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, 118 insertions, 92 deletions

diff --git a/src/common/backend.h b/src/common/backend.h
index 876a4ca..e3dc6de 100644
--- a/src/common/backend.h
+++ b/src/common/backend.h
@@ -1,48 +1,64 @@
-#ifndef YASL_BACKEND_H
-#define YASL_BACKEND_H
+#ifndef YASL_PRIVATE_BACKEND_H
+#define YASL_PRIVATE_BACKEND_H
 
-#include "yasl/yasl.h"
-#include "yasl/loop.h"
-#include "yasl/native.h"
+#include "common/types.h"
+#include "common/private_loop.h"
+#include "common/private_native.h"
 #include "common/input.h"
+#include "common/gl_options.h"
 #include "common/timing.h"
 
 #include <string.h>
 
-struct yasl_backend_ops;
-struct yasl_event_state;
+struct yasl_private_backend_ops;
+struct yasl_private_event_state;
 
-struct yasl_display {
-    const struct yasl_backend_ops *ops;
+struct yasl_private_display {
+    const struct yasl_private_backend_ops *ops;
     void *native_handle;
-    struct yasl_display_cbs callbacks;
-    struct yasl_loop *loop;
-    void *app_runner;
-    /* Backend's copy of yasl_display_spec.app_id, or NULL; for desktop services. */
+    struct yasl_private_display_cbs callbacks;
+    struct yasl_private_loop *loop;
+    /* Backend's copy of yasl_private_display_spec.app_id, or NULL; for desktop services. */
     const char *app_id;
     void *callback_ud;
-    struct yasl_event_state *events;
+    struct yasl_private_event_state *events;
     struct yasl_surface *surfaces;
 };
 
 struct yasl_surface {
-    struct yasl_display *display;
+    unsigned creation_flags;
+    enum yasl_private_presenter presenter;
+    struct yasl_surface *parent;
+    uint32_t *committed_pixels;
+    int committed_width, committed_height;
+    /* Window values last reported through public WINDOW events. */
+    struct yasl_private_vector2i reported_size;
+    uint32_t reported_scale_120, reported_state;
+    bool refresh_owed;
+    bool refresh_active;
+    void (*refresh_callback)(struct yasl_surface *, void *);
+    void *refresh_userdata;
+    bool text_input_active;
+    unsigned text_purpose;
+    char *text_surrounding;
+    size_t text_length, text_begin, text_end;
+    uint64_t text_revision, text_generation;
+    struct yasl_private_display *display;
     void *native_handle;
-    struct yasl_vector2i size;
+    struct yasl_private_vector2i size;
     uint32_t scale_120;
-    uint32_t state; /* Authoritative YASL_STATE_* bitmask, maintained by the backend. */
+    uint32_t state; /* Authoritative YASL_PRIVATE_STATE_* bitmask, maintained by the backend. */
     uint32_t bg_color;
-    struct yasl_window_cbs callbacks;
+    struct yasl_private_window_cbs callbacks;
     void *ud;
     uint64_t frame_generation;
     struct input_queue input;
-    enum yasl_pointer_mode pointer_mode;
-    struct yasl_frame_clock clock;
+    enum yasl_private_pointer_mode pointer_mode;
+    struct yasl_private_frame_clock clock;
     uint64_t frames_skipped;
-    yasl_timer_id *timers;
+    yasl_private_timer_id *timers;
     int timer_count;
     int timer_capacity;
-    void *app_surface;
     struct yasl_surface *event_next;
     uint64_t id;
     void *userdata;
@@ -51,40 +67,41 @@ struct yasl_surface {
     bool frame_presented;
     uint32_t reported_scale;
     uint64_t draw_index;
-    struct yasl_frame *active_frame;
-    yasl_pacing_mode pacing;
-    yasl_timer_id pacing_timer;
+    struct yasl_private_frame *active_frame;
+    yasl_private_pacing_mode pacing;
+    yasl_private_timer_id pacing_timer;
 };
 
-bool yasl_events_open(struct yasl_display *d);
-void yasl_events_close(struct yasl_display *d);
-int yasl_events_error(struct yasl_display *d);
-bool yasl_events_pending(struct yasl_display *d);
-struct yasl_surface *yasl_events_find(struct yasl_display *d, uint64_t id);
-bool yasl_events_register(struct yasl_surface *s);
-void yasl_events_unregister(struct yasl_surface *s);
-bool yasl_events_push(struct yasl_display *d, struct yasl_surface *queue_owner,
-                      const struct yasl_event *event);
-bool yasl_events_poll_surface(struct yasl_surface *s, struct yasl_event *event);
-void yasl_surface_notify_configure(struct yasl_surface *s, struct yasl_geometry geometry);
-void yasl_surface_notify_close(struct yasl_surface *s);
-void yasl_surface_notify_state(struct yasl_surface *s, uint32_t state);
-void yasl_surface_notify_drag(struct yasl_surface *s, enum yasl_drag_event ev, struct yasl_vector2i pos);
-void yasl_surface_notify_drop(struct yasl_surface *s, enum yasl_drop_event ev, struct yasl_vector2i pos);
-void yasl_surface_notify_composition(struct yasl_surface *s, const char *text, int begin, int end);
-void yasl_surface_draw(struct yasl_surface *s, struct yasl_frame *frame);
-void yasl_display_notify_event(struct yasl_display *d, enum yasl_event_type type);
-void yasl_surface_complete_paste(struct yasl_surface *s, uint64_t request_id,
-        enum yasl_transfer_status status, const char *text, size_t len);
-uint64_t yasl_events_request_id(struct yasl_display *d);
+bool yasl_private_events_open(struct yasl_private_display *d);
+void yasl_private_events_close(struct yasl_private_display *d);
+int yasl_private_events_error(struct yasl_private_display *d);
+bool yasl_private_events_pending(struct yasl_private_display *d);
+struct yasl_surface *yasl_private_events_find(struct yasl_private_display *d, uint64_t id);
+bool yasl_private_events_register(struct yasl_surface *s);
+void yasl_private_events_unregister(struct yasl_surface *s);
+bool yasl_private_events_push(struct yasl_private_display *d, struct yasl_surface *queue_owner,
+                      const struct yasl_private_event *event);
+bool yasl_private_events_poll_surface(struct yasl_surface *s, struct yasl_private_event *event);
+void yasl_private_surface_notify_configure(struct yasl_surface *s, struct yasl_private_geometry geometry);
+void yasl_private_surface_notify_refresh(struct yasl_surface *s);
+void yasl_private_surface_notify_close(struct yasl_surface *s);
+void yasl_private_surface_notify_state(struct yasl_surface *s, uint32_t state);
+void yasl_private_surface_notify_drag(struct yasl_surface *s, enum yasl_private_drag_event ev, struct yasl_private_vector2i pos);
+void yasl_private_surface_notify_drop(struct yasl_surface *s, enum yasl_private_drop_event ev, struct yasl_private_vector2i pos);
+void yasl_private_surface_notify_composition(struct yasl_surface *s, const char *text, int begin, int end);
+void yasl_private_surface_draw(struct yasl_surface *s, struct yasl_private_frame *frame);
+void yasl_private_display_notify_event(struct yasl_private_display *d, enum yasl_private_event_type type);
+void yasl_private_surface_complete_paste(struct yasl_surface *s, uint64_t request_id,
+        enum yasl_private_transfer_status status, const char *text, size_t len);
+uint64_t yasl_private_events_request_id(struct yasl_private_display *d);
 
-void yasl_surface_clear_timers(struct yasl_surface *s);
-struct yasl_surface *yasl_create_toplevel(struct yasl_display *d,
-        const struct yasl_window_spec *spec, void *graphics_device);
+void yasl_private_surface_clear_timers(struct yasl_surface *s);
+struct yasl_surface *yasl_private_create_toplevel(struct yasl_private_display *d,
+        const struct yasl_private_window_spec *spec, void *graphics_device);
 
 /* Report a presented CPU frame's extent, and copy it when out can hold it. */
-static inline bool yasl_copy_frame(const uint32_t *pixels, struct yasl_vector2i extent,
-        uint32_t *out, size_t cap, struct yasl_vector2i *size)
+static inline bool yasl_private_copy_frame(const uint32_t *pixels, struct yasl_private_vector2i extent,
+        uint32_t *out, size_t cap, struct yasl_private_vector2i *size)
 {
     *size = extent;
     size_t count = (size_t)extent.x * (size_t)extent.y;
@@ -93,83 +110,92 @@ static inline bool yasl_copy_frame(const uint32_t *pixels, struct yasl_vector2i
     return true;
 }
 
-static inline uint64_t yasl_frame_begin(struct yasl_surface *s)
+static inline uint64_t yasl_private_frame_begin(struct yasl_surface *s)
 {
     if (++s->frame_generation == 0) ++s->frame_generation;
     return s->frame_generation;
 }
 
-struct yasl_backend_ops {
-    enum yasl_backend type;
-    struct yasl_display *(*display_open)(struct yasl_loop *loop, const struct yasl_display_spec *spec);
-    void (*display_close)(struct yasl_display *d);
-    uint32_t (*display_caps)(const struct yasl_display *d);
-    int (*display_dispatch_timeout)(struct yasl_display *d, int timeout_ms);
-    void (*display_flush)(struct yasl_display *d);
-    int (*display_modifiers)(const struct yasl_display *d);
+typedef void (*yasl_private_gl_proc)(void);
+struct yasl_private_backend_ops {
+    struct yasl_surface *(*surface_create_gl)(struct yasl_private_display *, const struct yasl_private_window_spec *, const int *, struct yasl_surface *share);
+    bool (*gl_make_current)(struct yasl_private_display *, struct yasl_surface *);
+    yasl_private_gl_proc (*gl_get_proc_address)(struct yasl_private_display *, const char *);
+    bool (*gl_swap_interval)(struct yasl_private_display *, struct yasl_surface *, int);
+    bool (*gl_swap_buffers)(struct yasl_private_display *, struct yasl_surface *);
+    void *(*surface_get_metal_layer)(struct yasl_surface *);
+    bool (*surface_update_text_input)(struct yasl_surface *);
+
+    enum yasl_private_backend type;
+    struct yasl_private_display *(*display_open)(struct yasl_private_loop *loop, const struct yasl_private_display_spec *spec);
+    void (*display_close)(struct yasl_private_display *d);
+    uint32_t (*display_caps)(const struct yasl_private_display *d);
+    int (*display_dispatch_timeout)(struct yasl_private_display *d, int timeout_ms);
+    void (*display_flush)(struct yasl_private_display *d);
+    int (*display_modifiers)(const struct yasl_private_display *d);
     /* Optional; returns zero or less when the system reports no interval. */
-    int (*display_double_click_ms)(const struct yasl_display *d);
-    void (*display_copy)(struct yasl_display *d, enum yasl_selection sel, const char *text);
-    void (*display_paste)(struct yasl_display *d, enum yasl_selection sel, struct yasl_surface *target);
-    bool (*display_copy_text)(struct yasl_display *d, enum yasl_selection sel, const char *text);
-    bool (*display_request_paste)(struct yasl_display *d, enum yasl_selection sel,
+    int (*display_double_click_ms)(const struct yasl_private_display *d);
+    void (*display_copy)(struct yasl_private_display *d, enum yasl_private_selection sel, const char *text);
+    void (*display_paste)(struct yasl_private_display *d, enum yasl_private_selection sel, struct yasl_surface *target);
+    bool (*display_copy_text)(struct yasl_private_display *d, enum yasl_private_selection sel, const char *text);
+    bool (*display_request_paste)(struct yasl_private_display *d, enum yasl_private_selection sel,
                                   struct yasl_surface *target, uint64_t request_id);
-    bool (*display_drag_start)(struct yasl_display *d, struct yasl_surface *origin, const struct yasl_drag_image *image, const struct yasl_drag_listener *l, void *ud);
-    void (*display_drag_cancel)(struct yasl_display *d);
+    bool (*display_drag_start)(struct yasl_private_display *d, struct yasl_surface *origin, const struct yasl_private_drag_image *image, const struct yasl_private_drag_listener *l, void *ud);
+    void (*display_drag_cancel)(struct yasl_private_display *d);
     /* Create with callbacks disabled; common code installs them after return. */
-    struct yasl_surface *(*surface_create_toplevel)(struct yasl_display *d,
-            const struct yasl_window_spec *spec, void *graphics_device);
-    struct yasl_surface *(*surface_create_popup)(struct yasl_surface *parent, const struct yasl_popup_spec *spec);
-    bool (*surface_popup_reposition)(struct yasl_surface *popup, const struct yasl_popup_spec *spec);
+    struct yasl_surface *(*surface_create_toplevel)(struct yasl_private_display *d,
+            const struct yasl_private_window_spec *spec, void *graphics_device);
+    struct yasl_surface *(*surface_create_popup)(struct yasl_surface *parent, const struct yasl_private_popup_spec *spec);
+    bool (*surface_popup_reposition)(struct yasl_surface *popup, const struct yasl_private_popup_spec *spec);
     void (*surface_destroy)(struct yasl_surface *s);
     struct input_queue *(*surface_input_queue)(struct yasl_surface *s);
-    bool (*surface_set_size)(struct yasl_surface *s, struct yasl_vector2i size_logical);
+    bool (*surface_set_size)(struct yasl_surface *s, struct yasl_private_vector2i size_logical);
     bool (*surface_set_fullscreen)(struct yasl_surface *s, bool enabled);
     bool (*surface_set_maximized)(struct yasl_surface *s, bool enabled);
     bool (*surface_minimize)(struct yasl_surface *s);
-    struct yasl_display *(*surface_display)(const struct yasl_surface *s);
+    struct yasl_private_display *(*surface_display)(const struct yasl_surface *s);
     /* Copy only; must not invoke application callbacks. */
-    void (*surface_set_callbacks)(struct yasl_surface *s, const struct yasl_window_cbs *cbs, void *ud);
+    void (*surface_set_callbacks)(struct yasl_surface *s, const struct yasl_private_window_cbs *cbs, void *ud);
     void (*surface_set_title)(struct yasl_surface *s, const char *title);
     void (*surface_schedule_redraw)(struct yasl_surface *s);
-    bool (*surface_present)(struct yasl_surface *s, const struct yasl_framebuffer *fb, const struct yasl_damage_list *damage);
+    bool (*surface_present)(struct yasl_surface *s, const struct yasl_private_framebuffer *fb, const struct yasl_private_damage_list *damage);
     /* Optional; NULL means the common input queue is drained. */
-    bool (*surface_poll_event)(struct yasl_surface *s, struct yasl_event *ev);
-    /* Optional; NULL means only YASL_POINTER_NORMAL is supported. Backends that
+    bool (*surface_poll_event)(struct yasl_surface *s, struct yasl_private_event *ev);
+    /* Optional; NULL means only YASL_PRIVATE_POINTER_NORMAL is supported. Backends that
      * implement RELATIVE push POINTER_MOTION with delta set and pos frozen. */
-    bool (*surface_set_pointer_mode)(struct yasl_surface *s, enum yasl_pointer_mode mode);
-    struct yasl_geometry (*surface_geometry)(const struct yasl_surface *s);
-    struct yasl_timing (*surface_timing)(const struct yasl_surface *s);
+    bool (*surface_set_pointer_mode)(struct yasl_surface *s, enum yasl_private_pointer_mode mode);
+    struct yasl_private_geometry (*surface_geometry)(const struct yasl_surface *s);
+    struct yasl_private_timing (*surface_timing)(const struct yasl_surface *s);
     uint64_t (*surface_frame_time_ns)(struct yasl_surface *s, uint64_t now);
-    void (*surface_set_cursor)(struct yasl_surface *s, enum yasl_cursor cursor);
+    void (*surface_set_cursor)(struct yasl_surface *s, enum yasl_private_cursor cursor);
     void (*surface_set_background_color)(struct yasl_surface *s, uint32_t bg);
     const char *(*surface_ime_preedit)(const struct yasl_surface *s);
     bool (*surface_ime_preedit_cursor)(const struct yasl_surface *s, int *begin, int *end);
-    void (*surface_set_ime_caret)(struct yasl_surface *s, struct yasl_rect2i caret);
+    void (*surface_set_ime_caret)(struct yasl_surface *s, struct yasl_private_rect2i caret);
     bool (*surface_start_interactive_move)(struct yasl_surface *s);
-    bool (*surface_start_interactive_resize)(struct yasl_surface *s, enum yasl_resize_edge edge);
-    bool (*surface_show_window_menu)(struct yasl_surface *s, struct yasl_vector2i pos);
-    bool (*surface_drag_carry)(struct yasl_surface *s, struct yasl_vector2i offset);
-    bool (*surface_place_under_pointer)(struct yasl_surface *s, struct yasl_vector2i at);
+    bool (*surface_start_interactive_resize)(struct yasl_surface *s, enum yasl_private_resize_edge edge);
+    bool (*surface_show_window_menu)(struct yasl_surface *s, struct yasl_private_vector2i pos);
+    bool (*surface_drag_carry)(struct yasl_surface *s, struct yasl_private_vector2i offset);
+    bool (*surface_place_under_pointer)(struct yasl_surface *s, struct yasl_private_vector2i at);
     /* Optional; NULL means the bell is unsupported. */
     bool (*surface_bell)(struct yasl_surface *s);
     /* Optional; NULL means no readback. Fills size only for an available frame. */
     bool (*surface_read_pixels)(struct yasl_surface *s, uint32_t *out, size_t cap,
-            struct yasl_vector2i *size);
-    void *(*display_get_native_handle)(struct yasl_display *d);
+            struct yasl_private_vector2i *size);
+    void *(*display_get_native_handle)(struct yasl_private_display *d);
     void *(*surface_get_native_handle)(struct yasl_surface *s);
     bool (*surface_get_native_frame)(struct yasl_surface *s,
-            const struct yasl_framebuffer *target, struct yasl_native_frame *out);
+            const struct yasl_private_framebuffer *target, struct yasl_private_native_frame *out);
 };
 
 #if YASL_HAS_WAYLAND
-extern const struct yasl_backend_ops yasl_wayland_backend;
+extern const struct yasl_private_backend_ops yasl_private_wayland_backend;
 #endif
 #if YASL_HAS_X11
-extern const struct yasl_backend_ops yasl_x11_backend;
+extern const struct yasl_private_backend_ops yasl_private_x11_backend;
 #endif
 #if YASL_HAS_COCOA
-extern const struct yasl_backend_ops yasl_cocoa_backend;
+extern const struct yasl_private_backend_ops yasl_private_cocoa_backend;
 #endif
 
 #endif