Resizing window with Win32 API

Question

i'm writing a program with the Win32 API just to get a hang of it and have come across this annoying problem. After a little while of resizing the window minimizes and after bringing it up again it's visible but non-clickable and clicking on it just activates what's on the window below it. The only solution being exiting the program.

At first i thought it was because of my custom-made function for sizing the window (i use a custom gui and don't want the default windows sizebox border) but then i reactivated the default sizebox and the problem still persisted. It's hard to tell but the problem seems to consistently occur after roughly the same amount of time/ticks being resized.

I had a similar problem before where the window would minimize and then becoming completely white when brought up again, which for some reason was caused by a for-loop in the resizing function.

I have excluded as many potential problems as possible in the code but still haven't found a solution. Below is the source file where all the code handling how the window is drawn lies (with the default sizebox).

I appreciate any help i can get.

Ps. I apologize for any bad language (non-native speaker), incorrectly used terms or bad syntax (first time venturing this far into the API).

//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
    {
        //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);

        //Color the captionbarregion
        hBrush = CreateSolidBrush(COLOR_CAPTIONBAR);
        FillRgn(hdc, rgnCaptionbar, hBrush);

        //Color the button backgrounds
        hBrush = CreateSolidBrush(COLOR_BUTTON_BACKGROUND);
        FillRgn(hdc, btnClose->GetRegion(), hBrush);
        FillRgn(hdc, btnMinimize->GetRegion(), hBrush);
        FillRgn(hdc, btnMaximize->GetRegion(), hBrush);

        //Color the button icons
        hBrush = CreateSolidBrush(COLOR_BUTTON_ICON);
        FillRgn(hdc, btnClose->GetIcon(), hBrush);
        FillRgn(hdc, btnMinimize->GetIcon(), hBrush);
        FillRgn(hdc, btnMaximize->GetIcon(), hBrush);

        //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);
        }

        //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);
    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;

    //Register the classEx
    return RegisterClassEx(&wc);
}

Your WM_PAINT handler leaks resources like nobody's business. That's probably where your problem comes from. The limit on GDI objects is extremely high, but you will eventually hit it if you leak like a sieve when repainting and force a lot of repaints... Why are you not letting the operating system do what the operating system is designed to do? Let it draw the window caption and frame, handle mouse events and resizing, etc. — Cody Gray
Also if you want a resizable window without a border handle the WM_NCHITTEST message and return the appropriate HT* value. Then let the OS handle resizing the window on its own. If you want to help/control/modify how it does that, handle the WM_WINDOWPOSCHANGING message. — theB
@CodyGray I'm having a litte bit of trouble seeing where the memory leaks are (the same handles are reused every time), but thanks for mentioning it. The reason i'm not letting it draw the window caption and frame is because i'm using the regions to make the gui i was mentioning and don't wand the standard windows appearence. Seems i have some reading up to do. — user4515695
The main leak is when you're calling hBrush = CreateSolidBrush(COLOR_MAIN); then hBrush = CreateSolidBrush(COLOR_CAPTIONBAR); without a DeleteObject in between. You create 4-5 brushes each paint cycle but only delete 1. In WM_SIZE you don't delete the regions before assigning new ones. — theB

Unknown Unknown · Accepted Answer · 2016-07-03T07:24:21

As @CodyGray suggested here's the working code aswell as the class and the functions dealing with freeing up memory for the region and now brushes too.

Edit: The problem was caused by a memory leak in WM_PAINT when creating, and not deleting, brushes (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);
}

Again, thanks to @CodyGray @theB and @AdrianMcCarthy !

Resizing window with Win32 API

1 Answers