Could one say Compose ui is more equivalent to flu...
# composeu
ursus
11/27/2021, 5:03 AMCould one say Compose ui is more equivalent to flutter ui, than os native?
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K Merle
11/27/2021, 5:15 AMYes. Both of them have declarative way of writing UI, unlike old View system that is imperative.
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Albert Chang
11/27/2021, 8:40 AMIn terms of code style it may be true but in terms of internals, not really. Flutter does many things (e.g. all the rendering) itself while Jetpack Compose usually uses platform native mechanism.
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yschimke
11/27/2021, 11:07 AMMy understanding was that Compose actually reimplements the native controls and draws to a canvas.
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agrosner
11/27/2021, 1:21 PMCompose is similar to flutter. It doesn't use native mechanics in terms of the view- flutter same thing. If you meant like React Native which reuses android view widgets
agrosner
11/27/2021, 1:21 PMCompose and flutter both draw straight to canvas
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Albert Chang
11/27/2021, 2:40 PMNot really. Jetpack Compose doesn’t directly draw to canvas. It uses RenderNode API on API 23-27 and API 29+, and View API on API 21-22 and API 28. Rendering is all done by the platform, same as View system. See the source here for details.
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ursus
11/27/2021, 2:47 PMYea one big ComposeView but your actual ui elements are "just" canvas calls, no?
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Stylianos Gakis
11/27/2021, 2:48 PMWhat happened with API 28 in particular? Seems really odd that older versions use RenderNode that the latest use too, but all of a sudden API 28 also uses what’s being used by the quite old API 21-22 versions?
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Albert Chang
11/27/2021, 2:50 PMAnother obvious proof is that Jetpack Compose doesn’t bundle any rendering libraries, while flutter bundles Skia for rendering.
Albert Chang
11/27/2021, 2:50 PMBefore API 29
RenderNode➕ 1
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ursus
11/27/2021, 2:54 PMSo is my assumption wrong? Thats its one big View instance from OS point of view?
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Albert Chang
11/27/2021, 2:54 PMIt’s true on API 23-27 and API 29+.
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ursus
11/27/2021, 2:58 PMAnd flutter doesnt do the same thing? i.e. on big FlutterView where its draws by opengl or whatever they do
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Albert Chang
11/27/2021, 3:10 PMJetpack Compose: Create a custom view, override its
onDraw()CanvasSurfaceViewSurfaceu
ursus
11/27/2021, 3:23 PMyea
btw isnt canvas implemented in skia?
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Albert Chang
11/27/2021, 3:44 PMThe rendering part of Android is called HWUI. If you are interested you can do some searching using that keyword but tl;dr: not necessarily.
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Adam Powell
11/27/2021, 3:51 PM@Albert Chang has the right of it. If you're looking for a quick analogy, Compose UI is closer to being a RecyclerView2 than it is to Flutter in terms of how they interact with Android
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romainguy
11/27/2021, 6:14 PMAnd to be clear: the platform’s Canvas uses Skia internally
romainguy
11/27/2021, 6:15 PMhwui is a layer on top that did all the drawing for many years but since P, Skia does the drawing again. hwui does a lot of other things though (managing render nodes, animations, frame pacing, etc.)
romainguy
11/27/2021, 6:16 PM(And before Android 3.0, Canvas was pure, direct Skia)
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agrosner
11/27/2021, 6:19 PMSo…Skia everywhere 😅
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romainguy
11/27/2021, 6:20 PMMore or less yes. Skia came from Android so it makes sense we and other google teams use it
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romainguy
11/27/2021, 6:20 PMChrome uses Skia too