Screen shot help please

Just started to use "WindowScreenShot" in my code but experiencing unusual results!!

File saves OK
First signal saved the full chart which included the sub-window.
2nd signal .. same currency, same signal , ...saved file ok BUT....

the subwindow in the saved chart is shown blank without the indicator.

What can/does cause this and how can it be avoided?

TIA

Hi Futurespec

without seeing the code you used it's hard to tell what the problem is

the relevant section...


-------------

mFile = Symbol()+" "+Day()+"_"+Month()+"_"+Year()+" "+Hour()+"_"+Minute()+".gif";
if(mScreenShot)
WindowScreenShot(mFile, 1280, 1024);
if(mEmail)
SendMail(mEmailHead, mDetails);
}

you probably need to put a sleep in there or something. my guess is as soon as you get your 'signal' is the same time that the indicator is also doing a refresh... and because mt4 is such a piece of shit it allows your screenshot script to run in the middle of mt4 redrawing the sub-window. so if you can give the cpu a few more cycles to finish the redraw then your screenshot will likely include the updated sub-window.

Appreciate the help, Thankyou.

Again this is something that I would never have thought of.

Think that you are being much tooo kind to mt4 !!!!! ;-)))

Will mt5 be much better? and how long before everyone is using it?
(and NO I do not relish all the recoding)

don't know, and don't know.

i'm sure they will find interesting and new ways to break mt5.

so, was that all it was and you have fixed it?

Waiting for indi to be triggered; will update when I know the results.

Thankyou

the other thing i do is to force mt4 to print the screen as is

ie

WindowScreenShot( strFile, 1000, 600, -1, -1, -1 );

i've never had a problem with this

Thanks JMW
Think that is what I started out with and still had the problems so that is why I changed it slightly.

Think that nubcake may have the answer as the problem appears to happen on the open of a new bar when various things are updating.

Waiting in hope that that is the answer.

Update later.

if it gets fickle then you could try something simpler like...

mark a bool as true when you get the signal. on NEXT tick if bool is true take snapshot.

if you are taking screenshots on the start of a new bar then i'd bet money that it's blank due to the entire sub window requiring a complete redraw that you are catching before it has done it's thing, so doing a screenshot on the next tick is almost guaranteed to be ok (with the caveat that perhaps the rightmost sub-window buffer position might be the previous value or blank). of course, if you then get a candle with a volume of 1 (extremely unlikely) then your code will break since the next tick will be the next candle forming and you are back to the original issue.

The sleep (Sleep(500)did not work ... I put it immediately after the WindowScreenShot(mFile, 1280, 1024);

Should it be before?

"gets fickle" ... well begins with "f**!" anyway.

uh, yes.

the flawed concept i'm assuming is that mt4 decides to redraw the sub-window, blanks the area, lets your indicator run to do any buffer maths, then outputs the result onto the draw area.

so you either screenshot on any tick except the very first one (being when the buffer needs to do a complete redraw), or you can put a sleep in right before taking the screenshot to see if mt4 is running threads (one taking care of screen draws, and another dealing with indicator updates etc) in which case it may complete the redraw before your screenshot gets called.

Yep should have known that :-(

Just tried it and think that it is now ok (hopes and prays!)

Why is life never simple?

it can be simple, just not necessarily correct.

i'd just do it on the second tick and be done with fucking around using sleeps etc which rely on your cpu not getting caught dealing with a hdd read/write that is taking too long or some other random event that overshoots the ability of the redraw to occur before the screenshot is triggered.

you could always have something like this in your start routine or whatever routine does the screenshot

static datetime ldt_Last.Bar;

other code


// Perform screenshot

if (Time[0] == ldt_Last.Bar)
{
WindowScreenShot etc.
}

ldt_Last.Bar = Time[0];

---

This would ensure, that when there is a new bar it won't perform a screenshot on the first tick as ldt_Last.Bar would still contain the time of the old bar, on subsequent ticks of the bar it could perform the screen shot

Regards, John

Thanks a lot guys, nubs, John.

And poor simple old me (less of the old please) was thinking that all I needed was the original 1 liner ... some hope!!!

Now I have to write a whole (well nearly) program to deal with potential errors from c**p MT4.

** EDIT :

and all this on NFP day and with the world crashing around us!

I have been messing around with screen shot lately and have found the answer, but not the explanation. The speculation in this thread is reasonable but at best are educated guesses.

The solution is simple - put the WindowScreenShot() into an EA and it works perfectly every time. Don't know why and don't particularly want to know.

because ea's likely run AFTER indicators... therefore it makes sense that an indicator goes to update the draw area but also inside the indicator calls for a screenshot reveals nothing but a blank area. the indicator hasn't even finished setting buffer data and whatnot before the screenshot is requested. so the indi runs, updates buffers, finishes running the script, finishes the redraw. then ea's get called that might call a screenshot which now miraculously works. just think about it... ea's are able to call data from indicators, both custom and internal, therefore it only makes sense that indicators run before any ea's so that the indicators are up to date before any ea's try to touch their data.

it's like taking a photo, taking the lens cap off, then handing it to someone else to see if they can get it to work since it seems to only take entirely black pictures. the order of events is all fucked-up so no wonder it works one way but not another. the solution is simple... don't take screenshots within an indicator on the first tick of a new candle because the draw area is in the process of being redrawn and therefore produces shitty results.

Each EA runs in a separate thread. An EA can be run in a Loop, in which case it does not run after or before anything in particular, it is run after a sleep() timeout. Ie it is asynchronous. RefreshRates() is used to manually update the current data for the EA when needed. EA's calculate all the data they use based on the history data copies they keep, and are not dependent on what the indicators in the chart are doing.

The indicators all run in the same thread, which is the same thread as the window/charting system runs in.

Try calling WindowRedraw( ) before taking a screen shot. Note that WindowRedraw() is probably resource intensive so it is not a good idea to call it on every tick. Maybe just on new bars, if that is when you have a problem.

very nice.