|
Hello,
The point is that you don't understand execution
model of AB.
If you click on ANY place chart pane, all panes
belonging to given chart are
refreshed. This is so because the SELECTED
date/time changed for all panes
and you want your custom Title, chart
values,
and indicators recalculated. There are many
formulas that use SelectedValue()
to display things that depend on the selected
date.
AFL execution is ALREADY _event_ driven. It is NOT
polled. It executes ONLY when there is an event
(mouse click, real-time refresh, zoom in/out,
change of current symbol, user-defined timer (RequestTimedRefresh)
etc).
The callback idea on the surface looks attractive,
but once implemented you wil
see yourself repeating lots of code or calling the
same global functions over and over
again and this would inefficient.
For example, let's say that your indicator that you
use for trading takes 0.5 second
to execute.
With current design, when mouse click occurs your
indicator is calculated ONCE
and you can use its values stored in a variable for
anything (draw chart, handle mouse clicks,
auto-trade, display alarms, perform more
calculations) - all with ONE calculation
of your time-consuming indicator.
If your call-back driven model was implemented
after mouse click the following call back
functions would be called:
OnLButtondDown
OnChartRefresh
OnNewDateTimeSelected
And you would need to calculate your indicator
THREE times in each function
if you want its values. This is because the
callback approach assumes that
there is NO "global" code executed always. And this
would be three times slower.
Actually the whole distinction about this call-back
thing is rather "philosophical"
because in practice in Windows the application has
SINGLE application message loop (per thread)
and messages from ALL sources land in ONE queue
that is handled
by one simple loop (see
PeekMessage/GetMessage/DispatchMessage)
The message is pumped to active window.
All those call-backs and what you see in
higher-level languages are
just functions called from big switch and/or
message map (which is also switch / if-like construct)
that is inside WindowProc function that receives
all messages.
http://msdn2.microsoft.com/en-us/library/aa452701.aspx
This has NOTHING to do with interrupts.
Interrupts exist on PC platform on HARDWARE level
and are used by operating system only. Interrupts
are asynchronous and one interrupt can
actually stop the execution of other code to handle
the interrupt.
Message processing (what software applications do)
is fully sequential and message processing is
NOT interrupted (i.e. one message must be fully
processed before processing next one).
I am of course speaking what happens on single
thread level (not couting that your app may be switched out by
pre-emptive OS)
For this reason, you can implement your "callback"
approach by yourself, just write a switch
Store code below in "myCallbackHandler.afl" file in
the Include folder so you can use it whenever you want
function EventHandler()
{
local b, x,
y;
b = GetCursorMouseButtons();
x = GetCursorXPosition();
y = GetCursorYPosition();
if( b
& 1 )
OnLMouseButton( x, y );
if( b
& 2 )
OnRMouseButton( x, y );
if( b
& 4 )
OnMMouseButton( x, y );
}
EventHandler();
Then in your formula put #include
<mycallbackhandler.afl> at the END of the formula:
function OnLMouseButton(x, y)
{
_TRACE("LButton x = " + DateTimeToStr( x )
+ " y = " + y );
}
function OnRMouseButton(x, y)
{
_TRACE("RButton x = " + DateTimeToStr( x )
+ " y = " + y );
}
function OnMMouseButton(x, y)
{
_TRACE("MButton x = " + DateTimeToStr( x )
+ " y = " + y );
}
Graph0=C;
#include <mycallbackhandler.afl>
And Herman is CORRECT in his response. The only
thing needed to actually know to make it work
perfectly is window handle that received the mouse
click (chartID is not enough as there can be
two panes shareing the same). The ability to know
window handle that received mouse click will be added.
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "scourt2000" <stevehite@xxxxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Wednesday, January 30, 2008 2:51
AM
Subject: [amibroker] Re: Trading platform +
AB
>
> "This can be done now using
GetCursorMouseButtons(),
> GetCursorXPosition() and GetCursorYPosition()
. HOWEVER there is no
> function that returns the ChartID for the
chartpane over which the
> mouse is clicked"
>
> Hi Herman,
>
> All of that chartID stuff would not be
necessary if you tied the
> mouse button clicks to well-known event
routines (like that ones I
> mentioned as an example) which get called
specifically from the AFL
> code behind a chart pane.
>
> You want this type of facility event-driven,
not polled. Polling
> puts more work on the user's side and brings
up other unpleasant side-
> effects like what you just described.
>
> Which would you rather do?
>
> 1) Code a rats nest of polling inline with
your other AFL code
>
> -or-
>
> 2) Have a well-known function called on a
mouse click with all of the
> information you need provided as the function
parameters directed to
> the script already bound to a particular chart
pane?
>
> Anyone who chooses #1 last seriously
programmed a computer more than
> 20 years ago.
>
> "That's available now - check the list of
functions, duude."
>
> No it's not...duude [sic]
>
>
>
> Please note that this group is for discussion
between users only.
>
> To get support from AmiBroker please send an
e-mail directly to
> SUPPORT {at} amibroker.com
>
> For NEW RELEASE ANNOUNCEMENTS and other news
always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> For other support material please check
also:
> http://www.amibroker.com/support.html
>
> Yahoo! Groups Links
>
> <*> To visit your group on the web, go
to:
> http://groups.yahoo.com/group/amibroker/
>
> <*> Your email settings:
> Individual Email |
Traditional
>
> <*> To change settings online go
to:
> http://groups.yahoo.com/group/amibroker/join
> (Yahoo! ID required)
>
> <*> To change settings via
email:
> mailto:amibroker-digest@xxxxxxxxxxxxxxx
> mailto:amibroker-fullfeatured@xxxxxxxxxxxxxxx
>
> <*> To unsubscribe from this group, send
an email to:
> amibroker-unsubscribe@xxxxxxxxxxxxxxx
>
> <*> Your use of Yahoo! Groups is subject
to:
> http://docs.yahoo.com/info/terms/
> |