win32 c++ handle button press, PeekMessage not working? - c++

Question

I want to handle a c++ win32 API button press in a native window, I'm currently attempting doing it like so -
#include <stdint.h>
#include <Windows.h>
#include <process.h>
#include <iostream>
#include <sstream>
#include <tchar.h>
#include <strsafe.h>
#include <crtdefs.h>
#include <stdafx.h>
#include <stdio.h>
#include "stdafx.h"
#include "name.h"
#include "libobs/obs.h"
#include "libobs/obs-module.h"
#define uploadName "Upload Window"
#define uploadWNDWidth 500
#define uploadWNDHeight 500
#define IDC_SELECT_VIDEO (100)
HWND hBtnParent = HWND("UploadVideo");
HWND SelectVideoBTN, UploadBTN, hWnd, hBtn;
WPARAM wmId, wmEvent;
HINSTANCE hUpload;
WNDCLASSEX wcexUpload;
int nCmdShowUpload = 1;
using namespace std;
LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);
//load obs modules
class load{
public:
void static loading(){
obs_module_load;
obs_module_load_locale;
}
};
LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case BM_CLICK:
if (wParam == IDC_SELECT_VIDEO) {
MessageBox(hWnd, L"if", L"if", 0);
}
else{
MessageBox(hWnd, L"else", L"else", 0);
}
break;
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}
}
bool obs_module_load(void)
{
//init handler
//HANDLE messageLoopThreadHandler;
//set the handler to the thread
//messageLoopThreadHandler = (HANDLE)_beginthreadex(0, 0, &messageLoopThread, 0, 0, 0);
//wait for object to be in specified state
//WaitForSingleObject(messageLoopThreadHandler, INFINITE);
//startMessageThreadLoop ThreadLoopInstance;
//ThreadLoopInstance.startMyThread();
MessageBox(hWnd, L"ThreadStart", L"ThreadStart", 0);
//create message loop for buttons
//cleanup thread created by _beginThreadEx
//CloseHandle(messageLoopThreadHandler);
WNDCLASSEX vidUploader;
vidUploader.cbSize = sizeof(WNDCLASSEX);
vidUploader.style = CS_HREDRAW | CS_VREDRAW;
vidUploader.lpfnWndProc = WndProc;
vidUploader.cbClsExtra = 0;
vidUploader.cbWndExtra = 0;
vidUploader.hInstance = hUpload;
vidUploader.hIcon = LoadIcon(hUpload, MAKEINTRESOURCE(IDI_P2GOVIDEOUPLOADER20));
vidUploader.hCursor = LoadCursor(NULL, IDC_ARROW);
vidUploader.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
vidUploader.lpszMenuName = MAKEINTRESOURCE(IDC_P2GOVIDEOUPLOADER20);
vidUploader.lpszClassName = (LPCWSTR)(L"UploadVideo");
vidUploader.hIconSm = LoadIcon(wcexUpload.hInstance, MAKEINTRESOURCE(IDI_SMALL));
RegisterClassEx(&vidUploader);
hInst = hUpload; // Store instance handle in our global variable
// The parameters to CreateWindow explained:
// szWindowClass: the name of the application
// szTitle: the text that appears in the title bar
// WS_OVERLAPPEDWINDOW: the type of window to create
// CW_USEDEFAULT, CW_USEDEFAULT: initial position (x, y)
// 500, 100: initial size (width, length)
// NULL: the parent of this window
// NULL: this application dows not have a menu bar
// hInstance: the first parameter from WinMain
// NULL: not used in this application
hWnd = CreateWindow((LPCWSTR)(L"UploadVideo"), (LPCWSTR)(L"Upload Video's"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 500, 100, NULL, NULL, hUpload, NULL);
SelectVideoBTN = CreateWindow(
L"BUTTON", // Predefined class; Unicode assumed
L"Select Video's", // Button text
WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON, // Styles
10, // x position
460, // y position
100, // Button width
25, // Button height
hWnd, // Parent window
(HMENU)IDC_SELECT_VIDEO, // Assign appropriate control ID
(HINSTANCE)GetWindowLong(hWnd, GWL_HINSTANCE),
NULL); // Pointer not needed.
UploadBTN = CreateWindow(
L"BUTTON", // Predefined class; Unicode assumed
L"Upload", // Button text
WS_TABSTOP | WS_VISIBLE | WS_CHILD | BS_DEFPUSHBUTTON, // Styles
390, // x position
460, // y position
100, // Button width
25, // Button height
hWnd, // Parent window
NULL, // No menu.
(HINSTANCE)GetWindowLong(hWnd, GWL_HINSTANCE),
NULL); // Pointer not needed.
RECT rect = { 0, 0, uploadWNDWidth, uploadWNDHeight };
AdjustWindowRect(&rect, GetWindowLong(hWnd, GWL_STYLE), FALSE);
SetWindowPos(hWnd, 0, 0, 0, rect.right - rect.left, rect.bottom - rect.top, SWP_NOZORDER | SWP_NOMOVE);
if (!hWnd)
{
MessageBox(NULL, _T("Call to CreateWindow failed!"), _T("Win32 Guided Tour"), NULL);
return 1;
}
MSG msge = { 0 };
while (PeekMessage(&msge, NULL, 0, 0, PM_REMOVE) > 0)
{
//translate and send messages
TranslateMessage(&msge);
DispatchMessage(&msge);
}
MSG msg;
// The parameters to ShowWindow explained:
// hWnd: the value returned from CreateWindow
//nCmdShow: the fourth parameter from WinMain
ShowWindow(hWnd, nCmdShowUpload);
UpdateWindow(hWnd);
load::loading();
return true;
}
When I currently load OBS, after having included the dll what happens is -
OBS starts
Window pops u
I click on window
Nothing happens
where on step 4, right after clicking on the button a MessageBox should popup saying - MessageBox(hWnd, L"else", L"else", 0); if it goes into the else, and if the if statement is true then MessageBox(hWnd, L"if", L"if", 0);
However my code won't even enter the callback function.
edit -
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;
switch (message)
{
case WM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
load::loading();
// Parse the menu selections:
switch (wmId)
{
case IDM_ABOUT:
DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
break;
case IDM_EXIT:
DestroyWindow(hWnd);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
break;
case WM_PAINT:
hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code here...
EndPaint(hWnd, &ps);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}
This is where the WndProc references refer to.

Answer 1

You're handling the receive of the button click incorrect. You should handle a WM_COMMAND message and check the high word of the WPARAM for the notification code.

Answer 2

You should use GetMessage, it won't hang the program.
You can use PeekMessage if you want constant update. For example in a game where you need to constantly paint the window. It has to be something like this:
//create window...
//show window...
MSG msg = { 0 };
while (msg.message != WM_QUIT)
{
//default message processing
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
//constantly paint the window when there is no other message
render_window(hwnd);
}
}
//do cleanup here
return 0;
Note that the program terminates when the above while loop is finished. You cannot put ShowWindow/UpdateWindow after that.
Second, your main window seems to be vidUploader. And the window procedure for it is set to vidUploader.lpfnWndProc = WndProc; But you have not defined WndProc. Instead you have something else called WindowProcedure
To check for button notification:
case WM_COMMAND:
if (LOWORD(wParam) == IDC_SELECT_VIDEO)
MessageBox...;
break;