[LV2013] Events ordering (mouse down vs. value changed) ?

Hi,
I've encountered a problem with my real-time behaving UI.
The event distribution mechanism registers several events
linked to various UI controls.
Two of them are set this way :
String control: value changed
Tree control : mouse down
The problem is that the String control is used both to display
and modify values within the tree. Click an item, its name is
displayed in the String control, modify the String control, the
new value is reflected into the Tree control.
The issue is when I edit a string inside the String control and
click another item in the Tree Control, the first event fired is
the Mouse down event on the Tree control. Then only the
Value changed event is fired.
What happens is that case is the value edited in the String
control gets overwritten with the new clicked item's value,
then it is saved inside the previous item's value.
Is there a way to give a kind of priority on some events
rather than others ?
David Koch

How is LabVIEW "nasty, nasty"?
While it isn't doing what you want for your particular situation, it is doing exactly what it is supposed to do and is pretty logical.
1. You are in a control.
2. That control's value isn't update until you leave it.
3. Your method of leaving the control is by clicking on something else (the mouse down).
4. The mouse down is what happens first, once LabVIEW detects the mouse down on another control, it then says, okay, now I need to take the focus from the first control and place it here.
5. It is the loss of focus from the first control that is what fires the value change event on the first control.
So the precise order of events is:
1. Mouse Down event on control 2
2. Value change on control 1
and that makes perfect sense.
Your idea of reversing the order of events does not make sense to me. I want LabVIEW to enqueue events as they happen, not rearrange them. Supposed some other part of your VI is simultaneously issuing another value change event, or a user event. Where should that event fall into the queue related to the other events you've had LabVIEW rearrange?
From what I've seen from this message of yours and others in the past is you get quite upset when LabVIEW doesn't conform to your vision of the world and rather than figuring out how LabVIEW works and how to work with it, you try to fight how LabVIEW works and then take to the forums to complain. If that is actually picture of you in your user icon, then that is exactly how I envision you while you are working on the computer.

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Targeting the properties of the mouse event: ROLL_OVER, MOUSE:DOWN

Hi - I am targeting the states of the button ie: ROLL_OVER is tweened a little bigger.
Then I want it to go back to its original size.
BUT it doesn't recognise the start and reverse methods.
Scene 1, Layer 'Layer 2', Frame 1, Line 60    1061: Call to a possibly undefined method start through a reference with static type gs:TweenLite.
button.addEventListener(MouseEvent.ROLL_OVER, rollOverHandler, false, 0, true);
button.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler, false, 0, true);
//button.addEventListener(Event.MOUSE_UP, mouseUpHandler);
button.addEventListener(MouseEvent.ROLL_OUT, rollOutHandler, false, 0, true);
var myTween:TweenLite = new TweenLite(button,1,{scaleX:1.05,scaleY:1.05,onComplete:myReverseFunction});
function rollOverHandler(e:MouseEvent):void
    //TweenLite.to(button, 1, {scaleX:1.05, scaleY:1.05, ease:Elastic.easeOut});
    myTween.start();
function myReverseFunction():void
    myTween.reverse();

I took a look at the ASdocs for Tweenlite.
- http://www.greensock.com/as/docs/tween/_tweenlite.html -
Maybe try this.
private var myTween:TweenLite;
private function rollOverHandler(e:MouseEvent):void{
     myTween = TweenLite.to(button, 1, {scaleX:1.05, scaleY:1.05, ease:Elastic.easeOut, onComplete:myCompleteFunction});
     //TweenLite.to() returns a TweenLite instance that is now referenced (at class scope) by myTween;
private function myCompleteFunction():void{
     myTween.reverse();
If this doesnt work I'll have to take another look later tonight when I'm at my home machine..
Looking back over your original code..it all looks correct (although I can't test). I mean nothing pops out.--
You created a TweenLite instance outside of function scope (the documentation on greensocks site says this is fine even though its a static class) and referenced it within the same class scope.

Event structure to detect value change of a control within a cluster in an array

I have 1D array that contains a cluster. The cluster contains a numeric and a boolean control.
If the user starts to edit the numeric control value i would like to call one subVI, and if the boolean control value is changed, call a different subVI.
The array control on the front panel allows the user to edit a number of the array elements.
I would like to use an event structure to detect a value change in the cluster. When editing the Events, in the Event Sources panel i get the option to select only the array, not the cluster within the array or the controls within the cluster. Can the Event structure be opened up to show controls within clusters and arrays?
The solution i am using is to detect a mouse up event on the array and then use property nodes to determine if the key focus is on the numeric, and a case structure to determine which subVI to call. This works, but is there a better (simpler) way?
Thanks, Blue.

Thanks for the responses guys.
The tricky bit was that i wanted the numeric control values to flag they were going to be edited, so i could call a subVI, before their values were changed by the user. This is done by using the key focus property node, - i need to detect changes on the fly rather than post the event. Probably didn't make this clear enough in my original post.
The array is of variable size depending on if the user decides to insert or delete elements. The user also has the option to click and edit the array without having to do to much scrolling through the array index, as the FP shows several elements at a time. The Event Structure does a good job of automatically determining which element in the array is being edited, and returning those values to the property nodes. Turned out simpler than i thought it might be at one point!
Cheers, Blue.
Message Edited by BlueTwo on 01-15-2009 06:52 AM
Attachments:
evstrct1.jpg ‏63 KB

Value change using DataSocket can't create value change event on remote computer?

I am trying to create an event on the remote computer:
Local computer:
Change a value in remote computer by DataSocket.
Remote Computer:
create a event: when the value changes.
I can see the value change on the remote computer; however, the value change doesn't cause the "value change event".
Anyone tried this before? Thanks.
------- LabVIEW 2009, So Easy, Even a Therapist Can Do It -------

Hi,
Event Structure monitors a specified event based on user interaction on the front-panel objects. However, it does not monitor event generated programmatically like a change in the DataSocket data value. In order to generate a value change event with the DataSocket, you will need to use the "value (signaling)" property node for the DataSocket data or control. This property node sets the value of the control and also generates a Value Change event.
To create the property node, simply right click the control and select "Create>>Property Node>> Value (Signaling)". You can then wire the output from the DataSocket read to this property.
You can also checkout this knowledgebase entry for additional information.
Tunde

Event mouse down in an array

Hi,
If I use the the Event "Array" Mouse Down, Is there any way to know which element in the array was clicked???
Thanks.
Raymundo Cassani
Solved!
Go to Solution.
Attachments:
imagen.JPG ‏51 KB
imagen.JPG ‏51 KB

In the LAVA Code repository there is a piece of code that check that for you, it takes the current index position into account, size of the eleements.
Unfortunatly the website is currently down. Let me check later.
Ton
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Using an event structure to reset a boolean control with ring menu value change

I am trying to get two boolean buttons to reset when the value of a ring menu changes. For this I am using an event structure set to execute with a ring value change. However I have other code that needs to be executing while the event structure waits for the value change. I place my event structure inside the while loop the buttons reset as expected but my other code does not run (except at the moment of value change). If I place it outside the loop the rest of the code functions as expected but the buttons do not reset. Any help you can offer is much appreciated.
Solved!
Go to Solution.
Attachments:
event structure reset.vi ‏11 KB

try this
Attachments:
event structure reset_edit.vi ‏14 KB

Multicolumn listbox value change and mouse up event in one case of event structure

Hello All,
Am facing two problems:
1. I have two multicolumn events, one is value change for deleting the rows of Multicolumn listbox and another one is mouse up for sorting the columns. But I can't combine both the events in one case. And if I create two separate cases then each time the event of mouse up executes and sorting takes place irrespective of selection of delete event.
2. I have a selection VI in which user selects which parameter he wants to show it in a multicolumn listbox. I want this parameters to be retain or stored when next time I run the VI after closing it.
Am using LabVIEW 11. Pls reply soon.
Thanks & Regards,
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try this
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Drop Down Lists and Value Change Events

I have 4 drop down lists each with a set of values from the database.
Based on the value of the first list(ValueChangeEvent only for list1) , I fetch data from the database and set the 'selected value' in the other lists.
I have a Submit button which takes values from these 4 lists and puts it in the database.
Problem:
I change list 2 through list 4 and hit a Submit button which inserts all the values in the database.
However,on Clicking the Submit button I never get the new selected values, it always refers to the previously fetched values.
I tried to recreate this case in a Sandbox without a database , Here is the code:
Page1.jsp
<h:selectOneMenu id="list1" value="#{SessionBean1.selectedList1}" valueChangeListener="#{SessionBean1.list1ValueChangeListener}" onchange="this.form.submit();" >
               <f:selectItems id="dropdown1SelectItems" value="#{SessionBean1.list1}"/>
</h:selectOneMenu>
<h:selectOneMenu id="list2" value="#{SessionBean1.selectedList2}" >
              <f:selectItems id="dropdown2SelectItems" value="#{SessionBean1.list2}"/>
   </h:selectOneMenu>
   <h:commandButton id="add" actionListener="#{SessionBean1.addActionListener}" value="Add"/>
    <h:inputText id="result" value="#{SessionBean1.result}" />SessionBean1
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        list1.add(new SelectItem("1","1"));
        list1.add(new SelectItem("2","2"));
        list1.add(new SelectItem("3","3"));
        list2.add(new SelectItem("a","a"));
        list2.add(new SelectItem("b","b"));
        list2.add(new SelectItem("c","c"));
        list2.add(new SelectItem("d","d"));
        map.put("0", "a");
        map.put("1", "b");
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        map.put("3", "d");
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         selectedList2=map.get(value);
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    public void addActionListener(ActionEvent event){
        result=selectedList2;
    }I tried debugging and found that after the Value Change Event is fired only selectedList1 gets a new value during Update Model Values Phase and selectedList2 still has the old value.
With this sand box project I cannot even get the second list to show the corresponding value.
Any insight on this would be helpful

Thank You Balus C,
I just realized the reason why this is not working, I found the reason in your article Populating Child Menu's article, I am just
putting it as a reference here.
One concern is that the skipping of the UPDATE_MODEL_VALUES will also cause that the new values of the menu's which have immediate="true" set won't be set in the backing bean. This can partly be fixed by getting the new value from the ValueChangeEvent inside the valueChangeListener method and assign it to the appropriate property. But this won't work for other menu's of which the valueChangeListener isn't been invoked. This would cause problems if you select a child menu value and then select the parent menu back to null and then reselect it to same value again, the child menu which will show up again would remain the same selection instead of null while its child will not be rendered! To solve this we need to bind the menu's to the backing bean so that we can use UIInput#setValue() and UIInput#getValue() to set and get the actual values.+ The JSF lifecycle will set and get them in the RESTORE_VIEW and RENDER_RESPONSE phases respectively.+
I am not sure I understand whether or not it is a limitation but the reason above is valid and I rolled back to binding my menus and getting to work with that.
Is Binding UI components a wise idea because most of the attributes can be programmed using properties in Backing Beans unless you have to build new components?
Thanks Again

Mouse down event reading a string terminal trick

Hi,
I wondered why I was getting frustrated entering a pasword that was verified in the mouse down event of the OK button. This is becuase when you click the OK button the entered text is still in the buffer and not copied to the terminal. (Which is more natural than clicking somewhere on the FP first). Note pressing enter or tab gets the string control out of enter text mode.
Turns out need update value while typing turned on if you want to gaurantee a correct read of a text input control in a mouse down event. As this is one of those not obvious but sometimes happens bugs... I have posted for reference for others :-)
Example attached v8.6.1.
Attachments:
TestMouseDownEvent.vi ‏13 KB

Nick wrote:
Turns out need update value while typing turned on if you want to gaurantee a correct read of a text input control in a mouse down event.
AFAIK, "Update value while typing" will trigger only a Value Change event of the Str Ctl.
Mouse Down event will preceed a Value Change event, if you have both the event cases configured in your code.
- Partha
LabVIEW - Wires that catch bugs!

Mouse down event handling of table control in subvi

Hello Everyone.......
I have created a vi which has a table control and xy graph... the function of the vi is to plot the data of two particular column of table into xy-graph after user selects the data from table.... In this vi , I have used mouse down event for selecting data set so that the color of selected row get changed for user reference....... the vi is working fine.....
My problem is that this vi is a part of main vi.. and I want to use this vi as a subvi.... So, in my main vi I have a table control which is connected as input to the subvi... I come to know that I need to register event for triggering a event in a subvi.......
(1) How to register Mouse down event of table control which is on Main Vi to trigger mouse down event of table in subvi.... Another Important thing is... how to link every property of table control of subvi to the table control of main vi... so it just act as single control adapting every property like when user selects a particular row its color changes in subvi....so it should be reflected even if user selects a row in main vi... I mean table control of main vi and subvi should be a single control...is it possible?
I hope I am clear......Thanks ..

See the modified version of the VI. I use the 'Point to Row Column' method to get the cell that was clicked on - your method also worked using 'Selection Start' but I thought I'd show you an alternative.
I've used a single event structure to update two table controls - the point is that if you have the references to the controls you can update the control from anywhere. You can also 'register for events' to allow you to register for events from a different VI (again, using the references) that doesn't have the control on the front panel.
Couple of things about your VI:
You don't need to put a wait node if you have a timeout on your event structure.
You don't need the for loop for the columns/rows - if you look at the help for the 'Active Cell' property you can use a value of -2 for the row/column to select all cells in the row/column.
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Attachments:
Highlight Selected Row in Table Control_lv2009.vi ‏13 KB

Event Structure's value change, not detecting changes when tabbing thru array of clusters

Hi! I have an array of clusters (int, int, string, int) control, and want to detecting changes made to the it. I used the Event Structure's value change case on the array, it works excellent except that it'll only detect the changes when you click out of the element or press the enter key (the one by the numbers, not carriage return). I want it to detect the changes when I tab thru the cluster or array too, but I can't figure it out... Does anyone have any ideas?
Thanks!

mfitzsimons wrote:
altenbach
Tried Value Change with my example done in 7.1 and it doesn't trgger an event. That is why I suggested Mouse Down.
Curious. I did a few minor edits in 8.0 before saving as 7.1, but the simple value change event got triggered just fine when the value vas terminated with a tab in 7.1. Every time. Strange....
Are you on 7.1 or 7.1.1? Maybe there's a difference (I am using 7.1.1).
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Mouse down event and Click event in List Box Very urgent.

Hi,
How can i differentiate mouse down and itemclick in ListBox.Its very urgent.
Regards,
Jayagopal.

Nick wrote:
Turns out need update value while typing turned on if you want to gaurantee a correct read of a text input control in a mouse down event.
AFAIK, "Update value while typing" will trigger only a Value Change event of the Str Ctl.
Mouse Down event will preceed a Value Change event, if you have both the event cases configured in your code.
- Partha
LabVIEW - Wires that catch bugs!

LV7: how to catch 'Value change' event for cursor position in XY graph?

I try to catch an event when the cursor position of a graph's cursor
changes. I created a reference for the cursor array and registered a dynamic
event 'Value change' for it. The event does not fire when the cursor changes
(either by dragging it with the mouse or by direct entry of a new value in
the cursor's X or Y fields. In contrast, when I register e.g. the 'Mouse Up'
event for the cursor array, the event IS detected.
-Franz

So this is the same behaviour as that of a regular control which also does
not fire a 'Value changed' event when it gets updated by e.g. writing to a
local.
At least the cursor's behavior is consistent then...
But unfortunately also the direct user interaction with the cursor's numeric
field does not fire the event, which is NOT consistent.
I was trying to catch cursor changes in my event loop and had used a 'Mouse
Up' event of the graph indicator to look for cursor changes (whose last
position I had kept in a local or shift reg). In order not to miss a direct
user interaction in the numeric field I added the dynamic event 'Value
change' to the same event case, but with no success, it missed the direct
entry ...
according to what you say this seems to b
e a bug then...
-Franz
"Greg McKaskle" schrieb im Newsbeitrag
news:[email protected]..
> > I try to catch an event when the cursor position of a graph's cursor
> > changes. I created a reference for the cursor array and registered a
dynamic
> > event 'Value change' for it. The event does not fire when the cursor
changes
> > (either by dragging it with the mouse or by direct entry of a new value
in
> > the cursor's X or Y fields. In contrast, when I register e.g. the 'Mouse
Up'
> > event for the cursor array, the event IS detected.
> >
>
> The reason is that value change events fire when user action directly on
> the control changes its value. They do not fire when other programmatic
> value changes occur. If you are looking at a value change on the cursor
> palette, user interaction with the numeric should fire it, but updates
> due to cursor movement are more like programmatic updates.
>
> Additional events will likely be added in future
releases, and these may
> make it easier to catch cursor movement events on a graph.
>
> Greg McKaskle
>

How to tackle the dataflow problem when Value Change event always triggers after another GUI event

We know that Value change event always triggers after another GUI event. Eg, the user modifies string control, the user clicks on a boolean control. Then event boolean clicked is triggered before event string control value change.
Now suppose somehow the GUI event that must happen to subsequently trigger the Value change event can potentially affect the data that Value change event is supposed to work on. How can we tackle this problem ?
For example, in a mockup application that the grand purpose is to have user entered values in a textbox logged to a file (no missing information is accepted, and there is a boolean to determine how the information is logged).
There are 2 controls, boolean A when clicked (mouse down) will load random number in text box B. Text box B is designed with event structure VALUE change which saves whatever values user enters into text box B to a log file.
There are 3 problems when instead of clicking anywhere on the front panel after modifying text box B, the user ends up clicking on boolean control A.
1. Event mouse down on Boolean control A will execute first, modifying text box B content before the user entered values in B get saved.
2. The value of boolean A can potentially affect how textbox B is loggged.
3. The value of boolean A affects how the file is logged and this is indeterminate. Somehow when running this VI with no Highlighting, the textbox B Value change event executes -before- boolean A value is updated (F to T). When running this VI with Highlighting, the boolean A value is updated (F to T) (because we click on it) -before- textbox B value change event occurs. Why is it like this ?
Now the situation I made up seems non-sense, but I believe it resembles one way or another a problem that you might run into. How would you solve this problem elegantly ?

You can set the string control to "update while typing".
Are you sure appending the log to itself is reasonable? Wouldn't it grow without bounds if the users keeps entering strings or pressing the ingore button?
Why isn't the "constant" a diagram constant instead of a control. Is the user allowed to change it?
To reset just write empty strings or a false to local variables of the controls (renit to defaults" seems a bit heavy handed).
All you probably need is a single event case for "ignore:value change" and "String" value changed", no need for the local variable..
Also add a stop button and an event for it.
You don't need the timeout event.

Intensive slider control use may lead to LabVIEW hang and system instability when coupled to event loop "Value Change"

Occasionally, over the past year or two, I have noticed on different machines and versions of LabVIEW (8.0 and 8.5) that intensive operation of the LabVIEW slider control (holding down the left mouse button and shaking the mouse quickly back and forth to move the slider for several seconds) may cause LabVIEW to hang with high CPU usage (50% on my current test machine, which has a Pentium IV "hyperthreaded" processor, so 50% is the max that a single thread can take up). In some instances, after the LabVIEW process is forced to quit, the system itself becomes unstable (more high CPU usage) or hangs, up to and including the need for a hard restart. I have seen this behavior both when handling slider change events the "old fashioned" way with a while loop and a case structure; and also when using a while loop with an event structure handling the "Value Change" event for the slider.
Attached is an .rtf file dump of the front panel and block diagram of a simple test VI that replicates this problem in my hands (using an event structure). The loop count runs to at least several hundred iterations before the crash occurs.
At least for the "old fashioned" loop handling method, adding a forced wait of a few dozen msec per loop didn't seem to be a workaround. I haven't tried this idea with the event structure, but don't expect joy to follow. The possibility of a system hang discourages aggressive experimentation.
Is this a known issue? Can anyone else replicate it (carefully)? In any case, I'd welcome other suggestions for workarounds.
Thanks,
Darin Nelson
Attachments:
Hang Slider.rtf ‏683 KB

Thanks for all your responses, and especially to those who are waggling their mice around trying to reproduce this. I'll respond to (most aspects of) the last several posts in one message.
LabViewGuruWannabe:
I'll see if I can get the original code to post in a separate message, I posted the .rtf originally because I thought there might be filtering on forum posts (I'm sort of new here). But I doubt you re-created it wrong.
The "more modern" test hardware was an Intel Core2 , 2.4 GHz, 2Gb RAM, on an Intel 965 family motherboard. As I said, it took me two tries to trigger the error on this hardware; in the case where it triggered, I was at almost 12000 iterations before things went south. 10000 iterations, therefore, might not be enough--or you might never get it, for all I know. My Pentium 4 Hyperthreaded machine (3.2 GHz, 2 Gb RAM) triggers the hang much more easily (always within 2500 iterations, usually within 1000), so there seems to be some hardware dependence here. Maybe the workaround is just to use hardware recent enough that no one not under the influence of strange compulsions will accidentally trigger the hang.
TonP:
After reading your suggestion, I tried something even more radical -- getting rid of the handling code altogether. I took the slider node out of the while loop, and removed all code inside the "Slide" case of the event structure.
On my Pentium 4 machine, the hang triggered after 677 iterations.
Brian Beal:

Huh, I never even noticed that checkbox existed. Anyway, yes, I
kept the default to lock out the front panel while the event process. If I
disable it… I still get the hang.
Message Edited by dman on 02-04-2008 06:36 AM

[LV2013] Events ordering (mouse down vs. value changed) ?

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