How can I disable the snap feature of Windows 7 for my application (progmatically)? Or is there any way to detect if the application has been snapped, and specifically call an API function to unsnap it?
Calling SetWindowPos() or ShowWindow() does not unsnap it correctly *(SW_MAXIMIZE does). Calling SetWindowPos() actually causes strange behavior in future calls to SetWindowPos() and MoveWindow(). The same inconsistencies do not apply to a window that is maximized.
I figured out a way to unsnap, by calling ShowWindow() with SW_MAXIMIZE. This is odd since no other values unsnap with this call, even though the window can be moved away, it is still anchored to the side of the screen. Maximizing it fixes the problem, whereafter I can move the window where it needs to be.
#define WM_RESTOREORIGINALSTYLE WM_USER+... /* your first free USER message */
case WM_SYSCOMMAND:
{
if(wParam==(SC_MOVE|2)) wParam=SC_SIZE|9;
if((wParam&0xFFE0)==SC_SIZE && (wParam&0x000F)) // handles MOVE and SIZE in one "if"
{
long int oldStyle=GetWindowLongW(hwnd,GWL_STYLE);
PostMessageW(hwnd,WM_RESTOREORIGINALSTYLE,GWL_STYLE,oldStyle);
SetWindowLongW(hwnd,GWL_STYLE,oldStyle &0xFEFEFFFF); // disable WS_MAXIMIZE and WS_MAXIMIZEBOX
DefWindowProcW(hwnd,WM_SYSCOMMAND,wParam,lParam);
return 0;
}
return DefWindowProcW(hwnd,WM_SYSCOMMAND,wParam,lParam);
}
case WM_RESTOREORIGINALSTYLE:
{
if((long int)wParam==GWL_STYLE)
SetWindowLongW(hwnd,GWL_STYLE,lParam);
return 0;
}
The PostMessage will be processed in subsequent message loop - it means ASAP after entering into move-size loop.
If you use own drawing method of frame, please do not forget to redraw your frame correctly on WM_STYLECHANGED message, internally store oldStyle in your class.
Why it works? Windows check snap condition at start of move/size action. If WS_MAXIMIZE and WS_MAXIMIZEBOX are disabled at start, the snap behaviour is disabled.
The SC_SIZE|9 is equivalent of SC_MOVE|2 without blocking redrawing for half a second.
If you don't want to enable dragging maximized windows if they are fully maximized, check state of SC_MOVE item in system menu and if it is enabled, directly return 0 in WM_SYSCOMMAND.
Verified on Windows 8.1.
I've a dialog based Win32-app on Win7-Aero which only displays a dialog. The dialog should have a title bar. I don't want that the user can move the dialog on the screen.
I've no luck so far... handling WM_NCHITTEST, WM_SYSCOMMAND... setting SWP_NOMOVE.
What is the best way to achieve NoMove? I think DWM changes something on Win7.
You could do this by handling WM_WINDOWPOSCHANGING and when you see an attempted move, change the coordinates back to where they should be. E.g.
switch (uMsg)
{
case WM_WINDOWPOSCHANGING:
if (!(reinterpret_cast<LPWINDOWPOS>(lParam)->flags & SWP_NOMOVE))
{
reinterpret_cast<LPWINDOWPOS>(lParam)->x = g_iMyXCoord;
reinterpret_cast<LPWINDOWPOS>(lParam)->y = g_iMyYCoord;
}
return 0;
}
You would probably need to add some intelligence to this to distinguish between attempted moves by the user, and moves that your own program makes (or that the system makes if necessary - e.g. if a monitor disappears for instance).
Even though you say it doesn't work, I would have thought you could also do this by trapping WM_NCHITTEST and returning HTBORDER whenever HTCAPTION would have been returned - however you would have to do this by sub-classing the window rather than in the DialogProc (because you would need to call the default handler first and then process/change the return value). Same for WM_SYSCOMMAND (to catch moves the user attempts via the system menu).
I want to make Application where you can see only one window at a time in order to save memory. Let's say, we have one window, after pressing a button another window shows, but the previous is deleted. If the button pressing is handled in window callback function, is it safe to delete the window from inside of that window function and recreate it after the new window is closed? Something like that:
void callback(...) {
...
if (msgID == ENTER_KEY) {
deleteMyself();
showWindow2();
createMyself();
}
...
}
Could you suggest better approach if this one is not good?
I think this is generally on a desktop a bad idea. So you would loose everything the userinput. And depending on your application the user maybe confuses why an options dialog closes the main window.
However on a mobile device it is normal only to have just one window (except you use dialogs). But in those cases all inputs should be stored so that the window can be reovered to its old state.
In general if you have trouble with the memory managment better check if you leak somewhere memory in most cases the GUI does not need so much memory.
I'm looking for a way to check to see that a window I am creating is visible and entirely on one monitor. I have seen too many programs do nasty things when they try to restore their position and the place no longer exists and I don't want my program to be vulnerable to this.
How do I find the information on the actual layout of the monitors?
The Screen class contains a lot of functionality for this.
You should check for yourself if a form is outside the Bounds of the Screen, but this is pretty straightforward:
if (!Screen.GetWorkingArea(myWindow).Bounds.Contains(myWindow.Bounds)) {
// Adjust location
}
Just a small syntax correction, or perhaps an update in Visual Studio 2012:
if (!Screen.GetWorkingArea(myWindow).Contains(myWindow.Bounds))
{
//Adjust location
}
In Windows, is it possible to set window A such that it is always on top of window B, yet allow other windows to work as normal and appear over the top of both, when active.
In other words, I want a parent-child relationship between two windows. Can this be done without making window A a child of window B, MDI-style? Window B isn't mine (Internet Explorer), and screws my dialog A's graphics up when I try to achieve this with SetParent.
I thought I'd cracked it with this idea from an MSDN forum post, but alas windows A is still always on top of everything, not just window B.
// Place window A on top
SetWindowPos(hWndWindow, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE|SWP_NOSIZE);
// Place window B underneath it
SetWindowPos(hWndParent, HWND_NOTOPMOST, 0, 0, 0, 0, SWP_NOSIZE|SWP_NOMOVE);
Is it possible?
Wouldn't creating an ownership relationship do the trick?
SetWindowLong(hwndChild, GWL_HWNDPARENT, hwndOwner)
The windows can be in different processes and you can call this from any process. This will ensure that the child window is always above the owner window. This is different than SetParent which actually creates a Parent / Child relationship. Read through this article (its from 1993 but still mostly correct) to see the distinction between ownership and parenting.
When your window's Z-order (or size or position) is changing, it should receive a WM_WINDOWPOSCHANGING message. If you process that message, you have an opportunity to modify the final Z-order (or size or position) to which the window is moved.
To illustrate, in hWndA's window procedure:
case WM_WINDOWPOSCHANGING:
DefWindowProc(hWnd, msg, wParam, lParam);
WINDOWPOS *p = (WINDOWPOS*)lParam;
p->hwndInsertAfter = hWndB;
p->flags &= ~SWP_NOZORDER;
return 0;
should insert hWndA after hWndB in the Z-order any time hWndA's position changes.
Until Vista, one way to do it would have been to use SetWindowsHookEx, and hook the WH_CBT or WH_CALLWNDPROC hook, and then take appropriate action when you detect the Z order changing. However this doesn't work with Vista (as far as I can tell from googling).
The only other solution I can think of is to set up a timer to fire every few seconds, and then when you receive a WM_TIMER, you interrogate the system using GetNextWindow to find out which window is behind yours. If it's not IE, then call SetWindowPos to position your window above IE (I assume you have a HWND for the IE window you care about - remember there can be multiple IE windows).
This will cause problems if people try to bring your window to the front - it will flip back to being just above IE. In this case, in your code you could handle WM_ACTIVATE and try to change the Z-order of IE's window so it's below your window (call SetWindowPos to move IE's window so it's above the window that is currently below your window). This solution may be fraught with problems as Windows may try to prevent you messing with the windows of another process, for security reasons. On the other hand, the MSDN docs for SetWindowPos don't explicitly mention that you can't manipulate the windows of another process. There may be obscure limitations though.
Even with this timer hack, you're going to effectively have a busy-waiting loop in your app (with the frequent WM_TIMER messages) and this is generally a bad thing to do, especially for battery life of laptops etc. (because you prevent the CPU from entering a sleep state, and so on).
I'd say there's no good way of doing this, and anything you're likely to get working will be brittle and cause problems. I strongly recommend not trying to do it. Is it possible to make your program into some kind of plug-in or toolbar for IE instead?
NB Be particularly aware that SetWindowsHookEx imposes a performance penalty at a system-wide level if you go down this route.
Maurice's answer is the best out of what's here but is missing an important step. When you call show on your window that you want as the overlay, you need to call the show method that has the parameter. You'll need to define a class that implements the IWin32Window interface and just make a new instance of that. The only thing that interface cares about is the Handle so just set that to the handle of the IE window and it should work pretty well
If the parent-child relationship is made by yourself with the SetWindowPos() function, your desire can be implemented.
Can you access the Z-order of the windows?
I cannot recall the default z-order of windows, but I think it is 1. You might be able to set IE to a -1 and your app to 0.
Try this:
// Place window A on top of window B
SetWindowPos(hWndA, hWndB, 0, 0, 0, 0, SWP_NOMOVE|SWP_NOSIZE);
The second window handle parameter specifies the next window down in the Z order.
Note this doesn't actually change the window parent-child relationships - but you can simulate it.