Cursor shape does not change unless I add Application.ProcessMessages
lazarus / 32-Linux

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fedkad · 2022-01-27 10:25

Create a new project with an empty form. Add a button and put the
following code to the OnClick event:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
Screen.BeginWaitCursor;  sleep(2000);  Screen.EndWaitCursor;
On Windows it will act as expected. However, on Linux the cursor shape
will not change. You have to change the Linux code to something like
this to work:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
Screen.BeginWaitCursor;  Application.ProcessMessages;  sleep(2000); 
Screen.EndWaitCursor;
Why?

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Zvoni · 2022-01-27 11:03

Quote from: fedkad on January 27, 2022, 11:25:15 amWhy?
[SARCASM ON]
Because this has nothing to do with installing Lazarus/FPC on Linux?
[SARCASM OFF]

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trev · 2022-01-27 11:08

Moving from Linux > Installation sub-forum to OS > Linux sub-forum ...
just for context for Zvoni's response

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fedkad · 2022-01-27 11:41

Thanks for moving the topic and sorry for posting to wrong section!

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Zvoni · 2022-01-27 12:56

As for the original question: https://lists.lazarus-
ide.org/pipermail/lazarus/2011-April/192333.html
QuoteThe LCL is not a winapi emulator.Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Screen.BeginWaitCursor;{$IFDEF LINUX}Application.ProcessMessages;{$END
IF}sleep(2000);Screen.EndWaitCursor;

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fedkad · 2022-01-27 13:22

Quote from: Zvoni on January 27, 2022, 01:56:49 pmAs for the original
question: https://lists.lazarus-
ide.org/pipermail/lazarus/2011-April/192333.html
QuoteThe LCL is not a winapi emulator.Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
Screen.BeginWaitCursor;{$IFDEF LINUX}Application.ProcessMessages;{$END
IF}sleep(2000);Screen.EndWaitCursor; 
That is what I am using right now. But, I just wanted to reduce those
{$ifdef Linux}Application.ProcessMessages;{$endif}s in my program.

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Zvoni · 2022-01-27 13:40

Well then. The link above has the answer: the LCL is not a winapi-
emulator.
On windows, the WinAPI itself makes sure the screen-object is updated
(and that way showing the change of cursor)

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Josh · 2022-01-27 13:56

Hi

To save all the if def you could ceate a proc;
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
Do_Application_Processes_By_Os;inline;begin  {$ifdef linux} 
Application.ProcessMessages;  {$endif}end;
then you could add the code into your routines;
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Screen.Begi
nWaitCursor;Do_Application_Processes_By_Os;sleep(2000);Screen.EndWaitC
ursor;
or create youself the set cursor routine;

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
Do_BeginWaitCursor;inline;begin  // under windows cursor state is set
immediately by winapi  // under linux you must call processmessage to
force the state change to happen.  Screen.BeginWaitCursor;  {$ifdef
linux}  Application.ProcessMessages;  {$endif}end; procedure
Do_EndWaitCursor;inline;begin  // under windows cursor state is set
immediately by winapi  // under linux you must call processmessage to
force the state change to happen.  Screen.EndWaitCursor;  {$ifdef
linux}  Application.ProcessMessages; 
{$endif}end; ...... Do_BeginWaitCursor;sleep(2000);Do_EndWaitCursor;

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zeljko · 2022-01-27 14:16

Quote from: fedkad on January 27, 2022, 11:25:15 amCreate a new
project with an empty form. Add a button and put the following code to
the OnClick event:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
Screen.BeginWaitCursor;  sleep(2000);  Screen.EndWaitCursor;
On Windows it will act as expected. However, on Linux the cursor shape
will not change. You have to change the Linux code to something like
this to work:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  
Screen.BeginWaitCursor;  Application.ProcessMessages;  sleep(2000); 
Screen.EndWaitCursor;
Why?

What widgetset under linux ? I'm using qt/qt5 and haven't spotted such
problem.

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MarkMLl · 2022-01-27 14:26

Quote from: zeljko on January 27, 2022, 03:16:27 pmWhat widgetset
under linux ? I'm using qt/qt5 and haven't spotted such problem.

That being a massively-important omission from the OP.

Calling Application.ProcessMessages is unavoidable if one wants the UI
to be immediately-responsive to minor changes.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i      
Screen.BeginWaitCursor;      sleep(2000);    // SUSPENDS ENTIRE
PROGRAM: DOES NOT CALL APM      Screen.EndWaitCursor; 
In any event, one has to be careful overusing APM: if it's in code
that's called- even indirectly- via Synchronize() then it can go
recursive.

MarkMLl

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fedkad · 2022-01-27 16:02

Quote from: zeljko on January 27, 2022, 03:16:27 pmWhat widgetset
under linux ? I'm using qt/qt5 and haven't spotted such problem.

I am using GTK2. That info was already given in my signature.

Josh's proposal seems to be the closest solution to my problem.
Thanks.

Sleep was actually a placeholder for a group a statements that do file
and/or network IO and may take a few seconds to complete.