add veilid flutter plugin skeleton

veilid-flutter/example/windows/runner/win32_window.h

@@ -0,0 +1,98 @@
+#ifndef RUNNER_WIN32_WINDOW_H_
+#define RUNNER_WIN32_WINDOW_H_
+
+#include <windows.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+
+// A class abstraction for a high DPI-aware Win32 Window. Intended to be
+// inherited from by classes that wish to specialize with custom
+// rendering and input handling
+class Win32Window {
+ public:
+  struct Point {
+    unsigned int x;
+    unsigned int y;
+    Point(unsigned int x, unsigned int y) : x(x), y(y) {}
+  };
+
+  struct Size {
+    unsigned int width;
+    unsigned int height;
+    Size(unsigned int width, unsigned int height)
+        : width(width), height(height) {}
+  };
+
+  Win32Window();
+  virtual ~Win32Window();
+
+  // Creates and shows a win32 window with |title| and position and size using
+  // |origin| and |size|. New windows are created on the default monitor. Window
+  // sizes are specified to the OS in physical pixels, hence to ensure a
+  // consistent size to will treat the width height passed in to this function
+  // as logical pixels and scale to appropriate for the default monitor. Returns
+  // true if the window was created successfully.
+  bool CreateAndShow(const std::wstring& title,
+                     const Point& origin,
+                     const Size& size);
+
+  // Release OS resources associated with window.
+  void Destroy();
+
+  // Inserts |content| into the window tree.
+  void SetChildContent(HWND content);
+
+  // Returns the backing Window handle to enable clients to set icon and other
+  // window properties. Returns nullptr if the window has been destroyed.
+  HWND GetHandle();
+
+  // If true, closing this window will quit the application.
+  void SetQuitOnClose(bool quit_on_close);
+
+  // Return a RECT representing the bounds of the current client area.
+  RECT GetClientArea();
+
+ protected:
+  // Processes and route salient window messages for mouse handling,
+  // size change and DPI. Delegates handling of these to member overloads that
+  // inheriting classes can handle.
+  virtual LRESULT MessageHandler(HWND window,
+                                 UINT const message,
+                                 WPARAM const wparam,
+                                 LPARAM const lparam) noexcept;
+
+  // Called when CreateAndShow is called, allowing subclass window-related
+  // setup. Subclasses should return false if setup fails.
+  virtual bool OnCreate();
+
+  // Called when Destroy is called.
+  virtual void OnDestroy();
+
+ private:
+  friend class WindowClassRegistrar;
+
+  // OS callback called by message pump. Handles the WM_NCCREATE message which
+  // is passed when the non-client area is being created and enables automatic
+  // non-client DPI scaling so that the non-client area automatically
+  // responsponds to changes in DPI. All other messages are handled by
+  // MessageHandler.
+  static LRESULT CALLBACK WndProc(HWND const window,
+                                  UINT const message,
+                                  WPARAM const wparam,
+                                  LPARAM const lparam) noexcept;
+
+  // Retrieves a class instance pointer for |window|
+  static Win32Window* GetThisFromHandle(HWND const window) noexcept;
+
+  bool quit_on_close_ = false;
+
+  // window handle for top level window.
+  HWND window_handle_ = nullptr;
+
+  // window handle for hosted content.
+  HWND child_content_ = nullptr;
+};
+
+#endif  // RUNNER_WIN32_WINDOW_H_