[OpenLayers-Dev] multipleSelectFeature on one layer

Eric Lemoine eric.c2c at gmail.com
Sun Jan 25 03:08:22 EST 2009

Hi Alex

Consider this sequence: mouse goes over feature, feature is clicked
(for selection), and clicked again (for unselection). With your "stack
of intents" logic, the feature isn't redrawn as a result of the second
click; instead it should be redrawn with the hover control's render
intent, shouldn't it?


2009/1/23, Alexandre Dube <adube at mapgears.com>:
> Hi devs,
>   Eric was right :
> <<<
> A first note. The current select feature implementation should
> accomodate this use case: two controls on the same layer, one working
> on click and the other on hover, only one of them actually changing
> the feature style. This is achievable by registering a
> beforefeatureselected listener, and have this listener return false.
> Adding beforefeatureunselected might help fully accomodate that use
> case.
> Now if we want the two controls to do feature styling, we need the
> stuff I mentioned previously - per-control selectedFeatures arrays and
> events. But this is unfortunately not sufficient. Use case: two
> controls, one working on click and the other on hover, both doing
> feature styling but with different render intents. If we have this
> sequence "mouse goes over feature, mouse clicks feature, mouse goes
> out of feature", then the feature ends up being rendered with the
> "default" render intent, while it's still selected from the click
> control's perspective. In most cases, this isn't desirable I think.
> At this point I don't have a solution to the above issue.
>  >>>
> An idea that could resolve this issue : features could have a stack of
> renderIntent instead of a normal string value.  Instead of assigning new
> renderIntent value, it would stack in renderIntents array.  Instead of
> reseting to "default", it would remove the last renderIntent in the
> stack.  When the stack is empty, the "default" renderIntent is applied.
>   That could work.  I'll try this and come back with more details.
> Alexandre
> Alexandre Dube wrote:
>> Hi devs,
>>   I would like to propose some changes about the SelectFeature control.
>>   First, I'll introduce what I want to do : I want to change the color
>> of a feature while the mouse is over it without selecting it.  I managed
>> to do this by building a customized control similar to the SelectFeature
>> control named HighlightFeature.  I shared the code and some people
>> showed interest in this feature.  In fact, it was a good enough to be
>> added to trunk but there was a problem : it's too similar to the
>> SelectFeature control.
>>   My first new option was to modify the SelectFeature control to be able
>> to select and highlight.  That's what I did, but I hit a wall : I needed
>> to add more new events "beforefeaturehighlighted", "featurehighlighted",
>> etc.  a new array of highlightedFeatures, etc...  That also became a
>> pain because it was yet an other duplication of something already
>> existant ( similair "select" feature events, an array of selected
>> features, etc....)
>>   SO, that brings me to this solution, the first one Eric Lemoine
>> proposed : an array of selectedFeatures and select events for the
>> control ( without removing the ones of the layer ).  Doing that, one
>> vector layer could have multiple select feature controls that would know
>> which feature it has selected, they could all have a different
>> renderIntent value ( this is already possible ) or their own style.
>> Then, the user could interact directly with the desired control's
>> selectedFeatures.
>>   My example : One SelectFeature that select on click, has the default
>> render intent "select", on which I register a "featureselected" to
>> display a form to fill.  And one other SelectFeature that select on
>> hover, has a custom render intent "temporary" to have a different color
>> and an event registered to "featureselected" to display a quick popup of
>> the infos of the hovered feature.
>>   Even my DeleteFeature control I created a couple of weeks ago could
>> work by using an other SelectFeature control and using its own
>> featureSelected array.
>>   I'll make thoses small changes, an example and propose this as an
>> enhancement.  What do you think ?
>>   Regards,
> --
> Alexandre Dubé
> Mapgears
> www.mapgears.com
> _______________________________________________
> Dev mailing list
> Dev at openlayers.org
> http://openlayers.org/mailman/listinfo/dev

More information about the Dev mailing list