SkiaSharp 3.119.0 / Svg.Skia - CRASH on iOS Release Build

[bnSonic]

DrawnUI is using SkiaSharp 3.119.0
My Apps were using 2.88.8.

So i updated it from 2.88.8 to 3.119.0
Then i had to add Svg.Skia because i'm loading / drawing SVG Files. With Skia.Svg i have a SKSvg again.

Good. This works in a Debug Build on iOS / Android in the Emulators. Fine.

BUT: The Release Build for iOS crashes as soon as the App tries to draw a SVG.

Please see the details infos and Crash-Log here:
wieslawsoltes/Svg.Skia#396 (comment)

When i activate the Interpreter for the Release Build (for the Svg.Skia - see the link above for details) it doesn't crash.
So my feeling is: Something in the Svg.Skia is not compatible with AOT Build … like some Reflection Methods or so.

Have you ever heard or experienced something like that?
Is there any other solution than enabling the interpreter (which makes my app too slow)?

Or maybe you know a way to load and draw SVG without the Svg.Skia Library?

currently my only option is to go back to SkiaSharp 2.88.8 - but then i'm out of the game for DrawnUi 😢

[taublast]

Hey, but, but..

1. DrawnUi already references and uses Svg.Skia to draw svgs!

        <PackageReference Include="Svg.Skia" Version="3.0.3" />

2. This all is AOT compatible verified with several "no-interpreter" ios apps publish to appstore (another exclamation mark).

3. Please do NOT reference skiasharp/skia.svg manually

Please provide more info about what svg.skia api do you use?

[bnSonic]

Hi :)

Yes i know DrawnUi is referencing Svg.Skia - BTW: I havn't tried a iOS Release Build via TestFlight yet with DrawnUi so i don't know if i would run into the same problem here - i would carefully say "no" because then you would have seen this already with your apps.

The thing is: I have an existing App, migrated from Xamarin.Forms to Maui.
This App is using Skia and the SKSvg Class to load and draw SVG-Files.

Now, to be able to try/test DrawnUi inside of this App, i need to upgrade SkiaSharp to 3.119.0 because DrawnUi references theses.
With SkiaSharp 3.119.0 there is no SKSvg in the Extension-Namespace anymore i saw online, that i should use Svg.Skia then

I have tried with Svg.Skia 3.0.3 and 3.0.4

To be more clear / specific: The Structure of the App is:

• A : AppName.csproj (the main project with all the UI and most of the logic)
• ……… referencing (C)
• A1 : AppName.Droid.csproj (the Android App Project with the MainActivity and so on)
• ……… referencing (C)
• A2 : AppName.ios.csproj (the iOS App with the AppDelegate and so on)
• ……… referencing (C)

Then there is:

• C : A common Library with some UI and some logic, used by A / A1 / A2

In (C) i have my Controls "SvgImage" and "SvgImageEx" which loads SVGs from Ressources or Strings etc. and draw them on a Skia-Canvas with some properties i can set via Bindables
It does this with the SKSvg Class and the .Load(...) to geht the Svg.Picture to then draw it to the canvas.
So (C) is using SkiaSharp and Svg.Skia

In (A) is also using Svg.Skia as it too has a function that uses SKSvg to Render and convert it.

So: When i compile (A2) (the iOS App) as Release with AOT/LLVM, no Interpreter, … (a fast running release): As soon as the App tries to draw a SVG it crashes (see the Crash log in the linked issue)

Maybe this i problem, because:

• Compiling A2 -> Referenced C -> Compiled C but then Trimmed to much out of C
  ??

I have no idea - i've tried a lot with setting the Libraries as Root (see the link again), i've tried rooting the Svg.Skia, my Library (C)
I've tried adding Svg.Custom and even Svg manually to my projects to be able to root them too … nothing helped :(

I may be able to Check ONE THING:

• Remove Svg.Skia from MY projects / libraries (i only need it for SVG drawing)
• (i cannot remove SkiaSharp completely as i need some functions for creating/drawing PDFs and such)
• Add DrawnUi instead

But then i would need a way to modify my SvgImage / SvgImageEx Controls to use DrawnUi to load / draw the Svg on a Canvas.

I know you have an own Svg Image Control but i need my own one with my logic and Bindables.
I'm not sure if / how i could geht a Svg.Picture from a SVG-String with DrawnUi without drawing the Svg twice (once in your control and then again on my control)? You know what i mean?

So how would i replace something like this when i don't have Svg.Skia but DrawnUi? (pseudocode)
using (var svg = new SKSvg());
svg.Load(mySvgString);
Canvas.Draw(svg.Picture, x, y, ...)

… when i don't want to change everything Skia in my App to DrawnUi completely …

[taublast]

Wa wait, i recall something. like month ago i had ios app crashing on release with crash log something related to skia.svg aot method not found blabla... i spent like a day blamiming skia.svg, looking at their issues etc.

The solution was to delete all bin obj (OF ALL THE PROJECTS) and recompiled from scratch.

[taublast]

As i see it you could reference drawnui with skia.svg for your "deep down lib" project, that would be referenced by all the others..

Yeah and that problem i had with aot/bin/obj was that drawnui was referenced by a "maui framework lib" and then this one was referenced by app.

[bnSonic]

i think i've found a (the?) problem and was able to build a repro … If you are interested, you can take a look at this Issue update:
wieslawsoltes/Svg.Skia#396 (comment)

I've added a repro and videos

After days digging down i came down to same crazy behaviour … then i realised: Maybe some specific SVG Files?
And yes! I found one SVG (my main Title SVG :D) that works fine in Debug-Mode but SKSvg (i think?) crashes in Release build on iOS
Luckily i was able to reproduce this in a small demo app :)

I hope that this can be tracked down inside Svg.Skia (?) and that it can be fixed.

[taublast]

This is a godly finding, man, might save a lot of people!

[bnSonic]

I don't know if the maintainer of the Svg.Skia Library had time to really look at my repro …
… so just to let you know: I've found a workaround - I've added it as comment on the issue:
wieslawsoltes/Svg.Skia#396 (comment)

I've seen you supporting the SkiaSharp Library so maybe this of interest for you. I have lost so many days now, I really cannot learn to understand the Svg.Skia Library on a deeper level to may be find a fix there 🥲 so I'm happy with my workaround for now and hope, that this solves the problem completely … as it doesn't fix any root cause I can only hope that no other crashes happen after using the app for a while 🤷‍♂️

[taublast]

Did you close that issue or the maintainer did?

Do you think we should include your workouround into SkiaSvg to make it safer?

[bnSonic]

He closed it after this comment: wieslawsoltes/Svg.Skia#396 (comment)
that was when he published 3.0.5 which I tested but it still crashes. 🤷‍♂️

See, I don't like to point fingers. I don't know him, I don't know what he has to do all day. It's alright … I just wished I got some feeling that he (or someone) really took a look at it instead of showing the last entries in the crash log and say… it's not in this library 🤔 (I have stopped counting the crashes and errors that occurs in some mono or even deep down in iOS / Android libraries when the root cause was some lazy / bad / too optimistic handling in MY code 🙈)

Anyway:
I think the SkiaSvg should be hardened agains any possible problems. A hard Crash is - in my humble opinion not an option. At least some try/catch should work … which don't in this case!

So yes: I think something somewhere in the SkiaSvg should be "fixed" / made more robust.
BUT: If my workaround is THE (or even A good) solution? I cannot say that! My hope ist, that with this knowledge someone might be able to see WHY it cause a crash… maybe then one could decide better if stripping the SVG-String is a fine solution or if some Loop simply should ignore some Tags 🤔 I don't know what would be best.

meanwhile I have changed my workaround to a:

        public static string StripSvgPreamble(this string svg)
        {
            if (string.IsNullOrWhiteSpace(svg)) return svg ?? string.Empty;

            var pos = svg.IndexOf("<svg", StringComparison.OrdinalIgnoreCase);
            if (pos <= 0) return svg; // Kein SVG-Tag gefunden oder ganz am Anfang, also nichts zu tun

            // Alles vor dem <svg-Tag entfernen
            svg = svg.Substring(pos);
            return svg;
        }

which seems to work fine for the SVG I have … If this is correct for every thing SVG? I don't know 😌

[taublast]

well this happens to me too i think that a new pub might fix something and then... you could maybe notify the maintainer that it didn't fix it.

we could implement your fix if the main skia repo does not, i just hope that wouldn't be the case.

[bnSonic]

Well - I did this. He closed the issue, I wrote that it still crashes and now the (my) workaround. What else could I do?

as said: not sure if my workaround would be a good solution. If I had more understanding of how that svg document works I could try to debug it to maybe find the root cause - but I don’t and don’t have the time to learn that too 😅

I think I showed an easy to reproduce crash, with Repro, with demo SVG - everything, right? 😀 I think now it’s up to someone with better knowledge about this library if this should and can be fixed or not 🤷‍♂️

personally - I myself if this were “my” library, I would dig deeper into the code to see what let the GC(?) collect what things that causes this crash … it’s just a bit outside of my expertise to do this 😩