Fluid Visualization Of Spreadsheet Structures (Page 3 of 8) in pdf

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Figure 3. Lightweight access to dataflow graphs .

The user can explore the dataflow graph simply

Figure 2. Transient visualization of a cell . The

by moving the cursor around. The graphs fade

transient local view visualizes the incoming and

in and fade out for minimal visual disturbance.

outgoing cells of the current cell. Incoming cells

are enclosed by thin lines, and outgoing cells

are filled with gray. B3 refers to A1 through D1,

role in achieving this integration—it can smoothly present

and is referred to by D3 and D4.

larger visual structures as the user moves the cursor about

the spreadsheet. Without the fading animation and careful

the cell that the user is interacting with. The system

timing, constant flashing of the dataflow information would

visualizes both incoming cells (cells that affect the current

occur. In particular, when the dataflow graph is extensive, it

cell—i.e., that appear in the current cell’s formula) and

would be very distracting to see large graphs appear and

outgoing cells (cells that are affected by the current cell—i.e.,

disappear frequently.

cells that have formulas that the current cell appears in). The

This transient interaction mode is suspended during

system visually distinguishes the two kinds of cells by using

some operations, like editing, so that incidental movements

color, line thickness, or other graphical characteristics. Our

of the cursor will not cause unwanted visualizations.

implementation groups incoming cells into spatially adjacent

regions and encloses each region with a rectangle. The

4 Static global view

rectangle is connected to the current cell with a hairline,

while outgoing cells are filled with gray. Figure 2 shows an

example of a transient local view of a cell. Grouping

The transient local view has several advantages. It does

incoming cells makes use of both the logical structure of the

not require special operations, so the user’s focus can remain

spreadsheet (they are inputs to the current cell) and the

on the spreadsheet content as he simply moves the cursor

physical structure of the spreadsheet (they are adjacent in

around to invoke the local visualizations. It does not clutter

space).

the screen because it limits the presentation of the dataflow

The reason we call this technique transient lies in the

graph to that associated with one cell. Finally, the fading

manner in which the user specifies the current cell. In

transition effect helps the user to view the global structure of

conventional spreadsheet applications, the user must move

a spreadsheet in a pleasing, non-jarring manner.

the cursor to a cell of interest and click in it to see the

However, there are also many cases when the user may

formula. In our system, the user specifies the current cell

want to see the entire structure at once. For example, a user

simply by moving the mouse cursor over the cell. When the

may want to quickly review the entire structure when he is

cursor comes into a cell, the dataflow graph associated with

handed a spreadsheet created by another user. We

the cell (incoming and outgoing cells) gradually appears on

implemented the static global view to show this kind of

the screen (fades in), and it gradually disappears when the

overall structural information. In this mode, every dataflow

cursor moves away from the cell (fades out). Thus, the user

connection appears on the screen—this means every

can explore the dataflow graph structure of a spreadsheet

incoming and outgoing cell for every cell in the spreadsheet

simply by moving the cursor around the spreadsheet (see

(Figure 4). As in the transient local views, cells are presented

Figure 3).

as groups, which serves both to minimize clutter and to

This “mouseover” style of interaction is present in other

summarize the dataflow.

systems. A notable example is Microsoft’s “ToolTips,”

Even with the grouping technique, overlapping of many

which are tiny windows containing a few words of

portions of the graph is unavoidable, and it can be difficult to

explanatory text. ToolTips appear when the cursor lingers

follow the detailed dataflow for particular cells. Instead, the

over an item. However, ToolTips are separate from the

static global view is useful for getting a general overview of

annotated objects and overlay them, while our presentation

the entire structure. In our implementation, we assign

of the dataflow graph is integrated with the original view of

different colors for vertical, horizontal and single-cell group

the spreadsheet, not obscuring the spreadsheet and not

structures. As a result, the user can quickly see how the

becoming too obtrusive. The fading effect plays an important

Fluid Visualization Of Spreadsheet Structures Page 3

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