win32_v.cpp

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "../stdafx.h"
#include "../openttd.h"
#include "../error_func.h"
#include "../gfx_func.h"
#include "../os/windows/win32.h"
#include "../blitter/factory.hpp"
#include "../core/geometry_func.hpp"
#include "../core/math_func.hpp"
#include "../core/random_func.hpp"
#include "../texteff.hpp"
#include "../thread.h"
#include "../progress.h"
#include "../window_gui.h"
#include "../window_func.h"
#include "../framerate_type.h"
#include "../library_loader.h"
#include "../core/utf8.hpp"
#include "win32_v.h"
#include <windows.h>
#include <imm.h>
#include <versionhelpers.h>
#if defined(_MSC_VER) && defined(NTDDI_WIN10_RS4)
#include <winrt/Windows.UI.ViewManagement.h>
#endif
 
#ifdef WITH_OPENGL
#include <GL/gl.h>
#include "../3rdparty/opengl/glext.h"
#include "../3rdparty/opengl/wglext.h"
#include "opengl.h"
#endif /* WITH_OPENGL */
 
#include "../safeguards.h"
 
/* Missing define in MinGW headers. */
#ifndef MAPVK_VK_TO_CHAR
#define MAPVK_VK_TO_CHAR    (2)
#endif
 
#ifndef PM_QS_INPUT
#define PM_QS_INPUT 0x20000
#endif
 
#ifndef WM_DPICHANGED
#define WM_DPICHANGED 0x02E0
#endif
 
bool _window_maximize;
static Dimension _bck_resolution;
DWORD _imm_props;
 
static Palette _local_palette; 
 
bool VideoDriver_Win32Base::ClaimMousePointer()
{
  MyShowCursor(false, true);
  return true;
}
 
struct Win32VkMapping {
  uint8_t vk_from;
  uint8_t vk_count;
  uint8_t map_to;
};
 
#define AS(x, z) {x, 1, z}
#define AM(x, y, z, w) {x, y - x + 1, z}
 
static const Win32VkMapping _vk_mapping[] = {
  /* Pageup stuff + up/down */
  AM(VK_PRIOR, VK_DOWN, WKC_PAGEUP, WKC_DOWN),
  /* Map letters & digits */
  AM('A', 'Z', 'A', 'Z'),
  AM('0', '9', '0', '9'),
 
  AS(VK_ESCAPE,   WKC_ESC),
  AS(VK_PAUSE,    WKC_PAUSE),
  AS(VK_BACK,     WKC_BACKSPACE),
  AM(VK_INSERT,   VK_DELETE, WKC_INSERT, WKC_DELETE),
 
  AS(VK_SPACE,    WKC_SPACE),
  AS(VK_RETURN,   WKC_RETURN),
  AS(VK_TAB,      WKC_TAB),
 
  /* Function keys */
  AM(VK_F1, VK_F12, WKC_F1, WKC_F12),
 
  /* Numeric part */
  AM(VK_NUMPAD0, VK_NUMPAD9, '0', '9'),
  AS(VK_DIVIDE,   WKC_NUM_DIV),
  AS(VK_MULTIPLY, WKC_NUM_MUL),
  AS(VK_SUBTRACT, WKC_NUM_MINUS),
  AS(VK_ADD,      WKC_NUM_PLUS),
  AS(VK_DECIMAL,  WKC_NUM_DECIMAL),
 
  /* Other non-letter keys */
  AS(0xBF,  WKC_SLASH),
  AS(0xBA,  WKC_SEMICOLON),
  AS(0xBB,  WKC_EQUALS),
  AS(0xDB,  WKC_L_BRACKET),
  AS(0xDC,  WKC_BACKSLASH),
  AS(0xDD,  WKC_R_BRACKET),
 
  AS(0xDE,  WKC_SINGLEQUOTE),
  AS(0xBC,  WKC_COMMA),
  AS(0xBD,  WKC_MINUS),
  AS(0xBE,  WKC_PERIOD)
};
 
static uint MapWindowsKey(uint sym)
{
  uint key = 0;
 
  for (const auto &map : _vk_mapping) {
    if (IsInsideBS(sym, map.vk_from, map.vk_count)) {
      key = sym - map.vk_from + map.map_to;
      break;
    }
  }
 
  if (GetAsyncKeyState(VK_SHIFT)   < 0) key |= WKC_SHIFT;
  if (GetAsyncKeyState(VK_CONTROL) < 0) key |= WKC_CTRL;
  if (GetAsyncKeyState(VK_MENU)    < 0) key |= WKC_ALT;
  return key;
}
 
uint8_t VideoDriver_Win32Base::GetFullscreenBpp()
{
  /* Check modes for the relevant fullscreen bpp */
  return _support8bpp != S8BPP_HARDWARE ? 32 : BlitterFactory::GetCurrentBlitter()->GetScreenDepth();
}
 
bool VideoDriver_Win32Base::MakeWindow(bool full_screen, bool resize)
{
  /* full_screen is whether the new window should be fullscreen,
   * _wnd.fullscreen is whether the current window is. */
  _fullscreen = full_screen;
 
  /* recreate window? */
  if ((full_screen != this->fullscreen) && this->main_wnd) {
    DestroyWindow(this->main_wnd);
    this->main_wnd = 0;
  }
 
  if (full_screen) {
    DEVMODE settings{};
    settings.dmSize = sizeof(settings);
    settings.dmFields =
      DM_BITSPERPEL |
      DM_PELSWIDTH |
      DM_PELSHEIGHT;
    settings.dmBitsPerPel = this->GetFullscreenBpp();
    settings.dmPelsWidth  = this->width_org;
    settings.dmPelsHeight = this->height_org;
 
    /* Check for 8 bpp support. */
    if (settings.dmBitsPerPel == 8 && ChangeDisplaySettings(&settings, CDS_FULLSCREEN | CDS_TEST) != DISP_CHANGE_SUCCESSFUL) {
      settings.dmBitsPerPel = 32;
    }
 
    /* Test fullscreen with current resolution, if it fails use desktop resolution. */
    if (ChangeDisplaySettings(&settings, CDS_FULLSCREEN | CDS_TEST) != DISP_CHANGE_SUCCESSFUL) {
      RECT r;
      GetWindowRect(GetDesktopWindow(), &r);
      /* Guard against recursion. If we already failed here once, just fall through to
       * the next ChangeDisplaySettings call which will fail and error out appropriately. */
      if ((int)settings.dmPelsWidth != r.right - r.left || (int)settings.dmPelsHeight != r.bottom - r.top) {
        return this->ChangeResolution(r.right - r.left, r.bottom - r.top);
      }
    }
 
    if (ChangeDisplaySettings(&settings, CDS_FULLSCREEN) != DISP_CHANGE_SUCCESSFUL) {
      this->MakeWindow(false, resize);  // don't care about the result
      return false;  // the request failed
    }
  } else if (this->fullscreen) {
    /* restore display? */
    ChangeDisplaySettings(nullptr, 0);
    /* restore the resolution */
    this->width = _bck_resolution.width;
    this->height = _bck_resolution.height;
  }
 
  {
    RECT r;
    DWORD style, showstyle;
    int w, h;
 
    showstyle = SW_SHOWNORMAL;
    this->fullscreen = full_screen;
    if (this->fullscreen) {
      style = WS_POPUP;
      SetRect(&r, 0, 0, this->width_org, this->height_org);
    } else {
      style = WS_OVERLAPPEDWINDOW;
      /* On window creation, check if we were in maximize mode before */
      if (_window_maximize) showstyle = SW_SHOWMAXIMIZED;
      SetRect(&r, 0, 0, this->width, this->height);
    }
 
    AdjustWindowRect(&r, style, FALSE);
    w = r.right - r.left;
    h = r.bottom - r.top;
 
    if (this->main_wnd != nullptr) {
      if (!_window_maximize && resize) SetWindowPos(this->main_wnd, 0, 0, 0, w, h, SWP_NOACTIVATE | SWP_NOOWNERZORDER | SWP_NOZORDER | SWP_NOMOVE);
    } else {
      int x = 0;
      int y = 0;
 
      /* For windowed mode, center on the workspace of the primary display. */
      if (!this->fullscreen) {
        MONITORINFO mi;
        mi.cbSize = sizeof(mi);
        GetMonitorInfo(MonitorFromWindow(0, MONITOR_DEFAULTTOPRIMARY), &mi);
 
        x = (mi.rcWork.right - mi.rcWork.left - w) / 2;
        y = (mi.rcWork.bottom - mi.rcWork.top - h) / 2;
      }
 
      std::string caption = VideoDriver::GetCaption();
      this->main_wnd = CreateWindow(L"OTTD", OTTD2FS(caption).c_str(), style, x, y, w, h, 0, 0, GetModuleHandle(nullptr), this);
      if (this->main_wnd == nullptr) UserError("CreateWindow failed");
      ShowWindow(this->main_wnd, showstyle);
    }
  }
 
  BlitterFactory::GetCurrentBlitter()->PostResize();
 
  GameSizeChanged();
  return true;
}
 
static LRESULT HandleCharMsg(uint keycode, char32_t charcode)
{
  static char32_t prev_char = 0;
 
  /* Did we get a lead surrogate? If yes, store and exit. */
  if (Utf16IsLeadSurrogate(charcode)) {
    if (prev_char != 0) Debug(driver, 1, "Got two UTF-16 lead surrogates, dropping the first one");
    prev_char = charcode;
    return 0;
  }
 
  /* Stored lead surrogate and incoming trail surrogate? Combine and forward to input handling. */
  if (prev_char != 0) {
    if (Utf16IsTrailSurrogate(charcode)) {
      charcode = Utf16DecodeSurrogate(prev_char, charcode);
    } else {
      Debug(driver, 1, "Got an UTF-16 lead surrogate without a trail surrogate, dropping the lead surrogate");
    }
  }
  prev_char = 0;
 
  HandleKeypress(keycode, charcode);
 
  return 0;
}
 
static bool DrawIMECompositionString()
{
  return (_imm_props & IME_PROP_AT_CARET) && !(_imm_props & IME_PROP_SPECIAL_UI);
}
 
static void SetCompositionPos(HWND hwnd)
{
  HIMC hIMC = ImmGetContext(hwnd);
  if (hIMC != nullptr) {
    COMPOSITIONFORM cf;
    cf.dwStyle = CFS_POINT;
 
    if (EditBoxInGlobalFocus()) {
      /* Get caret position. */
      Point pt = _focused_window->GetCaretPosition();
      cf.ptCurrentPos.x = _focused_window->left + pt.x;
      cf.ptCurrentPos.y = _focused_window->top  + pt.y;
    } else {
      cf.ptCurrentPos.x = 0;
      cf.ptCurrentPos.y = 0;
    }
    ImmSetCompositionWindow(hIMC, &cf);
  }
  ImmReleaseContext(hwnd, hIMC);
}
 
static void SetCandidatePos(HWND hwnd)
{
  HIMC hIMC = ImmGetContext(hwnd);
  if (hIMC != nullptr) {
    CANDIDATEFORM cf;
    cf.dwIndex = 0;
    cf.dwStyle = CFS_EXCLUDE;
 
    if (EditBoxInGlobalFocus()) {
      Point pt = _focused_window->GetCaretPosition();
      cf.ptCurrentPos.x = _focused_window->left + pt.x;
      cf.ptCurrentPos.y = _focused_window->top  + pt.y;
      if (_focused_window->window_class == WC_CONSOLE) {
        cf.rcArea.left   = _focused_window->left;
        cf.rcArea.top    = _focused_window->top;
        cf.rcArea.right  = _focused_window->left + _focused_window->width;
        cf.rcArea.bottom = _focused_window->top  + _focused_window->height;
      } else {
        cf.rcArea.left   = _focused_window->left + _focused_window->nested_focus->pos_x;
        cf.rcArea.top    = _focused_window->top  + _focused_window->nested_focus->pos_y;
        cf.rcArea.right  = cf.rcArea.left + _focused_window->nested_focus->current_x;
        cf.rcArea.bottom = cf.rcArea.top  + _focused_window->nested_focus->current_y;
      }
    } else {
      cf.ptCurrentPos.x = 0;
      cf.ptCurrentPos.y = 0;
      SetRectEmpty(&cf.rcArea);
    }
    ImmSetCandidateWindow(hIMC, &cf);
  }
  ImmReleaseContext(hwnd, hIMC);
}
 
static LRESULT HandleIMEComposition(HWND hwnd, WPARAM wParam, LPARAM lParam)
{
  HIMC hIMC = ImmGetContext(hwnd);
 
  if (hIMC != nullptr) {
    if (lParam & GCS_RESULTSTR) {
      /* Read result string from the IME. */
      LONG len = ImmGetCompositionString(hIMC, GCS_RESULTSTR, nullptr, 0); // Length is always in bytes, even in UNICODE build.
      std::wstring str(len + 1, L'\0');
      len = ImmGetCompositionString(hIMC, GCS_RESULTSTR, str.data(), len);
      str[len / sizeof(wchar_t)] = L'\0';
 
      /* Transmit text to windowing system. */
      if (len > 0) {
        HandleTextInput({}, true); // Clear marked string.
        HandleTextInput(FS2OTTD(str));
      }
      SetCompositionPos(hwnd);
 
      /* Don't pass the result string on to the default window proc. */
      lParam &= ~(GCS_RESULTSTR | GCS_RESULTCLAUSE | GCS_RESULTREADCLAUSE | GCS_RESULTREADSTR);
    }
 
    if ((lParam & GCS_COMPSTR) && DrawIMECompositionString()) {
      /* Read composition string from the IME. */
      LONG len = ImmGetCompositionString(hIMC, GCS_COMPSTR, nullptr, 0); // Length is always in bytes, even in UNICODE build.
      std::wstring str(len + 1, L'\0');
      len = ImmGetCompositionString(hIMC, GCS_COMPSTR, str.data(), len);
      str[len / sizeof(wchar_t)] = L'\0';
 
      if (len > 0) {
        static char utf8_buf[1024];
        convert_from_fs(str, utf8_buf);
 
        /* Convert caret position from bytes in the input string to a position in the UTF-8 encoded string. */
        LONG caret_bytes = ImmGetCompositionString(hIMC, GCS_CURSORPOS, nullptr, 0);
        Utf8View view(utf8_buf);
        auto caret = view.begin();
        const auto end = view.end();
        for (const wchar_t *c = str.c_str(); *c != '\0' && caret != end && caret_bytes > 0; c++, caret_bytes--) {
          /* Skip DBCS lead bytes or leading surrogates. */
          if (Utf16IsLeadSurrogate(*c)) {
            c++;
            caret_bytes--;
          }
          ++caret;
        }
 
        HandleTextInput(utf8_buf, true, caret.GetByteOffset());
      } else {
        HandleTextInput({}, true);
      }
 
      lParam &= ~(GCS_COMPSTR | GCS_COMPATTR | GCS_COMPCLAUSE | GCS_CURSORPOS | GCS_DELTASTART);
    }
  }
  ImmReleaseContext(hwnd, hIMC);
 
  return lParam != 0 ? DefWindowProc(hwnd, WM_IME_COMPOSITION, wParam, lParam) : 0;
}
 
static void CancelIMEComposition(HWND hwnd)
{
  HIMC hIMC = ImmGetContext(hwnd);
  if (hIMC != nullptr) ImmNotifyIME(hIMC, NI_COMPOSITIONSTR, CPS_CANCEL, 0);
  ImmReleaseContext(hwnd, hIMC);
  /* Clear any marked string from the current edit box. */
  HandleTextInput({}, true);
}
 
#if defined(_MSC_VER) && defined(NTDDI_WIN10_RS4)
/* We only use WinRT functions on Windows 10 or later. Unfortunately, newer Windows SDKs are now
 * linking the two functions below directly instead of using dynamic linking as previously.
 * To avoid any runtime linking errors on Windows 7 or older, we stub in our own dynamic
 * linking trampoline. */
 
static LibraryLoader _combase("combase.dll");
 
extern "C" int32_t __stdcall WINRT_IMPL_RoOriginateLanguageException(int32_t error, void *message, void *languageException) noexcept
{
  typedef BOOL(WINAPI *PFNRoOriginateLanguageException)(int32_t, void *, void *);
  static PFNRoOriginateLanguageException RoOriginateLanguageException = _combase.GetFunction("RoOriginateLanguageException");
 
  if (RoOriginateLanguageException != nullptr) {
    return RoOriginateLanguageException(error, message, languageException);
  } else {
    return TRUE;
  }
}
 
extern "C" int32_t __stdcall WINRT_IMPL_RoGetActivationFactory(void *classId, winrt::guid const &iid, void **factory) noexcept
{
  typedef BOOL(WINAPI *PFNRoGetActivationFactory)(void *, winrt::guid const &, void **);
  static PFNRoGetActivationFactory RoGetActivationFactory = _combase.GetFunction("RoGetActivationFactory");
 
  if (RoGetActivationFactory != nullptr) {
    return RoGetActivationFactory(classId, iid, factory);
  } else {
    *factory = nullptr;
    return winrt::impl::error_class_not_available;
  }
}
#endif
 
static bool IsDarkModeEnabled()
{
  /* Only build if SDK is Windows 10 1803 or later. */
#if defined(_MSC_VER) && defined(NTDDI_WIN10_RS4)
  if (IsWindows10OrGreater()) {
    try {
      /*
       * The official documented way to find out if the system is running in dark mode is to
       * check the brightness of the current theme's colour.
       * See: https://learn.microsoft.com/en-us/windows/apps/desktop/modernize/ui/apply-windows-themes#know-when-dark-mode-is-enabled
       *
       * There are other variants floating around on the Internet, but they all rely on internal,
       * undocumented Windows functions that may or may not work in the future.
       */
      winrt::Windows::UI::ViewManagement::UISettings settings;
      auto foreground = settings.GetColorValue(winrt::Windows::UI::ViewManagement::UIColorType::Foreground);
 
      /* If the Foreground colour is a light colour, the system is running in dark mode. */
      return ((5 * foreground.G) + (2 * foreground.R) + foreground.B) > (8 * 128);
    } catch (...) {
      /* Some kind of error, like a too old Windows version. Just return false. */
      return false;
    }
  }
#endif /* defined(_MSC_VER) && defined(NTDDI_WIN10_RS4) */
 
  return false;
}
 
static void SetDarkModeForWindow(HWND hWnd, bool dark_mode)
{
  /* Only build if SDK is Windows 10+. */
#if defined(NTDDI_WIN10)
  if (!IsWindows10OrGreater()) return;
 
  /* This function is documented, but not supported on all Windows 10/11 SDK builds. For this
   * reason, the code uses dynamic loading and ignores any errors for a best-effort result. */
  static LibraryLoader _dwmapi("dwmapi.dll");
  typedef HRESULT(WINAPI *PFNDWMSETWINDOWATTRIBUTE)(HWND, DWORD, LPCVOID, DWORD);
  static const PFNDWMSETWINDOWATTRIBUTE DwmSetWindowAttribute = _dwmapi.GetFunction("DwmSetWindowAttribute");
 
  if (DwmSetWindowAttribute != nullptr) {
    /* Contrary to the published documentation, DWMWA_USE_IMMERSIVE_DARK_MODE does not change the
     * window chrome according to the current theme, but forces it to either light or dark mode.
     * As such, the set value has to depend on the current theming mode.*/
    BOOL value = dark_mode ? TRUE : FALSE;
    if (DwmSetWindowAttribute(hWnd, 20 /* DWMWA_USE_IMMERSIVE_DARK_MODE */, &value, sizeof(value)) != S_OK) {
      DwmSetWindowAttribute(hWnd, 19 /* DWMWA_USE_IMMERSIVE_DARK_MODE_BEFORE_20H1 */, &value, sizeof(value)); // Ignore errors. It works or it doesn't.
    }
  }
#endif /* defined(NTDDI_WIN10) */
}
 
LRESULT CALLBACK WndProcGdi(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
  static uint32_t keycode = 0;
  static bool console = false;
 
  const float SCROLL_BUILTIN_MULTIPLIER = 14.0f / WHEEL_DELTA;
 
  VideoDriver_Win32Base *video_driver = (VideoDriver_Win32Base *)GetWindowLongPtr(hwnd, GWLP_USERDATA);
 
  switch (msg) {
    case WM_CREATE:
      SetWindowLongPtr(hwnd, GWLP_USERDATA, (LONG_PTR)((LPCREATESTRUCT)lParam)->lpCreateParams);
      _cursor.in_window = false; // Win32 has mouse tracking.
      SetCompositionPos(hwnd);
      _imm_props = ImmGetProperty(GetKeyboardLayout(0), IGP_PROPERTY);
 
      /* Enable dark mode theming for window chrome. */
      SetDarkModeForWindow(hwnd, IsDarkModeEnabled());
      break;
 
    case WM_SETTINGCHANGE:
      /* Synchronize dark mode theming state. */
      SetDarkModeForWindow(hwnd, IsDarkModeEnabled());
      break;
 
    case WM_PAINT: {
      RECT r;
      GetUpdateRect(hwnd, &r, FALSE);
      video_driver->MakeDirty(r.left, r.top, r.right - r.left, r.bottom - r.top);
 
      ValidateRect(hwnd, nullptr);
      return 0;
    }
 
    case WM_PALETTECHANGED:
      if ((HWND)wParam == hwnd) return 0;
      [[fallthrough]];
 
    case WM_QUERYNEWPALETTE:
      video_driver->PaletteChanged(hwnd);
      return 0;
 
    case WM_CLOSE:
      HandleExitGameRequest();
      return 0;
 
    case WM_DESTROY:
      if (_window_maximize) _cur_resolution = _bck_resolution;
      return 0;
 
    case WM_LBUTTONDOWN:
      SetCapture(hwnd);
      _left_button_down = true;
      HandleMouseEvents();
      return 0;
 
    case WM_LBUTTONUP:
      ReleaseCapture();
      _left_button_down = false;
      _left_button_clicked = false;
      HandleMouseEvents();
      return 0;
 
    case WM_RBUTTONDOWN:
      SetCapture(hwnd);
      _right_button_down = true;
      _right_button_clicked = true;
      HandleMouseEvents();
      return 0;
 
    case WM_RBUTTONUP:
      ReleaseCapture();
      _right_button_down = false;
      HandleMouseEvents();
      return 0;
 
    case WM_MOUSELEAVE:
      UndrawMouseCursor();
      _cursor.in_window = false;
 
      if (!_left_button_down && !_right_button_down) MyShowCursor(true);
      return 0;
 
    case WM_MOUSEMOVE: {
      int x = (int16_t)LOWORD(lParam);
      int y = (int16_t)HIWORD(lParam);
 
      /* If the mouse was not in the window and it has moved it means it has
       * come into the window, so start drawing the mouse. Also start
       * tracking the mouse for exiting the window */
      if (!_cursor.in_window) {
        _cursor.in_window = true;
        TRACKMOUSEEVENT tme;
        tme.cbSize = sizeof(tme);
        tme.dwFlags = TME_LEAVE;
        tme.hwndTrack = hwnd;
 
        TrackMouseEvent(&tme);
      }
 
      if (_cursor.fix_at) {
        /* Get all queued mouse events now in case we have to warp the cursor. In the
         * end, we only care about the current mouse position and not bygone events. */
        MSG m;
        while (PeekMessage(&m, hwnd, WM_MOUSEMOVE, WM_MOUSEMOVE, PM_REMOVE | PM_NOYIELD | PM_QS_INPUT)) {
          x = (int16_t)LOWORD(m.lParam);
          y = (int16_t)HIWORD(m.lParam);
        }
      }
 
      if (_cursor.UpdateCursorPosition(x, y)) {
        POINT pt;
        pt.x = _cursor.pos.x;
        pt.y = _cursor.pos.y;
        ClientToScreen(hwnd, &pt);
        SetCursorPos(pt.x, pt.y);
      }
      MyShowCursor(false);
      HandleMouseEvents();
      return 0;
    }
 
    case WM_INPUTLANGCHANGE:
      _imm_props = ImmGetProperty(GetKeyboardLayout(0), IGP_PROPERTY);
      break;
 
    case WM_IME_SETCONTEXT:
      /* Don't show the composition window if we draw the string ourself. */
      if (DrawIMECompositionString()) lParam &= ~ISC_SHOWUICOMPOSITIONWINDOW;
      break;
 
    case WM_IME_STARTCOMPOSITION:
      SetCompositionPos(hwnd);
      if (DrawIMECompositionString()) return 0;
      break;
 
    case WM_IME_COMPOSITION:
      return HandleIMEComposition(hwnd, wParam, lParam);
 
    case WM_IME_ENDCOMPOSITION:
      /* Clear any pending composition string. */
      HandleTextInput({}, true);
      if (DrawIMECompositionString()) return 0;
      break;
 
    case WM_IME_NOTIFY:
      if (wParam == IMN_OPENCANDIDATE) SetCandidatePos(hwnd);
      break;
 
    case WM_DEADCHAR:
      console = GB(lParam, 16, 8) == 41;
      return 0;
 
    case WM_CHAR: {
      uint scancode = GB(lParam, 16, 8);
      uint charcode = wParam;
 
      /* If the console key is a dead-key, we need to press it twice to get a WM_CHAR message.
       * But we then get two WM_CHAR messages, so ignore the first one */
      if (console && scancode == 41) {
        console = false;
        return 0;
      }
 
      /* IMEs and other input methods sometimes send a WM_CHAR without a WM_KEYDOWN,
       * clear the keycode so a previous WM_KEYDOWN doesn't become 'stuck'. */
      uint cur_keycode = keycode;
      keycode = 0;
 
      return HandleCharMsg(cur_keycode, charcode);
    }
 
    case WM_KEYDOWN: {
      /* No matter the keyboard layout, we will map the '~' to the console. */
      uint scancode = GB(lParam, 16, 8);
      keycode = scancode == 41 ? (uint)WKC_BACKQUOTE : MapWindowsKey(wParam);
 
      uint charcode = MapVirtualKey(wParam, MAPVK_VK_TO_CHAR);
 
      /* No character translation? */
      if (charcode == 0) {
        HandleKeypress(keycode, 0);
        return 0;
      }
 
      /* If an edit box is in focus, wait for the corresponding WM_CHAR message. */
      if (!EditBoxInGlobalFocus()) {
        /* Is the console key a dead key? If yes, ignore the first key down event. */
        if (HasBit(charcode, 31) && !console) {
          if (scancode == 41) {
            console = true;
            return 0;
          }
        }
        console = false;
 
        /* IMEs and other input methods sometimes send a WM_CHAR without a WM_KEYDOWN,
         * clear the keycode so a previous WM_KEYDOWN doesn't become 'stuck'. */
        uint cur_keycode = keycode;
        keycode = 0;
 
        return HandleCharMsg(cur_keycode, LOWORD(charcode));
      }
 
      return 0;
    }
 
    case WM_SYSKEYDOWN: // user presses F10 or Alt, both activating the title-menu
      switch (wParam) {
        case VK_RETURN:
        case 'F': // Full Screen on ALT + ENTER/F
          ToggleFullScreen(!video_driver->fullscreen);
          return 0;
 
        case VK_MENU: // Just ALT
          return 0; // do nothing
 
        case VK_F10: // F10, ignore activation of menu
          HandleKeypress(MapWindowsKey(wParam), 0);
          return 0;
 
        default: // ALT in combination with something else
          HandleKeypress(MapWindowsKey(wParam), 0);
          break;
      }
      break;
 
    case WM_SIZE:
      if (wParam != SIZE_MINIMIZED) {
        /* Set maximized flag when we maximize (obviously), but also when we
         * switched to fullscreen from a maximized state */
        _window_maximize = (wParam == SIZE_MAXIMIZED || (_window_maximize && _fullscreen));
        if (_window_maximize || _fullscreen) _bck_resolution = _cur_resolution;
        video_driver->ClientSizeChanged(LOWORD(lParam), HIWORD(lParam));
      }
      return 0;
 
    case WM_SIZING: {
      RECT *r = (RECT*)lParam;
      RECT r2;
      int w, h;
 
      SetRect(&r2, 0, 0, 0, 0);
      AdjustWindowRect(&r2, GetWindowLong(hwnd, GWL_STYLE), FALSE);
 
      w = r->right - r->left - (r2.right - r2.left);
      h = r->bottom - r->top - (r2.bottom - r2.top);
      w = std::max(w, 64);
      h = std::max(h, 64);
      SetRect(&r2, 0, 0, w, h);
 
      AdjustWindowRect(&r2, GetWindowLong(hwnd, GWL_STYLE), FALSE);
      w = r2.right - r2.left;
      h = r2.bottom - r2.top;
 
      switch (wParam) {
        case WMSZ_BOTTOM:
          r->bottom = r->top + h;
          break;
 
        case WMSZ_BOTTOMLEFT:
          r->bottom = r->top + h;
          r->left = r->right - w;
          break;
 
        case WMSZ_BOTTOMRIGHT:
          r->bottom = r->top + h;
          r->right = r->left + w;
          break;
 
        case WMSZ_LEFT:
          r->left = r->right - w;
          break;
 
        case WMSZ_RIGHT:
          r->right = r->left + w;
          break;
 
        case WMSZ_TOP:
          r->top = r->bottom - h;
          break;
 
        case WMSZ_TOPLEFT:
          r->top = r->bottom - h;
          r->left = r->right - w;
          break;
 
        case WMSZ_TOPRIGHT:
          r->top = r->bottom - h;
          r->right = r->left + w;
          break;
      }
      return TRUE;
    }
 
    case WM_DPICHANGED: {
      auto did_adjust = AdjustGUIZoom(true);
 
      /* Resize the window to match the new DPI setting. */
      RECT *prcNewWindow = (RECT *)lParam;
      SetWindowPos(hwnd,
        nullptr,
        prcNewWindow->left,
        prcNewWindow->top,
        prcNewWindow->right - prcNewWindow->left,
        prcNewWindow->bottom - prcNewWindow->top,
        SWP_NOZORDER | SWP_NOACTIVATE);
 
      if (did_adjust) ReInitAllWindows(true);
 
      return 0;
    }
 
/* needed for wheel */
#if !defined(WM_MOUSEWHEEL)
# define WM_MOUSEWHEEL 0x020A
#endif  /* WM_MOUSEWHEEL */
#if !defined(WM_MOUSEHWHEEL)
# define WM_MOUSEHWHEEL 0x020E
#endif  /* WM_MOUSEHWHEEL */
#if !defined(GET_WHEEL_DELTA_WPARAM)
# define GET_WHEEL_DELTA_WPARAM(wparam) ((short)HIWORD(wparam))
#endif  /* GET_WHEEL_DELTA_WPARAM */
 
    case WM_MOUSEWHEEL: {
      int delta = GET_WHEEL_DELTA_WPARAM(wParam);
 
      if (delta < 0) {
        _cursor.wheel++;
      } else if (delta > 0) {
        _cursor.wheel--;
      }
 
      _cursor.v_wheel -= static_cast<float>(delta) * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier;
      _cursor.wheel_moved = true;
      HandleMouseEvents();
      return 0;
    }
 
    case WM_MOUSEHWHEEL: {
      int delta = GET_WHEEL_DELTA_WPARAM(wParam);
 
      _cursor.h_wheel += static_cast<float>(delta) * SCROLL_BUILTIN_MULTIPLIER * _settings_client.gui.scrollwheel_multiplier;
      _cursor.wheel_moved = true;
      HandleMouseEvents();
      return 0;
    }
 
    case WM_SETFOCUS:
      video_driver->has_focus = true;
      SetCompositionPos(hwnd);
      break;
 
    case WM_KILLFOCUS:
      video_driver->has_focus = false;
      break;
 
    case WM_ACTIVATE: {
      /* Don't do anything if we are closing openttd */
      if (_exit_game) break;
 
      bool active = (LOWORD(wParam) != WA_INACTIVE);
      bool minimized = (HIWORD(wParam) != 0);
      if (video_driver->fullscreen) {
        if (active && minimized) {
          /* Restore the game window */
          Dimension d = _bck_resolution; // Save current non-fullscreen window size as it will be overwritten by ShowWindow.
          ShowWindow(hwnd, SW_RESTORE);
          _bck_resolution = d;
          video_driver->MakeWindow(true);
        } else if (!active && !minimized) {
          /* Minimise the window and restore desktop */
          ShowWindow(hwnd, SW_MINIMIZE);
          ChangeDisplaySettings(nullptr, 0);
        }
      }
      break;
    }
  }
 
  return DefWindowProc(hwnd, msg, wParam, lParam);
}
 
static void RegisterWndClass()
{
  static bool registered = false;
 
  if (registered) return;
 
  HINSTANCE hinst = GetModuleHandle(nullptr);
  WNDCLASS wnd = {
    CS_OWNDC,
    WndProcGdi,
    0,
    0,
    hinst,
    LoadIcon(hinst, MAKEINTRESOURCE(100)),
    LoadCursor(nullptr, IDC_ARROW),
    0,
    0,
    L"OTTD"
  };
 
  registered = true;
  if (!RegisterClass(&wnd)) UserError("RegisterClass failed");
}
 
static const Dimension default_resolutions[] = {
  {  640,  480 },
  {  800,  600 },
  { 1024,  768 },
  { 1152,  864 },
  { 1280,  800 },
  { 1280,  960 },
  { 1280, 1024 },
  { 1400, 1050 },
  { 1600, 1200 },
  { 1680, 1050 },
  { 1920, 1200 }
};
 
static void FindResolutions(uint8_t bpp)
{
  _resolutions.clear();
 
  DEVMODE dm;
  for (uint i = 0; EnumDisplaySettings(nullptr, i, &dm) != 0; i++) {
    if (dm.dmBitsPerPel != bpp || dm.dmPelsWidth < 640 || dm.dmPelsHeight < 480) continue;
    if (std::ranges::find(_resolutions, Dimension(dm.dmPelsWidth, dm.dmPelsHeight)) != _resolutions.end()) continue;
    _resolutions.emplace_back(dm.dmPelsWidth, dm.dmPelsHeight);
  }
 
  /* We have found no resolutions, show the default list */
  if (_resolutions.empty()) {
    _resolutions.assign(std::begin(default_resolutions), std::end(default_resolutions));
  }
 
  SortResolutions();
}
 
void VideoDriver_Win32Base::Initialize()
{
  this->UpdateAutoResolution();
 
  RegisterWndClass();
  FindResolutions(this->GetFullscreenBpp());
 
  /* fullscreen uses those */
  this->width  = this->width_org  = _cur_resolution.width;
  this->height = this->height_org = _cur_resolution.height;
 
  Debug(driver, 2, "Resolution for display: {}x{}", _cur_resolution.width, _cur_resolution.height);
}
 
void VideoDriver_Win32Base::Stop()
{
  DestroyWindow(this->main_wnd);
 
  if (this->fullscreen) ChangeDisplaySettings(nullptr, 0);
  MyShowCursor(true);
}
void VideoDriver_Win32Base::MakeDirty(int left, int top, int width, int height)
{
  Rect r = {left, top, left + width, top + height};
  this->dirty_rect = BoundingRect(this->dirty_rect, r);
}
 
void VideoDriver_Win32Base::CheckPaletteAnim()
{
  if (!CopyPalette(_local_palette)) return;
  this->MakeDirty(0, 0, _screen.width, _screen.height);
}
 
void VideoDriver_Win32Base::InputLoop()
{
  bool old_ctrl_pressed = _ctrl_pressed;
 
  _ctrl_pressed = this->has_focus && GetAsyncKeyState(VK_CONTROL) < 0;
  _shift_pressed = this->has_focus && GetAsyncKeyState(VK_SHIFT) < 0;
 
  /* Speedup when pressing tab, except when using ALT+TAB
   * to switch to another application. */
  this->fast_forward_key_pressed = this->has_focus && GetAsyncKeyState(VK_TAB) < 0 && GetAsyncKeyState(VK_MENU) >= 0;
 
  /* Determine which directional keys are down. */
  if (this->has_focus) {
    _dirkeys =
      (GetAsyncKeyState(VK_LEFT) < 0 ? 1 : 0) +
      (GetAsyncKeyState(VK_UP) < 0 ? 2 : 0) +
      (GetAsyncKeyState(VK_RIGHT) < 0 ? 4 : 0) +
      (GetAsyncKeyState(VK_DOWN) < 0 ? 8 : 0);
  } else {
    _dirkeys = 0;
  }
 
  if (old_ctrl_pressed != _ctrl_pressed) HandleCtrlChanged();
}
 
bool VideoDriver_Win32Base::PollEvent()
{
  MSG mesg;
 
  if (!PeekMessage(&mesg, nullptr, 0, 0, PM_REMOVE)) return false;
 
  /* Convert key messages to char messages if we want text input. */
  if (EditBoxInGlobalFocus()) TranslateMessage(&mesg);
  DispatchMessage(&mesg);
 
  return true;
}
 
void VideoDriver_Win32Base::MainLoop()
{
  this->StartGameThread();
 
  for (;;) {
    if (_exit_game) break;
 
    this->Tick();
    this->SleepTillNextTick();
  }
 
  this->StopGameThread();
}
 
void VideoDriver_Win32Base::ClientSizeChanged(int w, int h, bool force)
{
  /* Allocate backing store of the new size. */
  if (this->AllocateBackingStore(w, h, force)) {
    CopyPalette(_local_palette, true);
 
    BlitterFactory::GetCurrentBlitter()->PostResize();
 
    GameSizeChanged();
  }
}
 
bool VideoDriver_Win32Base::ChangeResolution(int w, int h)
{
  if (_window_maximize) ShowWindow(this->main_wnd, SW_SHOWNORMAL);
 
  this->width = this->width_org = w;
  this->height = this->height_org = h;
 
  return this->MakeWindow(_fullscreen); // _wnd.fullscreen screws up ingame resolution switching
}
 
bool VideoDriver_Win32Base::ToggleFullscreen(bool full_screen)
{
  bool res = this->MakeWindow(full_screen);
 
  InvalidateWindowClassesData(WC_GAME_OPTIONS, 3);
  return res;
}
 
void VideoDriver_Win32Base::EditBoxLostFocus()
{
  CancelIMEComposition(this->main_wnd);
  SetCompositionPos(this->main_wnd);
  SetCandidatePos(this->main_wnd);
}
 
static BOOL CALLBACK MonitorEnumProc(HMONITOR hMonitor, HDC, LPRECT, LPARAM data)
{
  auto &list = *reinterpret_cast<std::vector<int>*>(data);
 
  MONITORINFOEX monitorInfo = {};
  monitorInfo.cbSize = sizeof(MONITORINFOEX);
  GetMonitorInfo(hMonitor, &monitorInfo);
 
  DEVMODE devMode = {};
  devMode.dmSize = sizeof(DEVMODE);
  devMode.dmDriverExtra = 0;
  EnumDisplaySettings(monitorInfo.szDevice, ENUM_CURRENT_SETTINGS, &devMode);
 
  if (devMode.dmDisplayFrequency != 0) list.push_back(devMode.dmDisplayFrequency);
  return true;
}
 
std::vector<int> VideoDriver_Win32Base::GetListOfMonitorRefreshRates()
{
  std::vector<int> rates = {};
  EnumDisplayMonitors(nullptr, nullptr, MonitorEnumProc, reinterpret_cast<LPARAM>(&rates));
  return rates;
}
 
Dimension VideoDriver_Win32Base::GetScreenSize() const
{
  return { static_cast<uint>(GetSystemMetrics(SM_CXSCREEN)), static_cast<uint>(GetSystemMetrics(SM_CYSCREEN)) };
}
 
bool VideoDriver_Win32Base::LockVideoBuffer()
{
  if (this->buffer_locked) return false;
  this->buffer_locked = true;
 
  _screen.dst_ptr = this->GetVideoPointer();
  assert(_screen.dst_ptr != nullptr);
 
  return true;
}
 
void VideoDriver_Win32Base::UnlockVideoBuffer()
{
  assert(_screen.dst_ptr != nullptr);
  if (_screen.dst_ptr != nullptr) {
    /* Hand video buffer back to the drawing backend. */
    this->ReleaseVideoPointer();
    _screen.dst_ptr = nullptr;
  }
 
  this->buffer_locked = false;
}
 
 
static FVideoDriver_Win32GDI iFVideoDriver_Win32GDI;
 
std::optional<std::string_view> VideoDriver_Win32GDI::Start(const StringList &param)
{
  if (BlitterFactory::GetCurrentBlitter()->GetScreenDepth() == 0) return "Only real blitters supported";
 
  this->Initialize();
 
  this->MakePalette();
  this->AllocateBackingStore(_cur_resolution.width, _cur_resolution.height);
  this->MakeWindow(_fullscreen);
 
  MarkWholeScreenDirty();
 
  this->is_game_threaded = !GetDriverParamBool(param, "no_threads") && !GetDriverParamBool(param, "no_thread");
 
  return std::nullopt;
}
 
void VideoDriver_Win32GDI::Stop()
{
  DeleteObject(this->gdi_palette);
  DeleteObject(this->dib_sect);
 
  this->VideoDriver_Win32Base::Stop();
}
 
bool VideoDriver_Win32GDI::AllocateBackingStore(int w, int h, bool force)
{
  uint bpp = BlitterFactory::GetCurrentBlitter()->GetScreenDepth();
 
  w = std::max(w, 64);
  h = std::max(h, 64);
 
  if (!force && w == _screen.width && h == _screen.height) return false;
 
  BITMAPINFO *bi = (BITMAPINFO *)new char[sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD) * 256]();
  bi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
 
  bi->bmiHeader.biWidth = this->width = w;
  bi->bmiHeader.biHeight = -(this->height = h);
 
  bi->bmiHeader.biPlanes = 1;
  bi->bmiHeader.biBitCount = bpp;
  bi->bmiHeader.biCompression = BI_RGB;
 
  if (this->dib_sect) DeleteObject(this->dib_sect);
 
  HDC dc = GetDC(0);
  this->dib_sect = CreateDIBSection(dc, bi, DIB_RGB_COLORS, (VOID **)&this->buffer_bits, nullptr, 0);
  if (this->dib_sect == nullptr) {
    delete[] bi;
    UserError("CreateDIBSection failed");
  }
  ReleaseDC(0, dc);
 
  _screen.width = w;
  _screen.pitch = (bpp == 8) ? Align(w, 4) : w;
  _screen.height = h;
  _screen.dst_ptr = this->GetVideoPointer();
 
  delete[] bi;
  return true;
}
 
bool VideoDriver_Win32GDI::AfterBlitterChange()
{
  assert(BlitterFactory::GetCurrentBlitter()->GetScreenDepth() != 0);
  return this->AllocateBackingStore(_screen.width, _screen.height, true) && this->MakeWindow(_fullscreen, false);
}
 
void VideoDriver_Win32GDI::MakePalette()
{
  CopyPalette(_local_palette, true);
 
  LOGPALETTE *pal = (LOGPALETTE *)new char[sizeof(LOGPALETTE) + (256 - 1) * sizeof(PALETTEENTRY)]();
 
  pal->palVersion = 0x300;
  pal->palNumEntries = 256;
 
  for (uint i = 0; i != 256; i++) {
    pal->palPalEntry[i].peRed   = _local_palette.palette[i].r;
    pal->palPalEntry[i].peGreen = _local_palette.palette[i].g;
    pal->palPalEntry[i].peBlue  = _local_palette.palette[i].b;
    pal->palPalEntry[i].peFlags = 0;
 
  }
  this->gdi_palette = CreatePalette(pal);
  delete[] pal;
  if (this->gdi_palette == nullptr) UserError("CreatePalette failed!\n");
}
 
void VideoDriver_Win32GDI::UpdatePalette(HDC dc, uint start, uint count)
{
  RGBQUAD rgb[256];
 
  for (uint i = 0; i != count; i++) {
    rgb[i].rgbRed   = _local_palette.palette[start + i].r;
    rgb[i].rgbGreen = _local_palette.palette[start + i].g;
    rgb[i].rgbBlue  = _local_palette.palette[start + i].b;
    rgb[i].rgbReserved = 0;
  }
 
  SetDIBColorTable(dc, start, count, rgb);
}
 
void VideoDriver_Win32GDI::PaletteChanged(HWND hWnd)
{
  HDC hDC = GetWindowDC(hWnd);
  HPALETTE hOldPalette = SelectPalette(hDC, this->gdi_palette, FALSE);
  UINT nChanged = RealizePalette(hDC);
 
  SelectPalette(hDC, hOldPalette, TRUE);
  ReleaseDC(hWnd, hDC);
  if (nChanged != 0) this->MakeDirty(0, 0, _screen.width, _screen.height);
}
 
void VideoDriver_Win32GDI::Paint()
{
  PerformanceMeasurer framerate(PFE_VIDEO);
 
  if (IsEmptyRect(this->dirty_rect)) return;
 
  HDC dc = GetDC(this->main_wnd);
  HDC dc2 = CreateCompatibleDC(dc);
 
  HBITMAP old_bmp = (HBITMAP)SelectObject(dc2, this->dib_sect);
  HPALETTE old_palette = SelectPalette(dc, this->gdi_palette, FALSE);
 
  if (_local_palette.count_dirty != 0) {
    Blitter *blitter = BlitterFactory::GetCurrentBlitter();
 
    switch (blitter->UsePaletteAnimation()) {
      case Blitter::PaletteAnimation::VideoBackend:
        this->UpdatePalette(dc2, _local_palette.first_dirty, _local_palette.count_dirty);
        break;
 
      case Blitter::PaletteAnimation::Blitter: {
        blitter->PaletteAnimate(_local_palette);
        break;
      }
 
      case Blitter::PaletteAnimation::None:
        break;
 
      default:
        NOT_REACHED();
    }
    _local_palette.count_dirty = 0;
  }
 
  BitBlt(dc, 0, 0, this->width, this->height, dc2, 0, 0, SRCCOPY);
  SelectPalette(dc, old_palette, TRUE);
  SelectObject(dc2, old_bmp);
  DeleteDC(dc2);
 
  ReleaseDC(this->main_wnd, dc);
 
  this->dirty_rect = {};
}
 
#ifdef _DEBUG
/* Keep this function here..
 * It allows you to redraw the screen from within the MSVC debugger */
/* static */ int VideoDriver_Win32GDI::RedrawScreenDebug()
{
  static int _fooctr;
 
  VideoDriver_Win32GDI *drv = static_cast<VideoDriver_Win32GDI *>(VideoDriver::GetInstance());
 
  _screen.dst_ptr = drv->GetVideoPointer();
  UpdateWindows();
 
  drv->Paint();
  GdiFlush();
 
  return _fooctr++;
}
#endif
 
#ifdef WITH_OPENGL
 
#ifndef PFD_SUPPORT_COMPOSITION
# define PFD_SUPPORT_COMPOSITION 0x00008000
#endif
 
static PFNWGLCREATECONTEXTATTRIBSARBPROC _wglCreateContextAttribsARB = nullptr;
static PFNWGLSWAPINTERVALEXTPROC _wglSwapIntervalEXT = nullptr;
static bool _hasWGLARBCreateContextProfile = false; 
 
static OGLProc GetOGLProcAddressCallback(const char *proc)
{
  OGLProc ret = reinterpret_cast<OGLProc>(wglGetProcAddress(proc));
  if (ret == nullptr) {
    /* Non-extension GL function? Try normal loading. */
    ret = reinterpret_cast<OGLProc>(GetProcAddress(GetModuleHandle(L"opengl32"), proc));
  }
  return ret;
}
 
static std::optional<std::string_view> SelectPixelFormat(HDC dc)
{
  PIXELFORMATDESCRIPTOR pfd = {
    sizeof(PIXELFORMATDESCRIPTOR), // Size of this struct.
    1,                             // Version of this struct.
    PFD_DRAW_TO_WINDOW |           // Require window support.
    PFD_SUPPORT_OPENGL |           // Require OpenGL support.
    PFD_DOUBLEBUFFER   |           // Use double buffering.
    PFD_DEPTH_DONTCARE,
    PFD_TYPE_RGBA,                 // Request RGBA format.
    24,                            // 24 bpp (excluding alpha).
    0, 0, 0, 0, 0, 0, 0, 0,        // Colour bits and shift ignored.
    0, 0, 0, 0, 0,                 // No accumulation buffer.
    0, 0,                          // No depth/stencil buffer.
    0,                             // No aux buffers.
    PFD_MAIN_PLANE,                // Main layer.
    0, 0, 0, 0                     // Ignored/reserved.
  };
 
  pfd.dwFlags |= PFD_SUPPORT_COMPOSITION; // Make OpenTTD compatible with Aero.
 
  /* Choose a suitable pixel format. */
  int format = ChoosePixelFormat(dc, &pfd);
  if (format == 0) return "No suitable pixel format found";
  if (!SetPixelFormat(dc, format, &pfd)) return "Can't set pixel format";
 
  return std::nullopt;
}
 
static void LoadWGLExtensions()
{
  /* Querying the supported WGL extensions and loading the matching
   * functions requires a valid context, even for the extensions
   * regarding context creation. To get around this, we create
   * a dummy window with a dummy context. The extension functions
   * remain valid even after this context is destroyed. */
  HWND wnd = CreateWindow(L"STATIC", L"dummy", WS_OVERLAPPEDWINDOW, 0, 0, 0, 0, nullptr, nullptr, GetModuleHandle(nullptr), nullptr);
  HDC dc = GetDC(wnd);
 
  /* Set pixel format of the window. */
  if (SelectPixelFormat(dc) == std::nullopt) {
    /* Create rendering context. */
    HGLRC rc = wglCreateContext(dc);
    if (rc != nullptr) {
      wglMakeCurrent(dc, rc);
 
#ifdef __MINGW32__
      /* GCC doesn't understand the expected usage of wglGetProcAddress(). */
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-function-type"
#endif /* __MINGW32__ */
 
      /* Get list of WGL extensions. */
      PFNWGLGETEXTENSIONSSTRINGARBPROC wglGetExtensionsStringARB = (PFNWGLGETEXTENSIONSSTRINGARBPROC)wglGetProcAddress("wglGetExtensionsStringARB");
      if (wglGetExtensionsStringARB != nullptr) {
        std::string_view wgl_exts = wglGetExtensionsStringARB(dc);
        /* Bind supported functions. */
        if (HasStringInExtensionList(wgl_exts, "WGL_ARB_create_context")) {
          _wglCreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress("wglCreateContextAttribsARB");
        }
        _hasWGLARBCreateContextProfile = HasStringInExtensionList(wgl_exts, "WGL_ARB_create_context_profile");
        if (HasStringInExtensionList(wgl_exts, "WGL_EXT_swap_control")) {
          _wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress("wglSwapIntervalEXT");
        }
      }
 
#ifdef __MINGW32__
#pragma GCC diagnostic pop
#endif
      wglMakeCurrent(nullptr, nullptr);
      wglDeleteContext(rc);
    }
  }
 
  ReleaseDC(wnd, dc);
  DestroyWindow(wnd);
}
 
static FVideoDriver_Win32OpenGL iFVideoDriver_Win32OpenGL;
 
std::optional<std::string_view> VideoDriver_Win32OpenGL::Start(const StringList &param)
{
  if (BlitterFactory::GetCurrentBlitter()->GetScreenDepth() == 0) return "Only real blitters supported";
 
  Dimension old_res = _cur_resolution; // Save current screen resolution in case of errors, as MakeWindow invalidates it.
 
  LoadWGLExtensions();
 
  this->Initialize();
  this->MakeWindow(_fullscreen);
 
  /* Create and initialize OpenGL context. */
  auto err = this->AllocateContext();
  if (err) {
    this->Stop();
    _cur_resolution = old_res;
    return err;
  }
 
  this->driver_info = GetName();
  this->driver_info += " (";
  this->driver_info += OpenGLBackend::Get()->GetDriverName();
  this->driver_info += ")";
 
  this->ClientSizeChanged(this->width, this->height, true);
  /* We should have a valid screen buffer now. If not, something went wrong and we should abort. */
  if (_screen.dst_ptr == nullptr) {
    this->Stop();
    _cur_resolution = old_res;
    return "Can't get pointer to screen buffer";
  }
  /* Main loop expects to start with the buffer unmapped. */
  this->ReleaseVideoPointer();
 
  MarkWholeScreenDirty();
 
  this->is_game_threaded = !GetDriverParamBool(param, "no_threads") && !GetDriverParamBool(param, "no_thread");
 
  return std::nullopt;
}
 
void VideoDriver_Win32OpenGL::Stop()
{
  this->DestroyContext();
  this->VideoDriver_Win32Base::Stop();
}
 
void VideoDriver_Win32OpenGL::DestroyContext()
{
  OpenGLBackend::Destroy();
 
  wglMakeCurrent(nullptr, nullptr);
  if (this->gl_rc != nullptr) {
    wglDeleteContext(this->gl_rc);
    this->gl_rc = nullptr;
  }
  if (this->dc != nullptr) {
    ReleaseDC(this->main_wnd, this->dc);
    this->dc = nullptr;
  }
}
 
void VideoDriver_Win32OpenGL::ToggleVsync(bool vsync)
{
  if (_wglSwapIntervalEXT != nullptr) {
    _wglSwapIntervalEXT(vsync);
  } else if (vsync) {
    Debug(driver, 0, "OpenGL: Vsync requested, but not supported by driver");
  }
}
 
std::optional<std::string_view> VideoDriver_Win32OpenGL::AllocateContext()
{
  this->dc = GetDC(this->main_wnd);
 
  auto err = SelectPixelFormat(this->dc);
  if (err) return err;
 
  HGLRC rc = nullptr;
 
  /* Create OpenGL device context. Try to get an 3.2+ context if possible. */
  if (_wglCreateContextAttribsARB != nullptr) {
    /* Try for OpenGL 4.5 first. */
    int attribs[] = {
      WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
      WGL_CONTEXT_MINOR_VERSION_ARB, 5,
      WGL_CONTEXT_FLAGS_ARB, _debug_driver_level >= 8 ? WGL_CONTEXT_DEBUG_BIT_ARB : 0,
      _hasWGLARBCreateContextProfile ? WGL_CONTEXT_PROFILE_MASK_ARB : 0, WGL_CONTEXT_CORE_PROFILE_BIT_ARB, // Terminate list if WGL_ARB_create_context_profile isn't supported.
      0
    };
    rc = _wglCreateContextAttribsARB(this->dc, nullptr, attribs);
 
    if (rc == nullptr) {
      /* Try again for a 3.2 context. */
      attribs[1] = 3;
      attribs[3] = 2;
      rc = _wglCreateContextAttribsARB(this->dc, nullptr, attribs);
    }
  }
 
  if (rc == nullptr) {
    /* Old OpenGL or old driver, let's hope for the best. */
    rc = wglCreateContext(this->dc);
    if (rc == nullptr) return "Can't create OpenGL context";
  }
  if (!wglMakeCurrent(this->dc, rc)) return "Can't activate GL context";
 
  this->ToggleVsync(_video_vsync);
 
  this->gl_rc = rc;
  return OpenGLBackend::Create(&GetOGLProcAddressCallback, this->GetScreenSize());
}
 
bool VideoDriver_Win32OpenGL::ToggleFullscreen(bool full_screen)
{
  if (_screen.dst_ptr != nullptr) this->ReleaseVideoPointer();
  this->DestroyContext();
  bool res = this->VideoDriver_Win32Base::ToggleFullscreen(full_screen);
  res &= this->AllocateContext() == std::nullopt;
  this->ClientSizeChanged(this->width, this->height, true);
  return res;
}
 
bool VideoDriver_Win32OpenGL::AfterBlitterChange()
{
  assert(BlitterFactory::GetCurrentBlitter()->GetScreenDepth() != 0);
  this->ClientSizeChanged(this->width, this->height, true);
  return true;
}
 
void VideoDriver_Win32OpenGL::PopulateSystemSprites()
{
  OpenGLBackend::Get()->PopulateCursorCache();
}
 
void VideoDriver_Win32OpenGL::ClearSystemSprites()
{
  OpenGLBackend::Get()->ClearCursorCache();
}
 
bool VideoDriver_Win32OpenGL::AllocateBackingStore(int w, int h, bool force)
{
  if (!force && w == _screen.width && h == _screen.height) return false;
 
  this->width = w = std::max(w, 64);
  this->height = h = std::max(h, 64);
 
  if (this->gl_rc == nullptr) return false;
 
  if (_screen.dst_ptr != nullptr) this->ReleaseVideoPointer();
 
  this->dirty_rect = {};
  bool res = OpenGLBackend::Get()->Resize(w, h, force);
  SwapBuffers(this->dc);
  _screen.dst_ptr = this->GetVideoPointer();
 
  return res;
}
 
void *VideoDriver_Win32OpenGL::GetVideoPointer()
{
  if (BlitterFactory::GetCurrentBlitter()->NeedsAnimationBuffer()) {
    this->anim_buffer = OpenGLBackend::Get()->GetAnimBuffer();
  }
  return OpenGLBackend::Get()->GetVideoBuffer();
}
 
void VideoDriver_Win32OpenGL::ReleaseVideoPointer()
{
  if (this->anim_buffer != nullptr) OpenGLBackend::Get()->ReleaseAnimBuffer(this->dirty_rect);
  OpenGLBackend::Get()->ReleaseVideoBuffer(this->dirty_rect);
  this->dirty_rect = {};
  _screen.dst_ptr = nullptr;
  this->anim_buffer = nullptr;
}
 
void VideoDriver_Win32OpenGL::Paint()
{
  PerformanceMeasurer framerate(PFE_VIDEO);
 
  if (_local_palette.count_dirty != 0) {
    Blitter *blitter = BlitterFactory::GetCurrentBlitter();
 
    /* Always push a changed palette to OpenGL. */
    OpenGLBackend::Get()->UpdatePalette(_local_palette.palette, _local_palette.first_dirty, _local_palette.count_dirty);
    if (blitter->UsePaletteAnimation() == Blitter::PaletteAnimation::Blitter) {
      blitter->PaletteAnimate(_local_palette);
    }
 
    _local_palette.count_dirty = 0;
  }
 
  OpenGLBackend::Get()->Paint();
  OpenGLBackend::Get()->DrawMouseCursor();
 
  SwapBuffers(this->dc);
}
 
#endif /* WITH_OPENGL */