GUI enabling/disabling of controls: Difference between revisions

=={{header|C}}==

{{works with|C (with Win32 API)}}

<pre>file main.c</pre>

<lang c>#include <windows.h>

#include "resource.h"

#define MIN_VALUE 0

#define MAX_VALUE 10

BOOL CALLBACK DlgProc( HWND hwnd, UINT msg, WPARAM wPar, LPARAM lPar );

void Increment( HWND hwnd );

void Decrement( HWND hwnd );

void SetControlsState( HWND hwnd );

int WINAPI WinMain( HINSTANCE hInst, HINSTANCE hPInst, LPSTR cmdLn, int show ) {

return DialogBox( hInst, MAKEINTRESOURCE(IDD_DLG), NULL, DlgProc );

}

BOOL CALLBACK DlgProc( HWND hwnd, UINT msg, WPARAM wPar, LPARAM lPar ) {

switch( msg ) {

case WM_INITDIALOG:

srand( GetTickCount() );

SetDlgItemInt( hwnd, IDC_INPUT, 0, FALSE );

break;

case WM_COMMAND:

switch( LOWORD(wPar) ) {

case IDC_INCREMENT:

Increment( hwnd );

break;

case IDC_DECREMENT:

Decrement( hwnd );

break;

case IDC_INPUT:

// update controls' state according

// to the contents of the input field

if( HIWORD(wPar) == EN_CHANGE ) SetControlsState( hwnd );

break;

case IDC_QUIT:

SendMessage( hwnd, WM_CLOSE, 0, 0 );

break;

default: ;

}

break;

case WM_CLOSE: {

int reply = MessageBox( hwnd,

"Do you really want to quit?",

"Quit confirmation", MB_ICONQUESTION|MB_YESNO );

if( reply == IDYES )

EndDialog( hwnd, 0 );

} break;

default: ;

}

return 0;

}

void Increment( HWND hwnd ) {

UINT n = GetDlgItemInt( hwnd, IDC_INPUT, NULL, FALSE );

if( n < MAX_VALUE ) {

SetDlgItemInt( hwnd, IDC_INPUT, ++n, FALSE );

SetControlsState( hwnd );

}

}

void Decrement( HWND hwnd ) {

UINT n = GetDlgItemInt( hwnd, IDC_INPUT, NULL, FALSE );

if( n > MIN_VALUE ) {

SetDlgItemInt( hwnd, IDC_INPUT, --n, FALSE );

SetControlsState( hwnd );

}

}

void SetControlsState( HWND hwnd ) {

UINT n = GetDlgItemInt( hwnd, IDC_INPUT, NULL, FALSE );

EnableWindow( GetDlgItem(hwnd,IDC_INCREMENT), n<MAX_VALUE );

EnableWindow( GetDlgItem(hwnd,IDC_DECREMENT), n>MIN_VALUE );

}</lang>

<pre>file resource.h</pre>

<lang c>#define IDD_DLG 101

#define IDC_INPUT 1001

#define IDC_INCREMENT 1002

#define IDC_DECREMENT 1003

#define IDC_QUIT 1004</lang>

<pre>file resource.rc</pre>

<lang c>#include <windows.h>

#include "resource.h"

LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL

IDD_DLG DIALOG 0, 0, 154, 46

STYLE DS_3DLOOK | DS_CENTER | DS_MODALFRAME | DS_SHELLFONT | WS_CAPTION | WS_VISIBLE | WS_POPUP | WS_SYSMENU

CAPTION "GUI Component Interaction"

FONT 12, "Ms Shell Dlg" {

EDITTEXT IDC_INPUT, 33, 7, 114, 12, ES_AUTOHSCROLL | ES_NUMBER

PUSHBUTTON "Increment", IDC_INCREMENT, 7, 25, 50, 14

PUSHBUTTON "Decrement", IDC_DECREMENT, 62, 25, 50, 14, WS_DISABLED

PUSHBUTTON "Quit", IDC_QUIT, 117, 25, 30, 14

RTEXT "Value:", -1, 10, 8, 20, 8

}</lang>