First Commit

Projects/02_ClassroomTimer/countdown.h

@@ -0,0 +1,23 @@
+#pragma once
+#include <QtGlobal>
+
+// 界面负责取得当前时间，模型只负责计算；测试可传入确定的毫秒数。
+class Countdown {
+public:
+    enum class State { Ready, Running, Paused, Finished };
+    explicit Countdown(qint64 durationMs = 300000);
+    bool setDuration(qint64 durationMs);
+    void start(qint64 nowMs);
+    void pause(qint64 nowMs);
+    void reset();
+    void update(qint64 nowMs);
+    qint64 remaining(qint64 nowMs) const;
+    qint64 duration() const { return m_duration; }
+    State state() const { return m_state; }
+private:
+    qint64 m_duration;
+    qint64 m_remainingAtStart;
+    qint64 m_segmentStarted = 0;
+    State m_state = State::Ready;
+};
+