refactor(codec): de-Qt oakcodec and wrap it in a pure C ABI; switch common handles to refcounted value structs

- oakcodec: de-Qt all 20 sources (QThread decode loop -> std::thread,
  QObject/signals -> callbacks), pure C ABI in include/codec with
  refcounted neutral handles (OakFrame/OakDecoder/OakEncoder),
  framemanager moved in from render, frame_to_buffer/buffer_to_frame
  moved in from oakcommon oiioutils, codec->task via submit callback
  (M8 will register), all cross-module calls go through the other
  side's C API, -fvisibility=hidden + OAKCODEC_API
- oakcommon: handles become refcounted value structs
  {ctx, addref, release, abi_version} (FFmpeg-style), pass-by-value
  signatures, free() as release wrapper; init_from_native/get_native
  for copyable value objects; OakCommonXxx renamed to OakXxx
- oakcommon: add logging (log_debug/info/warning/critical with level
  filtering and sink injection) + printf-style oakcommon_log C wrapper
- oakrender: add CancelAtom C API family; complete
  oakrender_color_processor_convert_frame; fix get_processor() missing
  definition and OCIO env var lookup
- tests: oakcommon 174, oaknode 96, oakrender 42, oakcodec 18, all
  green in their standalone builds

src/render/c_api/CMakeLists.txt

@@ -1,6 +1,7 @@
 target_sources(oakrender PRIVATE
         renderer.cpp
         cache.cpp
+        cancelatom.cpp
         color.cpp
         manager.cpp
 )

src/render/c_api/cancelatom.cpp

@@ -0,0 +1,135 @@
+/***
+
+  Oak Video Editor - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "../../../include/render/cancelatom.h"
+
+#include <atomic>
+#include <cstdint>
+
+#include "alivecount.h"
+
+#include "cancelatom.h"
+
+namespace
+{
+
+/**
+ * @brief Heap box behind every OakCancelAtom's ctx pointer.
+ *
+ * Holds the wrapped CancelAtom plus its atomic reference count. addref
+ * and release are emitted in this translation unit so the function
+ * pointers stored in a handle always run code from the DLL that created
+ * the object.
+ */
+struct CancelAtomBox {
+	olive::CancelAtom impl;
+	std::atomic<uint32_t> refs;
+
+	CancelAtomBox()
+		: refs(1)
+	{
+	}
+};
+
+CancelAtomBox *box(OakCancelAtom atom)
+{
+	return static_cast<CancelAtomBox *>(atom.ctx);
+}
+
+olive::CancelAtom *impl(OakCancelAtom atom)
+{
+	auto *b = box(atom);
+	return b ? &b->impl : nullptr;
+}
+
+/**
+ * @brief Handle addref thunk: atomically increments the count.
+ */
+void cancel_atom_addref(void *ctx)
+{
+	auto *b = static_cast<CancelAtomBox *>(ctx);
+	if (b)
+		b->refs.fetch_add(1, std::memory_order_relaxed);
+}
+
+/**
+ * @brief Handle release thunk: decrements the count, destroys at zero.
+ */
+void cancel_atom_release(void *ctx)
+{
+	auto *b = static_cast<CancelAtomBox *>(ctx);
+	if (b && b->refs.fetch_sub(1, std::memory_order_acq_rel) == 1) {
+		delete b;
+		oakrender_c_api::alive_dec();
+	}
+}
+
+} // namespace
+
+OakCancelAtom oakrender_cancelatom_init(void)
+{
+	OakCancelAtom h = {};
+	try {
+		h.ctx = new CancelAtomBox();
+	} catch (...) {
+		h.ctx = nullptr;
+	}
+	h.addref = &cancel_atom_addref;
+	h.release = &cancel_atom_release;
+	h.abi_version = OAKRENDER_ABI_VERSION;
+	if (h.ctx)
+		oakrender_c_api::alive_inc();
+	return h;
+}
+
+void oakrender_cancelatom_free(OakCancelAtom *atom)
+{
+	if (!atom || !atom->ctx || !atom->release)
+		return;
+	atom->release(atom->ctx);
+	atom->ctx = nullptr;
+}
+
+int oakrender_cancelatom_cancel(OakCancelAtom atom)
+{
+	auto *c = impl(atom);
+	if (!c)
+		return OAKRENDER_E_INVALID;
+	c->cancel();
+	return OAKRENDER_OK;
+}
+
+int oakrender_cancelatom_is_cancelled(OakCancelAtom atom, int *cancelled)
+{
+	auto *c = impl(atom);
+	if (!c || !cancelled)
+		return OAKRENDER_E_INVALID;
+	*cancelled = c->is_cancelled() ? 1 : 0;
+	return OAKRENDER_OK;
+}
+
+int oakrender_cancelatom_heard_cancel(OakCancelAtom atom, int *heard)
+{
+	auto *c = impl(atom);
+	if (!c || !heard)
+		return OAKRENDER_E_INVALID;
+	*heard = c->heard_cancel() ? 1 : 0;
+	return OAKRENDER_OK;
+}

src/render/c_api/color.cpp

@@ -30,6 +30,7 @@
 
 #include "color/colormanager/colormanager.h"
 #include "filefunctions.h"
+#include <OpenColorIO/OpenColorIO.h>
 
 namespace
 {
@@ -57,7 +58,7 @@ OakColorProcessor *oakrender_color_processor_create(const char *src_space,
 		return nullptr;
 	}
 	try {
-		ocio::ConstConfigRcPtr config = olive::ColorManager::get_default_config();
+		OCIO_NAMESPACE::ConstConfigRcPtr config = olive::ColorManager::get_default_config();
 		if (!config) {
 			return nullptr;
 		}
@@ -69,17 +70,17 @@ OakColorProcessor *oakrender_color_processor_create(const char *src_space,
 			src = config->getCanonicalName(src_space);
 		}
 
-		// OCIO failures are non-fatal (matching the C++ behavior): the
+		// OCIO_NAMESPACE failures are non-fatal (matching the C++ behavior): the
 		// handle is still returned, but holds a null processor and
 		// conversions pass through.
-		ocio::ConstProcessorRcPtr processor;
+		OCIO_NAMESPACE::ConstProcessorRcPtr processor;
 		try {
 			if (direction == OAKRENDER_COLOR_DIRECTION_NORMAL) {
 				processor = config->getProcessor(src.c_str(), dst_transform);
 			} else {
 				processor = config->getProcessor(dst_transform, src.c_str());
 			}
-		} catch (ocio::Exception &) {
+		} catch (OCIO_NAMESPACE::Exception &) {
 			processor = nullptr;
 		}
 
@@ -169,7 +170,7 @@ int oakrender_color_manager_display_transform(const char *display,
 		return OAKRENDER_E_INVALID;
 	}
 	try {
-		ocio::ConstConfigRcPtr config = olive::ColorManager::get_default_config();
+		OCIO_NAMESPACE::ConstConfigRcPtr config = olive::ColorManager::get_default_config();
 		if (!config) {
 			return OAKRENDER_E_STATE;
 		}
@@ -197,25 +198,44 @@ int oakrender_color_manager_display_transform(const char *display,
 		}
 
 		// Source = the config's reference colorspace (role lookup).
-		ocio::ConstColorSpaceRcPtr ref_cs =
-			config->getColorSpace(ocio::ROLE_REFERENCE);
+		OCIO_NAMESPACE::ConstColorSpaceRcPtr ref_cs =
+			config->getColorSpace(OCIO_NAMESPACE::ROLE_REFERENCE);
 		if (!ref_cs) {
 			return OAKRENDER_E_STATE;
 		}
 
-		auto dvt = ocio::DisplayViewTransform::Create();
+		auto dvt = OCIO_NAMESPACE::DisplayViewTransform::Create();
 		dvt->setSrc(ref_cs->getName());
 		dvt->setDisplay(display);
 		dvt->setView(view);
 
-		ocio::ConstProcessorRcPtr processor = config->getProcessor(dvt);
+		OCIO_NAMESPACE::ConstProcessorRcPtr processor = config->getProcessor(dvt);
 		if (!processor) {
 			return OAKRENDER_E_NOT_FOUND;
 		}
 		return write_string(processor->getCacheID(), buf, n);
-	} catch (ocio::Exception &) {
+	} catch (OCIO_NAMESPACE::Exception &) {
 		return OAKRENDER_E_NOT_FOUND;
 	} catch (...) {
 		return OAKRENDER_E_FAILED;
 	}
 }
+
+int oakrender_color_processor_convert_frame(OakColorProcessor *processor,
+											OakCodecFrame *frame)
+{
+	if (!processor || !processor->ptr || !frame || !frame->ptr) {
+		return OAKRENDER_E_INVALID;
+	}
+	try {
+		// In-place: ColorProcessor::convert_frame() applies the CPU
+		// processor to the frame's pixel buffer through an
+		// OCIO::PackedImageDesc view. A processor whose underlying OCIO
+		// processor is null (creation failure was non-fatal) is a
+		// pass-through and still reports success, mirroring the C++ API.
+		processor->ptr->convert_frame(frame->ptr);
+		return OAKRENDER_OK;
+	} catch (...) {
+		return OAKRENDER_E_FAILED;
+	}
+}