shell/platform/windows/win32_window.cc - external/github.com/flutter/engine - Git at Google

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "flutter/shell/platform/windows/win32_window.h"

 #include "dpi_utils.h"

 namespace flutter {

 Win32Window::Win32Window() {
   // Get the DPI of the primary monitor as the initial DPI. If Per-Monitor V2 is
   // supported, |current_dpi_| should be updated in the
   // kWmDpiChangedBeforeParent message.
   current_dpi_ = GetDpiForHWND(nullptr);
 }

 Win32Window::~Win32Window() {
   Destroy();
 }

 void Win32Window::InitializeChild(const char* title,
                                   unsigned int width,
                                   unsigned int height) {
   Destroy();
   std::wstring converted_title = NarrowToWide(title);

   WNDCLASS window_class = RegisterWindowClass(converted_title);

   auto* result = CreateWindowEx(
       0, window_class.lpszClassName, converted_title.c_str(),
       WS_CHILD | WS_VISIBLE, CW_DEFAULT, CW_DEFAULT, width, height,
       HWND_MESSAGE, nullptr, window_class.hInstance, this);

   if (result == nullptr) {
     auto error = GetLastError();
     LPWSTR message = nullptr;
     size_t size = FormatMessageW(
         FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
             FORMAT_MESSAGE_IGNORE_INSERTS,
         NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
         reinterpret_cast<LPWSTR>(&message), 0, NULL);
     OutputDebugString(message);
     LocalFree(message);
   }
 }

 std::wstring Win32Window::NarrowToWide(const char* source) {
   size_t length = strlen(source);
   size_t outlen = 0;
   std::wstring wideTitle(length, L'#');
   mbstowcs_s(&outlen, &wideTitle[0], length + 1, source, length);
   return wideTitle;
 }

 WNDCLASS Win32Window::RegisterWindowClass(std::wstring& title) {
   window_class_name_ = title;

   WNDCLASS window_class{};
   window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
   window_class.lpszClassName = title.c_str();
   window_class.style = CS_HREDRAW | CS_VREDRAW;
   window_class.cbClsExtra = 0;
   window_class.cbWndExtra = 0;
   window_class.hInstance = GetModuleHandle(nullptr);
   window_class.hIcon = nullptr;
   window_class.hbrBackground = 0;
   window_class.lpszMenuName = nullptr;
   window_class.lpfnWndProc = WndProc;
   RegisterClass(&window_class);
   return window_class;
 }

 LRESULT CALLBACK Win32Window::WndProc(HWND const window,
                                       UINT const message,
                                       WPARAM const wparam,
                                       LPARAM const lparam) noexcept {
   if (message == WM_NCCREATE) {
     auto cs = reinterpret_cast<CREATESTRUCT*>(lparam);
     SetWindowLongPtr(window, GWLP_USERDATA,
                      reinterpret_cast<LONG_PTR>(cs->lpCreateParams));

     auto that = static_cast<Win32Window*>(cs->lpCreateParams);
     that->window_handle_ = window;
   } else if (Win32Window* that = GetThisFromHandle(window)) {
     return that->MessageHandler(window, message, wparam, lparam);
   }

   return DefWindowProc(window, message, wparam, lparam);
 }

 void Win32Window::TrackMouseLeaveEvent(HWND hwnd) {
   if (!tracking_mouse_leave_) {
     TRACKMOUSEEVENT tme;
     tme.cbSize = sizeof(tme);
     tme.hwndTrack = hwnd;
     tme.dwFlags = TME_LEAVE;
     TrackMouseEvent(&tme);
     tracking_mouse_leave_ = true;
   }
 }

 LRESULT
 Win32Window::MessageHandler(HWND hwnd,
                             UINT const message,
                             WPARAM const wparam,
                             LPARAM const lparam) noexcept {
   int xPos = 0, yPos = 0;
   UINT width = 0, height = 0;
   auto window =
       reinterpret_cast<Win32Window*>(GetWindowLongPtr(hwnd, GWLP_USERDATA));
   UINT button_pressed = 0;
   if (window != nullptr) {
     switch (message) {
       case kWmDpiChangedBeforeParent:
         current_dpi_ = GetDpiForHWND(window_handle_);
         window->OnDpiScale(current_dpi_);
         return 0;
       case WM_SIZE:
         width = LOWORD(lparam);
         height = HIWORD(lparam);

         current_width_ = width;
         current_height_ = height;
         window->HandleResize(width, height);
         break;
       case WM_FONTCHANGE:
         window->OnFontChange();
         break;
       case WM_MOUSEMOVE:
         window->TrackMouseLeaveEvent(hwnd);

         xPos = GET_X_LPARAM(lparam);
         yPos = GET_Y_LPARAM(lparam);
         window->OnPointerMove(static_cast<double>(xPos),
                               static_cast<double>(yPos));
         break;
       case WM_MOUSELEAVE:;
         window->OnPointerLeave();
         // Once the tracked event is received, the TrackMouseEvent function
         // resets. Set to false to make sure it's called once mouse movement is
         // detected again.
         tracking_mouse_leave_ = false;
         break;
       case WM_LBUTTONDOWN:
       case WM_RBUTTONDOWN:
       case WM_MBUTTONDOWN:
       case WM_XBUTTONDOWN:
         if (message == WM_LBUTTONDOWN) {
           // Capture the pointer in case the user drags outside the client area.
           // In this case, the "mouse leave" event is delayed until the user
           // releases the button. It's only activated on left click given that
           // it's more common for apps to handle dragging with only the left
           // button.
           SetCapture(hwnd);
         }
         button_pressed = message;
         if (message == WM_XBUTTONDOWN) {
           button_pressed = GET_XBUTTON_WPARAM(wparam);
         }
         xPos = GET_X_LPARAM(lparam);
         yPos = GET_Y_LPARAM(lparam);
         window->OnPointerDown(static_cast<double>(xPos),
                               static_cast<double>(yPos), button_pressed);
         break;
       case WM_LBUTTONUP:
       case WM_RBUTTONUP:
       case WM_MBUTTONUP:
       case WM_XBUTTONUP:
         if (message == WM_LBUTTONUP) {
           ReleaseCapture();
         }
         button_pressed = message;
         if (message == WM_XBUTTONUP) {
           button_pressed = GET_XBUTTON_WPARAM(wparam);
         }
         xPos = GET_X_LPARAM(lparam);
         yPos = GET_Y_LPARAM(lparam);
         window->OnPointerUp(static_cast<double>(xPos),
                             static_cast<double>(yPos), button_pressed);
         break;
       case WM_MOUSEWHEEL:
         window->OnScroll(
             0.0, -(static_cast<short>(HIWORD(wparam)) / (double)WHEEL_DELTA));
         break;
       case WM_UNICHAR: {
         // Tell third-pary app, we can support Unicode.
         if (wparam == UNICODE_NOCHAR)
           return TRUE;
         // DefWindowProc will send WM_CHAR for this WM_UNICHAR.
         break;
       }
       case WM_CHAR:
       case WM_SYSCHAR: {
         if (wparam == VK_BACK)
           break;
         char32_t code_point = static_cast<char32_t>(wparam);
         static char32_t lead_surrogate = 0;
         // If code_point is LeadSurrogate, save and return.
         if ((code_point & 0xFFFFFC00) == 0xD800) {
           lead_surrogate = code_point;
           return TRUE;
         }
         // Merge TrailSurrogate and LeadSurrogate.
         if (lead_surrogate != 0 && (code_point & 0xFFFFFC00) == 0xDC00) {
           code_point = 0x10000 + ((lead_surrogate & 0x000003FF) << 10) +
                        (code_point & 0x3FF);
         }
         lead_surrogate = 0;
         window->OnChar(code_point);
         break;
       }
       case WM_KEYDOWN:
       case WM_SYSKEYDOWN:
       case WM_KEYUP:
       case WM_SYSKEYUP:
         unsigned char scancode = ((unsigned char*)&lparam)[2];
         unsigned int virtualKey = MapVirtualKey(scancode, MAPVK_VSC_TO_VK);
         const int key = virtualKey;
         const int action = message == WM_KEYDOWN ? WM_KEYDOWN : WM_KEYUP;
         window->OnKey(key, scancode, action, 0);
         break;
     }
     return DefWindowProc(hwnd, message, wparam, lparam);
   }

   return DefWindowProc(window_handle_, message, wparam, lparam);
 }

 UINT Win32Window::GetCurrentDPI() {
   return current_dpi_;
 }

 UINT Win32Window::GetCurrentWidth() {
   return current_width_;
 }

 UINT Win32Window::GetCurrentHeight() {
   return current_height_;
 }

 HWND Win32Window::GetWindowHandle() {
   return window_handle_;
 }

 void Win32Window::Destroy() {
   if (window_handle_) {
     DestroyWindow(window_handle_);
     window_handle_ = nullptr;
   }

   UnregisterClass(window_class_name_.c_str(), nullptr);
 }

 void Win32Window::HandleResize(UINT width, UINT height) {
   current_width_ = width;
   current_height_ = height;
   OnResize(width, height);
 }

 Win32Window* Win32Window::GetThisFromHandle(HWND const window) noexcept {
   return reinterpret_cast<Win32Window*>(
       GetWindowLongPtr(window, GWLP_USERDATA));
 }

 }  // namespace flutter
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "flutter/shell/platform/windows/win32_window.h"

	#include "dpi_utils.h"

	namespace flutter {

	Win32Window::Win32Window() {
	// Get the DPI of the primary monitor as the initial DPI. If Per-Monitor V2 is
	// supported, \|current_dpi_\| should be updated in the
	// kWmDpiChangedBeforeParent message.
	current_dpi_ = GetDpiForHWND(nullptr);
	}

	Win32Window::~Win32Window() {
	Destroy();
	}

	void Win32Window::InitializeChild(const char* title,
	unsigned int width,
	unsigned int height) {
	Destroy();
	std::wstring converted_title = NarrowToWide(title);

	WNDCLASS window_class = RegisterWindowClass(converted_title);

	auto* result = CreateWindowEx(
	0, window_class.lpszClassName, converted_title.c_str(),
	WS_CHILD \| WS_VISIBLE, CW_DEFAULT, CW_DEFAULT, width, height,
	HWND_MESSAGE, nullptr, window_class.hInstance, this);

	if (result == nullptr) {
	auto error = GetLastError();
	LPWSTR message = nullptr;
	size_t size = FormatMessageW(
	FORMAT_MESSAGE_ALLOCATE_BUFFER \| FORMAT_MESSAGE_FROM_SYSTEM \|
	FORMAT_MESSAGE_IGNORE_INSERTS,
	NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
	reinterpret_cast<LPWSTR>(&message), 0, NULL);
	OutputDebugString(message);
	LocalFree(message);
	}
	}

	std::wstring Win32Window::NarrowToWide(const char* source) {
	size_t length = strlen(source);
	size_t outlen = 0;
	std::wstring wideTitle(length, L'#');
	mbstowcs_s(&outlen, &wideTitle[0], length + 1, source, length);
	return wideTitle;
	}

	WNDCLASS Win32Window::RegisterWindowClass(std::wstring& title) {
	window_class_name_ = title;

	WNDCLASS window_class{};
	window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
	window_class.lpszClassName = title.c_str();
	window_class.style = CS_HREDRAW \| CS_VREDRAW;
	window_class.cbClsExtra = 0;
	window_class.cbWndExtra = 0;
	window_class.hInstance = GetModuleHandle(nullptr);
	window_class.hIcon = nullptr;
	window_class.hbrBackground = 0;
	window_class.lpszMenuName = nullptr;
	window_class.lpfnWndProc = WndProc;
	RegisterClass(&window_class);
	return window_class;
	}

	LRESULT CALLBACK Win32Window::WndProc(HWND const window,
	UINT const message,
	WPARAM const wparam,
	LPARAM const lparam) noexcept {
	if (message == WM_NCCREATE) {
	auto cs = reinterpret_cast<CREATESTRUCT*>(lparam);
	SetWindowLongPtr(window, GWLP_USERDATA,
	reinterpret_cast<LONG_PTR>(cs->lpCreateParams));

	auto that = static_cast<Win32Window*>(cs->lpCreateParams);
	that->window_handle_ = window;
	} else if (Win32Window* that = GetThisFromHandle(window)) {
	return that->MessageHandler(window, message, wparam, lparam);
	}

	return DefWindowProc(window, message, wparam, lparam);
	}

	void Win32Window::TrackMouseLeaveEvent(HWND hwnd) {
	if (!tracking_mouse_leave_) {
	TRACKMOUSEEVENT tme;
	tme.cbSize = sizeof(tme);
	tme.hwndTrack = hwnd;
	tme.dwFlags = TME_LEAVE;
	TrackMouseEvent(&tme);
	tracking_mouse_leave_ = true;
	}
	}

	LRESULT
	Win32Window::MessageHandler(HWND hwnd,
	UINT const message,
	WPARAM const wparam,
	LPARAM const lparam) noexcept {
	int xPos = 0, yPos = 0;
	UINT width = 0, height = 0;
	auto window =
	reinterpret_cast<Win32Window*>(GetWindowLongPtr(hwnd, GWLP_USERDATA));
	UINT button_pressed = 0;
	if (window != nullptr) {
	switch (message) {
	case kWmDpiChangedBeforeParent:
	current_dpi_ = GetDpiForHWND(window_handle_);
	window->OnDpiScale(current_dpi_);
	return 0;
	case WM_SIZE:
	width = LOWORD(lparam);
	height = HIWORD(lparam);

	current_width_ = width;
	current_height_ = height;
	window->HandleResize(width, height);
	break;
	case WM_FONTCHANGE:
	window->OnFontChange();
	break;
	case WM_MOUSEMOVE:
	window->TrackMouseLeaveEvent(hwnd);

	xPos = GET_X_LPARAM(lparam);
	yPos = GET_Y_LPARAM(lparam);
	window->OnPointerMove(static_cast<double>(xPos),
	static_cast<double>(yPos));
	break;
	case WM_MOUSELEAVE:;
	window->OnPointerLeave();
	// Once the tracked event is received, the TrackMouseEvent function
	// resets. Set to false to make sure it's called once mouse movement is
	// detected again.
	tracking_mouse_leave_ = false;
	break;
	case WM_LBUTTONDOWN:
	case WM_RBUTTONDOWN:
	case WM_MBUTTONDOWN:
	case WM_XBUTTONDOWN:
	if (message == WM_LBUTTONDOWN) {
	// Capture the pointer in case the user drags outside the client area.
	// In this case, the "mouse leave" event is delayed until the user
	// releases the button. It's only activated on left click given that
	// it's more common for apps to handle dragging with only the left
	// button.
	SetCapture(hwnd);
	}
	button_pressed = message;
	if (message == WM_XBUTTONDOWN) {
	button_pressed = GET_XBUTTON_WPARAM(wparam);
	}
	xPos = GET_X_LPARAM(lparam);
	yPos = GET_Y_LPARAM(lparam);
	window->OnPointerDown(static_cast<double>(xPos),
	static_cast<double>(yPos), button_pressed);
	break;
	case WM_LBUTTONUP:
	case WM_RBUTTONUP:
	case WM_MBUTTONUP:
	case WM_XBUTTONUP:
	if (message == WM_LBUTTONUP) {
	ReleaseCapture();
	}
	button_pressed = message;
	if (message == WM_XBUTTONUP) {
	button_pressed = GET_XBUTTON_WPARAM(wparam);
	}
	xPos = GET_X_LPARAM(lparam);
	yPos = GET_Y_LPARAM(lparam);
	window->OnPointerUp(static_cast<double>(xPos),
	static_cast<double>(yPos), button_pressed);
	break;
	case WM_MOUSEWHEEL:
	window->OnScroll(
	0.0, -(static_cast<short>(HIWORD(wparam)) / (double)WHEEL_DELTA));
	break;
	case WM_UNICHAR: {
	// Tell third-pary app, we can support Unicode.
	if (wparam == UNICODE_NOCHAR)
	return TRUE;
	// DefWindowProc will send WM_CHAR for this WM_UNICHAR.
	break;
	}
	case WM_CHAR:
	case WM_SYSCHAR: {
	if (wparam == VK_BACK)
	break;
	char32_t code_point = static_cast<char32_t>(wparam);
	static char32_t lead_surrogate = 0;
	// If code_point is LeadSurrogate, save and return.
	if ((code_point & 0xFFFFFC00) == 0xD800) {
	lead_surrogate = code_point;
	return TRUE;
	}
	// Merge TrailSurrogate and LeadSurrogate.
	if (lead_surrogate != 0 && (code_point & 0xFFFFFC00) == 0xDC00) {
	code_point = 0x10000 + ((lead_surrogate & 0x000003FF) << 10) +
	(code_point & 0x3FF);
	}
	lead_surrogate = 0;
	window->OnChar(code_point);
	break;
	}
	case WM_KEYDOWN:
	case WM_SYSKEYDOWN:
	case WM_KEYUP:
	case WM_SYSKEYUP:
	unsigned char scancode = ((unsigned char*)&lparam)[2];
	unsigned int virtualKey = MapVirtualKey(scancode, MAPVK_VSC_TO_VK);
	const int key = virtualKey;
	const int action = message == WM_KEYDOWN ? WM_KEYDOWN : WM_KEYUP;
	window->OnKey(key, scancode, action, 0);
	break;
	}
	return DefWindowProc(hwnd, message, wparam, lparam);
	}

	return DefWindowProc(window_handle_, message, wparam, lparam);
	}

	UINT Win32Window::GetCurrentDPI() {
	return current_dpi_;
	}

	UINT Win32Window::GetCurrentWidth() {
	return current_width_;
	}

	UINT Win32Window::GetCurrentHeight() {
	return current_height_;
	}

	HWND Win32Window::GetWindowHandle() {
	return window_handle_;
	}

	void Win32Window::Destroy() {
	if (window_handle_) {
	DestroyWindow(window_handle_);
	window_handle_ = nullptr;
	}

	UnregisterClass(window_class_name_.c_str(), nullptr);
	}

	void Win32Window::HandleResize(UINT width, UINT height) {
	current_width_ = width;
	current_height_ = height;
	OnResize(width, height);
	}

	Win32Window* Win32Window::GetThisFromHandle(HWND const window) noexcept {
	return reinterpret_cast<Win32Window*>(
	GetWindowLongPtr(window, GWLP_USERDATA));
	}

	} // namespace flutter