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, 19 insertions, 0 deletions

diff --git a/include/yasl/vulkan.h b/include/yasl/vulkan.h
new file mode 100644
index 0000000..afa1089
--- /dev/null
+++ b/include/yasl/vulkan.h
@@ -0,0 +1,19 @@
+/** @file Vulkan WSI only; application owns all Vulkan objects. */
+#ifndef YASL_VULKAN_H
+#define YASL_VULKAN_H
+#include "yasl/yasl.h"
+#include <vulkan/vulkan.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+YASL_API bool yasl_vulkan_init(PFN_vkGetInstanceProcAddr loader);
+/** Borrowed list through shutdown; merge with app extensions before instance creation. */
+YASL_API const char *const *yasl_vulkan_instance_extensions(const yasl_surface *surface, uint32_t *count);
+YASL_API VkInstanceCreateFlags yasl_vulkan_instance_flags(const yasl_surface *surface);
+/** Uses injected loader; destroy returned VkSurfaceKHR before YASL surface. */
+YASL_API VkResult yasl_vulkan_create_surface(yasl_surface *surface, VkInstance instance,
+    const VkAllocationCallbacks *allocator, VkSurfaceKHR *out);
+#ifdef __cplusplus
+}
+#endif
+#endif