifest/display_mode.mojom.h"
#include "ui/base/ui_base_types.h"
#include "ui/display/screen_infos.h"
#include "ui/gfx/geometry/size.h"

namespace blink {

// Visual properties contain context required to render a frame tree.
// For legacy reasons, both Page visual properties [shared by all Renderers] and
// Widget visual properties [unique to local frame roots] are passed along the
// same data structure. Separating these is tricky because they both affect
// rendering, and if updates are received asynchronously, this can cause
// incorrect behavior.
// Visual properties are also used for Pepper fullscreen and popups, which are
// also based on Widgets.
//
// The data flow for VisualProperties is tricky. For legacy reasons, visual
// properties are currently always sent from RenderWidgetHosts to RenderWidgets.
// However, RenderWidgets can also send visual properties to out-of-process
// subframes [by bouncing through CrossProcessFrameConnector]. This causes a
// cascading series of VisualProperty messages. This is necessary due to the
// current implementation to make sure that cross-process surfaces get
// simultaneously synchronized. For more details, see:
// https://docs.google.com/document/d/1VKOLBYlujcn862w9LAyUbv6oW9RZgD65oDCI_G5AEVQ/edit#heading=h.wno2seszsyen
// https://docs.google.com/document/d/1J7BTRsylGApm6KHaaTu-m6LLvSWJgf1B9CM-USKIp1k/edit#heading=h.ichmoicfam1y
//
// Known problems:
// + It's not clear which properties are page-specific and which are
// widget-specific. We should document them.
// + It's not clear which properties are only set by the browser, which are only
// set by the renderer, and which are set by both.
// + Given the frame tree A(B(A')) where A and A' are same-origin, same process
// and B is separate origin separate process:
//   (1) RenderWidget A gets SynchronizeVisualProperties, passes it to proxy for
//   B, sets values on RenderView/Page.
//   (2) RenderWidget B gets SynchronizeVisualProperties, passes it to proxy for
//   A'
//   (3) RenderWidget A' gets SynchronizeVisualProperties.
// In between (1) and (3), frames associated with RenderWidget A' will see
// updated page properties from (1) but are still seeing old widget properties.

struct BLINK_COMMON_EXPORT VisualProperties { … };

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_PUBLIC_COMMON_WIDGET_VISUAL_PROPERTIES_H_
chromium/third_party/blink/public/common/widget/visual_properties.h
