AW: can I lock screen over more than one handler?

jonathandlynch at gmail.com jonathandlynch at gmail.com
Wed Jul 5 10:19:32 EDT 2017


I have found that lock screen only blocks screen updates within the main LC context.

So, for example, it does not block whatever is happening in a browser.

For some reason, it also sometimes seems smoother to call a function rather than a handler, but perhaps I misperceived what was happening.


Sent from my iPhone

> On Jul 5, 2017, at 9:57 AM, Tiemo Hollmann TB via use-livecode <use-livecode at lists.runrev.com> wrote:
> 
> Thanks Jonathan, Trevor and Sean for your comments.
> 
> Meanwhile I could drill down my "flickering" problem (post from yesterday)
> to an unexpected command.
> In one of those handlers I "set the filename of player "myVideoPlayer" to
> tFile". This command withdraws the focus from the window and passes it back
> after some milliseconds. On my Win 10 machine with a white window title bar
> I almost can't see it, but on Win 8 with the standard violet title bar it is
> an ugly flickering, each time I set the filename (which happens very
> frequently in a quiz loop).
> 
> And I can't prevent this flickering with a lock screen right before the
> setting of the filename. The setting of the filename seems to release the
> lock screen or it takes the focus of the window off and back. Very ugly in
> my case.
> 
> Tiemo
> 
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: use-livecode [mailto:use-livecode-bounces at lists.runrev.com] Im Auftrag
> von Sean Cole (Pi) via use-livecode
> Gesendet: Mittwoch, 5. Juli 2017 15:30
> An: How to use LiveCode <use-livecode at lists.runrev.com>
> Cc: Sean Cole (Pi) <sean at pidigital.co.uk>
> Betreff: Re: can I lock screen over more than one handler?
> 
> Hi Tiemo,
> The solution here is to call another lockScreen at the beginning of
> handler2. You don't have to use the unlockScreen at the end of handler 1 and
> 2 as it will do that automatically but it is advisable to include the
> command anyway. Is there a reason why you had an aversion to using a
> lockScreen at the start of handler2?
> 
> All the best
> 
> Sean Cole
> *Pi Digital Productions Ltd*
> 
> On 5 July 2017 at 14:09, Trevor DeVore via use-livecode <
> use-livecode at lists.runrev.com> wrote:
> 
>> On Wed, Jul 5, 2017 at 6:45 AM, Tiemo Hollmann TB via use-livecode < 
>> use-livecode at lists.runrev.com> wrote:
>>> 
>>> 
>>> Is this possible?
>>> 
>>> on handler1
>>> 
>>> lock screen
>>> 
>>> -- do some stuff here
>>> 
>>> send "handler2" in 0 milliseconds
>>> 
>>> end handler1
>>> 
>>> 
>>> 
>>> on handler2
>>> 
>>> -- do some other stuff here
>>> 
>>> unlock screen
>>> 
>>> end handler2
>>> 
>> 
>> No it is not. From the docs for `lock screen`:
>> 
>> "When all pending handlers are finished executing, the lockScreen 
>> property is set back to false and the user sees the current state of 
>> stack windows on the screen."
>> 
>> The use of the word "pending" is confusing because when you use `send` 
>> you end up with an entry in the `pendingMessages`. But the screen is 
>> going to be unlocked each time through the event loop. If `handler` 
>> called `handler2` directly (without using `send`) then you would not 
>> see the screen update. You should see the result you are looking for 
>> if you change your code to look like this:
>> 
>> ```
>> on handler1
>>  lock screen
>> 
>>  -- do some stuff here
>> 
>>  handler2
>> end handler1
>> ```
>> 
>> If you need to call `handler2` in time then you will need to figure 
>> out another approach to updating the screen. Perhaps all screen 
>> updates will need to happen in `handler2`.
>> 
>> --
>> Trevor DeVore
>> ScreenSteps
>> www.screensteps.com
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