Layer order and arranging layers

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(Arranging Layers Example)
(Arranging layers example)
 
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Layer stack is an ordered set of layers. Layer's position in the stack reflects to the topic resolution in Wandora. Layer order in the stack has an effect to the topics and associations in Wandora. General rule is that a topic inherits properties from the top layer consisting the topic property. Top property overlays all other properties in lower layers.
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Layer stack is an ordered set of layers. Each layer contains topics and associations. If two layers contain a topic with a same subject identifier, these topics merge. Wandora views a merged topic that inherits it's properties from both topics. Inherited properties include topic names, occurrences and associations. Wandora's topic map model is limited and a topic may contain only one base and one subject locator in Wandora. Now, what happens if two layers contain a topic with a same subject identifier, and both topics have different base name. Which base name is viewed in the merged topic. The answer relates to the order of layers in the layer stack. Wandora solves topic properties from top to down and a base name locating top layer hides a base name locating lower layer. Same applies to subject locators, occurrences and variant names. If both merged topics carry an occurrence with same scope, the merged topic views only an occurrence from the higher layer. The occurrence in lower layer is hidden.
  
To arrange layer order in the stack you can
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Saying this, it is clear that the user may want to switch layer order. To arrange topic map layer order in the layer stack Wandora user can
 
* Drag and drop layers.
 
* Drag and drop layers.
 
* Use submenus in '''Layers > [[ArrangeLayers|Arrange layers]]'''.
 
* Use submenus in '''Layers > [[ArrangeLayers|Arrange layers]]'''.
  
== Arranging Layers Example ==
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== Arranging layers example ==
  
Lets say we have two layers in Wandora, layer1 and layer2. Both layers contain a topic with subject identifier of http://www.wandora.net/Finland describing our home country Finland. Due to merge rule these two topics merge in Wandora. Now lets assume that both topics have different base name. Topic in layer1 has a base name '''Suomi''' while the topic in layer layer2 has a base name '''Finland'''. Both are valid base names and the question is which base name should Wandora use for the merged topic? Remember that topics may contain only one unscoped base name in Wandora. The answer to the question lies in the order of layer1 and layer2. When layer1 is above layer2 merged topic has base name '''Suomi''' and when the layer1 is below the layer2 merged topic has base name '''Finland'''. This applies not only to base names but also variant names and occurrences of same type and scope.
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Lets say we have added two layers in Wandora. These layer are labeled as '''layer1''' and '''layer2'''. Both layers contain a topic with subject identifier of http://www.wandora.net/Finland representing a concept of country Finland. As both topics contain same subject identifier, topics merge in Wandora. Now lets say that both topics have different base name. Topic in '''layer1''' has a base name '''Suomi''' while the topic in layer '''layer2''' has a base name '''Finland'''. Which base name Wandora views for the merged topic? When '''layer1''' is above '''layer2''' the merged topic has a base name '''Suomi''' and when the '''layer1''' is below the '''layer2''' the merged topic has a base name '''Finland'''.
  
Below is a screenshot of Wandora where layer1 overlays layer2. We are viewing topic '''Suomi'''. Notice that layer distribution vector 1:1:0 indicates the topic has a merged companion in layer2 also but not in layer Base.
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Below is an image of Wandora where '''layer1''' overlays '''layer2'''. Wandora views topic '''Suomi'''. Notice that topic's layer distribution is '''[ 1:1:0 ]'''. Topic's layer distribution is shown in the footer and indicates the topic has a merged companion in '''layer1''' and '''layer2''' but not in the layer Base.
  
[[Image:arrange_layers_example1.gif]]
 
  
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[[Image:arrange_layers_example1.gif|center]]
  
[[Image:arrange_layers_example2.gif]]
 
  
Analogy drawn earlier between the layer concept of Wandora and graphic design applications may lighten the effect of layer order also. In graphic design applications the graphic element in top layer overlays the elements in lower layers. Similarly the base name in Wandora's top layer overlays base name's of merged topics in lower layers. Similarly the occurrence text of top layer overlays the occurrence of merged topics in lower layers.
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Ok, now the user switches the layer order and drags the '''layer2''' to the top. Topic's base name changes automatically to '''Finland''' as the topic in '''layer2''' has different base name than the topic in '''layer1'''.  
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[[Image:arrange_layers_example2.gif|center]]
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Next Wandora user deletes the base name in '''layer2'''. The base name from '''layer1''' pops up in red. Red color indicates the base name doesn't originate current layer and you can't change it directly. Yes, you can override the base name again but the ''lower'' base name stays unchanged and pop ups again if you delete the overlaying name. To change the ''lower'' base name you need to select the layer where base name locates. Topic's layer distribution '''[ 1:1:0 ]''' hints which layer to choose.
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[[Image:arrange_layers_example3.gif|center]]
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It may be easier to think the layer concept of Wandora similar to the layer concept of modern graphic design applications. Graphic design application views an element drawn to the top layer on top of the elements drawn into the lower layers. If the layer order is changed, the order of graphic elements changes too.
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== See also ==
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* [[Introduction to Layered Topic Maps]]
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* [[Layered topic map]]
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* [[Creating new layers]]
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* [[Topic's layer distribution]]

Latest revision as of 19:48, 3 December 2013

Layer stack is an ordered set of layers. Each layer contains topics and associations. If two layers contain a topic with a same subject identifier, these topics merge. Wandora views a merged topic that inherits it's properties from both topics. Inherited properties include topic names, occurrences and associations. Wandora's topic map model is limited and a topic may contain only one base and one subject locator in Wandora. Now, what happens if two layers contain a topic with a same subject identifier, and both topics have different base name. Which base name is viewed in the merged topic. The answer relates to the order of layers in the layer stack. Wandora solves topic properties from top to down and a base name locating top layer hides a base name locating lower layer. Same applies to subject locators, occurrences and variant names. If both merged topics carry an occurrence with same scope, the merged topic views only an occurrence from the higher layer. The occurrence in lower layer is hidden.

Saying this, it is clear that the user may want to switch layer order. To arrange topic map layer order in the layer stack Wandora user can

[edit] Arranging layers example

Lets say we have added two layers in Wandora. These layer are labeled as layer1 and layer2. Both layers contain a topic with subject identifier of http://www.wandora.net/Finland representing a concept of country Finland. As both topics contain same subject identifier, topics merge in Wandora. Now lets say that both topics have different base name. Topic in layer1 has a base name Suomi while the topic in layer layer2 has a base name Finland. Which base name Wandora views for the merged topic? When layer1 is above layer2 the merged topic has a base name Suomi and when the layer1 is below the layer2 the merged topic has a base name Finland.

Below is an image of Wandora where layer1 overlays layer2. Wandora views topic Suomi. Notice that topic's layer distribution is [ 1:1:0 ]. Topic's layer distribution is shown in the footer and indicates the topic has a merged companion in layer1 and layer2 but not in the layer Base.


Arrange layers example1.gif


Ok, now the user switches the layer order and drags the layer2 to the top. Topic's base name changes automatically to Finland as the topic in layer2 has different base name than the topic in layer1.


Arrange layers example2.gif


Next Wandora user deletes the base name in layer2. The base name from layer1 pops up in red. Red color indicates the base name doesn't originate current layer and you can't change it directly. Yes, you can override the base name again but the lower base name stays unchanged and pop ups again if you delete the overlaying name. To change the lower base name you need to select the layer where base name locates. Topic's layer distribution [ 1:1:0 ] hints which layer to choose.


Arrange layers example3.gif


It may be easier to think the layer concept of Wandora similar to the layer concept of modern graphic design applications. Graphic design application views an element drawn to the top layer on top of the elements drawn into the lower layers. If the layer order is changed, the order of graphic elements changes too.

[edit] See also

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