Initial commit: MouseHighlighter project

A lightweight Windows mouse highlight overlay tool with halo circle
and click ripple animations, built with C++17 and Win32 API.

include/SharedState.h

@@ -0,0 +1,96 @@
+#pragma once
+
+#include <atomic>
+#include <array>
+#include <cstdint>
+#include <cstring>
+#include <windows.h>
+
+// 对齐至缓存行 (64 字节) 避免伪共享
+#pragma pack(push, 8)
+
+/**
+ * @brief 点击事件结构 - 无锁环形队列中的单个元素
+ */
+struct ClickEvent {
+    int32_t x, y;           // 屏幕坐标
+    uint32_t timestamp;     // GetTickCount64() 毫秒戳
+    uint8_t button;         // 0=Left, 1=Right, 2=Middle
+};
+
+/**
+ * @brief 钩子线程与渲染线程间的共享状态
+ * 
+ * - 钩子线程写入：cursorX, cursorY, isDirty, clickQueue
+ * - 渲染线程读取：同上
+ * - 所有操作无锁，仅原子变量
+ */
+struct alignas(64) SharedMouseState {
+    // 鼠标实时坐标 - 钩子线程写，渲染线程读
+    std::atomic<int32_t> cursorX{0};
+    std::atomic<int32_t> cursorY{0};
+    
+    // 脏标记 - 通知渲染线程需要更新
+    std::atomic<bool> isDirty{false};
+    
+    // 点击事件环形队列
+    static constexpr size_t MAX_CLICK_EVENTS = 8;
+    std::array<ClickEvent, MAX_CLICK_EVENTS> clickQueue{};
+    
+    // 环形队列指针 - 只能单调递增
+    // 注意: 不追回溯，无需 CAS；仅需 load/store 序列化
+    std::atomic<uint8_t> clickHead{0};  // 写指针 (钩子线程写)
+    std::atomic<uint8_t> clickTail{0};  // 读指针 (渲染线程读)
+    
+    /**
+     * @brief 钩子线程调用 - 尝试入队一个点击事件
+     * @return true 成功入队，false 队列满
+     */
+    bool TryEnqueueClick(int32_t x, int32_t y, uint8_t button) noexcept {
+        uint8_t head = clickHead.load(std::memory_order_relaxed);
+        uint8_t tail = clickTail.load(std::memory_order_acquire);
+        
+        // 检查队列是否满
+        uint8_t nextHead = (head + 1) % MAX_CLICK_EVENTS;
+        if (nextHead == tail) {
+            return false;  // 队列满，丢弃
+        }
+        
+        // 写入事件
+        clickQueue[head].x = x;
+        clickQueue[head].y = y;
+        clickQueue[head].timestamp = GetTickCount();
+        clickQueue[head].button = button;
+        
+        // 推进写指针
+        clickHead.store(nextHead, std::memory_order_release);
+        isDirty.store(true, std::memory_order_release);
+        return true;
+    }
+    
+    /**
+     * @brief 渲染线程调用 - 尝试出队一个点击事件
+     * @return true 成功出队到 event，false 队列空
+     */
+    bool TryDequeueClick(ClickEvent& event) noexcept {
+        uint8_t head = clickHead.load(std::memory_order_acquire);
+        uint8_t tail = clickTail.load(std::memory_order_relaxed);
+        
+        if (tail == head) {
+            return false;  // 队列空
+        }
+        
+        // 读取事件
+        event = clickQueue[tail];
+        
+        // 推进读指针
+        clickTail.store((tail + 1) % MAX_CLICK_EVENTS, std::memory_order_release);
+        return true;
+    }
+};
+
+#pragma pack(pop)
+
+// 编译期检查
+static_assert(sizeof(SharedMouseState) <= 256, "SharedMouseState should not exceed 256 bytes");
+static_assert(alignof(SharedMouseState) == 64, "SharedMouseState must be cache-line aligned");