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A11y callback #8005

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merged 8 commits into from
Mar 7, 2019
Merged

A11y callback #8005

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acb9dd9
implement callback for a11y readiness
dnfield Mar 1, 2019
6f0125f
Merge remote-tracking branch 'upstream/master' into a11y_callback
dnfield Mar 1, 2019
c51c40b
fix unintended change, update docs, nit
dnfield Mar 1, 2019
d8e6ba5
save before commiting
dnfield Mar 1, 2019
f814fcc
Use NSNotificationCenter
dnfield Mar 4, 2019
865043e
Add doc with notification name
dnfield Mar 6, 2019
1d2b8c1
add constant
dnfield Mar 6, 2019
f5e8b39
use FlutterSemanticsUpdateNotification from header, move to VC header
dnfield Mar 7, 2019
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20 changes: 20 additions & 0 deletions shell/platform/darwin/ios/framework/Headers/FlutterEngine.h
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Original file line number Diff line number Diff line change
Expand Up @@ -133,6 +133,26 @@ FLUTTER_EXPORT
*/
- (void)destroyContext;

/**
* Ensures that Flutter will generate a semantics tree.
*
* This is enabled by default if certain accessibility services are turned on by
* the user, or when using a Simulator. This method allows a user to turn
* semantics on when they would not ordinarily be generated and the performance
* overhead is not a concern, e.g. for UI testing. Note that semantics should
* never be programatically turned off, as it would potentially disable
* accessibility services an end user has requested.
*
* This method must only be called after launching the engine via
* `-runWithEntrypoint:` or `-runWithEntryPoint:libraryURI`.
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Let me know if I'm wrong: In the perspective FlutterViewController user, it's hard to find a right time to enable semantics before the first semantics tree being built.

I think it will be easier if FlutterViewController can take the preference and invoke this method when _engineNeedsLaunch is used :).

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Semantics might already be enabled based on device settings or if it's a simulator. It should be safe to call this method even if semantics are enabled - if they're not, no semantics tree will be built.

We could make it an option in the initializer, but I'm not sure how that would help for testing.

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Or maybe a property/one-way-method of FlutterViewController? User can check if they need to force enabling semantics through several ways, such as plist or envs. If it's the case, they can flip the bit after calling initilizer, but before load the VC.

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The ensureSemanticsEnabled is safe to call at any time. Basically, the idea is to just call it right after you register for the callback. You could in theory call it in a loop after that as long as you let the main runloop make progress.

*
* You can subscribe to semantics updates via `NSNotificationCenter` by adding
* an observer for the name `FlutterSemanticsUpdateNotification`. The `object`
* parameter will be the `FlutterViewController` associated with the semantics
* update.
*/
- (void)ensureSemanticsEnabled;

/**
* Sets the `FlutterViewController` for this instance. The FlutterEngine must be
* running (e.g. a successful call to `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI`)
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8 changes: 8 additions & 0 deletions shell/platform/darwin/ios/framework/Headers/FlutterViewController.h
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Expand Up @@ -17,6 +17,14 @@

@class FlutterEngine;

/**
* The name used for semantic update nofications via `NSNotificationCenter`.
*
* The object passed as the sender is the `FlutterViewController` associated
* with the update.
*/
const NSNotificationName FlutterSemanticsUpdateNotification = @"FlutterSemanticsUpdate";

/**
* A `UIViewController` implementation for Flutter views.
*
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4 changes: 4 additions & 0 deletions shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
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Expand Up @@ -146,6 +146,10 @@ - (void)dispatchPointerDataPacket:(std::unique_ptr<blink::PointerDataPacket>)pac
return _shell->GetTaskRunners().GetPlatformTaskRunner();
}

- (void)ensureSemanticsEnabled {
self.iosPlatformView->SetSemanticsEnabled(true);
}

- (void)setViewController:(FlutterViewController*)viewController {
FML_DCHECK(self.iosPlatformView);
_viewController = [viewController getWeakPtr];
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6 changes: 3 additions & 3 deletions shell/platform/darwin/ios/platform_view_ios.h
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Expand Up @@ -40,6 +40,9 @@ class PlatformViewIOS final : public PlatformView {

void SetTextInputPlugin(fml::scoped_nsprotocol<FlutterTextInputPlugin*> plugin);

// |shell::PlatformView|
void SetSemanticsEnabled(bool enabled) override;

private:
fml::WeakPtr<FlutterViewController> owner_controller_;
std::unique_ptr<IOSSurface> ios_surface_;
Expand All @@ -57,9 +60,6 @@ class PlatformViewIOS final : public PlatformView {
// |shell::PlatformView|
sk_sp<GrContext> CreateResourceContext() const override;

// |shell::PlatformView|
void SetSemanticsEnabled(bool enabled) override;

// |shell::PlatformView|
void SetAccessibilityFeatures(int32_t flags) override;

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7 changes: 5 additions & 2 deletions shell/platform/darwin/ios/platform_view_ios.mm
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Expand Up @@ -90,8 +90,8 @@
// |shell::PlatformView|
void PlatformViewIOS::SetSemanticsEnabled(bool enabled) {
if (!owner_controller_) {
FML_DLOG(WARNING) << "Could not set semantics to enabled, this "
"PlatformViewIOS has no ViewController.";
FML_LOG(WARNING) << "Could not set semantics to enabled, this "
"PlatformViewIOS has no ViewController.";
return;
}
if (enabled && !accessibility_bridge_) {
Expand All @@ -111,8 +111,11 @@
// |shell::PlatformView|
void PlatformViewIOS::UpdateSemantics(blink::SemanticsNodeUpdates update,
blink::CustomAccessibilityActionUpdates actions) {
FML_DCHECK(owner_controller_);
if (accessibility_bridge_) {
accessibility_bridge_->UpdateSemantics(std::move(update), std::move(actions));
[[NSNotificationCenter defaultCenter] postNotificationName:FlutterSemanticsUpdateNotification
object:owner_controller_.get()];
}
}

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