Grid's Columns and Hflex
This section introduces the usage of ZK auto sizing APIs. All of these can apply to the following components:
Hflex and Width
There are basically two approaches to control the width of a column: width and hflex. They could be specified in the column's header, such as column and listheader. ).
While width (HtmlBasedComponent.setWidth(String)) specifies the width in precise number (such as width="100px"), hflex (HtmlBasedComponent.setHflex(String)) specifies the proportional width (such as hflex="1") or the minimal width (such as hflex="min").
Span
If the total width of all columns is smaller than the grid, there will be some whitespace shown at the right side of the grid.
If you prefer to make each column's width a bit wider to cover the whole grid, you could specify span="true" in grid/listbox/tree (such as Grid.setSpan(String)).
If you want to make a particular column larger to cover the whole grid, you could specify a number, such as span="2" to expand the third column.
sizedByContent
If you want to make each column as minimal as possible, you could specify hflex="min" for each column. Alternatively, you could specify sizedByContent="true" in the grid/listbox/tree (Grid.setSizedByContent(boolean)). In other words, it implies the width of a column that is not assigned with width and hflex shall be minimal.
In general, you will specify span="true" too to cover the whole grid/listbox/tree.
Use Cases
Here we take listbox with listheaders as an example to show some different use cases.
Data Length : Short
<zk>
<zscript><![CDATA[
String[] msgs2 = {
"Application Developer's Perspective",
"Server+client Fusion architecture",
"Component Developer's Perspective",
"Execution Flow of Loading a Page",
"Execution Flow of Serving an Ajax Request",
"When to Send an Ajax Request"
};
]]></zscript>
<listbox width="800px">
<listhead>
<listheader label="Product" />
<listheader label="Description" />
<listheader label="Comment" />
</listhead>
<listitem>
<listcell><label value="${msgs2[0]}"></label></listcell>
<listcell><label value="${msgs2[1]}"></label></listcell>
<listcell><label value="${msgs2[2]}"></label></listcell>
</listitem>
<listitem>
<listcell><label value="${msgs2[3]}"></label></listcell>
<listcell><label value="${msgs2[4]}"></label></listcell>
<listcell><label value="${msgs2[5]}"></label></listcell>
</listitem>
</listbox>
</zk>
- Default : Data component will show the data correctly, with no width specification. (the exact widths of columns are rendered by browser automatically)
Proportional Width
You can use the hflex we have mentioned in previous section.
<listhead>
<listheader label="Product" hflex="1"/>
<listheader label="Description" hflex="2"/>
<listheader label="Comment" hflex="1" />
</listhead>
Minimum Flexibility
In the case of hflex=min, column's width will just fit the contents. As you can see, there might be blank space on the right of the listbox.
<zscript><![CDATA[
String[] msgs2 = {
"Application Developer's Perspective",
"Very Short Text",
"Server+client Fusion architecture",
"Execution Flow of Serving an Ajax Request",
"Very Short Text",
"When to Send an Ajax Request (Addition Text )"
};
]]></zscript>
<listbox width="800px">
<listhead>
<listheader label="Product" hflex="min"/>
<listheader label="Description" hflex="min"/>
<listheader label="Comment" hflex="min" />
</listhead>
- If you want your contents to fill the whole grid to eliminate the blank space, you can set span=true to make it proportionally expanded.
<listbox width="800px" span="true">
<listhead>
<listheader label="Product" hflex="min"/>
<listheader label="Description" hflex="min"/>
<listheader label="Comment" hflex="min" />
</listhead>
- If you want the rest of the space to be assigned to one of the columns, set span to a number. The number is 0-based index of columns.
<listbox width="800px" span="0">
<listhead>
<listheader label="Product" hflex="min" />
<listheader label="Description" hflex="min" />
<listheader label="Comment" hflex="min" />
</listhead>
- If you want the size of the Listbox determined by its content, assign hflex=min on the Grid, and make sure all the Listheaders either have hflex=min or a fixed width.
<listbox hflex='min'>
<listhead>
<listheader label="Product" hflex="min" />
<listheader label="Description" hflex="min" />
<listheader label="Comment" hflex="min" />
</listhead>
Data Length : Long
<zscript><![CDATA[
String[] msgs2 = {
"Application Developer's Perspective",
"Very Long Long Long Long Long Long Long Long Long Long Text",
"Server+client Fusion architecture",
"Execution Flow of Serving an Ajax Request",
"Very Long Long Long Long Long Long Long Long Long Long Text",
"When to Send an Ajax Request"
};
]]></zscript>
- Default : ZK data component will wrap the text to fit the width of column.
Scrollbar
When the sum of content width is larger than Grid width. The scroll appears if and only if
- The Columns and Column component are presented.
- Each of the Column components is given an hflex or width value.
Specify Width
This is a simple way to avoid text wrapped by given proper width. However, it can be difficult if you don't know the content length beforehand.
<listhead>
<listheader label="Product" width="250px"/>
<listheader label="Description" width="470px"/>
<listheader label="Comment" width="280px" />
</listhead>
Minimum Flexibility
- Set hflex=min and ZK will calculate the length of content and set proper width to the column accordingly.
- Notes: Remember to set every column with hflex=min or specify a specific width; otherwise those columns without setting minimum hflex or specifying a width could disappear if not enough space in the listbox.
<listhead>
<listheader label="Product" hflex="min" />
<listheader label="Description" hflex="min" />
<listheader label="Comment" hflex="min" />
</listhead>
Mixed Flexibility and width
Width + Hflex proportion
<listhead>
<listheader label="Product" width="120px" />
<listheader label="Description" hflex="2" />
<listheader label="Comment" hflex="1" />
</listhead>
Width + Hflex min
<listhead>
<listheader label="Product" width="150px" />
<listheader label="Description" hflex="min" />
<listheader label="Comment" hflex="min" />
</listhead>
Width + Hflex min + Hflex proportion
<listhead>
<listheader label="Product" width="120px" />
<listheader label="Description" hflex="min" />
<listheader label="Comment" hflex="1" />
</listhead>
Data Length : Dynamic
If users can't control the data size, that means, you should take both the short data and the long data situation into consideration.
Now we have several attributes, rules, and situations, please choose the right solution for your case.
- (Blank) : Doesn't matter
- V : Must set
- X : Must not set
- ! : Acceptable but something needs notice.
| Specification | Span=true | Hflex proportion | Hflex=min | Specific Width |
|---|---|---|---|---|
| Fill whole Grid | One of these attributes was set | X | ! | |
| No Scrollbar Grid | V | X | ! | |
| No Content Wrapping Column | V | ! | ||
| Fill whole Grid + No Scrollbar Grid | V | X | ! | |
| Fill whole Grid + No Content Wrapping | V | All Column components should have one of these attributes | ||
- ! : Specific width must not be more than grid's width.
Version History
| Version | Date | Content |
|---|---|---|
| 5.0.6 | February 2011 | New specification of hflex and span. |