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UserInputPanel 

This panel allows you to prompt the user for data. What the user is prompted for is specified using an XML file which is included as a resource to the installer.  Most of the panels that come with IzPack take user input in some form. In some panels this is through a simple user acknowledgment in others the user can enter text or select a directory through a file open dialog. In all of those cases the user input is used for the specific purpose needed by the panel that takes the input. However, if you need user input during installation that will later on be available to your application then you need to use the user input panel.

To use this panel, list it in the install file with the class name UserInputPanel. In addition, you must write a XML specification and add it to the install resources. The name of this resource must be userInputSpec.xml.

A UserInputPanel can be highly dynamic from IzPack 4.3 on, as it will be refreshed every time the user input changes and will be rendered based on conditions. For instance, it would be possible to enable or disable some more options by clicking a checkbox.

Here's an example userInputSpec.xml (http://%7b%7bservername%7d%7d/sample-userInputSpec.html) showing 3 panels. There are some advanced features in this example, but the general flow should be looked at first.

The user input panel is a blank panel that can be populated with UI elements through a XML specification file. The specification supports text labels, input elements, explanatory text and some minor formatting options.

The following types of user input elements are supported:

  • Text
  • Combo Box
  • Radio Buttons
  • Check Box
  • Password
  • File
  • Multiple files
  • Directory
  • Rule Input Field
  • Search Field

Additionally visual elements can be added using the following types:

  • Static Text
  • Title
  • Space
  • Divider

The way in which this panel conveys the user input to your application is through the variable substitution system. User input is not directly inserted into your configuration files but the variables that you specify for this panel are set in the variable substitution system. After this operation has taken place the variables and associated values are available for all substitutions made. This way of operation has a number of implications that you should be aware of.

First, not only can you set additional variables in this way but you can also modify variables that are defined elsewhere -even built in variables. For this reason you should be careful to avoid overlaps when choosing variable names. Although there might be cases when it seems useful to modify the value of other variables, it is generally not a good idea to do so. Because you might not exactly know when other variables are set and when and where they are used throughout the installation process, there might be unintended side effects.

Second, the panel must be shown at a point during the installation process before the variables are used. In most cases you will use the values to substitute variables in launch and configuration files that you supply with your installation. For this to work you place this panel before the install panel, because the install panel uses the variable substitutor to replace all such variables. Although using this panel any later in the process will correctly set the variables internally, there won't be any affect on the files written to disk. You can also use variables set in this way in other panels that you have written yourself. There is a section in the chapter on writing your own panel that explains how to do this. Also in this case it is important to place the associated input panel in the process before the variables are used.

At this point I would also like to mention that it is possible to hide every field element based on conditions.

It would also be possible to hide select elements on the panel or the panel altogether if certain packs are not selected. For this to work you must place this panel after the packs panel. One side effect of using this feature is that it is not possible to step back once the user input panel is displayed. This is because the user might make changes in the packs selection that would require a complete rebuild of the UI. Unfortunately, building the UI is an irreversible process, therefore the user can not be allowed to go back to the packs panel.

Basic XML Structure

A UserInputPanel is defined in a separate descriptor file, referred to as resource "userInputSpec.xml" from the installation descriptor.

Basic syntax of a UserInputPanel definition

The top level XML section is called <userInput>. For most panels it does not make sense to present them more than once, however you might want to present multiple user input panels -with different content of course. Therefore the <userInput> section can contain multiple tags that each specify the details for one panel instance.

The tag name for this is <panel>The <panel> tag uses the following attributes:

Name

Required

Description

Values

id

yes

This is the id of the user input panel for which this specification should be used. This id links to the panel specification in the install.xml file.

String Value

layout

no

Sets the alignment of fields used in the panelThere are three general layout rules this panel uses, they are left, center and right. While i think left is most commonly used, you might want to experiment with this attribute and see which you like best. The default is left.

left, center, right default: left

border

no

Normally the user input is shown with a small border. To prevent this border set this attribute to false.

true, false default: true

column_width

no

This can be used to set the column width of the two column layout. This value is in percent of the whole size. If it is set to 0, which is the default, the with will be set automatically. It it is set to 50 the gap between the left and right column is in the middle of the panel. This makes it possible to make a centered layout.

0-100 percent default: 0

Each panel can have a number of visible elements, fields.

Internationalization

To provide internationalization you can create a file named userInputLang.xml_xyz where xyz is the ISO3 code of the language in lowercase. Please be aware that case is significant. This file has to be inserted in the resources section of install.xml with the id and src attributes set at the name of the file.

Example:

If you have the following userInputSpec.xml and you want to internationalize input.comment, input.proxy, input.port for English and French you have to create two files named userInputLang.xml_eng and userInputLang.xml_fra:

userInputLang.xml_eng
userInputLang.xml_fra

you will also have to add the following to the install.xml file

install.xml
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