The GetMath command extracts the content from a canvas inserted by the ShowCanvas command, or Maple Learn canvas constructed by a command, or fetched by the GetCanvas command.

Note that ShowCanvas and button actions clicked in an active canvas will set the global variable, _canvas.  If the first argument is omitted, the _canvas global will be used. The returned list will contain Record structures describing the content.  Each Record will have a type field, such that elem[i]:-type will return "math", "text", or other identifier.  For elements that have their type member set to "math", there will be a math member containing the value.  Similarly text elements will have a text member containing the value.

A "canvas" is an interactive section of a Maple document created by the NewCanvas command, or a shared web-based Maple Learn document.  See the Script command for a more complete description.

When the keeptext=true option is given, the text content is returned in addition to the math.  The default is to return only the math content.

When the keepall=true option is given, text and other content such as buttons are returned in addition to the math.  

Empty math structures are normally pruned from the result.  Use the keepempty=true option to retain these.  Their math member will be set to the empty string, "".

When the inert=true option is specified, operators will remain in InertForm style.  This prevents simplification, for example, returning `%+`(1,1) instead of 2.

When the mathmlonly=true option is specified, the record's math field will be set to NULL, but the mathml field will remain populated.

The DocumentTools[Canvas][GetMath] command was introduced in Maple 2021.

For more information on Maple 2021 changes, see Updates in Maple 2021.