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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include <utility>
#include "base/callback.h"
#include "base/containers/flat_map.h"
#include "base/containers/flat_set.h"
#include "base/macros.h"
#include "base/scoped_observer.h"
#include "ui/aura/aura_export.h"
#include "ui/aura/native_window_occlusion_tracker.h"
#include "ui/aura/window.h"
#include "ui/aura/window_observer.h"
#include "ui/aura/window_tree_host_observer.h"
#include "ui/compositor/layer_animation_observer.h"
struct SkIRect;
class SkRegion;
namespace gfx {
class Transform;
namespace aura {
namespace test {
class WindowOcclusionTrackerTestApi;
class WindowOcclusionChangeBuilder;
// Notifies tracked Windows when their occlusion state change.
// To start tracking the occlusion state of a Window, call
// aura::Window::TrackOcclusionState()
// A Window is occluded if its bounds and transform are not animated and one of
// these conditions is true:
// - The Window is hidden (Window::IsVisible() is true).
// - The bounds of the Window are completely covered by opaque and axis-aligned
// Windows whose bounds and transform are not animated.
// Note that an occluded window may be drawn on the screen by window switching
// features such as "Alt-Tab" or "Overview".
class AURA_EXPORT WindowOcclusionTracker : public ui::LayerAnimationObserver,
public WindowObserver,
public WindowTreeHostObserver {
// Prevents window occlusion state computations within its scope. If an event
// that could cause window occlusion states to change occurs within the scope
// of a ScopedPause, window occlusion state computations are delayed until all
// ScopedPause objects have been destroyed.
class AURA_EXPORT ScopedPause {
// Used to exclude a window and all descendants from occlusion calculation.
// The occlusion state of the window and all descendants is set from the
// the drawn state of the window, *not* based on what windows may be stacked
// above them. Further, ignores the window that is excluded and its
// descendants when computing the occlusion state of other windows in the
// tree.
// This is useful for a window being dragged or resized to avoid unnecessary
// occlusion state change triggered by these operation, because the window
// bounds are temporary until it is finished.
// Note that this is intended to be used by window manager, such as Ash.
class AURA_EXPORT ScopedExclude : public WindowObserver {
explicit ScopedExclude(Window* window);
~ScopedExclude() override;
Window* window() { return window_; }
// WindowObserver:
void OnWindowDestroying(Window* window) override;
void Shutdown();
Window* window_;
// Forces the occlusion state of a window to VISIBLE regardless of the drawn
// state of the window. Causes the occlusion state of descendants of the
// window that is forced VISIBLE to be computed as if they were in an
// isolated tree with a root that is drawn. Ignores the window that is forced
// VISIBLE and its descendants when computing the occlusion state of other
// windows in the tree.
// This function is primarily useful for situations that show the contents of
// a hidden window, such as overview mode on ChromeOS.
class AURA_EXPORT ScopedForceVisible : public WindowObserver {
explicit ScopedForceVisible(Window* window);
~ScopedForceVisible() override;
// WindowObserver:
void OnWindowDestroying(Window* window) override;
void Shutdown();
Window* window_;
// Holds occlusion related information for tracked windows.
struct OcclusionData {
// Occlusion state for a tracked window.
Window::OcclusionState occlusion_state = Window::OcclusionState::UNKNOWN;
// Region in root window coordinates that is occluded.
SkRegion occluded_region;
// Start tracking the occlusion state of |window|.
void Track(Window* window);
// Compute the occlusion state and occluded region that |window| will have
// once all bounds, transform, opacity, and visibility animations have
// completed. |window| must be a window that has its occlusion state tracked.
OcclusionData ComputeTargetOcclusionForWindow(Window* window);
// Returns true if there are ignored animating windows.
bool HasIgnoredAnimatingWindows() const { return !animated_windows_.empty(); }
// Set a callback to determine whether a window has content to draw in
// addition to layer type check (window layer type != ui::LAYER_NOT_DRAWN).
using WindowHasContentCallback = base::RepeatingCallback<bool(const Window*)>;
void set_window_has_content_callback(WindowHasContentCallback callback) {
window_has_content_callback_ = std::move(callback);
// Set the factory to create WindowOcclusionChangeBuilder.
using OcclusionChangeBuilderFactory =
void set_occlusion_change_builder_factory(
OcclusionChangeBuilderFactory factory) {
occlusion_change_builder_factory_ = std::move(factory);
bool IsPaused() const { return num_pause_occlusion_tracking_; }
friend class test::WindowOcclusionTrackerTestApi;
friend class Env;
friend std::unique_ptr<WindowOcclusionTracker>::deleter_type;
struct RootWindowState {
// Number of Windows whose occlusion state is tracked under this root
// Window.
int num_tracked_windows = 0;
// Whether the occlusion state of tracked Windows under this root is stale.
bool dirty = false;
// The occlusion state of the root window's host.
Window::OcclusionState occlusion_state = Window::OcclusionState::UNKNOWN;
~WindowOcclusionTracker() override;
// Returns true iff the occlusion states in |tracked_windows| match those
// returned by Window::occlusion_state().
static bool OcclusionStatesMatch(
const base::flat_map<Window*, OcclusionData>& tracked_windows);
// Recomputes the occlusion state of tracked windows under roots marked as
// dirty in |root_windows_| if there are no active ScopedPause instance.
void MaybeComputeOcclusion();
// Recomputes the occlusion state of |window| and its descendants.
// |parent_transform_relative_to_root| is the transform of |window->parent()|
// relative to the root window. |clipped_bounds| is an optional mask for the
// bounds of |window| and its descendants. |occluded_region| is a region
// covered by windows which are on top of |window|. Returns true if at least
// one window in the hierarchy starting at |window| is NOT_OCCLUDED.
bool RecomputeOcclusionImpl(
Window* window,
const gfx::Transform& parent_transform_relative_to_root,
const SkIRect* clipped_bounds,
SkRegion* occluded_region);
// Returns true if |window| can occlude other windows (e.g. because it is
// not transparent or has opaque regions for occlusion).
// |window| must be visible.
bool VisibleWindowCanOccludeOtherWindows(Window* window) const;
// Returns true if |window| has content.
bool WindowHasContent(Window* window) const;
// Removes windows whose bounds and transform are not animated from
// |animated_windows_|. Marks the root of those windows as dirty.
void CleanupAnimatedWindows();
// If the bounds or transform of |window| are animated and |window| is not in
// |animated_windows_|, adds |window| to |animated_windows_| and returns true.
bool MaybeObserveAnimatedWindow(Window* window);
// Calls SetOccluded() with |is_occluded| as argument for |window| and its
// descendants. |is_parent_visible| is true if the parent is visible.
void SetWindowAndDescendantsAreOccluded(Window* window,
bool is_occluded,
bool is_parent_visible);
// Updates the occlusion state of |window| in |tracked_windows_|, based on
// |is_occluded| and window->IsVisible(). Updates the occluded region of
// |window| using |occluded_region|. No-op if |window| is not in
// |tracked_windows_|.
void SetOccluded(Window* window,
bool is_occluded,
bool is_parent_visible,
const SkRegion& occluded_region);
// Returns true if |window| is in |tracked_windows_|.
bool WindowIsTracked(Window* window) const;
// Returns true if |window| is in |animated_windows_|.
bool WindowIsAnimated(Window* window) const;
// Returns true if |window| is in |excluded_windows_|.
bool WindowIsExcluded(Window* window) const;
// Returns true if |window| is considered visible. Use this over IsVisible()
// to ensure forced visible windows are considered.
bool WindowIsVisible(Window* window) const;
// Returns true if |window| is forced visible. This does *not* recurse and
// only checks |window|. Use WindowIsVisible() to consider parents.
bool WindowIsForcedVisible(Window* window) const;
// If the root of |window| is not dirty and |predicate| is true, marks the
// root of |window| as dirty. Then, calls MaybeComputeOcclusion().
// |predicate| is not evaluated if the root of |window| is already dirty when
// this is called.
template <typename Predicate>
void MarkRootWindowAsDirtyAndMaybeComputeOcclusionIf(Window* window,
Predicate predicate);
// Marks |root_window_state| as dirty.
void MarkRootWindowStateAsDirty(RootWindowState* root_window_state);
// Marks |root_window| as dirty. Returns false if none of the descendent
// windows in |root_window| are tracked.
bool MarkRootWindowAsDirty(Window* root_window);
// Returns true if |window| or one of its parents is in |animated_windows_|.
bool WindowOrParentIsAnimated(Window* window) const;
// Returns true if |window| or one of its descendants is in
// |tracked_windows_| and visible.
bool WindowOrDescendantIsTrackedAndVisible(Window* window) const;
// Returns true if |window| or one of its descendants is visible, has some
// opaque region and is not in |animated_windows_|. If |assume_parent_opaque|
// is true, the function assumes that the combined opacity of window->parent()
// is 1.0f. If |assume_window_opaque|, the function assumes that the opacity
// of |window| is 1.0f.
bool WindowOrDescendantCanOccludeOtherWindows(
Window* window,
bool assume_parent_opaque = false,
bool assume_window_opaque = false) const;
// Returns true if changing the opacity or alpha state of |window| could
// affect the occlusion state of a tracked window.
bool WindowOpacityChangeMayAffectOcclusionStates(Window* window) const;
// Returns true if changing the transform, bounds or stacking order of
// |window| could affect the occlusion state of a tracked window.
bool WindowMoveMayAffectOcclusionStates(Window* window) const;
// Called when a tracked |window| is added to a root window.
void TrackedWindowAddedToRoot(Window* window);
// Called when a tracked |window| is removed from a root window.
void TrackedWindowRemovedFromRoot(Window* window);
// Removes |this| from the observer list of |window| and its descendants,
// except if they are in |tracked_windows_| or |windows_being_destroyed_|.
void RemoveObserverFromWindowAndDescendants(Window* window);
// Add |this| to the observer list of |window| and its descendants.
void AddObserverToWindowAndDescendants(Window* window);
// Pauses/unpauses the occlusion state computation.
void Pause();
void Unpause();
// Exclude/Unexclude a window from occlusion tracking. See comment on
// ScopedExclude.
void Exclude(Window* window);
void Unexclude(Window* window);
// Called from ScopedForceVisible.
void ForceWindowVisible(Window* window);
void RemoveForceWindowVisible(Window* window);
// Returns true if the occlusion tracker should use target bounds, opacity
// transform, and visibility for occlusion computation. This will be true
// if the target occlusion state of a window is being computed via
// |ComputeTargetOcclusionForWindow|.
bool ShouldUseTargetValues() const;
// ui::LayerAnimationObserver:
void OnLayerAnimationEnded(ui::LayerAnimationSequence* sequence) override;
void OnLayerAnimationAborted(ui::LayerAnimationSequence* sequence) override;
void OnLayerAnimationScheduled(ui::LayerAnimationSequence* sequence) override;
// WindowObserver:
void OnWindowHierarchyChanged(const HierarchyChangeParams& params) override;
void OnWindowAdded(Window* window) override;
void OnWillRemoveWindow(Window* window) override;
void OnWindowVisibilityChanged(Window* window, bool visible) override;
void OnWindowBoundsChanged(Window* window,
const gfx::Rect& old_bounds,
const gfx::Rect& new_bounds,
ui::PropertyChangeReason reason) override;
void OnWindowOpacitySet(Window* window,
ui::PropertyChangeReason reason) override;
void OnWindowAlphaShapeSet(Window* window) override;
void OnWindowTransparentChanged(Window* window,
ui::PropertyChangeReason reason) override;
void OnWindowTransformed(Window* window,
ui::PropertyChangeReason reason) override;
void OnWindowStackingChanged(Window* window) override;
void OnWindowDestroyed(Window* window) override;
void OnWindowAddedToRootWindow(Window* window) override;
void OnWindowRemovingFromRootWindow(Window* window,
Window* new_root) override;
void OnWindowLayerRecreated(Window* window) override;
void OnWindowOpaqueRegionsForOcclusionChanged(Window* window) override;
// WindowTreeHostObserver
void OnOcclusionStateChanged(WindowTreeHost* host,
Window::OcclusionState new_state) override;
// Windows whose occlusion data is tracked.
base::flat_map<Window*, OcclusionData> tracked_windows_;
// Windows whose target visibility is forced to true.
base::flat_map<Window*, size_t> forced_visible_count_map_;
// Windows whose bounds or transform are animated.
// To reduce the overhead of the WindowOcclusionTracker, windows in this set
// and their descendants are considered non-occluded and cannot occlude other
// windows. A window is added to this set the first time that occlusion is
// computed after it was animated. It is removed when the animation ends or is
// aborted.
base::flat_set<Window*> animated_windows_;
// Windows that are excluded from occlustion tracking. See comment on
// ScopedExclude.
base::flat_set<Window*> excluded_windows_;
// Root Windows of Windows in |tracked_windows_|.
base::flat_map<Window*, RootWindowState> root_windows_;
// Number of times that occlusion has been recomputed in this process. We keep
// track of this for tests.
int num_times_occlusion_recomputed_ = 0;
// Number of times that the current call to MaybeComputeOcclusion() has
// recomputed occlusion states. Always 0 when not in MaybeComputeOcclusion().
int num_times_occlusion_recomputed_in_current_step_ = 0;
// Counter of the current occlusion tracking pause.
int num_pause_occlusion_tracking_ = 0;
// Tracks the observed windows.
ScopedObserver<Window, WindowObserver> window_observer_{this};
// Callback to be invoked for additional window has content check.
WindowHasContentCallback window_has_content_callback_;
// Optional factory to create occlusion change builder.
OcclusionChangeBuilderFactory occlusion_change_builder_factory_;
// Stores the window for which the occlusion tracker is computing the
// occlusion based on target bounds, opacity, transform, and visibility
// values. If the occlusion tracker is not computing for a specific window
// (most of the time it is not), this will be nullptr.
Window* target_occlusion_window_ = nullptr;
// Shim to connect WindowOcclusionTracker with native window occlusion
// tracker(s), currently just NativeWindowOcclusionTrackerWin.
NativeWindowOcclusionTracker native_window_occlusion_tracker_;
} // namespace aura