使用Win32 API调整窗口大小

正如@CodyGray所建议的，这里是工作代码以及处理释放区域内存的类和函数，现在画笔也是

编辑:这个问题是由创建WM_PAINT时的内存泄漏引起的，而不是删除，画笔(HBRUSH)。

//WinMain.cpp
#include <Windows.h>
#include "Utility.h"
#include "Mouse.h"
#include "AppInfo.h"
#include "Buttons.h"
//Function prototypes
ATOM MainRegister();
bool MainInit(HWND &hWnd, int nCmdShow);
void MatchRectToWnd(RECT &rect);
//Variables define in AppInfo.h
HRGN rgnMain, rgnCaptionbar;
bool _APPRUNNING = true;
const char _APPTITLE[] = "Dark";
//Variables
bool WIREFRAME = false;
//Pointers to buttons (singelton design)
btnCloseClass * btnCloseClass::s_Instance = 0;
btnMaximizeClass * btnMaximizeClass::s_Instance = 0;
btnMinimizeClass * btnMinimizeClass::s_Instance = 0;
LRESULT CALLBACK MainWndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch (msg)
    {
    case WM_LBUTTONDBLCLK: //Left mouse button double-clicked
        Mouse.CheckDblClick(hWnd, wParam);
        Mouse.m_Pressed = false;
    break;
    case WM_LBUTTONDOWN: //Left mouse button clicked
        //Update the mouse position variables
        GetCursorPos(&Mouse.prevPt);
        GetCursorPos(&Mouse.m_LastClick);
        Mouse.m_Pressed = true; 
        Mouse.CheckClickDown(hWnd);
    break;
    case WM_LBUTTONUP: //Left mouse button released
    {
        GetCursorPos(&Mouse.prevPt);
        Mouse.CheckClickUp(hWnd);
        Mouse.m_Pressed = false;
    }
    break;
    case WM_SIZE: //Check if the window has been resized
    {
        DeleteObject(rgnMain);
        DeleteObject(rgnCaptionbar);
        //Update the buttons
        btnClose->Update(hWnd);
        btnMaximize->Update(hWnd);
        btnMinimize->Update(hWnd);
        //Update the regions
        RECT rect; GetWindowRect(hWnd, &rect);
        rgnMain = CreateRectRgn(0, 0, rect.right - rect.left, rect.bottom- rect.top);
        rgnCaptionbar = CreateRectRgn(0, 0, rect.right - rect.left, CAPTIONBAR_HEIGHT);
    }
    break;
    case WM_PAINT: //Draw the window
    {
        HDC hdc;
        PAINTSTRUCT ps;
        HBRUSH hBrush;
        hdc = BeginPaint(hWnd, &ps);
        //Color the mainregion
        hBrush = CreateSolidBrush(COLOR_MAIN);
        FillRgn(hdc, rgnMain, hBrush);
        DeleteObject(hBrush);
        //Color the captionbarregion
        hBrush = CreateSolidBrush(COLOR_CAPTIONBAR);
        FillRgn(hdc, rgnCaptionbar, hBrush);
        DeleteObject(hBrush);
        //Color the button backgrounds
        FillRgn(hdc, btnClose->GetRegion(), btnClose->GetBrush());
        FillRgn(hdc, btnMinimize->GetRegion(), btnMinimize->GetBrush());
        FillRgn(hdc, btnMaximize->GetRegion(), btnMaximize->GetBrush());
        //Color the button icons
        FillRgn(hdc, btnClose->GetIcon(), btnClose->GetBrushIcon());
        FillRgn(hdc, btnMinimize->GetIcon(), btnMinimize->GetBrushIcon());
        FillRgn(hdc, btnMaximize->GetIcon(), btnMaximize->GetBrushIcon());
        //Paint the wireframe
        if (WIREFRAME)
        {
            hBrush = CreateSolidBrush(COLOR_WIREFRAME);
            FrameRgn(hdc, rgnMain, hBrush, 1, 1);
            FrameRgn(hdc, rgnCaptionbar, hBrush, 1, 1);
            FrameRgn(hdc, btnClose->GetRegion(), hBrush, 1, 1);
            FrameRgn(hdc, btnMaximize->GetRegion(), hBrush, 1, 1);
            FrameRgn(hdc, btnMinimize->GetRegion(), hBrush, 1, 1);
            FrameRgn(hdc, btnClose->GetIcon(), hBrush, 1, 1);
            FrameRgn(hdc, btnMaximize->GetIcon(), hBrush, 1, 1);
            FrameRgn(hdc, btnMinimize->GetIcon(), hBrush, 1, 1);
            DeleteObject(hBrush);
        }
        //Free up memomry
        DeleteObject(hBrush);
        EndPaint(hWnd, &ps);
    }
    break;
    case WM_KEYDOWN:
    {
        switch (wParam)
        {
        case VK_TAB: //If TAB is pressed
        {
            if (WIREFRAME) //Activate the wireframe
                WIREFRAME = false;
            else
                WIREFRAME = true;
            InvalidateRgn(hWnd, NULL, true);
        }
        break;
        case VK_ESCAPE: //If the ESCAPE is pressed
            PostMessage(hWnd, WM_DESTROY, 0, 0);
        break;
        }
    }
    break;
    case WM_DESTROY: //Free up memory and exit the program
        _APPRUNNING = false;
        DeleteObject(rgnMain);
        DeleteObject(rgnCaptionbar);
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, msg, wParam, lParam);
        break;
    }
    return 0;
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    HWND hWnd;
    MSG msg;
    _APPRUNNING = true;
    //Register the main window
    if (!MainRegister())
    {
        MessageBox(hWnd, "Error registering main window!", "Error", MB_ICONERROR);
        return false;
    }
    //Initialize the main window
    MainInit(hWnd, nCmdShow);
    //App-loop
    while (_APPRUNNING)
    {
        if ((GetKeyState(VK_LBUTTON) & 0x80) == 0) //Make sure the mouse's status gets updated
        {
            Mouse.m_Pressed = false;
        }
        Mouse.Update(hWnd);
        //Message-loop
        if (PeekMessage(&msg, hWnd, 0, 0, PM_REMOVE) > 0)
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
    return msg.wParam;
}
bool MainInit(HWND &hWnd, int nCmdShow)
{
    //Create the window
    hWnd = CreateWindowEx(
        WS_EX_LAYERED,
        _APPTITLE,
        _APPTITLE,
        WS_OVERLAPPEDWINDOW,
        0, 0, //Starting positons (x,y)
        START_WIDTH, START_HEIGHT, //Width and height
        NULL, //Parent-handle
        NULL, //Menu-handle
        GetModuleHandle(NULL),
        NULL);
    //Make sure the window was created properly
    if (hWnd == NULL)
    {
        MessageBox(hWnd, "Error initializing main window!", "Error!", MB_ICONERROR);
        return false;
    }
    SetLayeredWindowAttributes(hWnd, NULL, NULL, NULL);
    //Get and set the window's style
    DWORD wndStyle = GetWindowLong(hWnd, GWL_STYLE);
    wndStyle &= ~(WS_CAPTION | WS_SIZEBOX);
    SetWindowLong(hWnd, GWL_STYLE, wndStyle);
    //Create regions
    rgnMain = CreateRectRgn(0, 0, START_WIDTH, START_HEIGHT);
    rgnCaptionbar = CreateRectRgn(0, 0, START_WIDTH, CAPTIONBAR_HEIGHT);
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
    return true;
}
ATOM MainRegister()
{
    //Create the window's classEx (extended class)
    WNDCLASSEX wc;
    wc.cbClsExtra = 0;
    wc.cbSize = sizeof(WNDCLASSEX);
    wc.cbWndExtra = 0;
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
    wc.hIcon = NULL;
    wc.hIconSm = NULL;
    wc.hInstance = GetModuleHandle(NULL);
    wc.lpfnWndProc = MainWndProc;
    wc.lpszClassName = _APPTITLE;
    wc.lpszMenuName = NULL;
    wc.style = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
    //Register the classEx
    return RegisterClassEx(&wc);
}
//Button.h
//Header file for the class responsible for handling the memory of the
//regions and brushes
class Button
{
protected:
    //Protected default constructor
    Button();
    //Protected default destructor
    ~Button();
    //Protected variables
    HRGN m_Rgn;
    HRGN m_Icon;
    HBRUSH m_hBrush;
    HBRUSH m_hBrush_Icon;
    bool m_Hovered;
public:
    //Public functions
    virtual void CreateIcon() = 0;
    virtual void Update(HWND hWnd) = 0;
    bool Clicked(POINT pt);
    bool CheckIfHovered(HWND hWnd);
    HRGN GetRegion() { return m_Rgn; }
    HRGN GetIcon() { return m_Icon; }
    HBRUSH GetBrush() { return m_hBrush; }
    HBRUSH GetBrushIcon() { return m_hBrush_Icon; }
};
//Button.cpp
//Default constructor
Button::Button()
{
    m_hBrush = CreateSolidBrush(COLOR_BUTTON_BACKGROUND);
    m_hBrush_Icon = CreateSolidBrush(COLOR_BUTTON_ICON);
    m_Hovered = false;
}
//Default destructor
Button::~Button()
{
    //Free up memory
    DeleteObject(m_Rgn);
    DeleteObject(m_Icon);
    DeleteObject(m_hBrush);
    DeleteObject(m_hBrush_Icon);
}

再次感谢@CodyGray @theB和@AdrianMcCarthy !