Tight Table Layouts

In a recent publication, Hurst et al. presented four different table layout al-gorithms [71]. The area approximation algorithm (AA) exploits the fact that the table cell area remains approximately constant over all minimal width-height configurations. The constant text area constraint can be expressed using a convex cone constraints. Linear constraints are used to guarantee each cell’s minimum width and height. The conjunction of linear constraints and cone constraints is also convex. Commercial solvers like Mosek [95] are capable of solving systems of conic and linear constraints.

The iterative column widening algorithm (ICW) begins by setting each table cell to its minimum width. Then, the algorithm iteratively reduces the table height by calculating the next widest table configuration that reduces

6.2. QUANTITATIVE EVALUATION 133 the table height by at least one line. Both algorithms use completely inde-pendent strategies that are combined by the authors to create several hybrid algorithms.

The hybrid of area-approximation and iterative column widening (AA-ICW) uses the area approximation algorithm to compute an initial table layout and then tries to improve the result by using ICW. The hybrid HTML-ICW algorithm used a simple table layout strategy to compute the initial table layout. The HTML table layout algorithm (HTML) calculates a table layout by resizing each column proportionally to the number of contained text.

The four algorithms and the simple HTML algorithm were evaluated by the authors on a set of seven sample tables. Each table had to be rendered for a range of maximum allowed table widths in the range of 450 - 1200 pt.

The authors compared both the achieved table height and the performance of all five algorithms to the table layout engine of the Mozilla web browser.

The Mozilla table layout engine performed much worse than all algorithms as Fig. 6.11 shows.

The ICBM layout algorithm differs in several aspects from table layout algorithms. First of all, given a constraint system representing a table, the ICBM system does not explicitly try to minimize the table height. While this optimization criterion is useful for tables, it is not really applicable to general document layouts. The ICBM system will try to fit the table into the surrounding space, i.e., the whole page. If there is a lot of free space, the ICBM system may insert gaps inside some table cells, thus resizing them to occupy more space than strictly necessary. If the available space is very limited, the user would expect the ICBM system to find a table configuration with minimum width and height.

Second, both the table layout algorithms and the ICBM system will lay-out a table with the minimum width if the desired width is less than the minimum required width. If, however, the desired width is very large, the table layout algorithms will never exceed the maximum necessary width, i.e., the width achieved if every paragraph in every cell occupied only a single line.

The ICBM system will always fulfill the width constraint if it is feasible. If necessary, the table cells will receive a very large margin.

Third, if the iterative column widening algorithm has found the smallest table height for a given table width, it will in turn also calculate the smallest necessary table width to achieve the same height. Thus, the desired width is interpreted as a maximum width and the resulting table width will typi-cally be less than that. These differences must be taken into account while designing the evaluation experiment.

Tables are one of the most powerful and useful design elements in current web document standards such as (X)HTML, CSS and XSL.

Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information.

Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

Tables are one of the most powerful and useful design elements in current web document standards such as (X)HTML, CSS and XSL. Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information. Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

(Mozilla)

Tables are one of the most powerful and useful design elements in current web document standards such as (X)HTML, CSS and XSL.

Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information.

Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

Tables are one of the most powerful and useful design elements in current web document standards such as (X) HTML, CSS and XSL. Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information. Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

(ICBM)

Tables are one of the most powerful and useful design elements in current web document standards such as (X)HTML, CSS and XSL.

Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information.

Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

Tables are one of the most powerful and useful design elements in current web document standards such as (X) HTML, CSS and XSL. Indeed because of their power, tables are frequently (mis)used by web designers to finely control page layout, not just to display tabular information. Unlike for tables provided in many document formatting systems, for example LaTeX, authors do not need to precisely specify the width of the table columns, instead the author may allow these to adapt to the viewing context while still preserving the general design intended by the author.

(AA-ICW)

The first meeting for this year will be at 11am Friday week 18th Feb (this will be the new time and day for the meeting) and will be held fortnightly thereafter. The room is the usual one.

short

also short

SVG 1.2 enables a block of text and graphics to be rendered inside a shape while automatically wrapping the objects into lines using the flowRoot element. The idea is to mirror, as far as practical, the existing SVG text elements.

(Mozilla)

The first meeting for this year will be at 11am Friday week 18th Feb (this will be the new time and day for the meeting) and

will be held fortnightly thereafter. The room is the usual one. short

also

short SVG 1.2 enables a block of text and graphics to be rendered inside a shape while automatically wrapping the objects into lines using the flowRoot element. The idea is to mirror, as far as practical, the existing SVG text elements.

(ICBM)

The first meeting for this year will be at 11am Friday week 18th Feb (this will be the new time and day for the meeting) and will be held fortnightly thereafter. The room is the usual one. short also

short SVG 1.2 enables a block of text and graphics to be rendered inside a shape while automatically wrapping the objects into lines using the flowRoot element. The idea is to mirror, as far as practical, the existing SVG text elements.

(AA-ICW)

Figure 6.11: Even on simple tables, Mozilla performs worse than the ICBM layout algorithm. The AA-ICW algorithm achieves tables that are both narrower and flatter.

6.2. QUANTITATIVE EVALUATION 135