Subclassin button WinApi - c++

Question

In my project i have created a simple Button class:
button.hpp:
class Button : public Control {
std::string text;
int id;
std::function<void(void)>&& callback{};
static inline const char* sClassName = "Button";
static LRESULT CALLBACK ButtonSubclassProc(HWND, UINT, WPARAM, LPARAM, UINT_PTR, DWORD_PTR);
public:
Button(HWND parent, POINT position, SIZE size, int id, const std::string& text) noexcept;
virtual ~Button() noexcept;
inline void SetCallback(std::function<void(void)>&& callback) noexcept { this->callback = callback; }
NODISCARD inline int GetId() const noexcept { return id; }
private:
NODISCARD bool CreateControl(HWND) noexcept override;
void DestroyControl() noexcept override;
void Invoke() const noexcept;
};
button.cpp:
#include "button.hpp"
Button::Button(HWND parent, POINT position, SIZE size, int id, const std::string& text) noexcept
: Control(position, size), id(id), text(text) {
isCreated = CreateControl(parent);
SetWindowSubclass(hwnd, &Button::ButtonSubclassProc, id, reinterpret_cast<DWORD_PTR>(this));
}
Button::~Button() noexcept {
RemoveWindowSubclass(hwnd, &Button::ButtonSubclassProc, id);
DestroyControl();
}
NODISCARD bool Button::CreateControl(HWND parent) noexcept {
hwnd = CreateWindow(sClassName, text.c_str(), WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON, position.x, position.y, size.cx, size.cy, parent, reinterpret_cast<HMENU>(id), reinterpret_cast<HINSTANCE>(GetWindowLong(parent, GWL_HINSTANCE)), NULL);
return hwnd != NULL;
}
void Button::DestroyControl() noexcept {
Control::DestroyControl();
}
void Button::Invoke() const noexcept {
if (callback) {
callback();
}
}
LRESULT CALLBACK Button::ButtonSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR id, DWORD_PTR refData) {
auto button = reinterpret_cast<Button*>(refData);
if (uMsg == WM_COMMAND) {
MessageBox(0, std::to_string(id).c_str(), 0, 0);
button->Invoke();
return TRUE;
}
return DefSubclassProc(hwnd, uMsg, wParam, lParam);
}
that's how i pass message from main window procedure:
case WM_COMMAND: {
return SendMessage(reinterpret_cast<HWND>(lParam), WM_COMMAND, wParam, lParam);
}
And it works fine when only one button is created, but when i try to create more, it does not matter which button i would push, i always get callback of the last created button.
I suppose this happens because of SetWindowSubclass call in counstructor and passing it this pointer, but i do not know what should i do. Read about GetWindowSubclass but i dont clearly understand how to use it.
Buttons are created in main window class:
mainwnd.hpp
class MainWindow : public NonCopyable, public NonMovable {
HINSTANCE handle;
HWND hwnd;
int width;
int height;
bool isRegistered{ false };
bool isCreated{ false };
IRenderer* renderer;
Button* buttonStart;
Button* buttonStop;
static inline const char* sClassName = "MAIN_WINDOW_CLASS";
static LRESULT CALLBACK WindowProc(HWND, UINT, WPARAM, LPARAM);
public:
explicit MainWindow(HINSTANCE handle, int width, int height) noexcept;
~MainWindow() noexcept;
NODISCARD inline bool IsRegistered() const noexcept { return isRegistered; }
NODISCARD inline bool IsCreated() const noexcept { return isCreated; }
NODISCARD bool CheckControls() const noexcept;
NODISCARD inline int Width() const noexcept { return width; }
NODISCARD inline int Height() const noexcept { return height; }
void Update() noexcept;
private:
NODISCARD bool RegisterMainClass() const noexcept;
NODISCARD bool CreateMainWindow() noexcept;
void UnregisterMainClass() noexcept;
void DestroyMainWindow() noexcept;
void CreateControls() noexcept;
void DestroyControls() noexcept;
void OnButtonStartPushed();
void OnButtonStopPushed();
};
mainwnd.cpp
#include "main_window.hpp"
MainWindow::MainWindow(HINSTANCE handle, int width, int height) noexcept
: width(width), height(height), handle(handle) {
isRegistered = RegisterMainClass();
isCreated = CreateMainWindow();
CreateControls();
}
MainWindow::~MainWindow() noexcept {
DestroyControls();
DestroyMainWindow();
UnregisterMainClass();
}
bool MainWindow::RegisterMainClass() const noexcept {
WNDCLASS wc;
memset(&wc, 0, sizeof(WNDCLASSA));
if (!GetClassInfo(handle, sClassName, &wc)) {
wc.style = 0;
wc.hInstance = handle;
wc.lpszClassName = sClassName;
wc.lpfnWndProc = WindowProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = sizeof(LONG_PTR);
wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE + 1);
wc.hIcon = NULL;
wc.hCursor = NULL;
wc.lpszMenuName = NULL;
}
return RegisterClass(&wc) != 0;
}
bool MainWindow::CreateMainWindow() noexcept {
if (IsRegistered()) {
hwnd = CreateWindow(sClassName, NULL, WS_VISIBLE | WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, width, height, NULL, NULL, handle, this);
}
return hwnd != NULL;
}
void MainWindow::UnregisterMainClass() noexcept {
UnregisterClass(sClassName, handle);
isRegistered = false;
}
void MainWindow::DestroyMainWindow() noexcept {
if (hwnd) {
DestroyWindow(hwnd);
hwnd = NULL;
}
isCreated = false;
}
void MainWindow::CreateControls() noexcept {
this->renderer = new Canvas(hwnd, { 10,10 }, { 200,200 });
buttonStart = new Button(hwnd, { 300,50 }, { 100,40 }, 145, "Start");
buttonStart->SetCallback(std::bind(&MainWindow::OnButtonStartPushed, this));
buttonStop = new Button(hwnd, { 300,150 }, { 100,40 }, 168, "Stop");
buttonStop->SetCallback(std::bind(&MainWindow::OnButtonStopPushed, this));
}
void MainWindow::DestroyControls() noexcept {
delete renderer;
delete buttonStart;
delete buttonStop;
}
bool MainWindow::CheckControls() const noexcept {
return renderer != 0;
}
void MainWindow::Update() noexcept {
renderer->Redraw();
}
void MainWindow::OnButtonStartPushed() {
MessageBox(0, "Start", 0, 0);
}
void MainWindow::OnButtonStopPushed() {
MessageBox(0, "Stop", 0, 0);
}
LRESULT CALLBACK MainWindow::WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
if (uMsg == WM_NCCREATE) {
MainWindow* window = reinterpret_cast<MainWindow*>(lParam);
SetWindowLongPtr(hwnd, GWL_USERDATA, reinterpret_cast<LONG_PTR>(window));
return TRUE;
}
auto window = reinterpret_cast<MainWindow*>(GetWindowLongPtr(hwnd, GWL_USERDATA));
if (window == nullptr) {
return FALSE;
}
switch (uMsg) {
case WM_DESTROY: {
PostQuitMessage(0);
return 0;
}
case WM_COMMAND: {
return SendMessage(reinterpret_cast<HWND>(lParam), WM_COMMAND, wParam, lParam);
}
default:
return DefWindowProc(hwnd, uMsg, wParam, lParam);
}
return TRUE;
}
Message Loop:
MSG message;
memset(&message, 0, sizeof(MSG));
while (true) {
if (PeekMessage(&message, 0, 0, 0, PM_REMOVE) != 0) {
if (message.message == WM_QUIT) {
break;
}
TranslateMessage(&message);
DispatchMessage(&message);
} else {
mainWindow.Update();
}
}