1 files changed, 37 insertions, 0 deletions
diff --git a/video/out/dr_helper.h b/video/out/dr_helper.h
new file mode 100644
index 0000000..cf2ed14
--- /dev/null
+++ b/video/out/dr_helper.h
@@ -0,0 +1,37 @@
+#pragma once
+
+// This is a helper for implementing thread-safety for DR callbacks. These need
+// to allocate GPU buffers on the GPU thread (e.g. OpenGL with its forced TLS),
+// and the buffers also need to be freed on the GPU thread.
+// This is not a helpful "Dr.", rather it represents Satan in form of C code.
+struct dr_helper;
+
+struct mp_image;
+struct mp_dispatch_queue;
+
+// dr_helper_get_image() calls will use the dispatch queue to run get_image on
+// a target thread, which processes the dispatch queue.
+// Note: the dispatch queue must process outstanding async. work before the
+//       dr_helper instance can be destroyed.
+struct dr_helper *dr_helper_create(struct mp_dispatch_queue *dispatch,
+            struct mp_image *(*get_image)(void *ctx, int imgfmt, int w, int h,
+                                          int stride_align, int flags),
+            void *get_image_ctx);
+
+// Make DR release calls (freeing images) reentrant if they are called on current
+// thread. That means any free call will directly release the image as allocated
+// with get_image().
+// Only 1 thread can use this at a time. Note that it would make no sense to
+// call this on more than 1 thread, as get_image is assumed not thread-safe.
+void dr_helper_acquire_thread(struct dr_helper *dr);
+
+// This _must_ be called on the same thread as dr_helper_acquire_thread() was
+// called. Every release call must be paired with an acquire call.
+void dr_helper_release_thread(struct dr_helper *dr);
+
+// Allocate an image by running the get_image callback on the target thread.
+// Always blocks on dispatch queue processing. This implies there is no way to
+// allocate a DR'ed image on the render thread (at least not in a way which
+// actually works if you want foreign threads to be able to free them).
+struct mp_image *dr_helper_get_image(struct dr_helper *dr, int imgfmt,
+                                     int w, int h, int stride_align, int flags);