Creating a Tabbed Dialog Box

The example in this section creates a dialog box that uses tabs to provide multiple pages of controls. The main dialog box is a modal dialog box. Each page of controls is defined by a dialog box template that specifies the WS_CHILD style. When a tab is selected, the example creates a modeless dialog box for the incoming page and destroys the dialog box for the outgoing page.

Note In many cases, you can implement multiple-page dialog boxes more easily by using property sheets. For more information about property sheets, see Property Sheets.

The template for the main dialog box simply defines two button controls. When processing the WM_INITDIALOG message, the dialog box procedure creates a tab control and loads the dialog template resources for each of the child dialog boxes.

The information is saved in an application-defined structure called DLGHDR. A pointer to this structure is associated with the dialog box window by using the SetWindowLong function. The structure is defined in the application's header file, as follows.

#define C_PAGES 3

typedef struct tag_dlghdr {

HWND hwndTab; // tab control

HWND hwndDisplay; // current child dialog box

RECT rcDisplay; // display rectangle for the tab control

DLGTEMPLATE *apRes[C_PAGES];

} DLGHDR;

The following function processes the WM_INITDIALOG message for the main dialog box. The function allocates the DLGHDR structure, loads the dialog template resources for the child dialog boxes, and creates the tab control.

The size of each child dialog box is specified by the DLGTEMPLATE structure. The function examines the size of each dialog box and uses the macro for the TCM_ADJUSTRECT message to calculate an appropriate size for the tab control. Then it sizes the dialog box and positions the two buttons accordingly. This example sends TCM_ADJUSTRECT by using the TabCtrl_AdjustRect macro.

VOID WINAPI OnTabbedDialogInit(HWND hwndDlg)

{

DLGHDR *pHdr = (DLGHDR *) LocalAlloc(LPTR, sizeof(DLGHDR));

DWORD dwDlgBase = GetDialogBaseUnits();

int cxMargin = LOWORD(dwDlgBase) / 4;

int cyMargin = HIWORD(dwDlgBase) / 8;

TC_ITEM tie;

RECT rcTab;

HWND hwndButton;

RECT rcButton;

int i;

// Save a pointer to the DLGHDR structure.

SetWindowLong(hwndDlg, GWL_USERDATA, (LONG) pHdr);

// Create the tab control.

InitCommonControls();

pHdr->hwndTab = CreateWindow(

WC_TABCONTROL, "",

WS_CHILD | WS_CLIPSIBLINGS | WS_VISIBLE,

0, 0, 100, 100,

hwndDlg, NULL, g_hinst, NULL

);

if (pHdr->hwndTab == NULL) {

// handle error

}

// Add a tab for each of the three child dialog boxes.

tie.mask = TCIF_TEXT | TCIF_IMAGE;

tie.iImage = -1;

tie.pszText = "First";

TabCtrl_InsertItem(pHdr->hwndTab, 0, &tie);

tie.pszText = "Second";

TabCtrl_InsertItem(pHdr->hwndTab, 1, &tie);

tie.pszText = "Third";

TabCtrl_InsertItem(pHdr->hwndTab, 2, &tie);

// Lock the resources for the three child dialog boxes.

pHdr->apRes[0] = DoLockDlgRes(MAKEINTRESOURCE(DLG_FIRST));

pHdr->apRes[1] = DoLockDlgRes(MAKEINTRESOURCE(DLG_SECOND));

pHdr->apRes[2] = DoLockDlgRes(MAKEINTRESOURCE(DLG_THIRD));

// Determine the bounding rectangle for all child dialog boxes.

SetRectEmpty(&rcTab);

for (i = 0; i < C_PAGES; i++) {

if (pHdr->apRes[i]->cx > rcTab.right)

rcTab.right = pHdr->apRes[i]->cx;

if (pHdr->apRes[i]->cy > rcTab.bottom)

rcTab.bottom = pHdr->apRes[i]->cy;

}

rcTab.right = rcTab.right * LOWORD(dwDlgBase) / 4;

rcTab.bottom = rcTab.bottom * HIWORD(dwDlgBase) / 8;

// Calculate how large to make the tab control, so

// the display area can accomodate all the child dialog boxes.

TabCtrl_AdjustRect(pHdr->hwndTab, TRUE, &rcTab);

OffsetRect(&rcTab, cxMargin - rcTab.left,

cyMargin - rcTab.top);

// Calculate the display rectangle.

CopyRect(&pHdr->rcDisplay, &rcTab);

TabCtrl_AdjustRect(pHdr->hwndTab, FALSE, &pHdr->rcDisplay);

// Set the size and position of the tab control, buttons,

// and dialog box.

SetWindowPos(pHdr->hwndTab, NULL, rcTab.left, rcTab.top,

rcTab.right - rcTab.left, rcTab.bottom - rcTab.top,

SWP_NOZORDER);

// Move the first button below the tab control.

hwndButton = GetDlgItem(hwndDlg, BTN_CLOSE);

SetWindowPos(hwndButton, NULL,

rcTab.left, rcTab.bottom + cyMargin, 0, 0,

SWP_NOSIZE | SWP_NOZORDER);

// Determine the size of the button.

GetWindowRect(hwndButton, &rcButton);

rcButton.right -= rcButton.left;

rcButton.bottom -= rcButton.top;

// Move the second button to the right of the first.

hwndButton = GetDlgItem(hwndDlg, BTN_TEST);

SetWindowPos(hwndButton, NULL,

rcTab.left + rcButton.right + cxMargin,

rcTab.bottom + cyMargin, 0, 0,

SWP_NOSIZE | SWP_NOZORDER);

// Size the dialog box.

SetWindowPos(hwndDlg, NULL, 0, 0,

rcTab.right + cyMargin +

2 * GetSystemMetrics(SM_CXDLGFRAME),

rcTab.bottom + rcButton.bottom + 2 * cyMargin +

2 * GetSystemMetrics(SM_CYDLGFRAME) +

GetSystemMetrics(SM_CYCAPTION),

SWP_NOMOVE | SWP_NOZORDER);

// Simulate selection of the first item.

OnSelChanged(hwndDlg);

}

// DoLockDlgRes - loads and locks a dialog template resource.

// Returns a pointer to the locked resource.

// lpszResName - name of the resource

DLGTEMPLATE * WINAPI DoLockDlgRes(LPCSTR lpszResName)

{

HRSRC hrsrc = FindResource(NULL, lpszResName, RT_DIALOG);

HGLOBAL hglb = LoadResource(g_hinst, hrsrc);

return (DLGTEMPLATE *) LockResource(hglb);

}

The following function processes the TCN_SELCHANGE notification message for the main dialog box. The function destroys the dialog box for the outgoing page, if any. Then it uses the CreateDialogIndirect function to create a modeless dialog box for the incoming page.

// OnSelChanged - processes the TCN_SELCHANGE notification.

// hwndDlg - handle of the parent dialog box

VOID WINAPI OnSelChanged(HWND hwndDlg)

{

DLGHDR *pHdr = (DLGHDR *) GetWindowLong(

hwndDlg, GWL_USERDATA);

int iSel = TabCtrl_GetCurSel(pHdr->hwndTab);

// Destroy the current child dialog box, if any.

if (pHdr->hwndDisplay != NULL)

DestroyWindow(pHdr->hwndDisplay);

// Create the new child dialog box.

pHdr->hwndDisplay = CreateDialogIndirect(g_hinst,

pHdr->apRes[iSel], hwndDlg, ChildDialogProc);

}

The following function processes the WM_INITDIALOG message for each of the child dialog boxes. You cannot specify the position of a dialog box created using the CreateDialogIndirect function. This function uses the SetWindowPos function to position the child dialog within the tab control's display area.

// OnChildDialogInit - Positions the child dialog box to fall

// within the display area of the tab control.

VOID WINAPI OnChildDialogInit(HWND hwndDlg)

{

HWND hwndParent = GetParent(hwndDlg);

DLGHDR *pHdr = (DLGHDR *) GetWindowLong(

hwndParent, GWL_USERDATA);

SetWindowPos(hwndDlg, HWND_TOP,

pHdr->rcDisplay.left, pHdr->rcDisplay.top,

0, 0, SWP_NOSIZE);

}

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