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discman1028

Drop-down menus in a Windows application

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I'm wondering if anyone knows of a simple wrapper class for using drop-down menus. This is for a GDI+ app in C++. I would like the menus to appear when I right-click anywhere within the window. GLUT has a great implementation of this...

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It's not hard to implement a wrapper of your own. Here's an example:


/ Win32.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "Win32.h"
#include <string>
#include <vector>

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst; // current instance
TCHAR szTitle[MAX_LOADSTRING]; // The title bar text
TCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name

class ShortcutMenu
{
private:
typedef void (*CommandEvent)(ShortcutMenu *sender);
HMENU m_hmenu;
std::vector<CommandEvent> command_events;
UINT current_item;
friend void DispatchMenuCommand(HWND hWnd,WPARAM wParam,LPARAM lParam);
void OnItem(UINT item)
{
CommandEvent comm=command_events[item];
comm(this);
}
public:
ShortcutMenu():current_item(0)
{
m_hmenu=CreatePopupMenu();
MENUINFO mi;
mi.cbSize=sizeof(mi);
mi.fMask=MIM_MENUDATA|MIM_STYLE;
mi.dwMenuData=(ULONG_PTR)this;
mi.dwStyle=MNS_NOTIFYBYPOS;
SetMenuInfo(m_hmenu,&mi);
}
void AddItem(std::string caption,CommandEvent command_event)
{
command_events.push_back(command_event);
AppendMenu(m_hmenu,MF_ENABLED|MF_STRING,current_item,caption.c_str());
++current_item;
}
void Track(HWND hwnd,int x,int y)
{
POINT p;
p.x=x;p.y=y;
ClientToScreen(hwnd,&p);
TrackPopupMenuEx(m_hmenu,0,p.x,p.y,hwnd,NULL);
}
};

void DispatchMenuCommand(HWND hWnd,WPARAM wParam,LPARAM lParam)
{
MENUINFO mi;
mi.cbSize=sizeof(mi);
mi.fMask=MIM_MENUDATA;
GetMenuInfo((HMENU)lParam,&mi);
ShortcutMenu* menu=(ShortcutMenu*)mi.dwMenuData;
UINT item=GetMenuItemID((HMENU)lParam,wParam);
if (menu)
{
menu->OnItem(item);
}
}

class MyMenu:public ShortcutMenu
{
public:
MyMenu():ShortcutMenu()
{
AddItem("Start",&MyMenu::OnStart);
AddItem("Stop",&MyMenu::OnStop);
}
static void OnStart(ShortcutMenu *sender)
{
MessageBox(0,"Start!","Menu command",MB_OK);
}
static void OnStop(ShortcutMenu *sender)
{
MessageBox(0,"Stop","Menu command",MB_OK);
}
};


MyMenu myMenu;

// Forward declarations of functions included in this code module:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY _tWinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPTSTR lpCmdLine,
int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);

// TODO: Place code here.
MSG msg;
HACCEL hAccelTable;

// Initialize global strings
LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
LoadString(hInstance, IDC_WIN32, szWindowClass, MAX_LOADSTRING);
MyRegisterClass(hInstance);

// Perform application initialization:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}

hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_WIN32));


// Main message loop:
while (GetMessage(&msg, NULL, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}

return (int) msg.wParam;
}



//
// FUNCTION: MyRegisterClass()
//
// PURPOSE: Registers the window class.
//
// COMMENTS:
//
// This function and its usage are only necessary if you want this code
// to be compatible with Win32 systems prior to the 'RegisterClassEx'
// function that was added to Windows 95. It is important to call this function
// so that the application will get 'well formed' small icons associated
// with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEX wcex;

wcex.cbSize = sizeof(WNDCLASSEX);

wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_WIN32));
wcex.hCursor = LoadCursor(NULL, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCE(IDC_WIN32);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

return RegisterClassEx(&wcex);
}

//
// FUNCTION: InitInstance(HINSTANCE, int)
//
// PURPOSE: Saves instance handle and creates main window
//
// COMMENTS:
//
// In this function, we save the instance handle in a global variable and
// create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
HWND hWnd;

hInst = hInstance; // Store instance handle in our global variable

hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

if (!hWnd)
{
return FALSE;
}

ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);

return TRUE;
}

//
// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// PURPOSE: Processes messages for the main window.
//
// WM_COMMAND - process the application menu
// WM_PAINT - Paint the main window
// WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;

switch (message)
{
case WM_RBUTTONDOWN:
myMenu.Track(hWnd,LOWORD(lParam),HIWORD(lParam));
break;
case WM_MENUCOMMAND:
DispatchMenuCommand(hWnd,wParam,lParam);
break;
case WM_COMMAND:
wmId = LOWORD(wParam);
wmEvent = HIWORD(wParam);
// 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;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
UNREFERENCED_PARAMETER(lParam);
switch (message)
{
case WM_INITDIALOG:
return (INT_PTR)TRUE;

case WM_COMMAND:
if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
{
EndDialog(hDlg, LOWORD(wParam));
return (INT_PTR)TRUE;
}
break;
}
return (INT_PTR)FALSE;
}




All you have to do is derive a class from ShortcutMenu and of course handle WM_RBUTTONDOWN(to show the menu) and WM_MENUCOMMAND.

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It's not "hard" but there's no doubt time involved. I would if I was adding this to my engine... but I am making a quick and dirty app.

Thank you for the example however. :) And thanks for the TrackPopupMenuEx() link, Colin.

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