Collectors

From ConTeXt wiki

< Layout | Columns | Overlays | Logos | Layers >

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}}

\composedcollector{example}

\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}}

\composedcollector{example2}

\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)