think-cell technical report TC2003/01 A GUI-based Interaction ...

4.3 Specifying the User Interface INTERACTION CONCEPT
convenient to encode this kind of information, because this is where the user’s fo-
cus of vision is most of the time. Therefore, the information comes to the user’s
attention immediately without distracting from the visual context.
4.3 Specifying the User Interface
Now that I have presented a constraint-based concept for abstract specification
of slide layout (Sect. 4.1) and have reviewed the available interaction techniques
(Sect. 4.2), in this section I apply the interaction techniques to enable the smart
grid concept.
4.3.1 Inserting a New Element
In current PowerPoint, there are two slightly different interactions for inserting new
elements. In both cases, the desired element (box, circle, etc.) is selected from the
toolbar by clicking the associated button. The button indicates the mode switch:
it stays pressed. The mouse cursor changes to a cross hair shape.
In the first case, the user simply clicks at some position within the slide. The
selected shape is then inserted at a standard size with its upper left corner positioned
at the mouse cursor. In the second case, the user specifies a rectangular area by
drag-and-drop. The inserted shape is then stretched to fill the selected area. In
both cases, the associated toolbar button leaves its pressed state immediately after
the element is inserted and the mouse cursor changes back to the default arrow.
Strangely, more complex objects including charts and tables are immediately
inserted with a default size at a default position, when the respective button is
clicked. Any desired placement other than the default location requires the user to
move and resize the object after insertion. This inconsistent behavior is probably
due to implementation details of OLE objects, which should better be hidden from
the user in favor of better usability. The Microsoft way to represent OLE objects
in the user interface is discussed in section 4.2.4.
My interaction pattern for the insertion of new elements is based on the insertion
of native PowerPoint shapes (Fig. 16): The user chooses a smart element from the
think-cell toolbar (1) and the mouse cursor turns into a cross hair shape. Again,
there are two ways to specify the new element’s location: Single-click (2a) and
drag-and-drop (2b).
There are ways provided to leave the insertion mode in case that it was entered
by mistake. The user may chose another element to insert, either from the think-cell
toolbar or from the ordinary PowerPoint toolbar. Alternatively, she can leave the
insertion mode altogether by pressing the escape key. Again, the insertion mode
is implicitly left immediately after the new element is inserted. This behavior is
questionable but was inherited from PowerPoint for consistency.
Finally, after the insertion the bindings of shapes to gridlines are updated, new
gridlines are created where necessary (3) and the solver is triggered to update the
over-all layout (4).
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