DrawnUI For Xamarin Forms

A Light version of DrawnUI for .Net MAUI ported to Xamarin.Forms.

Use case

To remove UI lags in Xamarin projects by replacing native views with drawn controls. At the same time to prepare projects to be more easily ported to MAUI as all UI-related nugets like shadows, cards, gradients etc.. will be replaced with just DrawnUI.

Installation

Install the nuget package __AppoMobi.Xamarin.DrawnUi__ into shared/native Xamarin app projects. Then initialize the library:

• iOS - inside your AppDelegate.cs in the FinishedLaunching method:

 AppoMobi.Xamarin.DrawnUi.Apple.DrawnUi.Initialize<App>();

• Android - inside MainActivity.cs in the OnCreate method:

AppoMobi.Xamarin.DrawnUi.Droid.DrawnUi.Initialize<App>(this);

Also in Xamarin for many Canvases around the app it's better to use

Super.CanUseHardwareAcceleration = false; //RIP XAMARIN

For single Canvas this should not be needed.

The How To

This light Xamarin version has some limitations and some controls are missing in comparision to the original MAUI Library. Meanwhile please refer to the original library documentation.

There is also a sample project in this repo with a drawn About page:

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Xamarin Limitations

Contrary to MAUI version:

• Xamarin XAML HotReload is found to be working occasionally. I still struggle to understand why and where it breaks and why it's suddenly working.. Good news in MAUI we do not have this issue, there it breaks for foundable reasons, though should create a ticker for all cases i just personally know why it breaks but we have zero info about it in console, log etc.. :)

• For same reasons ItemTemplate is not set when defined in <DataTemplate> XAML so set it like this:

    <draw:SkiaLayout
        CommandChildTapped="{Binding CommandOpenFile}"
        HorizontalOptions="Fill"
        ItemTemplate="{Binding CreateUploadCell}"
        ItemsSource="{Binding Uploads}"
        Type="Column" />

and

    public DataTemplate CreateUploadCell => new DataTemplate(() =>
    {
        return new CellUpload();
    });

SkiaLabel FontSize property accepts double only, setting something like FontSize="Title" will result in a XFC0000 error.

• Loading resources is different from MAUI version:

1. SkiaLottie and SkiaSvg Source property will always read files from shared project, files must be inlcuded with build action as Embeeded resource, for example Source = "Resources\Lottie\plus.json". You can specify an internet url too.

2. SkiaImage read files from native projects by default. With "resource://" prefix you can load file from shared project, for example Source="resource://Resources.Images.breath.jpg". You can of course pass an internet url too.

To Note

Uses a modified Glidex.Forms project created by Jonathan Peppers for caching images on Android.

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