Add NightShot source

include/overlay.hpp

@@ -0,0 +1,31 @@
+#pragma once
+#include "capture.hpp"
+#include "config.hpp"
+#include <windows.h>
+
+enum class OverlayMode {
+    Screenshot,
+    GifQuick,
+};
+
+class OverlayWindow {
+public:
+    static HWND create(HINSTANCE instance, ScreenCapture&& capture,
+                       HWND notificationTarget,
+                       OverlayMode mode = OverlayMode::Screenshot);
+
+private:
+    OverlayWindow(ScreenCapture&& capture, HWND notificationTarget,
+                  OverlayMode mode);
+    ~OverlayWindow();
+    OverlayWindow(const OverlayWindow&) = delete;
+    OverlayWindow& operator=(const OverlayWindow&) = delete;
+
+    static LRESULT CALLBACK windowProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam);
+    LRESULT handleMessage(UINT message, WPARAM wParam, LPARAM lParam);
+
+    struct Impl;
+    Impl* impl_;
+    int dispatchDepth_ = 0;
+    bool deletePending_ = false;
+};