Table of Contents

Frequently Asked Questions

🤔 Onboarding

Q: What is the difference between DrawnUi and other drawn frameworks?
A: Not really comparable since DrawnUI is just a library for .NET MAUI, to let you draw UI instead of using native views.

Q: Why choose drawn over native UI?
A: Rather a freedom choice to draw what you want and how you see it.
It also can bemore performant to draw a complex UI on just one canvas instead of composing it with many native views.

Q: Do I need to know how to draw on a canvas??
A: No, you can start by using prebuilt drawn controls and customize them. All controls are initially designed to be subclassed, customized, and almost every method is virtual.

Q: Can I still use XAML?
A: Yes you can use both XAML and code-behind to create your UI.

Q: Can I avoid using XAML at all costs?
A: Yes feel free to use code-behind to create your UI, up to using background thread to access and modify drawn controls properties.

Q: How do I create custom controls with DrawnUI?
A: Inherit from SkiaControl for basic controls or SkiaLayout for containers etc. Override the Paint method to draw with SkiaSharp.

Q: Can I embed native MAUI controls inside DrawnUI?
A: Yes! Use SkiaMauiElement to embed native MAUI controls like WebView inside your DrawnUI canvas. This allows you to combine the best of both worlds.

Q: Possible to create a game with DrawnUI?
A: Well, since you draw, why not just draw a game instead of a business app. DrawnUI comes with gaming helpers and custom accelerated platform views to assure a smooth display-synched rendering.

Thechnical Questions

Q: How do I create custom controls with DrawnUI?
A: Subclass SkiaControl for custom, SkiaLayout for container etc, . Override the Paint method to draw with SkiaSharp on the canvas provided inside drawing context.

Q: Can I embed native MAUI controls inside DrawnUI?
A: Yes! Use SkiaMauiElement to embed native MAUI controls like WebView inside your DrawnUI canvas. This allows you to combine the best of both worlds.

Q: Can I use MAUI's default Resources/Images folder?
A: Sorry, no, drawn resources lives inside Resources/Raw and subfolders. Note that MAUI supports only lowercase filenames of resources and while uppercase might works for you on some plaforms they will not be read on iOS.

Q: How do I change SkiaSvg source not from file/url?
A: set SvgString property to svg text string.

Q: Why my scroll is resetting at all time while Iproperly use ObservableCollection for LoadMore?
A: Check that your custom ObservableRangeCollection is sending Reset event when adding range of items.

Q: How do I change SkiaImage source not from file/url?
A: set directly: mySkiaImage.SetImageInternal(skiaImage).

Q: How do I prevent touch events from passing through overlapping controls?
A: Use the BlockGesturesBelow="True" property on the top control. Note that InputTransparent makes the control itself avoid gestures, not controls below.

Q: How do I internally rebuild the ItemsSource?
A: Directly call layout.ApplyItemsSource().

Troubleshooting

Q: Why is scrolling/rendering slow?

Solutions:

  1. Always use cache for layers of controls:
    • Do NOT cache scrolls/heavily animated controls and above
    • UseCache = SkiaCacheType.Operations for labels and svg
    • UseCache = SkiaCacheType.Image for complex layouts, buttons etc
    • UseCache = SkiaCacheType.ImageComposite for complex layouts where a region changes while others remain static, like a stack with different user-handled controls.
    • UseCache = SkiaCacheType.ImageDoubleBuffered for equally sized recycled cells. Will show old cache while preparing new one in background.
    • UseCache = SkiaCacheType.GPU for small static overlays like headers, navbars.
  2. Check that you do not have some logging running for every rendering frame.

Q: Why isn't my UI updating when ViewModel properties change:

Solutions:

  1. Ensure ViewModel implements INotifyPropertyChanged
  2. Check that property either has a static bindable property or calls OnPropertyChanged() in the setter.
  3. Check that property names match exactly; use nameof().
  4. Ensure all your overrides, if any, of void OnPropertyChanged([CallerMemberName] string propertyName = null) have a [CallerMemberName] attribute.

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