# Collectors

Collectors are an alternative to overlays that can be used to build-up composite objects. Layers, on the other hand, are used to define whole pages. See the details manual for further explanations.

## Example

Adding labels to a figure.

 ```\starttext \definecollector[example] \setcollector [example] {\externalfigure[cow][width=4cm,frame=on]} \setcollector [example] [corner={right,bottom},location={left,top}] {\framed{1}} \setcollector [example] [corner={right,top},location={left,bottom}] {\framed{2}} \setcollector [example] [corner={left,top},location={right,bottom}] {\framed{3}} \setcollector [example] [corner={left,bottom},location={right,top}] {\framed{4}} \startTEXpage \composedcollector{example} \stopTEXpage \stoptext ```

There is no confusion if the added text is placed within the first object. However,

 ```\starttext \definecollector[example2] \setcollector [example2] {\externalfigure[cow][width=4cm,frame=on]} \setcollector [example2] [corner={right,bottom},location={right,bottom}] {\framed{1}} \setcollector [example2] [corner={right,top},location={right,top}] {\framed{2}} \setcollector [example2] [corner={left,top},location={left,top}] {\framed{3}} \setcollector [example2] [corner={left,bottom},location={left,bottom}] {\framed{4}} \startTEXpage \composedcollector{example2} \stopTEXpage \stoptext ```

Notice that the size of the collected object grows as text is added. As a consequence, the positions of the corners get redefined as the bounding box grows.

 TODO: We need more documentation and examples for this complicated subject. (See: To-Do List)