Add explicit support tiers (#323)

Also adds `PULL_REQUEST_TEMPLATE.md` and fixes `CODEOWNERS`.

Author: madsmtm

.github/CODEOWNERS

@@ -1,23 +1,23 @@
 # Android
-/src/android.rs     @MarijnS95
+/src/backends/android.rs     @MarijnS95
 
 # Apple platforms
-/src/cg.rs          @madsmtm
+/src/backends/cg.rs          @madsmtm
 
 # DRM/KMS (no maintainer)
-/src/kms.rs
+/src/backends/kms.rs
 
 # Redox
-/src/orbital.rs     @jackpot51
+/src/backends/orbital.rs     @jackpot51
 
 # Wayland
-/src/wayland        @ids1024
+/src/backends/wayland        @ids1024
 
 # Web
-/src/web.rs         @daxpedda
+/src/backends/web.rs         @daxpedda
 
 # Windows
-/src/win32.rs       @notgull
+/src/backends/win32.rs       @notgull
 
 # X11
-/src/x11.rs         @notgull
+/src/backends/x11.rs         @notgull

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,16 @@
+<!-- Thanks for contributing! -->
+
+<!-- If your pull request only touches a single backend, feel free to prune the following list: -->
+
+Tested on:
+- [ ] AppKit (tier 1)
+- [ ] Wayland (tier 1)
+- [ ] Win32 (tier 1)
+- [ ] XCB / Xlib (tier 1)
+- [ ] Android NDK (tier 2)
+- [ ] UIKit (tier 2)
+- [ ] Web (tier 2)
+- [ ] DRM/KMS (tier 3)
+- [ ] Orbital (tier 3)
+
+<!-- Note that it's okay to leave these unchecked, this is just a signal to the reviewer that they need to test it themselves. PRs may be merged when all tier 1 backends have been tested. -->

README.md

@@ -27,35 +27,32 @@ pixels when its GPU-accelerated post-processing effects are not needed.
 This library is dual-licensed under MIT or Apache-2.0, just like minifb and rust. Significant portions of code were taken
 from the minifb library to do platform-specific work.
 
-## Platform support:
-
-Some, but not all, platforms supported in [raw-window-handle](https://crates.io/crates/raw-window-handle) are supported
-by Softbuffer. Pull requests are welcome to add new platforms! **Nonetheless, all major desktop platforms that winit uses
-on desktop are supported.**
-
-For now, the priority for new platforms is:
-
-1. to have at least one platform on each OS working (e.g. one of Win32 or WinRT, or one of Xlib, Xcb, and Wayland) and
-2. for that one platform on each OS to be the one that winit uses.
-
-(PRs will be accepted for any platform, even if it does not follow the above priority.)
-
-|  Platform ||
-|-----------|--|
-|Android NDK|✅|
-|   AppKit  |✅|
-|  Orbital  |✅|
-|    UIKit  |✅|
-|  Wayland  |✅|
-|    Web    |✅|
-|   Win32   |✅|
-|   WinRT   |❌|
-|    XCB    |✅|
-|   Xlib    |✅|
-
-✅: Present\
-❔: Immature\
-❌: Absent
+## Platform support
+
+Softbuffer supports many platforms, some to a higher degree than others. This is codified with a "tier" system. Tier 1 platforms can be thought of as "tested and guaranteed to work", tier 2 as "will likely work", and tier 3 as "builds in CI".
+
+The current status is as follows (based on the list of platforms exposed by [`raw-window-handle`](https://crates.io/crates/raw-window-handle)):
+
+|  Platform          | Tier | Available |
+| ------------------ | ---- | --------- |
+| AppKit (macOS)     | 1    | ✅ |
+| Wayland            | 1    | ✅ |
+| Win32              | 1    | ✅ |
+| XCB / Xlib (X11)   | 1    | ✅ |
+| Android NDK        | 2    | ✅ |
+| UIKit (iOS)        | 2    | ✅ |
+| WebAssembly        | 2    | ✅ |
+| DRM/KMS            | 3    | ✅ |
+| Orbital            | 3    | ✅ |
+| GBM/KMS            | N/A  | ❌ |
+| Haiku              | N/A  | ❌ |
+| OpenHarmony OS NDK | N/A  | ❌ ([#261](https://github.com/rust-windowing/softbuffer/pull/261)) |
+| WinRT              | N/A  | ❌ |
+| UEFI               | N/A  | ❌ ([#282](https://github.com/rust-windowing/softbuffer/pull/282)) |
+
+Beware that big endian targets are much less tested, and may behave incorrectly.
+
+Pull requests to add support for new platforms are welcome!
 
 ## WebAssembly