Implement system fonts system channel listener #38930

chunhtai · 2019-08-20T23:10:33Z

Description

This pr add a system channel listener to repaint RenderParagraph and RenderEditable upon receiving system fonts change notification. We will have engine side change coming soon

flutter/engine#12276

Related Issues

#38556

Tests

I added the following tests:

RenderParagraph relayout upon system fonts changes
RenderEditable relayout upon system fonts changes

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]). This will ensure a smooth and quick review process.

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I signed the CLA.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I updated/added relevant documentation (doc comments with ///).
All existing and new tests are passing.
The analyzer (flutter analyze --flutter-repo) does not report any problems on my PR.
I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require Flutter developers to manually update their apps to accommodate your change?

Yes, this is a breaking change (Please read Handling breaking changes). Replace this with a link to the e-mail where you asked for input on this proposed change.
No, this is not a breaking change.

goderbauer

What about other objects/widgets that use TextPainter to measure text (example: CupertinoDataPicker or Material's TimePicker)? Do we not have to notify them as well so they can rebuild?

goderbauer · 2019-08-26T19:26:00Z

packages/flutter/lib/src/rendering/binding.dart

Since this is about painting text, PaintingBinding is probably a better place for this.

goderbauer · 2019-08-26T19:28:17Z

packages/flutter/lib/src/rendering/binding.dart

There probably needs to be a public way to register listeners. Not all listeners are going to be RenderObjects (e.g. all the the non-RenderObject that use TextPainter, which are for example Widgets using CustomPaint like the TimePicker).

goderbauer · 2019-08-26T19:30:46Z

packages/flutter/lib/src/rendering/binding.dart

Could we just pass in markNeedsLayout directly here? That way, interested RenderObjects would just have to implement the mixin and are good to go. (It also avoids an extra function call when this gets called).

goderbauer · 2019-08-26T19:34:13Z

packages/flutter/lib/src/widgets/binding.dart

It is odd that the message bubbles up all the way to the widget layer and is then redirected back to the rendering layer. What if you've implemented your own Widget system based on Flutter's rendering layer? You still want the font thing to work.

goderbauer · 2019-08-26T19:34:45Z

packages/flutter/test/rendering/system_fonts_test.dart

nit: end with blank line.

chunhtai · 2019-08-27T23:02:23Z

Ready for re review @goderbauer

chunhtai · 2019-08-29T19:26:55Z

packages/flutter/lib/src/widgets/binding.dart

I need to include this to get passed doc parsing.

goderbauer · 2019-09-03T20:03:46Z

packages/flutter/lib/src/rendering/binding.dart

Maybe call this "RelayoutWhenSystemFontsChangeMixin" to better describe what it does?

goderbauer · 2019-09-03T20:08:54Z

packages/flutter/lib/src/rendering/binding.dart

"Mixin for [RenderObject] that will call [markNeedsLayout] whenever the system fonts change".

Can you also add an explanation why/when a developer should mix this in?

goderbauer · 2019-09-03T20:09:48Z

packages/flutter/lib/src/rendering/binding.dart

Why would instance or systemFonts be null? Shouldn't they always be initialized when you get to this place?

goderbauer · 2019-09-03T20:09:54Z

packages/flutter/lib/src/rendering/binding.dart

goderbauer · 2019-09-03T20:10:23Z

packages/flutter/lib/src/rendering/binding.dart

We should probably find a better location then rendering/binding.dart for this.

goderbauer · 2019-09-03T20:15:46Z

packages/flutter/lib/src/painting/binding.dart

Maybe _SystemFontsListener

goderbauer · 2019-09-03T20:24:33Z

packages/flutter/lib/src/cupertino/date_picker.dart

This is awkward code to add to the framework. Can we find another way to test this?

goderbauer · 2019-09-03T20:26:51Z

packages/flutter/lib/src/cupertino/date_picker.dart

calling didChangeDependecies seems awkward (especially because that one calls super). Maybe factor out what you need from didChangeDependencies into a seperate method that we can call fro both places?

goderbauer · 2019-09-03T20:26:59Z

packages/flutter/lib/src/cupertino/date_picker.dart

goderbauer · 2019-09-03T20:31:49Z

packages/flutter/lib/src/services/binding.dart

Handler called for messages received on the [SystemChannels.system] call.

Other bindings may override this to respond to incoming system message.

goderbauer · 2019-09-09T16:16:11Z

packages/flutter/lib/src/cupertino/date_picker.dart

Put this statement into the setState closure? (That's the state getting changed here, right?)

goderbauer · 2019-09-09T16:16:28Z

packages/flutter/lib/src/cupertino/date_picker.dart

This comment seems outdated?

goderbauer · 2019-09-09T16:17:52Z

packages/flutter/lib/src/cupertino/date_picker.dart

Put this inside the setState since that's causing the state to change?

goderbauer · 2019-09-09T16:18:02Z

packages/flutter/lib/src/cupertino/date_picker.dart

This comment seems outdated?

goderbauer · 2019-09-09T16:19:12Z

packages/flutter/lib/src/cupertino/date_picker.dart

Maybe add a comment why we have to clear this on system font changes (e.g. because it was determined by measuring the width of text which may have changed with the new fonts).

goderbauer · 2019-09-09T16:24:49Z

packages/flutter/lib/src/rendering/object.dart

What's a text related painter?

using ui.Paragraph directly without going through text painter. I should update the doc comment

goderbauer · 2019-09-09T16:25:19Z

packages/flutter/lib/src/rendering/paragraph.dart

Can this import be removed?

goderbauer · 2019-09-09T16:25:58Z

packages/flutter/lib/src/services/binding.dart

call -> message channel.

goderbauer · 2019-09-09T16:26:07Z

packages/flutter/lib/src/services/binding.dart

message -> messages.

goderbauer · 2019-09-09T16:27:01Z

packages/flutter/lib/src/widgets/binding.dart

Why the change from a switch?

googlebot · 2019-09-13T18:26:44Z

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googlebot · 2019-09-16T19:53:02Z

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chunhtai · 2019-09-16T20:09:42Z

@goderbauer this is ready to review.

chunhtai · 2019-09-16T20:12:16Z

packages/flutter/lib/src/rendering/editable.dart

I am not sure how do we test _textPainter has been marked needs layout. this also apply to all the other widget.
The current test only verify renderobject is dirty after font change. unless I added a bunch of visibleforTesting for all the widgets that have textpainter

goderbauer · 2019-09-16T22:44:26Z

packages/flutter/lib/src/cupertino/date_picker.dart

we do not have updated values? Isn't clearing the cache causing the values to get recalculated/updated?

Maybe:

"Clear cached width to ensure that they get recalculated with the new system fonts."

goderbauer · 2019-09-16T22:44:45Z

packages/flutter/lib/src/cupertino/date_picker.dart

This one is not really clearing a cache? It's proactively recalculating the widths?

(You could probably just remove the second line.)

goderbauer · 2019-09-16T22:48:29Z

packages/flutter/lib/src/painting/binding.dart

Suggested change

/// Listenable for OSes system fonts change event.

/// Listenable that notifies when the fonts available on the system have changed.

goderbauer · 2019-09-16T22:50:36Z

packages/flutter/lib/src/painting/binding.dart

Instead of this slightly awkward cast you could have a correctly typed private _systemFonts variable and a public systemFonts getter for it.

goderbauer · 2019-09-16T22:51:49Z

packages/flutter/lib/src/painting/text_painter.dart

This should include information about when somebody may want to call this.

goderbauer · 2019-09-16T22:52:50Z

packages/flutter/lib/src/rendering/object.dart

Called when system fonts have changed.

goderbauer · 2019-09-16T22:53:00Z

packages/flutter/lib/src/rendering/object.dart

Subclasses should override this method to clear any cached values that depend on font-related metrics.

goderbauer · 2019-09-16T22:54:42Z

packages/flutter/lib/src/rendering/object.dart

By default, [mark needsLayout] is called on the [RenderObject] implementing this mixin.

goderbauer · 2019-09-16T22:57:29Z

packages/flutter/lib/src/material/slider.dart

Will _updateLabelPainter not automatically cause this to happen?

goderbauer · 2019-09-16T22:58:21Z

packages/flutter/lib/src/material/range_slider.dart

Will _updateLabelPainters not cause this to happen?

no, _updateLabelPainters will set the same property of existing textpainter, which will all get shortcircuited.

goderbauer

LGTM

goderbauer · 2019-09-18T23:02:26Z

packages/flutter/lib/src/rendering/object.dart

nit: no space after mark. (sorry...)

* Implement system fonts system channel listener

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googlebot added the cla: yes label Aug 20, 2019

chunhtai requested a review from goderbauer August 21, 2019 20:09

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I need to include this to get passed doc parsing.

goderbauer reviewed Sep 3, 2019

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Add system font change listener for windows flutter/engine#12276

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nit: no space after mark. (sorry...)

chunhtai force-pushed the issues/38556 branch 4 times, most recently from 974dfa6 to 7b41a5f Compare September 23, 2019 18:27

chunhtai added 2 commits September 24, 2019 09:41

Implement system fonts system channel listener

c48a041

fix test

75e1926

chunhtai force-pushed the issues/38556 branch from 614fefd to 75e1926 Compare September 24, 2019 16:42

chunhtai merged commit 0ca5e71 into flutter:master Sep 24, 2019

Inconnu08 pushed a commit to Inconnu08/flutter that referenced this pull request Sep 30, 2019

Implement system fonts system channel listener (flutter#38930)

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* Implement system fonts system channel listener

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	/// Listenable for OSes system fonts change event.
	/// Listenable that notifies when the fonts available on the system have changed.

Implement system fonts system channel listener #38930

Implement system fonts system channel listener #38930

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chunhtai commented Aug 20, 2019 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

Related Issues

Tests

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Breaking Change

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chunhtai commented Aug 27, 2019

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