Flutter 1.2.1 release notes

Our #1 priority since the Flutter v1.0 release has been to continue to address high priority issues reported both by Flutter developers and the Flutter team itself. This includes committing 672 pull requests in the Flutter engine and framework since December (we've been busy!). We've called out the new features and breaking changes that we think are noteworthy below. The biggest ones came from our Framework and Tool tags, but we also found and fixed a couple of Severe issues as well.



To more fully round-out Flutter's animation support, this release adds several more of the standard easing functions:

#25788 Add Robert Penner's easing functions

To integrate more fully with Android, this release adds support for Android App Bundles, a new packaging format that helps in reducing app size and enables new features like dynamic delivery for Android apps:

#24440 Adding support for android app bundle

To integrate more fully with iOS, this release adds several new features and fixes for iOS, including a new CupertinoTheme:

#25183 Add navigatorKey to CupertinoTabView

#25593 Let CupertinoTabScaffold handle keyboard insets too

#24876 Adds a fade in and out, rounds corners, fixes offset and fixes height of cursor on iOS

#23759 Adds CupertinoTheme

In addition to the iOS Cupertino theme support, this release continues to enhance the Material theme as well:

#24169 [Material] Theme-able elevation on dialogs

#25339 [Material] Theme-able TextStyles for AlertDialog

To integrate more fully with desktop form-factors like Android tablets and ChromeOS as well as desktop web and desktop OS support, this release builds more support for keyboard and mouse as first class input devices:

#7758 Recommended implementation of combining characters implementation

#27853 Hook up character events and unmodified code points to Android raw key event handling

#27620 Add a keyboard key code generator

#27627 Adding support for logical and physical key events

#6961 Add hover event support to the engine

#24830 Implement hover support for mouse pointers

As widgets are the core way to interact with users in Flutter, this release continues to add features and fixes to the Flutter widget set with particular attention paid to the SliverAppBar:

#26021 Fix SliverAppBar title opacity and test all cases

#26101 Fix a floating snapping SliverAppBar crash

#25091 Add animations to SliverAppBar doc

#24736 Provide some more locations for the FAB

#25585 Expose font fallback API in TextStyle, Roll engine 54a3577c0139..215ca1560088

#24457 Revise Android and iOS gestures on Material TextField

#24554 Adds force press gesture detector and recognizer

#23919 Allow detection of taps on TabBar

#25384 Adds support for floating cursor

#24976 Support TextField multi-line hint text

#26332 Strut: fine tuned control over text minimum line heights, allows forcing the line height to be a specified height

And finally, as Flutter usage continues to grow world-wide, we continue to enhance support for localizations across several languages, including Ukrainian, Polish, Swahili and Galician in this release.

#25394 Update localizations

#27506 Added support for Swahili (material_sw.arb)

#27352 Including Galician language



As in the framework and engine itself, we're continuing to focus on plugin quality as well:

flutter/engine#7317 Fix stale GrContext for iOS platform views

flutter/engine#7558 Fix lost touch events for iOS platform views

flutter/plugins#1157 [google_maps_flutter] Fix camera positioning issue on iOS

flutter/plugins#1176 [firebase_auth] Fix Firebase phone auth on Android

flutter/plugins#1037 [camera] Save photo orientation on iOS

flutter/plugins#1129 [android_alarm_manager] Fix "background start not allowed" issues, queue events that are received too early

flutter/plugins#1051 [image_picker] Fix crash on iOS when the picker is tapped multiple times

The webview_flutter plugin got a communication channel between Dart and JavaScript:

flutter/plugins#1116 Add WebView JavaScript channels (Dart side)

flutter/plugins#1130 WebView JavasScript channels Android implementation

flutter/plugins#1139 WebView JavaScript channels - iOS implementation

lutter/plugins1021 javascript evaluation ios/android

We've made progress building the In App Purchase plugin (which is still pre-release):

#1057 [IAP] Check if the payment processor is available

#1084 [IAP] Fetch SkuDetails from Google Play

#1068 IAP productlist ios

#1172 [In_app_purchase] add payment objc translators



The release contains a new Dart SDK which provides support for a new set literals syntax and increases AOT performance 10-20% by reducing the overhead of calling constructors or static methods:

#37 Set Literal

#33274 Add support for "naked" instructions: global object pool, pc-relative static calls, faster indirect calls, potential code sharing



We've added a number of new tools and new features to existing tools in this release.

This release continues to improve error messages across a range of tools:

#26107 Better error messages for flutter tool --dynamic flag

#26084 Improve message when saving compilation training data

#25863 Friendlier messages when using dynamic patching

This release also adds support for Java 1.8:

#25470 Support Java 1.8



In this release, we've found and fixed a few severe issues from the previous release, including two crashes and one performance degradation.


#7314 Flutter crash on startup (metabug)


#25381 Add cull opacity perf test to device lab

Breaking Changes


In an effort to continue to improve Flutter since 1.0 to meet customer needs, we have had to make a few breaking changes:

#8769 Rename ListItem to ListTile, document ListTile fixed height geometry


Many developers were confused by the fact that ListItem was fixed height. We've renamed it to ListTile, to indicate that (like other tiles) its height is fixed, and the documentation has been updated to clearly say that about ListTile. You'll need to rename instances of the ListItem class to ListTile in your code.

#7518 Update default flutter_assets path for iOS embedding


Flutter assets for iOS applications are now found in Frameworks/App.framework/flutter_assets instead of flutter_assets. The flutter command line tool should take care of this difference, but if you are writing an AddToApp application for iOS that shares assets with Flutter, you'll need to be aware of this change.

#27697 Cupertino TextField Cursor Fix


CupertinoTextField's cursorColor default now matches the app's theme. If this is undesirable, developers can use the cupertinoOverrideTheme property of ThemeData to provide a Cupertino-specific override using a CupertinoThemeData object, e.g:

Widget build(BuildContext context) { 
  // Set theme data for override in the CupertinoThemeData's constructor 
  Theme.of(context).cupertinoOverrideTheme = CupertinoThemeData(  
    brightness: Brightness.dark,  
    primaryColor: Color(0xFF42A5F5) 
  return Text( 
    style: Theme.of(context).textTheme.title, 

#23424 Teach drag start behaviors to DragGestureRecognizer


By default, a drag gesture detector's onStart callback will be called with the location of where a drag gesture is detected (i.e. after dragging a certain number of pixels) instead of at the touch down location. To use the old functionality with a given drag gesture recognizer, the dragStartBehavior variable of the recognizer should be set DragStartBehavior.down, e.g., include the bolded line below when declaring your GestureDecorator:

  dragStartBehavior: DragStartBehavior.down,
  onVerticalDragDown: myDragDown 
  onVerticalDragEnd: myDragEnd, 
  onVerticalDragStart: myDragStart, 
  onVerticalDragUpdate: myDragUpdate, 
  onVerticalDragCancel: myDragCancel, 
  onHorizontalDragDown: myDragDown 
  onHorizontalDragEnd: myDragEnd, 
  onHorizontalDragStart: myDragStart, 
  onHorizontalDragUpdate: myDragUpdate, 
  onHorizontalDragCancel: myDragCancel, 
// Other fields…

#26238 Remove long-deprecated TwoLevelList


Removed the long-deprecated TwoLevelList widget; use ListView with ExpansionTile instead. See this example for a sample that uses ExpansionTile.

####7442 Move Picture.toImage rasterization to the GPU thread

Picture.toImage now returns a Future<Image> instead. This permits image rasterization to occur on the GPU thread, improving performance in many cases and ensuring correct results. At a minimum, you'll need to declare methods invoking on Picture instances as async, and use await, like this:

void usePictureImage(Picture p) async { 
  var image = await p.toImage(); 
  // Do something with the pixels in image…. 

However, your application may well be performing other asynchronous actions, and you should consider how you want to handle image processing in that light. For more on Dart's support for asynchronous programming and the Future class, see https://www.dartlang.org/tutorials/language/futures.

#7567 Rename FlutterResult in embedder.h


In the Embedder API, the FlutterResult type has been renamed to FlutterEngineResult to better explain its purpose. You'll need to rename any instances of the former to the latter.

#7414 Strut implementation


Rename dart:ui ParagraphStyle.lineHeight to ParagraphStyle.height. The ParagraphStyle.lineHeight property previously did not do anything and was renamed to stay consistent with TextStyle.height. You'll need to rename any instances of the former to the latter.



Soon after our 1.2 release, we found two regressions:

  • #28640 NoSuchMethodError: android.view.MotionEvent.isFromSource

flutter/flutter#24830 ("Implement hover support for mouse pointers.") is using an Android API that doesn't exist on older devices. This can cause a crash on Android 4.1 (Jellybean) and 4.1 (Jellybean MR1).

  • #28484 Widget rendering strange since Flutter update

This can cause rendering issues when loading certain images on physical iOS devices.

To get a fix for these regressions, once beta 1.3 lands in March, you can switch to the beta channel and perform a "flutter upgrade" at the command line. At the time of this writing, that will update you to at least version 1.3.8, which includes flutter/engine#8006 ("Guard against using Android API not defined in API level 16 & 17") and the Skia commit that fixes the rendering issue. For the crashing issue, the two affected versions of Android are more than ten years old and represent at most 2.5% of Android users, few of which are likely to be installing new Android applications, whether they're Flutter or not. Even so, we hate to leave known regressions in a stable release, but after much internal debate, we decided it was the best way to proceed for Flutter developers and their app users.

Our ideal fix for any serious issue is to create a "hotfix" release by taking an existing release and "cherry picking" the fixes that we'd like to apply. The ability to hotfix an existing stable release is something that we implemented for 1.2 but have not quite gotten to production quality. The consequence of this is that if we had created a new stable "1.2.1-a" release with the fix for the regressions, we'd have stranded all of our users at that branch; updating to future branches would've required users to remove and reinstall Flutter from scratch, which was clearly unacceptable. We are working hard to validate our ability to hotfix in 1.3+ so that we don't have this problem again.

Another option would have been to bring 1.3 to a stable release. Our current policy is to only bring out a new stable release once per quarter to reduce churn for Flutter developers. As of this writing, the pre-stable 1.3 release contains 104 framework commits (and even more engine, Dart, and Skia commits), any of which is a risk to how your current apps are running. To reduce that risk, we leave releases in beta for a month, let developers test them, and only promote releases to the stable channel when we're confident in them. That's how we maintain stability in the quarterly releases.

Our next stable release is currently planned for May, 2019, which is the first stable release that will include the fix for this regression. If you are affected by #28640 and feel like the workaround to use the pre-release 1.3 is not an option for you, please let us know by on flutter/flutter#29235 itself. Similarly, if you are affected by #28484, et us know on flutter/flutter/#29360. If we find that there's a lot of feedback from the Flutter community that we made the wrong decision here, we'll use your feedback to reevaluate. Flutter is, after all, a community effort, and your opinions matter.

Tooling Releases


In addition to Flutter framework changes in the 1.2 release, we've made a number of tooling releases in the same timeframe, which you can read about here:

Full Issue List


You can see the full list of PRs committed in this release.