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content / app_shim_remote_cocoa / web_contents_occlusion_checker_mac.mm [blame]
// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#import "content/app_shim_remote_cocoa/web_contents_occlusion_checker_mac.h"
#include <memory>
#import "base/apple/foundation_util.h"
#import "base/apple/scoped_objc_class_swizzler.h"
#include "base/auto_reset.h"
#include "base/debug/crash_logging.h"
#include "base/debug/dump_without_crashing.h"
#include "base/feature_list.h"
#include "base/mac/mac_util.h"
#include "base/metrics/field_trial_params.h"
#include "base/no_destructor.h"
#include "content/common/features.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/content_client.h"
using features::kMacWebContentsOcclusion;
// Experiment features.
const base::FeatureParam<bool> kEnhancedWindowOcclusionDetection{
&kMacWebContentsOcclusion, "EnhancedWindowOcclusionDetection", false};
namespace {
NSString* const kWindowDidChangePositionInWindowList =
@"ChromeWindowDidChangePositionInWindowList";
constexpr char kWindowIsOccludedKey[] = "ChromeWindowIsOccludedKey";
bool IsBrowserProcess() {
return base::CommandLine::ForCurrentProcess()
->GetSwitchValueASCII("type")
.empty();
}
} // namespace
@interface WebContentsOcclusionCheckerMac ()
// Returns a pointer to the shared instance that can be cleared during tests.
+ (WebContentsOcclusionCheckerMac* __strong*)sharedOcclusionChecker;
- (base::apple::ScopedObjCClassSwizzler*)windowClassSwizzler;
@end
@implementation WebContentsOcclusionCheckerMac {
NSWindow* __weak _windowResizingOrMoving;
NSWindow* __weak _windowReceivingFullscreenTransitionNotifications;
BOOL _displaysAreAsleep;
BOOL _occlusionStateUpdatesAreScheduled;
BOOL _updatingOcclusionStates;
std::unique_ptr<base::apple::ScopedObjCClassSwizzler> _windowClassSwizzler;
}
+ (WebContentsOcclusionCheckerMac* __strong*)sharedOcclusionChecker {
static WebContentsOcclusionCheckerMac* sharedOcclusionChecker;
return &sharedOcclusionChecker;
}
+ (instancetype)sharedInstance {
WebContentsOcclusionCheckerMac* __strong* sharedInstance =
[self sharedOcclusionChecker];
// It seems a utility process can trigger a call to
// +[WebContentsViewCocoa initialize] (from a non-main thread!), which calls
// out to here to create the occlusion tracker. To guard against that, and
// any other other potential callers, only create the tracker if we're
// running inside the browser process. https://crbug.com/349984532 .
if (*sharedInstance == nil && IsBrowserProcess()) {
*sharedInstance = [[self alloc] init];
}
return *sharedInstance;
}
+ (BOOL)manualOcclusionDetectionSupportedForPackedVersion:(int)version {
if (version >= 13'00'00 && version < 13'03'00) {
return NO;
}
return YES;
}
+ (BOOL)manualOcclusionDetectionSupportedForCurrentMacOSVersion {
return [self manualOcclusionDetectionSupportedForPackedVersion:
base::mac::MacOSVersion()];
}
+ (void)resetSharedInstanceForTesting {
*[self sharedOcclusionChecker] = nil;
}
- (instancetype)init {
self = [super init];
DCHECK(base::FeatureList::IsEnabled(kMacWebContentsOcclusion));
DCHECK(IsBrowserProcess());
if (!IsBrowserProcess()) {
static auto* const crash_key = base::debug::AllocateCrashKeyString(
"MacWebContentsOcclusionChecker", base::debug::CrashKeySize::Size32);
base::debug::SetCrashKeyString(crash_key, "initialized");
}
[self setUpNotifications];
// There's no notification for NSWindows changing their order in the window
// list. Swizzle -orderWindow:relativeTo:, allowing the checker to initiate
// occlusion checks on window ordering changes.
_windowClassSwizzler = std::make_unique<base::apple::ScopedObjCClassSwizzler>(
[NSWindow class], [WebContentsOcclusionCheckerMac class],
@selector(orderWindow:relativeTo:));
return self;
}
- (void)dealloc {
[NSObject cancelPreviousPerformRequestsWithTarget:self
selector:@selector
(performOcclusionStateUpdates)
object:nil];
[[NSNotificationCenter defaultCenter] removeObserver:self];
[[[NSWorkspace sharedWorkspace] notificationCenter] removeObserver:self];
_windowClassSwizzler.reset();
}
- (base::apple::ScopedObjCClassSwizzler*)windowClassSwizzler {
return _windowClassSwizzler.get();
}
- (BOOL)isManualOcclusionDetectionEnabled {
return [WebContentsOcclusionCheckerMac
manualOcclusionDetectionSupportedForCurrentMacOSVersion] &&
kEnhancedWindowOcclusionDetection.Get();
}
// Alternative implementation of orderWindow:relativeTo:. Replaces
// NSWindow's version, allowing the occlusion checker to learn about
// window ordering events.
- (void)orderWindow:(NSWindowOrderingMode)orderingMode
relativeTo:(NSInteger)otherWindowNumber {
// Super.
[[WebContentsOcclusionCheckerMac sharedInstance] windowClassSwizzler]
->InvokeOriginal<void, NSWindowOrderingMode, NSInteger>(
self, _cmd, orderingMode, otherWindowNumber);
if (![[WebContentsOcclusionCheckerMac sharedInstance]
isManualOcclusionDetectionEnabled]) {
return;
}
[[NSNotificationCenter defaultCenter]
postNotificationName:kWindowDidChangePositionInWindowList
object:self
userInfo:nil];
}
- (void)setUpNotifications {
NSNotificationCenter* notificationCenter =
[NSNotificationCenter defaultCenter];
if ([self isManualOcclusionDetectionEnabled]) {
[notificationCenter addObserver:self
selector:@selector(windowWillMove:)
name:NSWindowWillMoveNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(windowDidMove:)
name:NSWindowDidMoveNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(windowWillStartLiveResize:)
name:NSWindowWillStartLiveResizeNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(windowWillEndLiveResize:)
name:NSWindowDidEndLiveResizeNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(windowWillClose:)
name:NSWindowWillCloseNotification
object:nil];
[notificationCenter
addObserver:self
selector:@selector(windowDidChangePositionInWindowList:)
name:kWindowDidChangePositionInWindowList
object:nil];
// orderWindow:relativeTo: was the override point that caught all window
// list ordering changes up until Sonoma. With Sonoma, it appears that
// window cycling (Cmd+`) goes directly to -[NSWindow makeKeyWindow]. Add
// these window main notifications to catch the changes. Unfortunately,
// there doesn't appear to be a way to trigger any of the the window
// cycling machinery, so automated testing is impossible.
[notificationCenter
addObserver:self
selector:@selector(windowDidChangePositionInWindowList:)
name:NSWindowDidBecomeMainNotification
object:nil];
[notificationCenter
addObserver:self
selector:@selector(windowDidChangePositionInWindowList:)
name:NSWindowDidResignMainNotification
object:nil];
[[[NSWorkspace sharedWorkspace] notificationCenter]
addObserver:self
selector:@selector(displaysDidSleep:)
name:NSWorkspaceScreensDidSleepNotification
object:nil];
[[[NSWorkspace sharedWorkspace] notificationCenter]
addObserver:self
selector:@selector(displaysDidWake:)
name:NSWorkspaceScreensDidWakeNotification
object:nil];
}
[notificationCenter addObserver:self
selector:@selector(windowChangedOcclusionState:)
name:NSWindowDidChangeOcclusionStateNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(fullscreenTransitionStarted:)
name:NSWindowWillEnterFullScreenNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(fullscreenTransitionComplete:)
name:NSWindowDidEnterFullScreenNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(fullscreenTransitionStarted:)
name:NSWindowWillExitFullScreenNotification
object:nil];
[notificationCenter addObserver:self
selector:@selector(fullscreenTransitionComplete:)
name:NSWindowDidExitFullScreenNotification
object:nil];
}
- (BOOL)windowCanTriggerOcclusionUpdates:(NSWindow*)window {
// We only care about occlusion because we want to inform web contents
// so they can update their visibility state. Therefore, we ignore windows
// that don't have a web contents (they essentially don't exist for our manual
// occlusion calculations).
if (![window containsWebContentsViewCocoa])
return NO;
// The checker cycles through the window list when performing its manual
// occlusion checks. Child windows don't appear in this list, so don't
// trigger an occlusion check unless `window` is a parent window
// (i.e. is not the child of another window).
if ([window parentWindow] == nil)
return YES;
// `window` is a child window but that wasn't always the case. When it was
// created and resized it was a "parent" window. If it came through this
// codepath, we may have marked it occluded. Since we don't trigger occlusion
// updates on child windows, now that the window is a child, there's a chance
// we'll never update its state to visible. To avoid this, ensure it's visible
// before we exit. See https://crbug.com/1337390 .
[window setOccluded:NO];
return NO;
}
- (void)windowWillClose:(NSNotification*)notification {
NSWindow* theWindow = [notification object];
// -windowCanTriggerOcclusionUpdates: returns NO if the window doesn't
// contain a webcontents. In some cases, however, a closing browser window
// will be stripped of its webcontents by the time we reach this method.
// As a result, if we use windowCanTriggerOcclusionUpdates:, the browser
// window's closure won't trigger an occlusion state update, leaving the
// webcontentses in windows it covered in the occluded state. To avoid this,
// we'll perform an occlusion update if the window isn't a child window.
// See http://crbug.com/1356622 .
if ([theWindow parentWindow] == nil)
[self scheduleOcclusionStateUpdates];
}
- (void)windowWillMove:(NSNotification*)notification {
NSWindow* theWindow = [notification object];
if (![self windowCanTriggerOcclusionUpdates:theWindow])
return;
_windowResizingOrMoving = theWindow;
[self scheduleOcclusionStateUpdates];
}
- (void)windowDidMove:(NSNotification*)notification {
// We would check _windowResizingOrMoving == nil and early out, except in
// cases where a window is moved programmatically, windowWillMove: never gets
// called, so _windowResizingOrMoving never gets set.
_windowResizingOrMoving = nil;
if ([self windowCanTriggerOcclusionUpdates:[notification object]])
[self scheduleOcclusionStateUpdates];
}
- (void)windowDidChangePositionInWindowList:(NSNotification*)notification {
if ([self windowCanTriggerOcclusionUpdates:[notification object]])
[self scheduleOcclusionStateUpdates];
}
- (void)windowWillStartLiveResize:(NSNotification*)notification {
NSWindow* theWindow = [notification object];
if (![self windowCanTriggerOcclusionUpdates:theWindow])
return;
_windowResizingOrMoving = theWindow;
[self scheduleOcclusionStateUpdates];
}
- (void)windowWillEndLiveResize:(NSNotification*)notification {
if (_windowResizingOrMoving == nil)
return;
_windowResizingOrMoving = nil;
[self scheduleOcclusionStateUpdates];
}
- (void)windowChangedOcclusionState:(NSNotification*)notification {
// Ignore the occlusion notifications we generate.
NSDictionary* userInfo = [notification userInfo];
NSString* occlusionCheckerKey = [self className];
if (userInfo[occlusionCheckerKey] != nil)
return;
if ([self windowCanTriggerOcclusionUpdates:[notification object]])
[self scheduleOcclusionStateUpdates];
}
- (void)displaysDidSleep:(NSNotification*)notification {
_displaysAreAsleep = YES;
[self scheduleOcclusionStateUpdates];
}
- (void)displaysDidWake:(NSNotification*)notification {
_displaysAreAsleep = NO;
[self scheduleOcclusionStateUpdates];
}
- (void)fullscreenTransitionStarted:(NSNotification*)notification {
// We only care about fullscreen transitions because macOS may send spurious
// occlusion update notifications. Track the transitioning window so we can
// ignore updates about this window until the transition is over.
_windowReceivingFullscreenTransitionNotifications = [notification object];
}
- (void)fullscreenTransitionComplete:(NSNotification*)notification {
_windowReceivingFullscreenTransitionNotifications = nil;
[self scheduleOcclusionStateUpdates];
}
- (BOOL)occlusionStateUpdatesAreScheduledForTesting {
return _occlusionStateUpdatesAreScheduled;
}
// Schedules an update of occlusion states for some time in the future.
// https://crbug.com/1300929 covers a crash where a webcontents gets added to
// a window, triggering an update to its visibility state. A visibility state
// observer creates a bubble, and that bubble triggers a call to
// -scheduleOcclusionStateUpdates. -scheduleOcclusionStateUpdates goes
// on to update the occlusion status of all windows, which triggers the
// visibility state observer a second time, leading to another bubble
// creation, another call to -scheduleOcclusionStateUpdates, and then a
// crash. We could make -scheduleOcclusionStateUpdates non-reentrant but that
// wouldn't prevent a visibility state observer from entering its observer
// code twice (as happened in the bug). By making the occlusion state
// update occur away from the notification, we can avoid the reentrancy
// problems with visibility observers.
- (void)scheduleOcclusionStateUpdates {
if (_occlusionStateUpdatesAreScheduled)
return;
_occlusionStateUpdatesAreScheduled = YES;
[self performSelector:@selector(performOcclusionStateUpdates)
withObject:nil
afterDelay:0];
}
- (void)performOcclusionStateUpdates {
_occlusionStateUpdatesAreScheduled = NO;
if (content::GetContentClient()->browser() &&
content::GetContentClient()->browser()->IsShuttingDown()) {
return;
}
DCHECK(!_updatingOcclusionStates);
_updatingOcclusionStates = YES;
NSArray<NSWindow*>* windowsFromFrontToBack =
[[[NSApplication sharedApplication] orderedWindows] copy];
for (NSWindow* window in windowsFromFrontToBack) {
// The fullscreen transition causes spurious occlusion notifications.
// See https://crbug.com/1081229 . Also, ignore windows that don't have
// web contentses.
if (window == _windowReceivingFullscreenTransitionNotifications ||
![window containsWebContentsViewCocoa])
continue;
[window setOccluded:[self isWindowOccluded:window
windowList:windowsFromFrontToBack]];
}
_updatingOcclusionStates = NO;
}
// Returns YES if `window` is occluded, either according to macOS or via
// our manual occlusion calculation.
- (BOOL)isWindowOccluded:(NSWindow*)window
windowList:(nonnull NSArray<NSWindow*>*)windowList {
if (_displaysAreAsleep) {
return YES;
}
BOOL windowOccludedPerMacOS =
!([window occlusionState] & NSWindowOcclusionStateVisible);
if (windowOccludedPerMacOS) {
// If macOS says the window is occluded, take that answer.
return YES;
}
// If manual occlusion detection is disabled, return the answer from macOS.
if (![self isManualOcclusionDetectionEnabled]) {
return NO;
}
NSRect windowFrame = [window frame];
// Determine if there's a window occluding `window`.
for (NSWindow* nextWindow in windowList) {
if (![nextWindow isVisible]) {
continue;
}
// If we come to our window in the list, we're done.
if (nextWindow == window) {
break;
}
// If the next window is moving or resizing, treat it as if it doesn't
// exist so that if it currently occludes `window` it will transition to
// visible. That way, `window`'s content, if it becomes visible, will be
// fresh. We'll recompute `window`'s occlusion state after the move or
// resize ends.
if (nextWindow == _windowResizingOrMoving) {
continue;
}
// Ideally we'd compute the region which is the sum of all windows above
// `window` and see if it completely contains `window`'s web contents.
// Unfortunately, we don't have a library that can perform general purpose
// region arithmetic. For example, if we have windows A and B side-by-side,
// at first glance it might seem like enough to just union the two frames.
// The problem is the small transparent regions outside the curved window
// corners. If A and B cover C, we can't know if a portion of C shows
// through these regions. The best we can do is see if any single browser
// window above completely contains our frame. This should happen more
// frequently on a laptop, where users typically maximize their windows to
// fit between the menu bar and dock.
if (NSContainsRect([nextWindow frame], windowFrame)) {
return YES;
}
}
return NO;
}
@end
@implementation NSWindow (WebContentsOcclusionCheckerMac)
- (BOOL)isOccluded {
return objc_getAssociatedObject(self, kWindowIsOccludedKey) != nil;
}
- (void)setOccluded:(BOOL)flag {
if (flag == [self isOccluded])
return;
objc_setAssociatedObject(self, kWindowIsOccludedKey, flag ? @YES : nil,
OBJC_ASSOCIATION_RETAIN_NONATOMIC);
NSString* occlusionCheckerKey = [WebContentsOcclusionCheckerMac className];
[[NSNotificationCenter defaultCenter]
postNotificationName:NSWindowDidChangeOcclusionStateNotification
object:self
userInfo:@{occlusionCheckerKey : @YES}];
}
@end