How to render content of Control object?

[alex-aparin]

I want to create lightweight custom control, which will only render its content in specific way (without any additional logic like mouse/key handling etc). I think that it will be derived from Control class. But I cannot understand the rendering model of Win UI 3. How can I redefine painting of control? Where can I find good description how rendering is performed within Win UI 3. P.S. due documentation, I guess that it uses similar model like WPF (but it is only my suspiction)

[llothar]

I hope we get this answered with documentation link and sample code.

The main difference is that it is now a retained drawing model where you don't redefine painting (thats only for backward compatibility and i would guess slower than the new native way) but setup composition drawing items which are keept in a scene graph. I currently port my Linux version from GTK3 -> GTK4 which is doing the same step as WinUI3 and it's all far from easy and self explaining. Especially when it comes to hand optimized drawing.

[alex-aparin]

@llothar By the way WPF has also retained drawing model. But it allows to override painting of controls. It has pretty effective way to draw lines, rectangle etc. (via direct drawing into visual object - these instruction will be serialized to be performed on GPU). Unfortunately WinUi 3 does not have such support. Instead you should use either builtin controls like Line, Path, Rectangle or some surfaces which support DirectX. Builtin controls derive Shape class, it cannot be effective way because such classes have memory overhead etc.

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