[mapserver] Java VM Crashes using the Mapscript API
Sean Gillies
sgillies at FRII.COM
Fri Jul 29 12:02:28 EDT 2005
Fernando,
A new layerObj instance is complete, except that 1) it contains no
child classObjs, 2) it might need to be added to a map. Same situation
for new instances of classObj: they are also complete except that they
contain no child styleObjs.
classObj.getLabel() returns a reference to the classObj's label
attribute. It is not a copy.
There is no need to delete any object that you have not explicitly
created. getLabel() returns a reference to an object owned by the
classObj. There is no need to delete the reference returned by
getLabel().
Sean
On Jul 29, 2005, at 9:20 AM, Fernando Simon wrote:
> Sean,
> Thanks for your reply.
> Now, after your hints, I have some doubts, using SWIG (Java
> support) if I do this code: lObjLabel = lObjClass.getLabel(); And
> after I change some attributes for the lObjLabel, these changes will
> affect the lObjClass.label? Is it the same objects, lObjLabel
> reference the same that lObjClass.getLabel(), or is a new copy? After
> I change the attributes I need to do a setLabel?
> The other doubt is about the delete() function for the objects. If
> I call this function the objects (in JavaSwig) will be release or
> clean the objects? In the lObjLabel, this function will be clean the
> lObjClass.label?
> The last doubt :) what is the objects that exist by default when I
> create a new class object or layer object?
> Thanks
>
> Fernando Simon
>
> Citando Sean Gillies <sgillies at frii.com>:
>
>> Now I understand. You should never bind a new labelObj to a
>> classObj.
>> All the MapServer classes exist primarily to support the CGI
>> mapserv
>> program, and therefore are complete. An new instance of classObj,
>> for
>> example, already contains a labelObj attribute named "label". To
>> set a
>> class's label color, you should do this
>>
>> class.label.color.setRGB(red, green, blue)
>>
>> Sean
>>
>> On Jul 28, 2005, at 1:59 PM, Fernando Simon wrote:
>>
>>> Hi Sean,
>>> Thanks for your reply, I will check my code to improve it
>> with
>>> your hints. The blank backgound appear when I define a
>> labelobject by
>>> hand using JavaMapscript and set the it (setLabel) to my class.
>>> If I save the "mapscript mapfile" the label appear with a
>> black
>>> definition for background. I solve this problem using the way
>> that I
>>> wrote in the last e-mail. Any hints why occur this black
>> backgound?
>>> Thanks.
>>>
>>> Fernando Simon
>>>
>>> Citando Sean Gillies <sgillies at FRII.COM>:
>>>
>>>> Fernando,
>>>>
>>>> This is improper usage and will result in memory leaks. An
>> instance
>>>> of
>>>> labelObj already holds references to many allocated colorObjs,
>> and
>>>> if
>>>> you bind new instances to the labelObj the originals will not
>> be
>>>> freed.
>>>> An example of proper usage is
>>>>
>>>> label.color.setRGB(0, 0, 0);
>>>>
>>>> All colors should be undefined (-1,-1,-1) by default, so I am at
>> a
>>>> loss
>>>> how you get a black label background.
>>>>
>>>> Sean
>>>>
>>>> On Jul 28, 2005, at 1:27 PM, Fernando Simon wrote:
>>>>
>>>>> Hi all,
>>>>> I found the same problem with black blackground here some
>>>> weeks
>>>>> ago, I solved the problem when I defined a blank color objects
>>>> for
>>>>> backgoundcolor and backgoundshadowcolor. Like:
>>>>> lObjCor = new colorObj(-1, -1, -1, 0);
>>>>> lObjLabel.setBackgroundcolor(lObjCor);
>>>>> lObjLabel.setBackgroundshadowcolor(lObjCor);
>>>>> So, using this way I can define all my layer using
>>>> JavaMapscript.
>>>>> To check the "mapscript mapfile" you can save it to see all
>> the
>>>>> definitions.
>>>>> Thanks.
>>>>>
>>>>>
>>>>> Fernando Simon
>>>>>
>>>>>
>>>>> Citando Rick Innis <rick at INNIS.CA>:
>>>>>
>>>>>> Im revisiting this somewhat old thread to contribute a few
>>>> insights
>>>>>>
>>>>>> I've found while dealing with the same issue, in the hope it
>>>> saves
>>>>>>
>>>>>> someone else time and effort in the future. The thread
>>>> "Mapscript
>>>>>>
>>>>>> API: for object manipulation, not object creation?" , from
>>>> earlier
>>>>>>
>>>>>> this year, also has some info on this topic.
>>>>>>
>>>>>>>>
>>>>>>>> Christian reported a crash in layerObj.delete() which I
>>>>>>>> also detected.
>>>>>>>> I think I understood the following:
>>>>>>>>
>>>>>>>> Let's say, we have an initialized mapObj mO;
>>>>>>>>
>>>>>>>> layerObj lO = new layerObj(mO);
>>>>>>>> // Say lO is the 5th layer now.
>>>>>>>> // Now lO.swigCMemOwn == true and
>>>>>>>> // lO.swigCPtr points onto the mO.swigCPtr->layers[4]
>>>>>>>>
>>>>>>>> ...
>>>>>>>> // now the mapObj is deleted but the Java-layerObj
>> continues
>>>> to
>>>>>> live.
>>>>>>>> // the C-layer-Object mO.swigCPtr->layers[4] will deleted
>> and
>>>>>>>> freed also!
>>>>>>>> mO.delete()
>>>>>>>> // From now on O.swigCPtr points into invalid piece of
>>>>>> C-memory.
>>>>>>>> ...
>>>>>>
>>>>>> I also encountered this a few months back but didn't have
>> time
>>>> to
>>>>>>
>>>>>> write it up so coherently. One workaround I was given by Sean
>>>> was
>>>>>> to
>>>>>> use insertLayer() to add the layer, which makes a copy,
>>>> allowing
>>>>>> the
>>>>>> allocated Java object to be disposed of cleanly. This also
>>>> requires
>>>>>>
>>>>>> making and inserting styleObj and classObj instances:
>>>>>>
>>>>>> // initially, layer not associated with any
>>>> map
>>>>>> layerObj myLayer = new layerObj(null);
>>>>>> // initialise layer
>>>>>> classObj myClass = new classObj(null);
>>>>>> styleObj myStyle = new styleObj(null);
>>>>>> // initialize style, then insert into class
>>>>>> myClass.insertStyle(styleObj, -1);
>>>>>> // insert class into layer
>>>>>> myLayer.insertClass(myClass, -1);
>>>>>> // insert layer into map - makes copy!
>>>>>> int ret = map.insertLayer(annos, -1);
>>>>>> // get reference to inserted copy
>>>>>> myLayer = map.getLayer(i);
>>>>>>
>>>>>>
>>>>>> However, when I started labelling my dynamic layers I found
>>>> that
>>>>>> my
>>>>>> labels ended up with a black background. The workaround I
>>>> found
>>>>>> was
>>>>>> to define an empty layer in my map, including empty style
>> info,
>>>> and
>>>>>>
>>>>>> use cloneLayer() to make copies as needed.
>>>>>>
>>>>>> The layer definition looks like this:
>>>>>>
>>>>>> # Blank generic annotation layer
>>>>>> LAYER
>>>>>> NAME user_layer
>>>>>> STATUS OFF
>>>>>> TYPE POINT
>>>>>> CLASS
>>>>>> STYLE
>>>>>> COLOR 255 255 255
>>>>>> END
>>>>>> LABEL
>>>>>> COLOR 255 255 255
>>>>>> END
>>>>>> END
>>>>>> END
>>>>>>
>>>>>> To use it, I grab the layer from the map, clone it,
>> initialize
>>>> it,
>>>>>>
>>>>>> and insert the clone into the map:
>>>>>>
>>>>>> layerObj myLayer = map.getLayerByName
>>>>>> ("blank_layer").cloneLayer();
>>>>>> // initialise...
>>>>>> int ret = map.insertLayer(annos, -1);
>>>>>>
>>>>>> The layer's type can be changed on the fly, so one definition
>>>>>> suffices for all layers.
>>>>>>
>>>>>> --Rick.
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -------------------------------------------------
>>>>> Univali - Webmail - http://webmail.univali.br
>>>>>
>>>>>
>>>> --
>>>> Sean Gillies
>>>> sgillies at frii dot com
>>>> http://zcologia.com
>>>>
>>>
>>>
>>>
>>>
>>> -------------------------------------------------
>>> Univali - Webmail - http://webmail.univali.br
>>>
>>
>>
>
>
>
>
> -------------------------------------------------
> Univali - Webmail - http://webmail.univali.br
>
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