Dialog box margins

Alexander Kindel

I'm generating dialog templates programmatically for a win32 project. A thing I often want to do is size the dialog box such that the distance between the left edge of the client region and the left edge of the leftmost control is the same as that between the right edge of the rightmost control and the right edge of the client region. Since the size of the dialog box as specified in the template, I believe, includes the non-client area, the only way I know of to do this is to use AdjustWindowRect on a RECT representing the desired client region. Since this requires the handle of the window being adjusted, I can't do it until after the dialog has been created. So I was wondering...if I can't ensure equal margins until runtime, how is it possible that one can use the GUI editor Visual Studio provides to create dialogs with equal margins ahead of time? I want to be able to do that too.

Lost User

You can select a set of controls in the editor and then use the toolbar tool that centres the group in the dialog. There are tools to centre horizontally or vertically, make equidistant, align together etc.

mo1492

I don't know if I'm misunderstanding your question but if you want to resize the dialog at runtime, you can calculate your control positions and use SetWindowPos(NULL, -1, -1, cx, cy, SWP_NOMOVE | SWP_NOACTIVATE | SWP_NOZORDER); in the OnInitDialog() function. sorry if I misunderstood.

Alexander Kindel

Resizing at runtime is what I'm currently doing, and it's an acceptable solution, but if possible I would like to specify the size of the dialog in the template, which is generated before runtime, such that it's correct relative to the controls it contains to begin with, without need of resizing. The fact that the dialog editor can do this suggests that it is indeed possible somehow.

mo1492

I did something like this a long time ago where I defined a dialog within a code module without the ui editor and I think you will have to implement the use of DLGTEMPLATE which is used to define the dialog and all of the associated controls. Take a look at InitModalIndirect() in the Mfc library dlgcore.cpp and I believe there was some needed functions in occmgr.cpp that will help to some extent. If you haven't used this structure before, it will required a bit of work. Oh yes, I'm still on V2005 so if you have the latest visual studio there may be some changes. Hope this is what you are looking for.

Maximilien

It is impossible (*) to do. Win32 and MFC do not implement design time dynamic resizing of dialog controls, and offer no automatic run time resizing of dialog controls (other than MoveWindow and SetWindowPos ). You need to do it manually; there are many 3rd party solutions available that will manage resizing at run time. All of them sucks one way or the other.

I'd rather be phishing!

leon de boer

In standard Win32 API the dialog will be passed a WM_INITDIALOG message after it is created but before it is displayed. WM_INITDIALOG message - Windows applications | Microsoft Docs[^] You can simply do a call to GetClientRect to get the parent area and change the dialog that is what the message is for. You can also use CreateDialogIndirectParam, CreateDialogParam, DialogBoxIndirectParam, or DialogBoxParam and pass a pointer to the area or anything else you may want to do at runtime. If you have not got access to the dialogs parent window handle you can get it by using the dialog handle with GetParent function | Microsoft Docs[^] The dialog has been created and all functions on the handle work it just has not been made visible at that point. You can also move and resize your child windows by handle or ID, they have all been created but nothing is visible at that point. You can also manually add child windows if you so desire at that point. The WM_PAINT message to draw the dialog will be straight after that message and if it's a modal dialog it will then enter modal mode. I am not sure how MFC encapsulates the WM_INITDIALOG probably ONINITDIALOG or something like that.

In vino veritas

leon de boer

Incorrect look at WM_INITDIALOG the message exists to do it. You simply move and resize the child windows before they become visible that is the whole point for the message to exist (read the message description). Everything is created but nothing has been drawn at that point. WM_INITDIALOG message - Windows applications | Microsoft Docs[^]

In vino veritas

leon de boer

A blank empty dialog template centred in it's parent at runtime and done the way speedbump is suggesting is coded below. It is pretty straight forward you just need to allocate global memory block as the template and you can fill the controls in at initialization

int DialogFromTemplate (HWND parent, int DialogWth, int DialogHt, char* DlgTitle, DLGPROC handler)
{
int nchar, ret;
int x, y;
RECT r;
HGLOBAL hgbl;
LPDLGTEMPLATE lpdt;
LPWORD lpw;
LPWSTR lpwsz;

GetClientRect(parent, &r); // Get parent client area
x = ((r.right+r.left)/2); // Calc x client centre position
y = ((r.bottom+r.top)/2); // Calc y client centre position

/\* from the client centre the dialog left is half width and top half height less \*/
x -= DialogWth/2;
y -= DialogHt/2;

/* template size and position are in multiples of 2 .. yeah its weird */
x /= 2; // X client left position in template units
y /= 2; // Y client top position in template units

hgbl = GlobalAlloc(GMEM_ZEROINIT, 1024); // Allocate memory
if (!hgbl) return -1; // If allocate fail exit
lpdt = (LPDLGTEMPLATE)GlobalLock(hgbl); // Lock the allocated memory
lpdt->style = WS_POPUP | WS_CAPTION | WS_SYSMENU; // Window style
lpdt->cdit = 0; // Number of controls
lpdt->x = x; // X position
lpdt->y = y; // Y psoition
lpdt->cx = DialogWth/2; // Window width (template units)
lpdt->cy = DialogHt/2; // Window height (template units)
lpw = (LPWORD)(lpdt + 1); // Set pointer address
*lpw++ = 0; // No menu
*lpw++ = 0; // Predefined dialog box class (by default)
lpwsz = (LPWSTR)lpw; // Typecast pointer
nchar = 1 + MultiByteToWideChar(CP_ACP, 0, DlgTitle,
-1, lpwsz, 50); // Title of dialog
lpw += nchar; // Increment by size of name
*lpw++ = 0; // No creation data
GlobalUnlock(hgbl); // Release lock on the memory block
ret = (int)DialogBoxIndirectParam(GetModuleHandle(0),
(LPDLGTEMPLATE)hgbl, parent, Handler, 0); // Create the dialog from template
GlobalFree(hgbl); // Free the allocated memory
return ret; // Return result
}

Alexander Kindel

What I'm doing already is setting the using the size information in the dialog template to store the size I want the client region to be, then calling GetWindowRect, AdjustWindowRect, and MoveWindow from the WM_INITDIALOG implementation. From the answers I've gotten, it sounds like this is about the most direct solution I could hope for, which is good to know.

leon de boer

There are two parts to things positioning and scaling Let me formally centre the dialog at runtime to it's parent in WM_INITDIALOG .. it is this simple

RECT R1, R2;
GetClientRect(GetParent(Wnd), &R1); // Parent client area
GetWindowRect(Wnd, &R2); // Dialog area
SetWindowPos(Wnd, 0,
(R1.right+R1.left)/2 - (R2.right-R2.left)/2 , // Parent x centre - half dialog width
(R1.top+R1.Bottom)/2 - (R2.bottom-R2.top)/2, // Parent y centre - half dialog height
0, 0, // No size data
SWP_NOSIZE | SWP_NOACTIVATE | SWP_NOZORDER);

Now if you want to centre and rescale generally you do the scale as a fraction to avoid floats so (numerator/denominator) where denominator must not be zero This usually works well because you have ( desired size / current size ) being the exact fraction

int Wth, Ht;
RECT R1, R2;
GetClientRect(GetParent(Wnd), &R1); // Parent client area
GetWindowRect(Wnd, &R2); // Dialog area
Wth = (R2.right-R2.left) * numerator; // Multiply dialog width by numerator
Wth /= denominator; // Divide dialog width by denominator
Ht = (R2.bottom-R2.top) * numerator; // Multiply dialog height by numerator
Ht /= denominator; // Divide dialog height by denominator
SetWindowPos(Wnd, 0,
(R1.right+R1.left)/2 - Wth/2 , // Parent x centre - half scaled dialog width
(R1.top+R1.Bottom)/2 - Ht/2, // Parent y centre - half dialog height
Wth, Ht, // New sizes
SWP_NOACTIVATE | SWP_NOZORDER);// Do not change order or activate

/* so if you want to scale the children windows you need to scale and move them */
/* now go thru each child by id (shown as xxx) and scale and move them with this */
RECT R3;
HWND cWnd = GetDlgItem(Wnd, xxxx); // Fetch and hold child handle from xxxx id
GetWindowRect(cWnd, &R3); // Fetch the child area
R3.left *= numerator; // Multiply child window left by numerator
R3.left /= denominator; // Divide child window left by denominator
R3.right *= numerator; // Multiply child window right by numerator
R3.right /= denominator; // Divide child window right by denominator
R3.top *= numerator; // Multiply child window top by numerator
R3.t

mo1492

Looks familiar... good job :)

Maximilien

There are no mechanisms in MFC or Win32 to automatically place and resize controls; you have to do it manually in WM_SIZE. WM_INITDIALOG will let you place controls at runtime, yes, but that's it; there is no API that says, hey, I want to attach the left side of my edit box to the left side of the dialog.

I'd rather be phishing!

leon de boer

The OP didn't ask for that ... he asked for the ability to rescale a template or resource based dialog which we all do for high DPI apps because the inbuilt behaviour sucks. Also for the record there are groups of controls that will do exactly what you have described they are called docking controls all you decide is where you want the anchor when you create them. I can easily give you a group of control that will automatically anchor themselves to the left side of a dialog it's trivial and CDockablePane in particular are often run that way in a dialog.

In vino veritas

David Crow

Alexander Kindel wrote:

...size the dialog box such that the distance between the left edge of the client region and the left edge of the leftmost control is the same as that between the right edge of the rightmost control and the right edge of the client region.

Unless I'm way out in left field, this is what you do via the resource editor. If you have the guides enabled (Format ==> Toggle Guides), then you can drag your leftmost control to the left until it snaps to the left, and drag your rightmost control to the right until it snaps to the right. If you don't have or want the guides enabled, you can do it manually. For the leftmost control, just drag it until its left edge is at whatever X pos you want, usually 7 DLUs. For the rightmost control, take the sum of the control's width and the guide value (e.g., 7), and subtract that from the from the dialog's width. That is X pos of the control. It sounds way more complicated than it is. Back when I was doing dialog design regularly, I could do it easily. Just get within 10 DLUs visually, and then do the math on the tens place in your head. Microsoft used to adhere to these guidelines where spacing, DLUs, and such were all explained, but that may have changed.

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