I'm trying to spoof keystrokes; to be a bit more precise: I'm replaying a number of keystrokes which should all get sent at a certain time - sometimes several at the same time (or at least as close together as reasonably possible).
Implementing this using XTestFakeKeyEvent, I've come across a problem. While what I've written so far mostly works as it is intended and sends the events at the correct time, sometimes a number of them will fail. XTestFakeKeyEvent never returns zero (which would indicate failure), but these events never seem to reach the application I'm trying to send them to. I suspect that this might be due to the frequency of calls being too high (sometimes 100+/second) as it looks like it's more prone to fail when there's a large number of keystrokes/second.
A little program to illustrate what I'm doing, incomplete and without error checks for the sake of conciseness:
// #includes ...
struct action {
int time; // Time where this should be executed.
int down; // Keydown or keyup?
int code; // The VK to simulate the event for.
};
Display *display;
int nactions; // actions array length.
struct action *actions; // Array of actions we'll want to "execute".
int main(void)
{
display = XOpenDisplay(NULL);
nactions = get_actions(&actions);
int cur_time;
int cur_i = 0;
struct action *cur_action;
// While there's still actions to execute.
while (cur_i < nactions) {
cur_time = get_time();
cur_action = actions + cur_i;
// For each action that is (over)due.
while ((cur_action = actions + cur_i)->time <= cur_time) {
cur_i++;
XTestFakeKeyEvent(display, cur_action->code,
cur_action->down, CurrentTime);
XFlush(display);
}
// Sleep for 1ms.
nanosleep((struct timespec[]){{0, 1000000L}}, NULL);
}
}
I realize that the code above is very specific to my case, but I suspect that this is a broader problem - which is also why I'm asking this here.
Is there a limit to how often you can/should flush XEvents? Could the application I'm sending this to be the issue, maybe failing to read them quickly enough?
It's been a little while but after some tinkering, it turned out that my delay between key down and key up was simply too low. After setting it to 15ms the application registered the actions as keystrokes properly and (still) with very high accuracy.
I feel a little silly in retrospect, but I do feel like this might be something others could stumble over as well.
Related
How do I know if the timer is running or already started? Without waiting the time is elapsed?
UINT_PTR nID = SetTimer(123, 60x1000, NULL); // Info after 1 Min.
bool bTimerStarted = false; // do I need this bool var to check the state of the timer?
if (nID == 123)
bTimerStarted = true;
You cannot. There is no API to query whether any given timer exists, without also resetting that timer (which SetTimer can do).
Then again, I cannot think of a situation where this would be required. Unless you've designed yourself into a corner previously. In that case, solve the architectural issue, and you'll find that you won't need this information either.
I am using wxTimerEvent() to call a function at a certain frequency. But it does not always call the function as expected.
For example, it works fine for a random time duration, and then it does not call the function at all for a few seconds. SHere is my block of code. Please help me figure out this issue...
class MyFrame : public wxFrame
{
public:
...
void OnTimer(wxTimerEvent& event);
private:
wxTimer *mTimer
wxDECLARE_EVENT_TABLE();
};
wxBEGIN_EVENT_TABLE(MyFrame, wxFrame)
EVT_TIMER(TIMER_ID, MyFrame::OnTimer)
wxEND_EVENT_TABLE()
MyFrame::MyFrame()
{
mTimer = new wxTimer(this, TIMER_ID)
m_timer.Start(100); // 100 millisecond interval
}
void MyFrame::OnTimer(wxTimerEvent& event)
{
// my logic -this is working fine... just set a flag.
}
Timers are not guaranteed to fire at exactly the specified interval, but for a 100ms timer to not be called for several seconds is not normal at all. I suspect your code doesn't return to the event loop, preventing it from dispatching the timer events. If you're sure this is not the case, you would really need to produce an example reproducing the problem (ideally the smallest possible change to the wxWidgets minimal sample) and open a bug report about it (please be sure to mention your wxWidgets version and platform if you do this).
I'm debugging Qt5.3.1 on Mac, because my program freezes sometimes (intermittent ). I discovered that it is because the QTimer can't work properly.
In Qt code, they use the following two lines to trigger function activateTimersSourceCallback
CFRunLoopSourceSignal(d->activateTimersSourceRef);
CFRunLoopWakeUp(mainRunLoop());
void QCocoaEventDispatcherPrivate::activateTimersSourceCallback(void *info)
{
static int counter = 0;
NSLog(#"finished activeteTimersSourceCallback %d", counter++);
}
but sometimes, these two lines doesn't work, activateTimersSourceCallback won't get called.
I googled, but I couldn't find any solution? is this a known OS bug?
the initialization details:
// keep our sources running when modal loops are running
CFRunLoopAddCommonMode(mainRunLoop(), (CFStringRef) NSModalPanelRunLoopMode);
CFRunLoopSourceContext context;
bzero(&context, sizeof(CFRunLoopSourceContext));
context.info = d;
context.equal = runLoopSourceEqualCallback;
// source used to activate timers
context.perform = QCocoaEventDispatcherPrivate::activateTimersSourceCallback;
d->activateTimersSourceRef = CFRunLoopSourceCreate(kCFAllocatorDefault, 0, &context);
Q_ASSERT(d->activateTimersSourceRef);
CFRunLoopAddSource(mainRunLoop(), d->activateTimersSourceRef, kCFRunLoopCommonModes);
Such behavior very likely can occur when UI event loop is overloaded with events or some business logic takes too long time. You should to check your business logic and move it to separate thread or run asynchronous.
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.
How would one click on a button, wait for an event like blur and then get the pagesource of the site?
I know i can use the getPagesource() method, but I only wanna do this after a jquery loading image has been shown.
If the blur event results in a visible effect, you could wait for that effect, like waiting for an image to be shown.
Otherwise, if there is no visible effect from that event, you would need a "testing hook" to tell your test that the function associated with that event already ran, like a javascript variable being set to a known value that you could query in the test.
For both cases you could use an explicit wait for the condition, like what is shown in the documentation:
http://seleniumhq.org/docs/04_webdriver_advanced.html#explicit-and-implicit-waits
EDIT:
Regarding your comment, Nyegaard, you could use an explicit wait like this one:
WebDriver driver = new FirefoxDriver();
driver.get("http://somedomain/url_that_delays_loading");
Boolean expectedTextAppeared =
(new WebDriverWait(driver, 10))
.until(ExpectedConditions.textToBePresentInElement(
By.id("ctl00_content_createnewschema_modalAlert_alertMessage"), "textYoureExpecting"));
This code will wait for "textYoureExpecting" to appear in the span with a timeout of 10 seconds. If it takes more time for it to appear, you just need to adjust the timeout.
For all AJAX requests in the webpage I use jQuery.Active flag to determine if the page is loaded or not. If jQuery.Active is non-zero that means those are the number of active requests the browser is dealing with. When it comes down to zero, that means number of active requests are none. I haven't used this flag for blur events, but you might as well give it a try. You should definitely use implicitly and explicitly waits Luiz suggested. Here is a function that waits for 5 minutes for active requests to complete. You could perhaps parameterize that, add try, catch etc.
public int waitforAJAXRequestsToComplete(){
long start = System.currentTimeMillis();
long duration;
boolean ajaxNotReady = true;
while(ajaxNotReady){
if(((JavascriptExecutor)driver).executeScript("return jQuery.active").toString().equals("0"))
return 0;
duration = System.currentTimeMillis() - start;
duration = (long) (duration/(60*1000F));
if(duration>5.0)
return 1;
}
return 1;
}