[iOS] Migrate VSyncClient to a pure Obj-C implementation (#186166)
Migrates `FlutterVSyncClient` from a hybrid C++/Obj-C implementation to
a pure Objective-C implementation by removing C++ types from its
interface and implementation.
Previously, `FlutterVSyncClient` stored a C++
`flutter::VsyncWaiter::Callback` and used a temporary
`std::unique_ptr<flutter::FrameTimingsRecorder>` to propagate vsync
timestamps. This was redundant:
* `FlutterVSyncClient` allocated a temporary `FrameTimingsRecorder` and
recorded vsync times.
* It passed this to a C++ lambda wrapper.
* The lambda extracted the start/target times as seconds and passed them
to the Obj-C block callback.
* The temporary recorder was immediately discarded.
* `VsyncWaiterIOS` converted the seconds back to `fml::TimePoint`.
* `VsyncWaiter::FireCallback` allocated *another* `FrameTimingsRecorder`
and recorded the same times again.
We now:
* manage the callback as pure Obj-C block that accepts raw
`CFTimeInterval` (double seconds) directly from `CADisplayLink`.
* Remove the redundant `FrameTimingsRecorder` and C++ lambda wrapper.
* Rely solely on `VsyncWaiter::FireCallback` to handle the final
`FrameTimingsRecorder` creation and recording, which it already does.
No test changes because this introduces no semantic change and is
covered by existing tests recently added in:
https://github.com/flutter/flutter/blob/master/engine/src/flutter/shell/platform/darwin/ios/framework/Source/VSyncClientTest.swift
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diff --git a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterVSyncClient.mm b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterVSyncClient.mm
index 57c744c..b484855 100644
--- a/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterVSyncClient.mm
+++ b/engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterVSyncClient.mm
@@ -3,7 +3,6 @@
// found in the LICENSE file.
#import "flutter/shell/platform/darwin/ios/framework/Source/FlutterVSyncClient.h"
-#include "flutter/shell/common/vsync_waiter.h"
#import <UIKit/UIKit.h>
@@ -16,7 +15,7 @@
NSString* const kCADisableMinimumFrameDurationOnPhoneKey = @"CADisableMinimumFrameDurationOnPhone";
@implementation FlutterVSyncClient {
- flutter::VsyncWaiter::Callback _callback;
+ void (^_callback)(CFTimeInterval startTime, CFTimeInterval targetTime);
CADisplayLink* _displayLink;
BOOL _isVariableRefreshRateEnabled;
}
@@ -35,11 +34,7 @@
_refreshRate = maxRefreshRate;
_isVariableRefreshRateEnabled = isVariableRefreshRateEnabled;
_allowPauseAfterVsync = YES;
- _callback = [callback](std::unique_ptr<flutter::FrameTimingsRecorder> recorder) {
- double start_time_seconds = recorder->GetVsyncStartTime().ToEpochDelta().ToSecondsF();
- double target_time_seconds = recorder->GetVsyncTargetTime().ToEpochDelta().ToSecondsF();
- callback(start_time_seconds, target_time_seconds);
- };
+ _callback = callback;
_displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(onDisplayLink:)];
_displayLink.paused = YES;
@@ -82,28 +77,17 @@
}
- (void)onDisplayLink:(CADisplayLink*)link {
- CFTimeInterval delay = CACurrentMediaTime() - link.timestamp;
- fml::TimePoint frame_start_time = fml::TimePoint::Now() - fml::TimeDelta::FromSecondsF(delay);
+ [FlutterTracing tracePlatformVsyncWithStartTime:link.timestamp targetTime:link.targetTimestamp];
CFTimeInterval duration = link.targetTimestamp - link.timestamp;
- fml::TimePoint frame_target_time = frame_start_time + fml::TimeDelta::FromSecondsF(duration);
-
- [FlutterTracing tracePlatformVsyncWithStartTime:frame_start_time.ToEpochDelta().ToSecondsF()
- targetTime:frame_target_time.ToEpochDelta().ToSecondsF()];
-
- std::unique_ptr<flutter::FrameTimingsRecorder> recorder =
- std::make_unique<flutter::FrameTimingsRecorder>();
-
if (duration > 0) {
_refreshRate = round(1 / duration);
}
- recorder->RecordVsync(frame_start_time, frame_target_time);
-
if (_allowPauseAfterVsync) {
link.paused = YES;
}
- _callback(std::move(recorder));
+ _callback(link.timestamp, link.targetTimestamp);
}
- (void)dealloc {
