Resize window to fit content after WM_PAINT - c++

Question

is there a way to resize after all WM_PAINT calls are done? so that i can automatically resize my window to fit whatever i have painted, since initially my window size is defined at a certain size, there may be leftover spaces that are not painted, how can i remove these leftover spaces?
As you can see from the screenshot below the white spaces are the leftover spaces.
#include <windows.h>
#include "resource.h"
#include "loadFromTextFile.h"
const char g_szClassName[] = "myWindowClass";
const int recLength = 3;
const int wndHeight = 700;
const int wndWidth = 700;
PAINTSTRUCT ps;
HDC hdc;
HBRUSH blackBrush = CreateSolidBrush(RGB(0, 0, 0));
HBRUSH whiteBrush = CreateSolidBrush(RGB(255, 255, 255));
HBRUSH redBrush = CreateSolidBrush(RGB(255, 0, 0));
HPEN myPen = CreatePen(PS_NULL, 1, RGB(0, 0, 0));
//load from text
string FILE_PATH = ("10x10.txt");
loadFromTextFile loaded = loadFromTextFile(FILE_PATH);
int mazeWidth = loaded.getColumns() * recLength;
int mazeHeight = loaded.getRows() * recLength;
void paintMaze(HWND hwnd, vector<vector<string> > grid){
hdc = ::BeginPaint(hwnd, &ps);
SelectObject(hdc, myPen);
for (int r = 0; r < loaded.getRows(); r++){
for (int c = 0; c < loaded.getColumns(); c++){
RECT rect;
rect.left = c*recLength;//x upper left
rect.top = r*recLength;//y upper left
rect.right = (c + 1)*recLength;//x lower right corner
rect.bottom = (r + 1)*recLength;//y lower right corner
if (grid[r][c] == "1"){//1 path
FillRect(hdc, &rect, blackBrush);
}
else if (grid[r][c] == "0"){//wall
FillRect(hdc, &rect, whiteBrush);
}
if (r == 50 && c == 50){
FillRect(hdc, &rect, redBrush);
}
}
}
DeleteObject(blackBrush);
DeleteObject(whiteBrush);
DeleteObject(redBrush);
DeleteObject(myPen);
EndPaint(hwnd, &ps);
}
// Step 4: the Window Procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch (msg)
{
case WM_COMMAND:
switch (LOWORD(wParam))
{
case ID_FILE_EXIT:
PostMessage(hwnd, WM_CLOSE, 0, 0);
break;
case ID_ABOUT:
SetWindowPos(hwnd, 0, 0, 0, mazeWidth, mazeHeight, SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE);
break;
}
break;
case WM_PAINT:
{
paintMaze(hwnd, loaded.getNodeGrid());
}
break;
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hwnd, msg, wParam, lParam);
}
return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
//Step 1: Registering the Window Class
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
wc.lpszMenuName = MAKEINTRESOURCE(IDR_MENU1);;
wc.lpszClassName = g_szClassName;
wc.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_ICON1));
wc.hIconSm = (HICON)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_ICON1), IMAGE_ICON, 32, 32, 0);
if (!RegisterClassEx(&wc))
{
MessageBox(NULL, "Window Registration Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
// Step 2: Creating the Window
hwnd = CreateWindowEx(
WS_EX_CLIENTEDGE,
g_szClassName,
" Maze",
WS_OVERLAPPED | WS_MINIMIZEBOX | WS_SYSMENU,//prevent resize
CW_USEDEFAULT, CW_USEDEFAULT, wndWidth, wndHeight,
NULL, NULL, hInstance, NULL);
if (hwnd == NULL)
{
MessageBox(NULL, "Window Creation Failed!", "Error!",
MB_ICONEXCLAMATION | MB_OK);
return 0;
}
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
// Step 3: The Message Loop
while (GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}

Answer 1

Paint in an offscreen buffer.
This allows you to resize the window.
Paint the window by copying the buffer.