Add Material 3 candidate window addon for Fcitx5

Fork of the classicui addon (Fcitx5 5.1.23) with a Material 3 look, spring
based animations and a right click action menu for candidates.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/common.h

@@ -0,0 +1,46 @@
+/*
+ * SPDX-FileCopyrightText: 2020-2020 CSSlayer <wengxt@gmail.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ */
+#ifndef _FCITX5_UI_CLASSIC_COMMON_H_
+#define _FCITX5_UI_CLASSIC_COMMON_H_
+
+#include <memory>
+#include <glib-object.h>
+#include <yoga/YGNode.h>
+#include "fcitx-utils/log.h"
+#include "fcitx-utils/misc.h"
+
+namespace fcitx::m3ui {
+
+template <typename T>
+using GObjectUniquePtr = UniqueCPtr<T, g_object_unref>;
+
+template <auto Getter>
+float absolute(YGNodeRef node) {
+    float offset = 0.0F;
+    while (node) {
+        offset += Getter(node);
+        node = YGNodeGetParent(node);
+    }
+    return offset;
+}
+
+template <auto Getter, typename T, typename Deleter>
+float absolute(const std::unique_ptr<T, Deleter> &node) {
+    return absolute<Getter>(node.get());
+}
+
+FCITX_DECLARE_LOG_CATEGORY(m3ui_logcategory);
+#define CLASSICUI_DEBUG()                                                      \
+    FCITX_LOGC(::fcitx::m3ui::m3ui_logcategory, Debug)
+#define CLASSICUI_ERROR()                                                      \
+    FCITX_LOGC(::fcitx::m3ui::m3ui_logcategory, Error)
+#define CLASSICUI_INFO()                                                       \
+    FCITX_LOGC(::fcitx::m3ui::m3ui_logcategory, Info)
+
+} // namespace fcitx::m3ui
+
+#endif // _FCITX5_UI_CLASSIC_COMMON_H_