Re: Delay in execution when Button is clicked.

See below...
On 10 Jan 2007 07:59:47 -0800, "Treadstone" <u.bhargav@xxxxxxxxx> wrote:

Hi,

I'm developing an application using MFC that plays WAV audio files. My
user interface consists of 3 buttons - Play, Pause and Stop.

When I click the play button, my program Reads the WAV file in chunks
of 1024bytes and stores them in a static array. The array is processed
in another function and the array is refilled in a while loop.


On clicking the Pause button the file being played should be Paused.

I am facing some difficulty here. Although the play and pause are
working fine, there is a delay in execution for the "OnPauseClick".
(When the pause button is clicked).

I do not face this problem while playing a file whose size is less than
50k. If I play a file that is around 500k, the delay is quite
significant i.e. the Pause button gets activated about 5secs after it
has been clicked.

Is there a problem with my buffer handling? (the way I read my file and
store it into an array)
I have attached just the buffer handling code below:

do{
ReadFile(hFile, <Pointer to array>, 1024, &NoOfBytesRead, NULL);
ProcessArray(Array);
}while(NoOfBytesRead > 0);
****
Where is this loop? If it is not in a separate worker thread, you are screwed. This is
because as long as this loop is running in the main GUI thread, a button click cannot be
seen. If it is in a secondary thread, you should have some way to detect that the button
has been activated in the GUI thread, and suspend processing; I see nothing in this code
that does it (it could also be in the ProcessArray handler, but you don't explictly say
that)
****

//Code that processes the array
void ProcessArray(char *)
{
...
...
}

Or does it have something to do with MFC? And yes, I have been testing
this on the emulator.
****
It almost certainly has to do with the architecture of your program, but you give
insufficient information to analyze that. I'm just guessing that you have made the
classic error of a long-loop-in-the-GUI-thread.
joe
****

Regards,
Treadstone
Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
.

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