Each thread have their own cursor count that is incremented/decremented by ShowCursor calls.
Is there a way to query that counter to determine if the cursor is currently visible?
This pattern is supposed to work but there are some problems with that:
ShowCursor (FALSE);
bool visible = (ShowCursor (TRUE) >= 0);
The windows app compatibility layer might silently not allow the counter to decrease below 0 so the first ShowCursor call does nothing and the second corrupts the counter.
It has some unwanted side effects like potential and needless cursor hiding/unhiding
You can test for cursor visibility directly with GetCursorInfo()
bool IsCursorVisible()
{
CURSORINFO ci = { sizeof(CURSORINFO) };
if (GetCursorInfo(&ci))
return ci.flags & CURSOR_SHOWING;
return false;
}
I'm not sure what it means for this call to fail so I just have it returning false if it fails.
Related
I'm a bit unsure of the meaning of some of the return values from a call to the GetWindowPlacement() function, so I'd like your help, please.
I'll be calling this to obtain the normal dimensions of a hidden window.
First, where do the values of the showCmd field come from? In the Microsoft documentation of the return structure (WINDOWPLACEMENT structure, all the descriptions of the possible values use verbs/action words; e.g., "SW_MAXIMIZE: Maximizes the specified window", or "SW_SHOWNOACTIVATE: Displays a window in its most recent size and position."
I want to obtain the dimensions of the hidden window without unhiding/restoring it first, so with the verbs it seems that I would have to call SetWindowPlacement() with showCmd set to SW_SHOWNOACTIVATE before calling GetWindowPlacement. Is that correct?
So do I understand correctly that the primary (and perhaps only) way that field gets its various values is by an explicit call to SetWindowPlacement() somewhere?
My second question relates to the rcNormalPosition return values. Do those data include the window decorations, or are they client values?
Thank you for your time!
The meaning of the showCmd member of the WINDOWPLACEMENT struct is a bit confusing because Win32 is reusing the SW_* commands used by ShowWindow().
Luckily, the meaning is documented on the GetWindowPlacement() function.
If the window identified by the hWnd parameter is maximized, the
showCmd member is SW_SHOWMAXIMIZED. If the window is minimized,
showCmd is SW_SHOWMINIMIZED. Otherwise, it is SW_SHOWNORMAL.
So, based on which of those 3 values is returned, you can tell whether the window is currently maximized, minimized or, normal (restored). And if you'd like to know what the normal placement is, you can just use the rcNormalPosition member. You do not need to call SetWindowPlacement() at all.
However, heed the warning that GetWindowPlacement() returns workspace coordinates rather than screen coordinates, which differ based on taskbar position and size. This is not a problem if you are only using the coordinates returned by GetWindowPlacement() to call SetWindowPlacement(). Otherwise, you might have to find a way to convert from workspace to screen coordinates.
I found these 2 functions to work for me.
void MyDialog::LoadDialogPlacement()
{
static WINDOWPLACEMENT last_wp = {};
// Load last stored DB version
WINDOWPLACEMENT *wp = new WINDOWPLACEMENT;
GetStoredWindowPlacement(&wp);
if (memcmp((void *)&last_wp, (const void *)wp, sizeof(WINDOWPLACEMENT)) == 0) return;
memcpy((void *)&last_wp, (const void *)wp, sizeof(WINDOWPLACEMENT));
SetWindowPlacement(wp);
delete[] wp;
}
void MyDialog::SaveDialogPlacement()
{
static WINDOWPLACEMENT last_wp = {};
if (IsWindowVisible())
{
WINDOWPLACEMENT wp = {};
wp.length = sizeof(WINDOWPLACEMENT);
GetWindowPlacement(&wp);
if (memcmp((void *)&last_wp, (const void *)&wp, wp.length) == 0) return;
memcpy((void *)&last_wp, (const void *)&wp, wp.length);
StoreWindowPlacement(&wp);
}
}
Can I somehow get the specific foreground window of the application? For example, not the HWND of the whole Skype application, but some currently selected internal window of this application (maybe it's chat window's text edit).
Thanks in advance.
You can use EnumChildWindows.
Basically, it goes through the child windows of a given window until you find the one that has the characteristics you want. And - it is good to know that the "parent" of all application windows is HWND_DESKTOP
Here is code:
EnumChildWindows(HWND_PARENT,findChildWithClass,(LPARAM)"NetUIHWND");
And somewhere else:
BOOL CALLBACK findChildWithClass(HWND hwndTest,LPARAM lParam) {
char *pszClass = (char *)lParam;
char szClass[64];
GetClassName(hwndTest,szClass,64);
if ( strlen(szClass) < 1 ) return TRUE;
if ( 0 == _strnicmp(pszClass,szClass,min(strlen(pszClass),strlen(szClass))) ) {
hwndFoundChild = hwndTest;
return FALSE;
}
EnumChildWindows(hwndTest,findChildWithClass,lParam);
if ( hwndFoundChild )
return FALSE;
return TRUE;
}
So, the function "findChildWithClass" will be repeatedly called by Windows with the handle to the next child of the specified parent.
When the characteristics of that child window match what you are looking for, in this case class name, the function sets the value of a global static and returns FALSE to indicate the enumeration should stop.
You can get the class name of any window using Spy++, in this case, I used spy++ to find the name of the MS Word frame window. However, since the particular code will also look at every child of every child sent to it - you could have also found an "inner" window of MS Word using it. Also - you don't have to use class name, perhaps something else (window contents ?) is unique to the application you are trying to discover the window for ( Skype ? )
I'm having some understanding problem of event-handling with Xlib functions.
My question would be - how do i press a key during an animation, without disturbing the animation.
My setup so far, is that i have some animation in a while loop and want to achieve a KeyPress event which modifies a parameter.
It looks something like this
while(1){
XNextEvent(dis, &report);
switch (report.type) {
case KeyPress:
if (XLookupKeysym(&report.xkey, 0) == XK_space){
//...modify parameter a..//}}
//...Some animation where parameter a is used to modify animation...//}
Now, the problem is that i have to press the key consistently to get the animation on my screen, otherwise nothing appears. I've tried some multiple code-modifications, with KeyRelease etc. but i don't have clou, really.
Trivially said - i need to hook a key during animation without the XNextEvent process, waiting for any event. But without the XNextEvent statement in my code, conditional statements for KeyPress event checking aren't working.
I guess formally this would mean:
while(1){
if(report.type==KeyPress) {
if (XLookupKeysym(&report.xkey, 0) == XK_space){
//...modify parameter a..//}}
//...Some animation where parameter a is used to modify animation...//}
Use XPending() to check for XEvents before getting them with XNextEvent().
XPending() returns then number of events in the event queue so modify your loop:
while(1){
if (XPending(dis) > 0) {
XNextEvent(dis, &report);
switch (report.type) {
case KeyPress:
if (XLookupKeysym(&report.xkey, 0) == XK_space){
//...modify parameter a..//
}
}
}
//...Some animation where parameter a is used to modify animation...//
}
I want hide cursor inside window client area without borders and title bar (it is simple opengl application). So, function
ShowCursor(FALSE);
is not suitable. After some searching the winapi i find this solution:
//when create window class for application window
WNDCLASSEX WndClass;
//...
BYTE CursorMaskAND[] = { 0xFF };
BYTE CursorMaskXOR[] = { 0x00 };
WndClass.hCursor = CreateCursor(NULL, 0,0,1,1, CursorMaskAND, CursorMaskXOR);
Is this a good way to solve this typical task? What way is the best?
MSDN says that you can set the WNDCLASSEX hCursor field to NULL, in which case you must explicitly set the cursor in your window procedure (which means handling the WM_SETCURSOR message). For example:
if (Msg == WM_SETCURSOR && LOWORD(lParam) == HTCLIENT)
{
SetCursor(NULL);
return TRUE;
}
// Remainder of window procedure code
Checking for HTCLIENT ensures that the cursor is only hidden in the client area, and that the window frame and caption will use the correct cursors.
The SetCursor() call you're using doesn't take a BOOL - it takes an HCURSOR. So you're calling SetCursor( NULL ) which means "hide that cursor". What I found in the old days on Windows is that this is video driver dependent and many drivers don't respect it. The most consistent way to handle this is to make a transparent cursor resource in your app, and return a handle to that cursor in the WM_SETCURSOR message from your main window.
I found that first setting hCursor to NULL:
wc.hCursor = NULL;
and then setting the cursor to NULL:
SetCursor(NULL);
will make it disappear.
From MSDN, I read that the application will set its own cursor by default if one is not defined in hCursor. That's what the first line of code is doing.
Then, after the application sets its own cursor, I mess with it with the second line of code. Or at least, I think that's what happens.
I'm writing an application that runs an algorithm, but allows you to 'step through' the algorithm by pressing a button - displaying what's happening at each step.
How do I listen for events while within a method?
eg, look at the code I've got.
static int proceed;
button1Event(GtkWidget *widget)
{
proceed = 0;
int i = 0;
for (i=0; i<15; i++) //this is our example 'algorithm'
{
while (proceed ==0) continue;
printf("the nunmber is %d\n", i);
proceed = 0;
}
}
button2Event(GtkWidget *widget)
{
proceed = 1;
}
This doesn't work because it's required to exit out of the button1 method before it can listen for button2 (or any other events).
I'm thinking something like in that while loop.
while(proceed == 0)
{
listen_for_button_click();
}
What method is that?
The "real" answer here (the one any experienced GTK+ programmer will give you) isn't one you will like perhaps: don't do this, your code is structured the wrong way.
The options include:
recommended: restructure the app to be event-driven instead; probably you need to keep track of your state (either a state machine or just a boolean flag) and ignore whichever button is not currently applicable.
you can run a recursive main loop, as in the other answer with gtk_main_iteration(); however this is quite dangerous because any UI event can happen in that loop, such as windows closing or other totally unrelated stuff. Not workable in most real apps of any size.
move the blocking logic to another thread and communicate via a GAsyncQueue or something along those lines (caution, this is hard-ish to get right and likely to be overkill).
I think you are going wrong here:
while(proceed == 0)
{
listen_for_button_click();
}
You don't want while loops like this; you just want the GTK+ main loop doing your blocking. When you get the button click, in the callback for it, then write whatever the code after this while loop would have been.
You could check for pending events & handle the events in while loop in the clicked callback. Something on these lines:
button1Event(GtkWidget *widget)
{
proceed = 0;
int i = 0;
for (i=0; i<15; i++) //this is our example 'algorithm'
{
while (proceed ==0)
{
/* Check for all pending events */
while(gtk_events_pending())
{
gtk_main_iteration(); /* Handle the events */
}
continue;
}
printf("the nunmber is %d\n", i);
proceed = 0;
}
}
This way when the events related click on the second button is added to the event queue to be handled, the check will see the events as pending and handle them & then proceed. This way your global value changes can be reflected & stepping should be possible.
Hope this helps!
If you want to do it like this, the only way that comes to my mind is to create a separate thread for your algorithm and use some synchronization methods to notify that thread from within button click handlers.
GTK+ (glib, to be more specific) has its own API for threads and synchronization. As far as I know Condition variables are a standard way to implement wait-notify logic.