[feat] add HarmonyOS desktop and mobile clients，issue #117

apps/harmony/desktop-port/pointer.h

@@ -0,0 +1,34 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-10-15
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _POINTER_H_
+#define _POINTER_H_
+
+#include <array>
+#include <utility>
+
+namespace crossdesk::harmony::desktop {
+// Preserve each button's last position. Cancellation/focus loss must release
+// every held button, while merely leaving the surface must preserve a drag.
+class PointerState {
+  std::array<bool, 3> pressed_{};
+  float x_ = 0, y_ = 0;
+ public:
+  void Update(int kind, int button, float x, float y) {
+    x_ = x; y_ = y;
+    if (button >= 0 && button < 3 && (kind == 0 || kind == 1)) pressed_[button] = kind == 0;
+  }
+  unsigned Buttons() const {
+    return (pressed_[0] ? 1u : 0u) | (pressed_[1] ? 4u : 0u) | (pressed_[2] ? 2u : 0u);
+  }
+  template<class Release> void Cancel(Release release) {
+    const auto pressed = std::exchange(pressed_, {});
+    for (int i = 0; i < 3; ++i) if (pressed[i]) release(i, x_, y_);
+  }
+};
+}
+
+#endif