| Re: oplot in Object Graphics [message #36945 is a reply to message #36940] |
Thu, 13 November 2003 16:05   |
Rick Towler
Messages: 821
Registered: August 1998
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Senior Member |
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"Miguel Angel Cordoba" wrote ...
> In my program the for statement only does 9 plots and before this,
> I create the Window, the View, the model and a ObjArr of IDLgrPlot.
> Then when the user moves the mouse in the for statement I only
> change the data property of the IDLgrPlot.
>
How are you capturing the mouse movement? If you set the MOTION_EVENTS
keyword to WIDGET_DRAW you'll be generating a *lot* of events and if inside
your event handler you have a FOR loop which updates the DATA property of
multiple (in your case 9) IDLgrGraphic objects you will be forcing IDL to do
a lot of work.
IDLgrGraphic objects cache internal properties so that they can be redrawn
quickly. When you change certain external properties (such as the DATA
property) the object marks the cache as dirty and recalculates these
internal properties upon the next call to IDLgrGraphic::Draw. As the number
of data points increase, so does the time it takes to update the internal
properties of the object.
So your program has a number of possible problems. Do you have to change
the DATA property? For all of the objects every event? Can you minimize
the size of DATA? Can you minimize the number of events by acquiring mouse
input in a differnt way? Why are you changing the DATA property?
I would suspect that the problem can be solved by taking a look at a pared
down version of your code or at least a description of your event loop.
-Rick
>
> Karl Schultz wrote:
>
>> It is hard to tell why it may be slow without seeing the entire program.
>>
>> However, I have the sneaking suspicion that you are running all of the
code
>> listed below for each time you draw to the screen, as you would have to
do
>> in Direct Graphics. In Object Graphics, this is not the case. You
create
>> all the objects (view, model, plots) just once and then call only the
>> window's draw method when you want to draw.
>>
>> The overall program logic would look something like this:
>>
>> Create Window
>>
>> Create View, Model, and Plots (essentially the code quoted below)
>>
>> Draw the view (e.g., oWindow->Draw, oView)
>>
>> REPEAT
>> user does something.
>> modify the data in the plot objects according to what the user did (if
>> needed)
>> Redraw the view (e.g., oWindow->Draw, oView)
>> UNTIL user wants to quit
>>
>> The important thing is that you want to perform the step of creating the
>> view, model, and plot objects only once. Then everytime you want to
redraw
>> the window, you just call Draw.
>>
>> If you really are doing it in the way I have just described, then you'll
>> have to tell us more about your program. Maybe you can post the entire
>> thing if it is not too long. How big is your plot data? How does the
code
>> work that triggers the drawing operation, etc..
>>
>> Karl
>>
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