Using List Boxes
This section explains how to perform certains tasks associated with list boxes.The following code examples demonstrate how to perform the tasks.
- Creating a Simple List Box
- Creating a Directory Listing in a Single-selection List Box
- Creating a Multiple-selection List Box
- Creating an Owner-drawn List Box
Creating a Simple List Box
The following example demonstrates how a dialog box procedure creates a simple list box and fills it with the names of people on a softball team. When a name in the list is selected, additional information about the player is displayed in the dialog box. The following illustration shows the dialog box.
The list box has the LBS_STANDARD style, a combination of LBS_SORT,
LBS_NOTIFY, WS_VSCROLL, and WS_BORDER. The code initializes the dialog box
while processing the
#define BUFFER MAX_PATH
#define NAMELENGTH 15
#define POSITIONLENGTH 20
#define TEAMSIZE 15
typedef struct
{
TCHAR tchName[NAMELENGTH];
TCHAR tchPosition[POSITIONLENGTH];
int nGamesPlayed;
int nInningsPlayed;
double xBattingAverage;
TCHAR tchFoodName[NAMELENGTH];
} Player;
Player Roster[] =
{
{"Alan", "Center field", 17, 56, .375, "Cannelloni"},
{"Colin", "Pitcher", 26, 96, .456, "Lefse"},
{"Cindy", "Second base", 13, 58, .207, "Tequila"},
{"Dave", "First base", 28, 138, .508, "Suds"},
{"David", "Center field", 18, 101, .612, "Bok Choy"}
{"Jack", "Pitcher", 27, 110, .542, "Animal Crackers"},
{"Julie", "Right field", 22, 101, .509, "Mashed Potatoes"},
{"Karen", "Second base", 26, 140, .238, "Pez"},
{"Kathie", "Left field", 26, 127, .353, "Baba Ganouj"},
{"Matt", "Shortstop", 24, 112, .579, "Oats"},
{"Miriam", "Right field", 24, 112, .393, "Zotz"},
{"Pete", "Shortstop", 26, 90, .608, "Beet"},
{"Seth", "Center field", 20, 76, .407, "Otter Pop"},
{"Suzanna", "Catcher", 16, 53, .286, "Toast"},
{"Wendy", "Third base", 25, 154, .493, "Ham"},
};
BOOL APIENTRY DlgTeamProc(
HWND hDlg, // window handle to dialog box
UINT message, // type of message
UINT wParam, // message-specific information
LONG lParam) // message-specific information
{
TCHAR tchBuffer[BUFFER];
int nItem;
int i;
HWND hwndList;
switch (message)
{
case WM_INITDIALOG:
{
hwndList = GetDlgItem(hDlg, IDL_SOFTBALL);
// Initialize the list box (fill it with player names).
for (i = 0; i < TEAMSIZE; i++)
{
SendMessage(hwndList, LB_ADDSTRING, 0,
(LPARAM) Roster[i].tchName);
SendMessage(hwndList, LB_SETITEMDATA, i, (LPARAM) i);
}
SetFocus(hwndList);
return FALSE;
}
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDL_SOFTBALL:
switch (HIWORD(wParam))
{
case LBN_SELCHANGE:
// Show the selected player's statistics.
hwndList = GetDlgItem(hDlg, IDL_SOFTBALL);
nItem = SendMessage(hwndList, LB_GETCURSEL,
0, 0);
i = SendMessage(hwndList, LB_GETITEMDATA,
nItem, 0);
SetDlgItemText(hDlg, IDS_POS,
Roster[i].tchPosition);
SetDlgItemText(hDlg, IDS_GAME,
_itoa(Roster[i].nGamesPlayed,
tchBuffer, 10));
SetDlgItemText(hDlg, IDS_INN,
_itoa(Roster[i].nInningsPlayed,
tchBuffer, 10));
SetDlgItemText(hDlg, IDS_BA,
_gcvt(Roster[i].xBattingAverage,
3, tchBuffer));
SetDlgItemText(hDlg, IDS_FOOD,
Roster[i].tchFoodName);
return TRUE;
}
break;
case IDOK:
case IDCANCEL:
// Destroy the dialog box.
EndDialog(hDlg, TRUE);
return TRUE;
default:
return FALSE;
}
default:
return FALSE;
}
}
Creating a Directory Listing in a Single-selection List Box
The following example demonstrates how to display the content of the current directory in a list box and enable the user to delete one file at a time.
In addition to the standard list box styles, this list box has the
LBS_MULTICOLUMN and LBS_HSCROLL styles. The code initializes the list box by
using the
#define BUFFER MAX_PATH
BOOL APIENTRY DlgDelFileProc(
HWND hDlg, // window handle to dialog box
UINT message, // type of message
UINT wParam, // message-specific information
LONG lParam)
{
DWORD cchCurDir;
LPTSTR lpszCurDir;
LPTSTR lpszFileToDelete;
int nItem;
int nTotal;
TCHAR tchBuffer[BUFFER+1];
BOOL fResult;
switch (message)
{
case WM_INITDIALOG:
// Initialize the list box by filling it with files from
// the current directory.
lpszCurDir = tchBuffer;
GetCurrentDirectory(cchCurDir, lpszCurDir);
lpszCurDir[BUFFER+1] = '\0';
DlgDirList(hDlg, lpszCurDir, IDL_FILES, IDS_PATHTOFILL, 0);
SetFocus(GetDlgItem(hDlg, IDL_FILES));
return FALSE;
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDOK:
// When the user presses the DEL (IDOK) button,
// delete the selected file.
lpszFileToDelete = tchBuffer;
DlgDirSelectEx(hDlg, lpszFileToDelete, MAX_PATH,
IDL_FILES);
fResult = DeleteFile(lpszFileToDelete);
if (!fResult)
{
MessageBox(hDlg, "Could not delete file.",
NULL, MB_OK);
}
else
{
nItem = SendMessage(GetDlgItem(hDlg,
IDL_FILES), LB_GETCURSEL, 0, 0);
nTotal = SendMessage(GetDlgItem(hDlg,
IDL_FILES), LB_DELETESTRING, nItem, 0);
// Update the list box.
if (nTotal > nItem)
{
SendMessage(GetDlgItem(hDlg, IDL_FILES),
LB_SETCURSEL, nItem, 0);
}
else
{
SendMessage(GetDlgItem(hDlg, IDL_FILES),
LB_SETCURSEL, nTotal, 0);
}
}
return TRUE;
case IDCANCEL:
// Destroy the dialog box.
EndDialog(hDlg, TRUE);
return TRUE;
default:
return FALSE;
}
default:
return FALSE;
}
}
Creating a Multiple-selection List Box
The following example displays and initializes the dialog box used in the
preceding example. However, this code uses the LBS_MULTIPLESEL style to enable
the user to select more than one file at a time. When the user chooses the Delete
button, the example sends the
#define BUFFER MAX_PATH
#define BIGBUFF 8192
BOOL APIENTRY DlgDelFilesProc(
HWND hDlg, // window handle to dialog box
UINT message, // type of message
UINT wParam, // message-specific information
LONG lParam)
{
DWORD cchCurDir;
LPTSTR lpszCurDir;
LPTSTR lpszFileToDelete;
int nSelItems;
int nSelItemsInBuffer;
TCHAR tchBuffer[BUFFER+1];
TCHAR tchMsgBuff[BUFFER+1];
int nBuffer[BIGBUFF];
int i;
BOOL fResult;
HWND hListBox;
HRESULT hr;
switch (message) {
case WM_INITDIALOG:
// Initialize the list box by filling it with files from
// the current directory.
lpszCurDir = tchBuffer;
GetCurrentDirectory(cchCurDir, lpszCurDir);
lpszCurDir[BUFFER+1] = '\0';
DlgDirList(hDlg, lpszCurDir, IDL_FILES, IDS_PATHTOFILL, 0);
SetFocus(GetDlgItem(hDlg, IDL_FILES));
return FALSE;
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDOK:
// When the user presses the Delete (IDOK)
// button, delete all the selected files.
lpszFileToDelete = tchBuffer;
hListBox = GetDlgItem(hDlg, IDL_FILES);
nSelItems = SendMessage(hListBox,
LB_GETSELCOUNT, 0, 0);
nSelItemsInBuffer = SendMessage(hListBox,
LB_GETSELITEMS, 512, (LPARAM) nBuffer);
if (nSelItems > nSelItemsInBuffer)
{
MessageBox(hDlg, "Too many items selected.",
NULL, MB_OK);
}
else
{
// Go through the list backwards because after
// deleting an item the indices change for
// every subsequent item. By going backward,
// the indices are never invalidated.
for (i = nSelItemsInBuffer - 1; i >= 0; i--)
{
SendMessage(hListBox, LB_GETTEXT,
nBuffer[i],
(LPARAM) lpszFileToDelete);
fResult = DeleteFile(lpszFileToDelete);
if (!fResult)
{
hr = StringCchPrintf(tchMsgBuff,
BUFFER,
"Could not delete file: %s "
"GetLastError = %u",
(LPARAM) lpszFileToDelete);
if (FAILED(hr))
{
//
// TODO: write error handler
//
}
// Call app-defined error handler.
ErrorHandler(tchMsgBuff);
}
else
{
SendMessage(hListBox, LB_DELETESTRING,
nBuffer[i], 0);
}
}
SendMessage(hListBox, LB_SETCARETINDEX, 0, 0);
}
return TRUE;
case IDCANCEL:
// Destroy the dialog box.
EndDialog(hDlg, TRUE);
return TRUE;
default:
return FALSE;
}
default:
return FALSE;
}
}
Creating an Owner-drawn List Box
The following example shows how to draw a list box that contains five owner-drawn items: four drawing implements and a fork. Each list item appears as a bitmap followed by the name of the object. A button prompts the user to select one item that is not like the others. Choosing the button with the fork selected displays a "You're right!" message and closes the dialog box. Choosing the button with any other list item selected displays a "Try again!" message.
The list box has the LBS_OWNERDRAW and LBS_HASSTRINGS styles, in addition
to the standard list box styles. The code initializes the list box by sending
the LB_ADDSTRING message to set the text, and then sends the
#define XBITMAP 80
#define YBITMAP 20
#define BUFFER MAX_PATH
HBITMAP hbmpPencil, hbmpCrayon, hbmpMarker, hbmpPen, hbmpFork;
HBITMAP hbmpPicture, hbmpOld;
void AddItem(HWND hwnd, LPSTR lpstr, HBITMAP hbmp)
{
int nItem;
nItem = SendMessage(hwndList, LB_ADDSTRING, 0, lpstr);
SendMessage(hwndList, LB_SETITEMDATA, nItem, hbmp);
}
DWORD APIENTRY DlgDrawProc(
HWND hDlg, // window handle to dialog box
UINT message, // type of message
UINT wParam, // message-specific information
LONG lParam)
{
int nItem;
TCHAR tchBuffer[BUFFER];
HBITMAP hbmp;
HWND hListBox;
TEXTMETRIC tm;
int y;
HDC hdcMem;
LPMEASUREITEMSTRUCT lpmis;
LPDRAWITEMSTRUCT lpdis;
RECT rcBitmap;
HRESULT hr;
size_t * pcch;
switch (message)
{
case WM_INITDIALOG:
// Load bitmaps.
hbmpPencil = LoadBitmap(hinst, MAKEINTRESOURCE(700));
hbmpCrayon = LoadBitmap(hinst, MAKEINTRESOURCE(701));
hbmpMarker = LoadBitmap(hinst, MAKEINTRESOURCE(702));
hbmpPen = LoadBitmap(hinst, MAKEINTRESOURCE(703));
hbmpFork = LoadBitmap(hinst, MAKEINTRESOURCE(704));
// Retrieve list box handle.
hListBox = GetDlgItem(hDlg, IDL_STUFF);
// Initialize the list box text and associate a bitmap
// with each list box item.
AddItem(hListBox, "pencil", hbmpPencil);
AddItem(hListBox, "crayon", hbmpCrayon);
AddItem(hListBox, "marker", hbmpMarker);
AddItem(hListBox, "pen", hbmpPen);
AddItem(hListBox, "fork", hbmpFork);
SetFocus(hListBox);
SendMessage(hListBox, LB_SETCURSEL, 0, 0);
return TRUE;
case WM_MEASUREITEM:
lpmis = (LPMEASUREITEMSTRUCT) lParam;
// Set the height of the list box items.
lpmis->itemHeight = 20;
return TRUE;
case WM_DRAWITEM:
lpdis = (LPDRAWITEMSTRUCT) lParam;
// If there are no list box items, skip this message.
if (lpdis->itemID == -1)
{
break;
}
// Draw the bitmap and text for the list box item. Draw a
// rectangle around the bitmap if it is selected.
switch (lpdis->itemAction)
{
case ODA_SELECT:
case ODA_DRAWENTIRE:
// Display the bitmap associated with the item.
hbmpPicture =(HBITMAP)SendMessage(lpdis->hwndItem,
LB_GETITEMDATA, lpdis->itemID, (LPARAM) 0);
hdcMem = CreateCompatibleDC(lpdis->hDC);
hbmpOld = SelectObject(hdcMem, hbmpPicture);
BitBlt(lpdis->hDC,
lpdis->rcItem.left, lpdis->rcItem.top,
lpdis->rcItem.right - lpdis->rcItem.left,
lpdis->rcItem.bottom - lpdis->rcItem.top,
hdcMem, 0, 0, SRCCOPY);
// Display the text associated with the item.
SendMessage(lpdis->hwndItem, LB_GETTEXT,
lpdis->itemID, (LPARAM) tchBuffer);
GetTextMetrics(lpdis->hDC, &tm);
y = (lpdis->rcItem.bottom + lpdis->rcItem.top -
tm.tmHeight) / 2;
hr = StringCchLength(tchBuffer, BUFFER, pcch);
if (FAILED(hr))
{
// TODO: write error handler
}
TextOut(lpdis->hDC,
XBITMAP + 6,
y,
tchBuffer,
pcch);
SelectObject(hdcMem, hbmpOld);
DeleteDC(hdcMem);
// Is the item selected?
if (lpdis->itemState & ODS_SELECTED)
{
// Set RECT coordinates to surround only the
// bitmap.
rcBitmap.left = lpdis->rcItem.left;
rcBitmap.top = lpdis->rcItem.top;
rcBitmap.right = lpdis->rcItem.left + XBITMAP;
rcBitmap.bottom = lpdis->rcItem.top + YBITMAP;
// Draw a rectangle around bitmap to indicate
// the selection.
DrawFocusRect(lpdis->hDC, &rcBitmap);
}
break;
case ODA_FOCUS:
// Do not process focus changes. The focus caret
// (outline rectangle) indicates the selection.
// The IDOK button indicates the final
// selection.
break;
}
return TRUE;
case WM_COMMAND:
switch (LOWORD(wParam))
{
case IDOK:
// Get the selected item's text.
nItem = SendMessage(GetDlgItem(hDlg, IDL_STUFF),
LB_GETCURSEL, 0, (LPARAM) 0);
hbmp = SendMessage(GetDlgItem(hDlg, IDL_STUFF),
LB_GETITEMDATA, nItem, 0);
// If the item is not the correct answer, tell the
// user to try again.
//
// If the item is the correct answer, congratulate
// the user and destroy the dialog box.
if (hbmp != hbmpFork)
{
MessageBox(hDlg, "Try again!", "Oops", MB_OK);
return FALSE;
}
else
{
MessageBox(hDlg, "You're right!",
"Congratulations.", MB_OK);
// Fall through.
}
case IDCANCEL:
// Destroy the dialog box.
EndDialog(hDlg, TRUE);
return TRUE;
default:
return FALSE;
}
case WM_DESTROY:
// Free any resources used by the bitmaps.
DeleteObject(hbmpPencil);
DeleteObject(hbmpCrayon);
DeleteObject(hbmpMarker);
DeleteObject(hbmpPen);
DeleteObject(hbmpFork);
return TRUE;
default:
return FALSE;
}
return FALSE;
}