Hello, I found specific json files are not working.
I attached jsons.zip (there are 2 json files)

And you can see correct output in below URL.
progress_bar.json
(https://www.lottiefiles.com/share/rH928l)
11 - Tag.json
(https://lottiefiles.com/share/tU944U)

Please check it.
Thank you.

jsons.zip

hi, I am using LottieUWP to develop a new uwp application, and I added a new method in your LottieDrawable class,so it can be rendered by win2d CanvasRenderTarget,but it doesnt work well,it lost something(for the following example its eyes).

I create a repository for display the problem:
https://github.com/HHChaos/LottieUwpTest

Added method in LottieDrawable.cs###

public CanvasCommandList GetCanvasImage(ICanvasResourceCreator resourceCreator, float scaleX, float scaleY)
    {
        lock (this)
        {
            var commandList = new CanvasCommandList(resourceCreator);
            using (var session = commandList.CreateDrawingSession())
            {
                var width = _composition.Bounds.Width * scaleX;
                var height = _composition.Bounds.Height * scaleY;
                if (_bitmapCanvas == null || _bitmapCanvas.Width < width || _bitmapCanvas.Height < height)
                {
                    _bitmapCanvas?.Dispose();
                    _bitmapCanvas = new BitmapCanvas(width, height);
                }

                using (_bitmapCanvas.CreateSession(resourceCreator.Device, (float) width,
                    (float) height, session))
                {
                    _bitmapCanvas.Clear(Colors.Transparent);
                    LottieLog.BeginSection("Drawable.Draw");
                    if (_compositionLayer == null)
                    {
                        return null;
                    }

                    _matrix.Reset();
                    _matrix = MatrixExt.PreScale(_matrix, scaleX, scaleY);
                    _compositionLayer.Draw(_bitmapCanvas, _matrix, _alpha);
                    LottieLog.EndSection("Drawable.Draw");
                }

            }

            return commandList;
        }
    }

Hi Alexandre ,

I'm using your nice port extensively. When having several LottieAnimationView on screen I observed severe memory consumption of my app ( 10 AnimationViews resulting in about 3mb / sec Memory growth). So I dug into the source code and I think I found the issue (though I'm not 100% sure of the root cause).
In BitmapCanvas.DrawPath a Geometry and a Brush get created but never get disposed (after getting handed over to _drawingSession.DrawGeometry respectively _drawingSession.FillGeometry). Please see the following excerpt of BitmapCanvas:

        public void DrawPath(Path path, Paint paint)
        {
            UpdateDrawingSessionWithFlags(paint.Flags);

            _drawingSession.Transform = GetCurrentTransform();

            var geometry = path.GetGeometry(_device);

			var gradient = paint.Shader as Gradient;
			var brush = gradient != null ? gradient.GetBrush(_device, paint.Alpha) : new CanvasSolidColorBrush(_device, paint.Color);
			brush = paint.ColorFilter?.Apply(this, brush) ?? brush;

			if (paint.Style == Paint.PaintStyle.Stroke)
				_drawingSession.DrawGeometry(geometry, brush, paint.StrokeWidth, GetCanvasStrokeStyle(paint));
			else
				_drawingSession.FillGeometry(geometry, brush);

			geometry.Dispose();
			brush.Dispose();
		}

of course this has to be changed to using statements and there are other places where this is applicable, I think (DrawRect for example). What do you think? should I create a pull request for this?

Greetings,
Michael

A simple Lottie Animation uses about 3/4% of CPU increasing the number to 5 even with caching we reach more than 30%.
Is there a way to make CPU load smaller?

Only part of the animation is rendered. On other platforms or on the web (https://www.lottiefiles.com/preview) it looks good.

device1.zip

hi is there any wpf version? how i can use it?

@ascora Replace Win2D with SharpDX and it's working well on WPF too
https://github.com/ascora/LottieSharp

When changing the MainPage of the app while an animation view is on screen an InvalidOperationException is thrown. Details below.

Cannot assign a native control without an Element; Renderer unbound and/or disposed. Please consult Xamarin.Forms renderers for reference implementation of OnElementChanged.

at Xamarin.Forms.Platform.UWP.VisualElementRenderer`2.SetNativeControl(TNativeElement control)
at Lottie.Forms.UWP.Renderers.AnimationViewRenderer.d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.b__6_0(Object state)
at System.Threading.WinRTSynchronizationContextBase.Invoker.InvokeCore()

Reproduction Link: https://drive.google.com/open?id=10B2Qhbe4MPyBaOBzn4emdCYmWSDgltBh

Hello.
I need to improve performance while playing JSON.
I think below logic takes long time while Draw.
(There is TODO comment also)

Path.cs
internal static double BezLength(float c0X, float c0Y, float c1X, float c1Y, float c2X, float c2Y, float c3X, float c3Y)
{
const double steps = 1000d; // TODO: improve

            var length = 0d;
            float prevPtX = 0;
            float prevPtY = 0;

            for (var i = 0d; i < steps; i++)
            {
                var pt = GetPointAtT(c0X, c0Y, c1X, c1Y, c2X, c2Y, c3X, c3Y, i / steps);

                if (i > 0)
                {
                    var x = pt.X - prevPtX;
                    var y = pt.Y - prevPtY;
                    length = length + Math.Sqrt(x * x + y * y);
                }

                prevPtX = pt.X;
                prevPtY = pt.Y;
            }
            return length;
        }

Please check it.
Thank you.

It appears LottieUWP is flattening bezier curves to be linear. We were able to verify that the iOS port maintained the curves and could find several references to 'bezier' in the source code. We have not had a chance to test the same animation in Android yet, but noted there was only 1 reference to 'bezier' in the Android code.

Needs to be fixed.

I have tried both L.json from sample and the one in lottie android. Neither render correctly.

https://raw.githubusercontent.com/airbnb/lottie-android/master/LottieSample/src/main/assets/Mobilo/L.json

When you navigate from a page playing an animation and go back to that page a null reference exception is thrown.

Com.Airbnb.Xamarin.Forms.Lottie: 2.5.1
LottieUWP: 2.5.1

System.NullReferenceException: Object reference not set to an instance of an object.
at LottieUWP.LottieDrawable.CanvasControlOnDraw(ICanvasAnimatedControl canvasControl, CanvasAnimatedDrawEventArgs args)

Reproduction project: https://drive.google.com/file/d/184cMHR9icG2NfUvPIwnsKrRDaE6M-D8P/view?usp=sharing

When you compile an UWP app with .NET Native tool chain, some lottie files make the library to crash.
For example with the sample app in release mode:

1. Select Assets\lottiefiles\gradient_animated_background.json
2. Select another one
3. Wait one or two seconds => The app crash with the following exception: System.Runtime.InteropServices.InvalidComObjectException: 'Excep_InvalidComObject_NoRCW_Wrapper. For more information, visit http://go.microsoft.com/fwlink/?LinkId=623485'

Another example less explicit:

1. Select Assets\lottiefiles\download.json
2. Select another one
3. Wait one or two seconds => The app crash with the following exception:
   Unhandled exception at 0x766C64A1 (combase.dll) in LottieUWP.Sample.exe: 0xC000027B

@martijn00 created LottieXamarin witch implements lottie for Android, iOS, MacOS and TvOS for Xamarin.

Would be great to have the UWP implementation added there.

What do you think @azchohfi ?

I can't even describe the bug, the first file run fine. Then all the rest of my json stop working
It's keep crashing

Hi,

first of all: thank you for that great port of lottie. It's coming in very handy for animating icons etc.
One question I have though: The official docs say, for replacing Colors one should use the ...addColorFilter methods. But it seems as if those methods were once a part of LottieUWP's LottieAnimationView but are no more ( http://airbnb.io/lottie/android/colors.html ). How do I change colors then? As I'm having a dark theme and a light theme I would have to have duplicate versions for every animation (one dark, one light).
Thank you very much,
Michael

虽然看了代码这个出现的地方，但是这种问题怎么解决呢

the animation went missing after the app enter background (by minimizing not closing), and after opening the app again from the minimized state, the animation gets blank..

ps: I load the animation via code behind, not declaratively from XAML..

Hello.

I happened a build error.

Error log is
Microsoft.Build.Tasks.Git.targets(20,5): error : Unable to locate repository containing directory 'C:\Users\daehor.song\Desktop\LottieUWP-master\LottieUWP-master\LottieUWP'.

Could you know about this error?

Thank you.

Hi, I'm not sure its a bug, or do I need to set something to fix it right.

In my case, I have a MainPage, and another BlankPage. In MainPage, I have a lottie animation. When I navigate to BlankPage from MainPage, and then navigate back, lottie disappears.

See my git: https://github.com/hupo376787/LottieBugOrNot

Our project compiles to treat warnings as errors.
When compiling a project using a LottieAnimationView in a XAML view, the compiler shows the warning below:

This is reproducible using the sample project on this GitHub page by changing the project Debug settings to treat all warnings as errors.
The property in question is found in LottieAnimationView, line 800.
The documentation for this property refers to the RepeatCount property; would it be feasible to remove usages of the Loop property and replace them with RepeatCount?
Many thanks!

I'm trying to use Lottie on UWP 8.1, but unfortunately it requires Win2d.uwp which is not supported on this framework. Is there any other way to use Win2d.win81 instead?

Can it run on Version 1803 (OS build 17134) ? Some devices get update way later. Just a thought. Any suggestion ?

LottieUWP will crash when using the lottie file exported by the latest Bodymovin.
The reason for the crash is that the EndValue of some keyframes is null (StartValue is a valid value), I think in this case the EndValue should be considered equal to StartValue instead of throwing an exception.

Here is the file that caused the crash, it works fine on lottiefiles.com.
testlottie.zip

I have a ItemTemplate inside a listview. When loading my data via my ViewModel (3 rows) I receive the foloowing error. This is random and happens maybe 2 out of five times. Visually each animation is further along than the other,

Exception Message:
System.Runtime.InteropServices.COMException: Unspecified error

Attempting to close a CanvasActiveLayer that is not top of the stack. The most recently created layer must be closed first.
at System.Runtime.InteropServices.WindowsRuntime.IClosable.Close()
at LottieUWP.LottieDrawable.CanvasControlOnDraw(ICanvasAnimatedControl canvasControl, CanvasAnimatedDrawEventArgs args)

The attached files are crashing in Release mode (assuming this is related to .NET native tool chain). They do not crash using Lottie.UWP version 2.6.1 but they do crash using version 2.8.0.

json_files.zip

Hi,

I'd like to export the animation as a video (eg: mp4), do you think is it possible? Can you provide me some directions on how to do it? thanks

regards

Is this repo still maintained and updated or is it moved to
https://github.com/windows-toolkit/Lottie-Windows
?

Our apps have a lot of dependencies on legacy hardware that prevents us from effectively migrating away from WPF to UWP, but as Lottie users on iOS & Android we'd love to be able to benefit from Lottie end-to-end.

What would be involved in migrating this work over to be compatible with WPF apps? Does it have dependencies on UWP-specific features?

When showing and hiding a View which contains a LottieAnimationView, the application sometimes crashes giving the error WinRT information: Attempting to close a CanvasActiveLayer that is not top of the stack. The most recently created layer must be closed first.

This happens randomly to me

at System.Runtime.InteropServices.WindowsRuntime.IClosable.Close() at System.Runtime.InteropServices.WindowsRuntime.IClosableToIDisposableAdapter.Dispose() at LottieUWP.LottieDrawable.Draw(CanvasDevice device, BitmapCanvas bitmapCanvas, CompositionLayer compositionLayer, Rect bounds, Single scale, Byte alpha, Matrix3X3 matrix, Double width, Double height, CanvasDrawingSession canvasDrawingSession) at LottieUWP.LottieDrawable.CanvasControlOnDraw(ICanvasAnimatedControl canvasControl, CanvasAnimatedDrawEventArgs args) at Windows.ApplicationModel.Core.UnhandledError.Propagate() at Microsoft.AppCenter.Utils.ApplicationLifecycleHelper.<.ctor>b__17_1(Object sender, UnhandledErrorDetectedEventArgs eventArgs) --- End of stack trace from previous location where exception was thrown --- at Microsoft.AppCenter.Utils.ApplicationLifecycleHelper.<.ctor>b__17_1(Object sender, UnhandledErrorDetectedEventArgs eventArgs)

Hi,

the following bug came when updating to the newest version of LottieUWP (2.5.0.365-beta)

When setting AutoPlay=False on LottieAnimationView, at first the view is totally blank. When triggering the animation once, it is subsequently drawn.
Steps to reproduce:

• take the sample app
• set AutoPlay=False on LottieAnimationView in MainPage.xaml
• start sample app
  => animation is shown only when pressing the "Resume/Pause" button

greetings,
Michael

Hello,

We are using json animation files rendered by Lottie. When navigating from the page hosting Lottie there is a crash in Microsoft.Graphics.Canvas.dll.
I have slightly modified Lottie sample to repro the crash. Diff file is attached.
The Lottie assembly changes are to fix build problems on VS2017 and are negligible. The ones in the sample are for the repro.
I have built Microsoft.Graphics.Canvas.dll (MS open source) and realized that although LottieDrawable.UserControl_Unloaded is called when navigating from the page, sometimes CanvasAnimatedControl::Unloaded (inside Microsoft.Graphics.Canvas.dll) is not called right after, and that's when the crash occurs.
Stack trace of the crash is attached too.

Repro steps (after the applying the diff):

1. Run the LottieUWP.Sample.
2. After the async code of MainPag.OnNavigatedTo is done Navigate button will be revealed.
3. Click Navigate and then click Back repeatedly. You'll get the crash after a few times.

Crash steps attached.

diff.txt
StackTrace.txt
LottieCrashSteps.zip

Could you help us understand and resolve this issue?

Thanks
Yakir

It appears the animations aren't playing when the app is deployed to an Xbox console. We can 'progress through' the animation, but it's not playing smoothly 'hands off' like it does when deployed as a standard desktop UWP. Have we verified this use case works as anticipated?

I am a fan of lottie and before I only use it with IOS but right now , I am developing an UWP app and I want to try Lottie in my app as well but seem like the animation in UWP is not as Smooth as in IOS. I want to know is there anyway to improve its smoothness ?

Thing to note
I am using the same animation.json in both IOS and UWP.

I was just curious as wanted to ask can we and should we use these animations as part of any custom xaml controls or on our xaml pages just as clickable controls or stuff like that? I mean are these animation controls as performant as normal xaml controls? or is there is limit to how many animations should we use in 1 xaml page. the reason of this question is I can see a lot of animations which might be useful in usual uwp apps, like loading animations, hamburger icon animation and stuff like that.

We have a trim path drawing circle (about100 blanks)in lottiefiles woking, but loaded from lottieuwp not working, what should I do?
usage_circle.zip

The link for the UWP samples is dead in the Try it out section

Unspecified error

Attempting to close a CanvasActiveLayer that is not top of the stack. The most recently created layer must be closed first.

at System.Runtime.InteropServices.WindowsRuntime.IClosable.Close()
at LottieUWP.LottieDrawable.Draw(CanvasDevice device, BitmapCanvas bitmapCanvas, CompositionLayer compositionLayer, Rect bounds, Single scale, Byte alpha, Matrix3X3 matrix, Double width, Double height, CanvasDrawingSession canvasDrawingSession)
at LottieUWP.LottieDrawable.CanvasControlOnDraw(ICanvasAnimatedControl canvasControl, CanvasAnimatedDrawEventArgs args)

Hello.

I have a question. I happen build error on LottieUWP 2.6.1

[LottieUWP\LottieCompositionFactory.cs]
312 : return await _taskCache[cacheKey].AsAsyncOperation().AsTask(cancellationToken);
320 : await task.AsAsyncOperation().AsTask(cancellationToken);

AsAsyncOperation is not defined in System.Threading.Tasks.Task.

How can I fix this error?

Thanks.