UI rewrite 3rd attempt

interfaces/Crafter.Graphics-Window.cppm

@@ -106,9 +106,19 @@ export namespace Crafter {
         void Resize(std::uint32_t width, std::uint32_t height);
         void Render();
         void Update();
-        void UpdateCursorImage();
-        void SetCusorImage(std::uint16_t sizeX, std::uint16_t sizeY);
-        void SetCusorImageDefault();
+        // Replace the system cursor with a custom image. `pixels` is
+        // `width*height*4` bytes in R8G8B8A8 memory order (matching
+        // stb_image's STBI_rgb_alpha output) with straight (non-premultiplied)
+        // alpha — the conversion to the compositor's expected format is
+        // handled internally. The hotspot is in image-pixel coordinates.
+        // Re-callable at any time.
+        void SetCursorImage(std::uint16_t width, std::uint16_t height,
+                            std::uint16_t hotspotX, std::uint16_t hotspotY,
+                            const std::uint8_t* pixels);
+
+        // Restore the default system cursor (releases any previously-uploaded
+        // cursor pixel buffer).
+        void SetDefaultCursor();
 
         #ifdef CRAFTER_TIMING
         std::chrono::nanoseconds totalUpdate;
@@ -139,6 +149,15 @@ export namespace Crafter {
         wl_surface* cursorSurface = nullptr;
         wl_buffer* cursorWlBuffer = nullptr;
         std::uint32_t cursorBufferOldSize = 0;
+        // mmap'd view of the SHM cursor buffer — the user-supplied pixels
+        // are written here in BGRA8888 order. Lifetime matches cursorWlBuffer.
+        std::uint8_t* cursorMmap_ = nullptr;
+        std::uint16_t cursorHotspotX_ = 0;
+        std::uint16_t cursorHotspotY_ = 0;
+        // Most recent serial from a wl_pointer.enter on this window's surface.
+        // Needed so `SetCursorImage` can re-issue `wl_pointer_set_cursor`
+        // mid-session (the hotspot only updates when set_cursor is recalled).
+        std::uint32_t lastPointerSerial_ = 0;
 
         static void xdg_surface_handle_preferred_scale(void* data, wp_fractional_scale_v1*, std::uint32_t scale);
         static void wl_surface_frame_done(void *data, wl_callback *cb, uint32_t time);