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Issues with PostMessageW in MQL4

  • #21
  • Feb 24, 2020 6:59am Feb 24, 2020 6:59am
Thanks for the responses, guys.

Quoting Jagg
wouldn't it be easier to make all your wanted chart constellations and save each once as a template and apply the needed one per click on a button or something like that with a call to ChartApplyTemplate() function?
No this is not feasible because my panel allows me to turn on or off over 10 indicators, Too many permmutations to a different template for each combination.


Quoting emmzett
{quote} Technically it's possible but the effort doing it the proposed way is to big. There are countless things code would have to account for to be stable, and things usually will go wrong. Imho it's not worth. I use a similar approach for passing inputs to custom loaded scripts (not to indicators) but it needs very special logic in the scripts. You cannot generally apply it to any other script (or indicator for that purpose). In general I would say I f you constantly find yourself executing MQL programs in a programmatic way something with your...
That's a bummer, but thanks for the insight. There is a particular indicator I have right now and am trying to add for which I don't have functional source code and if I can't get it, I'm not sure that I would have any other choice than to use an approach like this. Does it simplify things and make it more reasonable if I have a specific indicator and specific single parameter targeted that is just a plain text input?
  • #22
  • Edited 3:55am Mar 7, 2022 2:19am | Edited 3:55am
The OK click doesn't work. I have tried all your solutions. I am using MT4 Built 1353. I am running this from an indicator. The inputs window pops up and waits for a manual OK click. Any new solutions?

I mean, it works from script, doesn't work from indicator, and I want to use an indicator in order to delete another indicator every new candle and add it back.

2000 years later:
No matter what I do, the log says my indicator has been loaded successfully, and nothing else happens. The indicator settings window is waiting for manual confirmation.
.ex4/.ex5 files can't be fixed or modified / I'm not a coder!
  • #23
  • Edited 5:14am Mar 7, 2022 4:47am | Edited 5:14am
Quoting emmzett
{quote} As @jagg pointed out per PM the above approach doesn't work when called from an indicator. Why? Because Sleep() is not allowed in an indicator it is silently skipped - and FindWindow() is called immeadiately after at a time when the dialog does not yet exist. So it can't be found this way. If a custom indicator should be loaded from another custom indicator (not from a script or expert) then either one has to use the SleepEx() function from the Win32 API or the loop/wait cycle needs to be slightly...
I tried the SleepEx() and it didn't work.
I mean, SleepEx() works on its own, but the indicator config window still stays up.
There is no button error.
.ex4/.ex5 files can't be fixed or modified / I'm not a coder!
  • #24
  • Edited Jan 28, 2023 12:31pm Jan 27, 2023 3:57pm | Edited Jan 28, 2023 12:31pm
I stumbled across this thread when I was searching for how to get an indicator to trigger a "Refresh". I found the solution in another thread which I turned into a function that, so far, works fine. It uses PostMessageA from the user32.dll

Vaguely, without remembering why, I recall that there is a preference to instead use 'PostMessageW' and that's when I came across this thread.

What I notice in earlier code posted is that the arguments for PostMessageA and PostMessageW are swapped, yet my PostMessageA is working fine, and would appear to match online documentation for the last argument NOT being a passed uchar variable.

For what it's worth, here's my 'chartRefresh()' function:

Inserted Code
//+------------------------------------------------------------------+
#define  WM_COMMAND                    0x0111
#import "user32.dll"
   int   RegisterWindowMessageA(string lpstring);
   int   PostMessageA(int  hWnd,int  Msg,int  wParam,int lParam);  // "int lParam" seems correct, but some use "string lParam" which seems wrong to me.
   //int PostMessageW(int  hwnd,int  msg,int  wparam,uchar &Name[]);
   // Some posted code has the PostMessageA and PostMessageW arguments swapped, but... usage below works!
#import
void chartRefresh() export
{
   PostMessageA (WindowHandle (Symbol(), Period()), WM_COMMAND, 33324, 0);
   PostMessageA (WindowHandle (Symbol(), 0), RegisterWindowMessageA ("MetaTrader4_Internal_Message"), 2, 1);
   return;
}
void ChartRefresh() export { chartRefresh(); }
//+------------------------------------------------------------------+

Edit: Corrected 4th arg to use "int lParam" instead of "string lParam" to prevent compiler warnings, plus "int" matches MS documentation
  • #25
  • Last Post: Mar 10, 2023 10:13pm Mar 10, 2023 10:13pm
Quoting BestTraderEv
{quote} I tried the SleepEx() and it didn't work. I mean, SleepEx() works on its own, but the indicator config window still stays up. There is no button error.
Regarding the previous posts that said the user is forced to manually click the 'Ok' button for the indicator:

It seems that the OP started with code that issued a VK_RETURN key, but then Emmzett suggested code to cause an actual "Ok" button to be clicked, but there was the problem that it needed some delay, and "Sleep()" doesn't work in indicators. Though "SleepEx()" was suggested, BestTraderEv said he tried SleepEx() without success, that the Indicator window still remained up.

I don't know if this suggestion will offer any helpful clues or not, but when I use a normal MT4 Hotkey to add some script or indicator, it would usually require a manual click on the 'Ok' button. However, I discovered a keystroke-only workaround, which is: Tab Tab Tab Return (No mouse click required!)

I use Hotkeys to add Indicators/Scripts to my chart all the time, and by now its second nature for me to always hit Tab 3 times then Return. I'd really be bummed out if it stopped working and I was again forced to use a mouse click on "Ok".

How does hitting the Tab key 3 times work?

If one brings up the Indicator, then it comes up with the last used Tab (e.g. "About", "Common", "Inputs", "Dependencies", etc. depends on Indy/Script/...)

Even if you see that the "Ok" button is highlighted as if it's the current choice, a "Return" does absolutely nothing. Only a mouse click on "Ok" works.

But if you hit the Tab key, notice it cycles to another choice; hit Tab again, it cycles again to next choice; hit Tab 3rd time, it cycles BACK to the "Ok". For most menus, the 3 choices it cycles through are: Cancel Reset Ok; but for the Inputs menu, it cycles through: Load Save Ok (skipping for some reason the Cancel and Reset choices). Regardless of which menu, 3 Tab keys is enough to get back to "Ok".

And now, a simple "Return" will do the same thing as an "Ok". No mouse click necessary.

This suggestion might be useless if the "SleepEx()" is not working as needed. It might even make it worse to now need 3-4 sleeps, given that Tab Tab Tab Return keystrokes will probably need SleepEx() between each. But maybe it's worth a try to go back to these keystrokes rather than the command that literally does the "Ok" button command.

Fyi: #define VK_TAB 9 //TAB key

If anyone gets it working, please make a followup post.
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