Feature gate render in UI (fix bevy_test feature)

[BenjaminBrienen]

Objective

Fixes #16313 and #16316 and #3815

Solution

Add a lot of feature gates. It looks awful. All configurations build with no warnings, though!

Testing

PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.39s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features               
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.98s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_text
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.28s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_render
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.27s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_render --features bevy_text
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 14.28s

[BenjaminBrienen]

I think it makes sense to also fix bevy_text feature in this PR because there will be a lot of merge conflicts if split.

[BenjaminBrienen]

After merge:

PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.41s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_text
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.39s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_render
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.37s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_render --features bevy_text
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 6.15s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 12.60s

[alice-i-cecile]

I agree in principle but the diff here is extremely messy and needs to be reduced to a minimal set of changes.

[BenjaminBrienen]

Latest:

[bushrat011899]

I like this change, but I think it needs some polishing. There's some formatting changes that I don't understand the reason for, and I believe reflection was removed from ImageNode inadvertently.

[ickshonpe]

I haven't looked at the changes yet, but I've wanted to have the UI layout and rendering separated for years.
I think just feature gating the rendering isn't enough though, we need the UI rendering plugin moved into its own crate bevy_ui_render or something.

[ickshonpe]

Suggested change

	for (_camera_id, mut camera) in camera_layout_info.drain() {
	for (camera_id, mut camera) in camera_layout_info.drain() {

[ickshonpe]

There still seems to be something weird with the "bevy_text" feature as well.

Feature gating all the text spawning commands in the testbed_ui example by "bevy_text" and compiling without "bevy_text" enabled:

cargo run --example testbed_ui --no-default-features --features "android-game-activity android-game-activity android_shared_stdcxx animation bevy_asset bevy_audio bevy_color bevy_core_pipeline bevy_gilrs bevy_gizmos bevy_gltf bevy_mesh_picking_backend bevy_pbr bevy_picking bevy_remote bevy_render bevy_scene bevy_sprite bevy_sprite_picking_backend bevy_state bevy_ui bevy_ui_picking_backend bevy_window bevy_winit custom_cursor default_font hdr multi_threaded png smaa_luts sysinfo_plugin tonemapping_luts vorbis webgl2 x11"

results in errors like:

error[E0433]: failed to resolve: use of undeclared type `Text`
  --> examples/testbed/ui.rs:74:33
   |
74 | ...                   Text::new("Text Example"),
   |                       ^^^^ use of undeclared type `Text`

[BenjaminBrienen]

I'll look into it, thanks.

[BenjaminBrienen]

There still seems to be something weird with the "bevy_text" feature as well.

Feature gating all the text spawning commands in the testbed_ui example by "bevy_text" and compiling without "bevy_text" enabled:

cargo run --example testbed_ui --no-default-features --features "android-game-activity android-game-activity android_shared_stdcxx animation bevy_asset bevy_audio bevy_color bevy_core_pipeline bevy_gilrs bevy_gizmos bevy_gltf bevy_mesh_picking_backend bevy_pbr bevy_picking bevy_remote bevy_render bevy_scene bevy_sprite bevy_sprite_picking_backend bevy_state bevy_ui bevy_ui_picking_backend bevy_window bevy_winit custom_cursor default_font hdr multi_threaded png smaa_luts sysinfo_plugin tonemapping_luts vorbis webgl2 x11"

results in errors like:

error[E0433]: failed to resolve: use of undeclared type `Text`
  --> examples/testbed/ui.rs:74:33
   |
74 | ...                   Text::new("Text Example"),
   |                       ^^^^ use of undeclared type `Text`

I get a runtime error if I run this command

[BenjaminBrienen]

PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.43s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_render
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 11.25s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_text  
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.44s
PS C:\Users\BenjaminBrienen\source\bevy> cargo build -p bevy_ui --no-default-features --features bevy_text,bevy_render
   Compiling bevy_ui v0.15.0-dev (C:\Users\BenjaminBrienen\source\bevy\crates\bevy_ui)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 14.08s

[alice-i-cecile]

Cutting from the milestone: valuable, but not essential. At this point I expect this to be easier to redo from scratch: merge conflicts on this sort of work really really suck.