Magpie/tools/WindowCase/WindowBase.h

#pragma once

template <typename T>
class WindowBaseT {
public:
	WindowBaseT() noexcept = default;
	WindowBaseT(const WindowBaseT&) = delete;
	WindowBaseT(WindowBaseT&&) noexcept = default;

	HWND Handle() const noexcept {
		return _hWnd;
	}

	operator bool() const noexcept {
		return _hWnd;
	}

	void Destroy() const noexcept {
		if (_hWnd) {
			DestroyWindow(_hWnd);
		}
	}

protected:
	// 确保无法通过基类指针删除这个对象
	~WindowBaseT() noexcept {
		Destroy();
	}

	static LRESULT CALLBACK _WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {
		if (msg == WM_NCCREATE) {
			WindowBaseT* that = (WindowBaseT*)(((CREATESTRUCT*)lParam)->lpCreateParams);
			assert(that && !that->_hWnd);
			that->_hWnd = hWnd;
			SetWindowLongPtr(hWnd, GWLP_USERDATA, (LONG_PTR)that);
		} else if (T* that = (T*)GetWindowLongPtr(hWnd, GWLP_USERDATA)) {
			return that->_MessageHandler(msg, wParam, lParam);
		}

		return DefWindowProc(hWnd, msg, wParam, lParam);
	}

	LRESULT _MessageHandler(UINT msg, WPARAM wParam, LPARAM lParam) noexcept {
		switch (msg) {
		case WM_CREATE:
		{
			// 出于简单性考虑，不处理 DPI 更改
			_dpiScale = GetDpiForWindow(Handle()) / double(USER_DEFAULT_SCREEN_DPI);

			_hUIFont = CreateFont(
				std::lround(20 * _DpiScale()),
				0,
				0,
				0,
				FW_NORMAL,
				FALSE,
				FALSE,
				FALSE,
				DEFAULT_CHARSET,
				OUT_DEFAULT_PRECIS,
				CLIP_DEFAULT_PRECIS,
				DEFAULT_QUALITY,
				DEFAULT_PITCH | FF_DONTCARE,
				L"Microsoft YaHei UI"
			);

			return 0;
		}
		case WM_DESTROY:
		{
			_hWnd = NULL;
			return 0;
		}
		}

		return DefWindowProc(_hWnd, msg, wParam, lParam);
	}

	HFONT _UIFont() const noexcept {
		return _hUIFont;
	}

	double _DpiScale() const noexcept {
		return _dpiScale;
	}

private:
	HWND _hWnd = NULL;
	HFONT _hUIFont = NULL;
	double _dpiScale = 1.0;
};