This chapter is from the book
This chapter is from the book
This chapter is from the book
Panels
Up to this point, we have used HTML tables to lay out components. Creating table markup by hand is tedious, so now we'll look at alleviating some of that tedium with h:panelGrid, which generates the HTML markup for laying out components in rows and columns.
You can specify the number of columns with the columns attribute, like this:
<h:panelGrid columns="3"> ... </h:panelGrid>
The columns attribute is not mandatory—if you do not specify it, the number of columns defaults to 1. The h:panelGrid tag places components in columns from left to right and top to bottom. For example, if you have a panel grid with three columns and nine components, you will wind up with three rows, each containing three columns. If you specify three columns and 10 components, you will have four rows, and in the last row only the first column will contain the tenth component.
Table 4–8 lists h:panelGrid attributes.
Table 4–8. Attributes for h:panelGrid
|
Attributes |
Description |
|
bgcolor |
Background color for the table |
|
border |
Width of the table's border |
|
cellpadding |
Padding around table cells |
|
cellspacing |
Spacing between table cells |
|
columnClasses |
Comma-separated list of CSS classes for columns |
|
columns |
Number of columns in the table |
|
footerClass |
CSS class for the table footer |
|
frame |
Specification for sides of the frame surrounding the table that are to be drawn; valid values: none, above, below, hsides, vsides, lhs, rhs, box, border |
|
headerClass |
CSS class for the table header |
|
rowClasses |
Comma-separated list of CSS classes for rows |
|
rules |
Specification for lines drawn between cells; valid values: groups, rows, columns, all |
|
summary |
Summary of the table's purpose and structure used for nonvisual feedback, such as speech |
|
captionClass |
CSS class or style for the caption; a panel caption is optionally supplied by a facet named "caption" |
|
binding, id, rendered, value |
Basic attributesa |
|
dir, lang, style, styleClass, title, width |
HTML 4.0b |
|
onclick, ondblclick, onkeydown, onkeypress, onkeyup, onmousedown, onmousemove, onmouseout, onmouseover, onmouseup |
DHTML eventsc |
, captionStyle You can specify CSS classes for different parts of the table: header, footer, rows, and columns. The columnClasses and rowClasses specify lists of CSS classes that are applied to columns and rows, respectively. If those lists contain fewer class names than rows or columns, the CSS classes are reused. That makes it possible to specify classes, like this:
rowClasses="evenRows, oddRows"
and
columnClasses="evenColumns, oddColumns"
The cellpadding, cellspacing, frame, rules, and summary attributes are HTML pass-through attributes that apply only to tables. See the HTML 4.0 specification for more information.
h:panelGrid is often used with h:panelGroup, which groups two or more components so they are treated as one. For example, you might group an input field and its error message, like this:
<h:panelGrid columns="2">
...
<h:panelGroup>
<h:inputText id="name" value="#{user.name}">
<h:message for="name"/>
</h:panelGroup>
...
</h:panelGrid>
Grouping the text field and error message puts them in the same table cell. (We discuss the h:message tag in the section "Messages" on page 171.)
h:panelGroup is a simple tag with only a handful of attributes. Those attributes are listed in Table 4–9.
Table 4–9. Attributes for h:panelGroup
|
Attributes |
Description |
|
layout |
If the value is "block", use an HTML div to lay out the children; otherwise, use a span |
|
binding, id, rendered |
Basic attributesa |
|
style, styleClass |
HTML 4.0 b |