Add wgc demo

demo/Win32WindowEnumeration.h

@@ -0,0 +1,101 @@
+#pragma once
+#include <dwmapi.h>
+
+struct Window {
+public:
+  Window(nullptr_t) {}
+  Window(HWND hwnd, std::wstring const &title, std::wstring &className) {
+    m_hwnd = hwnd;
+    m_title = title;
+    m_className = className;
+  }
+
+  HWND Hwnd() const noexcept { return m_hwnd; }
+  std::wstring Title() const noexcept { return m_title; }
+  std::wstring ClassName() const noexcept { return m_className; }
+
+private:
+  HWND m_hwnd;
+  std::wstring m_title;
+  std::wstring m_className;
+};
+
+std::wstring GetClassName(HWND hwnd) {
+  std::array<WCHAR, 1024> className;
+
+  ::GetClassName(hwnd, className.data(), (int)className.size());
+
+  std::wstring title(className.data());
+  return title;
+}
+
+std::wstring GetWindowText(HWND hwnd) {
+  std::array<WCHAR, 1024> windowText;
+
+  ::GetWindowText(hwnd, windowText.data(), (int)windowText.size());
+
+  std::wstring title(windowText.data());
+  return title;
+}
+
+bool IsAltTabWindow(Window const &window) {
+  HWND hwnd = window.Hwnd();
+  HWND shellWindow = GetShellWindow();
+
+  auto title = window.Title();
+  auto className = window.ClassName();
+
+  if (hwnd == shellWindow) {
+    return false;
+  }
+
+  if (title.length() == 0) {
+    return false;
+  }
+
+  if (!IsWindowVisible(hwnd)) {
+    return false;
+  }
+
+  if (GetAncestor(hwnd, GA_ROOT) != hwnd) {
+    return false;
+  }
+
+  LONG style = GetWindowLong(hwnd, GWL_STYLE);
+  if (!((style & WS_DISABLED) != WS_DISABLED)) {
+    return false;
+  }
+
+  DWORD cloaked = FALSE;
+  HRESULT hrTemp =
+      DwmGetWindowAttribute(hwnd, DWMWA_CLOAKED, &cloaked, sizeof(cloaked));
+  if (SUCCEEDED(hrTemp) && cloaked == DWM_CLOAKED_SHELL) {
+    return false;
+  }
+
+  return true;
+}
+
+BOOL CALLBACK EnumWindowsProc(HWND hwnd, LPARAM lParam) {
+  auto class_name = GetClassName(hwnd);
+  auto title = GetWindowText(hwnd);
+
+  auto window = Window(hwnd, title, class_name);
+
+  if (!IsAltTabWindow(window)) {
+    return TRUE;
+  }
+
+  std::vector<Window> &windows =
+      *reinterpret_cast<std::vector<Window> *>(lParam);
+  windows.push_back(window);
+
+  return TRUE;
+}
+
+const std::vector<Window> EnumerateWindows() {
+  std::vector<Window> windows;
+  EnumWindows(EnumWindowsProc, reinterpret_cast<LPARAM>(&windows));
+
+  return windows;
+}