compat.accesskit 0.23.1: AccessKit's C bindings, prebuilt — one accessibility tree served to UIA, NSAccessibility and AT-SPI

The library is Rust, so upstream's release archive is the artifact: its header
and the static library of the host's platform (Linux x86_64, macOS arm64,
Windows x86_64 MSVC), linked with the system libraries upstream's own
accesskit-config.cmake names. tests/examples/accesskit builds a window and its
button, reads the update back through the library, and on Linux makes an AT-SPI
adapter and gives it the tree.

Signed-off-by: Sunrisepeak <speakshen@163.com>

Author: Sunrisepeak

mcpp.toml

@@ -41,6 +41,7 @@ members = [
     "tests/examples/abseil",
     "tests/examples/archive",
     "tests/examples/argparse",
+    "tests/examples/accesskit",
     "tests/examples/asio-module",
     "tests/examples/asio-ssl",
     "tests/examples/boost-asio",

pkgs/c/compat.accesskit.lua

@@ -0,0 +1,78 @@
+-- compat.accesskit — AccessKit's C bindings (accesskit-c), prebuilt: a UI
+-- describes its tree once and AccessKit serves it to each platform's
+-- assistive technology — UI Automation on Windows, NSAccessibility on macOS,
+-- AT-SPI on Linux (a screen reader, a magnifier, voice control).
+--
+-- THE LIBRARY IS RUST, SO ITS RELEASE IS THE ARTIFACT. Building it here would
+-- need a Rust toolchain in the recipe; upstream's release archive carries the
+-- header and a static library for every platform it supports, built from the
+-- tagged source by its own CI. This descriptor exposes the header and links the
+-- static library of the host's platform, with the system libraries upstream's
+-- own `accesskit-config.cmake` names for each.
+--
+-- WHAT IS NOT COVERED: upstream ships no Linux arm64 build, and this version
+-- links macOS arm64 and Windows x86_64 (the x86_64 Mac and arm64 Windows
+-- libraries are in the archive too, but the index states one library path per
+-- platform). A consumer that wants AccessKit there gates its use by platform.
+--
+-- One archive for all three platforms (about 64 MB): the paths below reach into
+-- its `accesskit-c-0.23.1/` wrap layer; mcpp rewrites a relative `-L` to the
+-- package's own directory.
+package = {
+    spec        = "1",
+    namespace   = "compat",
+    name        = "accesskit",
+    description = "AccessKit C bindings (prebuilt static library): one accessibility tree served to UIA, NSAccessibility and AT-SPI",
+    licenses    = {"MIT", "Apache-2.0"},
+    repo        = "https://github.com/AccessKit/accesskit-c",
+    type        = "package",
+
+    xpm = {
+        linux = {
+            ["0.23.1"] = {
+                url    = "https://github.com/AccessKit/accesskit-c/releases/download/0.23.1/accesskit-c-0.23.1.zip",
+                sha256 = "35b7ca8a6f1e038b5da35e1e9e5a0adaed9bfcf21e1496d29598fbbadcc7043f",
+            },
+            ["latest"] = { ref = "0.23.1" },
+        },
+        macosx = {
+            ["0.23.1"] = {
+                url    = "https://github.com/AccessKit/accesskit-c/releases/download/0.23.1/accesskit-c-0.23.1.zip",
+                sha256 = "35b7ca8a6f1e038b5da35e1e9e5a0adaed9bfcf21e1496d29598fbbadcc7043f",
+            },
+            ["latest"] = { ref = "0.23.1" },
+        },
+        windows = {
+            ["0.23.1"] = {
+                url    = "https://github.com/AccessKit/accesskit-c/releases/download/0.23.1/accesskit-c-0.23.1.zip",
+                sha256 = "35b7ca8a6f1e038b5da35e1e9e5a0adaed9bfcf21e1496d29598fbbadcc7043f",
+            },
+            ["latest"] = { ref = "0.23.1" },
+        },
+    },
+
+    mcpp = {
+        language     = "c++23",
+        import_std   = false,
+        c_standard   = "c11",
+        include_dirs = { "*/include" },
+        generated_files = {
+            ["mcpp_generated/accesskit_anchor.c"] = "int mcpp_compat_accesskit_anchor(void) { return 0; }\n",
+        },
+        sources = { "mcpp_generated/accesskit_anchor.c" },
+        targets = { ["accesskit"] = { kind = "lib" } },
+        deps    = {},
+        -- The static library and what upstream's accesskit-config.cmake links beside it.
+        linux = {
+            ldflags = { "-Laccesskit-c-0.23.1/lib/linux/x86_64/static", "-l:libaccesskit.a", "-static-libgcc", "-lm" },
+        },
+        macosx = {
+            ldflags = { "-Laccesskit-c-0.23.1/lib/macos/arm64/static", "-laccesskit",
+                        "-framework", "AppKit", "-framework", "Foundation", "-framework", "CoreFoundation", "-lobjc", "-lc++" },
+        },
+        windows = {
+            ldflags = { "-Laccesskit-c-0.23.1/lib/windows/x86_64/msvc/static", "-laccesskit",
+                        "-lbcrypt", "-lntdll", "-lpropsys", "-lruntimeobject", "-luiautomationcore", "-luserenv", "-lws2_32" },
+        },
+    },
+}

tests/examples/accesskit/mcpp.toml

@@ -0,0 +1,9 @@
+# compat.accesskit test project: a tree built and handed to AccessKit, and on
+# Linux an AT-SPI adapter made and given the tree. `compat` redirect inherited
+# from the workspace root.
+[package]
+name = "accesskit-tests"
+version = "0.1.0"
+
+[dependencies.compat]
+accesskit = "0.23.1"

tests/examples/accesskit/tests/tree.cpp

@@ -0,0 +1,58 @@
+// Behavioral test: compat.accesskit builds a tree (a window holding a button
+// with a label, focusable, clickable), reads it back through the library's own
+// debug view, and on Linux makes an AT-SPI adapter and gives it the tree. Not
+// merely an include: these calls reach the prebuilt Rust library.
+#include <accesskit.h>
+#include <cstdio>
+#include <cstring>
+
+static accesskit_tree_update *tree(void *userdata) {
+    (void)userdata;
+    accesskit_node *window = accesskit_node_new(ACCESSKIT_ROLE_WINDOW);
+    accesskit_node_set_label(window, "Settings");
+    accesskit_node_push_child(window, 2);
+    accesskit_node *button = accesskit_node_new(ACCESSKIT_ROLE_BUTTON);
+    accesskit_node_set_label(button, "Save");
+    accesskit_node_add_action(button, ACCESSKIT_ACTION_CLICK);
+    accesskit_node_add_action(button, ACCESSKIT_ACTION_FOCUS);
+    accesskit_tree_update *update = accesskit_tree_update_with_capacity_and_focus(2, 2);
+    accesskit_tree_update_set_tree_info(update, accesskit_tree_info_new(1));
+    accesskit_tree_update_push_node(update, 1, window);
+    accesskit_tree_update_push_node(update, 2, button);
+    return update;
+}
+
+#if defined(__linux__)
+static void act(accesskit_action_request *request, void *userdata) {
+    (void)userdata;
+    accesskit_action_request_free(request);
+}
+static void deactivated(void *userdata) { (void)userdata; }
+#endif
+
+int main(void) {
+    accesskit_tree_update *update = tree(nullptr);
+    if (!update) {
+        fprintf(stderr, "no tree update\n");
+        return 1;
+    }
+    char *debug = accesskit_tree_update_debug(update);
+    const int named = debug && strstr(debug, "Save") != NULL;
+    if (debug) accesskit_string_free(debug);
+    accesskit_tree_update_free(update);
+    if (!named) {
+        fprintf(stderr, "the tree update does not hold the button's label\n");
+        return 1;
+    }
+#if defined(__linux__)
+    accesskit_unix_adapter *adapter = accesskit_unix_adapter_new(reinterpret_cast<accesskit_activation_handler_callback>(tree), nullptr, act, nullptr, deactivated, nullptr);
+    if (!adapter) {
+        fprintf(stderr, "no AT-SPI adapter\n");
+        return 1;
+    }
+    accesskit_unix_adapter_update_window_focus_state(adapter, true);
+    accesskit_unix_adapter_free(adapter);
+#endif
+    printf("accesskit: a window and its button, served\n");
+    return 0;
+}