Simplify the public event and CPU API

Applications now need far less ceremony: hello.c is a 20-line loop that
handles REFRESH, CLOSE and QUIT and draws into the surface's own pixels.

- Fold GEOMETRY, STATE and FOCUS into one WINDOW event carrying size,
  scale and state; unchanged values send nothing.
- Guarantee REFRESH once a window has a size and after every resize,
  never at size zero.
- Merge DROP_HOVER into DROP with over/leave/data actions and give drag
  and drop actions enums.
- Keep event strings valid until the next wait and drop
  yasl_event_release; empty or failed waits report NONE.
- Replace copy-in presentation with a lent pixel buffer:
  yasl_cpu_pixels and yasl_cpu_present.
- Remove yasl_poll_event, yasl_cpu_read_pixels, unused event fields and
  comments that restated names.
- Wayland: resize floating windows in request_size instead of reporting
  it unsupported, and stop marking new GPU surfaces as Vulkan so
  yasl_vulkan_create_surface no longer fails with NATIVE_WINDOW_IN_USE.

Also includes the in-progress public API refactor that was uncommitted
in the tree (removal of the app/loop layer, new surface, GL and Vulkan
entry points).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 90 insertions, 0 deletions

diff --git a/src/common/private_native.h b/src/common/private_native.h
new file mode 100644
index 0000000..d3d9aae
--- /dev/null
+++ b/src/common/private_native.h
@@ -0,0 +1,90 @@
+/**
+ * @file
+ * Optional native handles and application-managed rendering.
+ *
+ * These extensions follow the core thread and lifetime rules. Handles are borrowed;
+ * never destroy them or dispatch their native connection independently. Typed
+ * backend accessors live in the yasl/native headers and are installed only for built
+ * backends. Application-managed drawing currently supports Cocoa/Metal only.
+ */
+#ifndef YASL_PRIVATE_NATIVE_H
+#define YASL_PRIVATE_NATIVE_H
+
+#include "common/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Optional platform interoperability. All handles are borrowed and expire on
+ * object destruction. Check yasl_private_display_backend() before casting:
+ *
+ *              display                  surface
+ * Wayland      struct wl_display *       struct wl_surface *
+ * X11          Display *                 Window (cast through uintptr_t)
+ * Cocoa        NSApplication *           NSWindow * (view: window.contentView)
+ */
+/**
+ * Get a borrowed, backend-specific display handle.
+ * @param d Display, or NULL.
+ * @return Native handle, or NULL. Inspect yasl_private_display_backend() before casting.
+ * Prefer a typed accessor from yasl/native/wayland.h, x11.h, or cocoa.h.
+ * The handle expires on display close; do not close or dispatch it independently.
+ */
+void *yasl_private_display_get_native_handle(struct yasl_private_display *d);
+/**
+ * Get a borrowed, backend-specific surface handle.
+ * @param s Surface, or NULL.
+ * @return Native handle, or NULL. X11 encodes a Window through uintptr_t.
+ * Prefer typed accessors. The handle expires on surface destruction. Do not
+ * change native ownership, event masks, buffer attachment, or surface roles.
+ */
+void *yasl_private_surface_get_native_handle(struct yasl_surface *s);
+
+/* Create a surface for application-managed native rendering. graphics_device
+ * must be non-NULL; currently an id<MTLDevice> on Cocoa, retained by the surface.
+ * Other backends return NULL with errno=ENOTSUP. CPU rendering uses the ordinary
+ * yasl_private_surface_create_toplevel() and requires no native device. */
+/**
+ * Create a toplevel for application-managed native rendering.
+ * @param d Display with YASL_PRIVATE_CAP_NATIVE_GRAPHICS.
+ * @param spec Copied window options, with logical-pixel size and optional callbacks.
+ * @param graphics_device Required native graphics device; currently id<MTLDevice> on Cocoa.
+ * @return Owned surface, or NULL with errno set: EINVAL for invalid arguments,
+ * ENOTSUP for an unsupported backend, or a backend error.
+ * Cocoa retains the device. Query the drawable during draw, submit/present it,
+ * then call yasl_private_surface_present() to record submission.
+ * Callback ownership and timing follow yasl_private_surface_create_toplevel().
+ */
+struct yasl_surface *yasl_private_surface_create_native(struct yasl_private_display *d,
+        const struct yasl_private_window_spec *spec, void *graphics_device);
+
+/** Borrowed native drawable for the current draw target, currently Cocoa/Metal. */
+struct yasl_private_native_frame {
+    /** Borrowed id<CAMetalDrawable> on Cocoa. */
+    void *drawable;
+    /** Cocoa CAMetalLayer presentsWithTransaction setting for this frame. */
+    bool transaction;
+};
+
+/* Query the current draw target's native drawable. Returns false for unsupported
+ * backends, stale targets, or outside the draw callback. The result expires on
+ * successful present, callback return, or surface destruction. Native renderers
+ * submit/present the drawable, then call yasl_private_surface_present() to record it. */
+/**
+ * Get the current draw target's native drawable.
+ * @param s Surface currently being drawn.
+ * @param target Exact framebuffer identity supplied to this draw callback.
+ * @param out Required output native frame.
+ * @return true if available, false for NULL arguments, unsupported backends,
+ * stale targets, or calls outside draw. The drawable is borrowed and expires on
+ * successful present, callback return, or surface destruction. Currently Cocoa only.
+ */
+bool yasl_private_surface_get_native_frame(struct yasl_surface *s,
+        const struct yasl_private_framebuffer *target, struct yasl_private_native_frame *out);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* YASL_PRIVATE_NATIVE_H */