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Re: [udig-devel] Difficulty with raster images using World Image Files
So it appears I'm wrong about External Graphics.  It seems they have to be known ahead of time.  That is a little annoying.  How many graphics will you have?  Is it an open set?

Jesse


On 16-Mar-06, at 6:50 AM, M.S.Bachler wrote:

Hi!
 
That all sounds wonderful :-)
 
I have only the vaguest idea about what it all meant at the moment.
 
I looked at the AttributeExpression class,  but I had no idea what to do next.
 
Any example code/usage with AttributeExpressions anywhere you can point me at to demistify things?
Googling was not fruitful, or maybe I Googled for the wrong thing.
 
Thanks.
 
Michelle
-----Original Message-----
From: udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Jesse Eichar
Sent: 14 March 2006 17:16
To: User-friendly Desktop Internet GIS
Subject: Re: [udig-devel] Difficulty with raster images using World Image Files

If you look at an SLD you can see that most properties of symbolizers and graphics are actually expressions.  In GeoTools there are AttributeExpressions which basically return the value of an attribute.  If each feature has an attribute which is a URL then an _expression_ can created which will return the URL.  You can construct a Graphic object whose URL is determined by an AttributeExpression.  In this way you do no need to hard-code the set of images that will be displayed.

Jesse 


On 14-Mar-06, at 3:37 AM, M.S.Bachler wrote:

Hi!
 
I think my problem is that I do not have a fixed set of icons I can hardcode into an SLD.
The user can create icon groups holding any images.
So I need the whole process to be dynamic somehow.
 
Not sure if this is possible. Still trying to understand how shapefiles and SLD information fits together.
But I hope so.
 
Michelle
-----Original Message-----
From: udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Mark Presling
Sent: 11 March 2006 09:49
To: User-friendly Desktop Internet GIS
Subject: Re: [udig-devel] Difficulty with raster images using World Image Files



M.S.Bachler wrote:
You wrote:
 
"Another possibility is to create a point shapefile and one of the attributes can be a URL to an image.
The style you can define for the layer can simply display that icon at the location of the point."
 
I think this is the way I need to go.
Bearing in mind I am not up to speed with uDig and GIS, this is what I believe I need to achieve and the associated question I have (some of which may be silly).
 
I need to create layers pointing to local shape files, which each will display one type of icon.
So they can turn the layers on an off. Display all the fish, then all the huts etc.
Q: Can one shapefile hold information about more than one icon/point? (I am sure it can - I just what to be certain)
I am writing an app at the moment that does a similar thing to what you are discussing. I am going to describe what I do so that you are aware of what can be done if you want to take that path.

I have a single layer that I create road events on. I wrote a tool that when I click on the map it selects the location (this tool is similar to the DnD option that you are discussing) and opens a form for the user to enter the road event details. At this stage they choose the type of road event, ie Road Works, Road Hazard, etc. When they save the form a new Feature is created on the layer with an attribute for the type. I use SLD with multiple Rules to display icons for each type of event on that layer, driven off the type attribute. If you want an example of the SLD with multiple rules let me know. Here's an example of what my map looks like:
<snapshot2.png>

The labels are just for testing. They are also defined in the SLD and are driven off another attribute to describe the state of the event.

I can also turn on and off each event type, exclude events inside/outside a date range, exclude closed events, etc with filters on the layer. In order to do this I had to extend BasicFeatureRenderer and register my own renderer using the uDig renderer extension point. It's just an exact copy of BasicFeatureRenderer, but the setQueries() method does something different. This renderer applies a Filter to the layer just before it is rendered. I have created a view with a form that the user selects the attributes that they want to filter on and then click apply. The filter is stored on the layer blackboard and then when the map is refreshed the renderer grabs the filter from the blackboard and applies it to the layer first. Here is an example of the same data being filtered to only show Road Hazards on the road event layer:
<snapshot4.png>


Obviously the fonts are set up for Windows and I'm developing in Linux...

In terms of your data, if the different types have the same attributes (ie you only store an id, name and geom for example) then you may be able to take this approach and use a single shape file. Otherwise you will have to continue using different layers/shapefiles.

Again, I don't know if this will help you, but I have taken a lot of knowledge/advice from the uDig guys and would like to put back what I can. Hopefully I will be able to develop some code that is not specific to my project that I can put back into uDig to do this sort of thing. ;-)

Mark


 
As they drag an icon from the palette, I need to determine if I have a layer already for that type of icon.
I was hoping to use the layer name = icon name.
Q: Is the layer name stored in the shape file, i.e. is it persistent?
 
If there is already a layer displaying say huts, I need to create a new point displaying the hut icon dropped else I need to create a new layer and add the icon to that.
Q: Is it possible to add a right-click menu to an icon on a layer (I guess to a point object - though I am still fuzzie about this a present)?
 
I need to be able to associated a point icon with a Compendium map (an external application).
I am going to use sockets to achieve this.
Q: What information do I need to store in Compendium for it to be able to request uDig to open a specific project, map and layer to link it back to a specific icon on a map? Is it just the .umap file and a layer ID of some kind? If so, how do I programmatically find out what the current .umap file is?, and how do I use that later to re-open that map?
 
Extra: They have not asked for this yet, but I am guessing that they may expect to be able to drag the icons around the map to relocate them.
Q: Is this currently possible. If not, is this as simple as adding a drag/drop event to an object somewhere, or are we talking really complicated?
 
Sorry about all the questions.
After a sleepless night worrying, I am trying to crystalize what I need to achieve, and some of the questions I have at this stage.
 
Thanks for your patients with me so far.
 
Michelle
 

-----Original Message-----
From: udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx [mailto:udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Jesse Eichar
Sent: 18 February 2006 01:24
To: User-friendly Desktop Internet GIS
Subject: Re: [udig-devel] Difficulty with raster images using World Image Files


For map graphic you don't have to worry about getting a mapgraphic context it will be passed in to the mapgraphic draw method.  So don't worry about that.  An example of the map graphic API in use is the scalebar mapgraphic in one of the printing plugins... printing.ui I think.

Another possibility is to create a point shapefile and one of the attributes can be a URL to an image. The style you can define for the layer can simply display that icon at the location of the point.

Jesse


M.S.Bachler wrote: 
Hi!

I am not sure which of the suggested routes to take.

Maybe I should explain a little more about these icons.
They are going to be used for land management for a research project in
Guyana.
So they will be images of fish, birds, huts, that sort of thing.

Users will want to drag a bird say, onto an area of the map where there
are a lot of these birds.
They will need to be able to double-click the bird icon and open a
discussion map in the Compendium application -
www.compendiuminstitute.org (the software I actually develop), where
that bird population can then be discussed or whatever. The Compendium
map will need to link back to that bird icon on that map (somehow!!?) so
users can move between the two applications easily.

This is much more complicated then my original brief. And goes into
areas I know nothing about.
I will need to understand much more about shape files and data storage
so that I can store the icon data position, associated Compendium map
details etc. I have no idea how to do any of this at the moment.

I am just starting to get my head into coding in Eclipse and for uDig.
So far I have managed to write a plugin to manage collections of icons
as groups, with the icons stored locally and the data stored in XML
files (easy really just using the Eclipse API).
I am just looking at writing the view to display these icon groups which
the user can drag from.
The rest of the Eclipse and uDig API is a complete mistery and I get
lost very easily.
I started looking at MapGraphic in the API and straight away could not
work out how to get a MapGraphicContext.

As usual in life, there is just me, with lost of projects and no time.
If someone could spoon-feed me a little with the image drop/shapefile
data storage issues to help me get into uDIG API quickly I would really
appreciate the help at this point.

Thanks

Michelle





-----Original Message-----
From: udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx
[mailto:udig-devel-bounces@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Jesse
Eichar
Sent: 10 February 2006 17:36
To: User-friendly Desktop Internet GIS
Subject: Re: [udig-devel] Difficulty with raster images using World
Image Files


That's a possibility too.  But only if the attribute exists in the 
feature.  If it is only for viewing then maybe not. 

Oh.  I should mention that map graphics don't automatically save.  
However things in the Map.getBlackboard() do save. Any object on the 
blackboard that has a "persister" extension can be saved and loaded.  
See the net.refractions.udig.project.persister extension point for more 
information on that.

Jesse

Jody Garnett wrote:
  
M.S.Bachler wrote:
    
Hi!

I need to create a panel of icons that can be dragged and dropped 
onto a map layer.
  
      
That sounds a like a "FeatureEditor" to me. Make a tool that adds
points to the map, and based on an attribute displays the correct 
icons. Then make a custom feature editor that will let the user change
    
  
the icon nicely. Finally make a view that has your icons on it, and 
based on the currently selected one it will create a feature of the 
appropriate type.

The actual data could be a shapefile, or a database or anything.

Jody

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