Extensions: INX widgets and parameters

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This page contains the reference documentation for INX widgets and parameters. Their primary goal is to make it easy to design GUIs for Inkscape Extensions using the built-in INX extension descriptor format, although (invisible) parameters can also be used for extensions that don't need to show a user interface.

Introduction

Extension GUIs consists of an arbitrary number of GUI elements, so-called Widgets. These can be simple text labels, boxes and spacers to control layout or more complex UI elements like images.

A special class of Widgets are Parameters. They differ from other Widgets in that they have a user-settable value, for example a boolean (implemented as checkbox) or integer (implemented as number entry). The value of each Parameter is passed to the extension on execution and can be used to control its behavior.

All Widgets are described using an easy-to-learn XML schema with predefined tags and attributes which are described in detail below.


Available Widgets

A general Widget takes the form

  <widget_name attribute1="value1" atribute2="value2" >value</widget_name>

where widget_name specifies the name of the widget and is one of the following:

  • labelsince 1.0
  • hboxsince 1.0/vboxsince 1.0
  • separatorsince 1.0/spacersince 1.0
  • imagesince 1.0
  • param (for all Parameter types)

Available Parameter types

A general Parameter takes the form

  <param type="parameter_type" attribute1="value1" atribute2="value2" >value</param >

where parameter_type specifies the type of the parameter and is one of the following:

  • boolsince 1.0
  • int
  • float
  • string
  • pathsince 1.0
  • optiongroup
  • notebook
  • color

If a parameter is made invisible (see gui-hidden attribute in the next section) it will not be shown in the GUI but it's value is still passed to an extension. This is useful if you want to hardcode parameter value the user should not be able to change. If all parameters (and potential widgets) are invisible, Inkscape will not show a GUI and execute the extension immediately instead, but will still pass the values of the invisible parameters.

Common attributes

For all Widgets
Attribute name Allowed value(s) Default value Required? Description
gui-hidden true,false false optional If set to true the Widget is hidden from the GUI (primarily used to add hidden parameters that are passed to the extension but are not supposed to be editable by the user.)

Note: If there are no visible parameters defined in a GUI, the extension is executed immediately without showing a dialog.

indent 0,1,2,… 0 optional Sets indentation level of the parameter. Increasing indentation adds padding to the start of the line.
 
Only for Parameters
Attribute name Allowed value(s) Default value Required? Description
name (text) - required Used as an identifier of the parameter. It has to be unique since the value of this attribute is used to save and transmit parameter values internally!
type (see above) - required Determines the type of the parameter, see the extensive description of Parameters below.
gui-text (text) - required (visible parameters),
optional (hidden parameters + notebooks)
Label shown for the parameter in the GUI.
gui-description (text) - optional Tooltip shown for the parameter when the user hovers the mouse cursor over the active area of the parameter in question.

Widgets

Parameter reference
Type Description / Code Result
hbox/vbox Creates a container for other widgets. No visual rendering but provides a possibility to align and layout other widgets. Child widgets are either added in horizontal (hbox) or vertical (vbox) direction.
<hbox></hbox>
<vbox></vbox>

A box can contain an arbitrary number of other widgets and parameters (including other boxes) to fine-tune the layout of the GUI.

Note: When you start with an empty extension GUI, you're basically starting with a vbox. Also notebook pages behave like vertically oriented boxes.

INX sample-separators.png


image Creates a widget displaying an image. The content of the <image> node specifies the path of the image file (ideally specify a path relative to the .inx file itself).
<image>path/to/image.svg</image>

By default the image will be rendered at it's actual size. Use attributes width/heigth to override the default size (in this case both attributes need to be supplied; units are pixels).

Implementation note: Loadable image formats are determined by GdkPixbuf and therefore system-specific. PNG should always work and is the safe choice. SVG should mostly work and is the preferred choice for obvious reasons.

INX sample-image.png

label Creates a widget showing text. The content of the <label> node corresponds to the text content that will be rendered.
<label>Some text here.</label>

Note: Labels are intended to provide additional information / help. For labeling parameters use the gui-text attribute; for short help texts that are specific to a single parameter prefer gui-description which will render as a tooltip.

  • When setting the attribute appearance="header" the text is styled as a heading and can be used as another possibility to group parameters.
  • When setting the attribute appearance="url" the text is rendered as a clickable link.
    Note: The text is escaped and used as the link target as-is. Creating a link text that differs from the URL is prevented for security reasons.
  • When setting the attribute xml:space="preserve" any white-space (spaces, tabs, line-breaks, etc.) in the label will be preserved, allowing to format the label accordingly. By default all leading/tailing and intermediary whitespace is collapsed into a single space character.
Different label types (in order):
  • default
  • appearance="header"
  • appearance="url"
  • xml:space="preserve"
separator Creates a separator for visual separation of other widgets. Renders as a horizontal/vertical line.
<separator />

The direction of the separator will automatically adjust depending on direction of the current container (vertical for "empty" extension GUIs and notebook pages; vertical/horizontal for vbox and hbox respectively).

INX sample-separators.png

spacer Creates a spacer for visual separation of other widgets. No visual rendering but provides variable spacing.
<spacer />

The direction of the spacer will automatically adjust depending on direction of the current container (vertical for "empty" extension GUIs and notebook pages; vertical/horizontal for vbox and hbox respectively).

Use the size attribute to set the spacing in pixels (default: size="10"). The special value expand results in a spacer that grows dynamically and always uses up as much space as possible (useful for aligning content).

Different spacer types:
  1. default
  2. size="20"
  3. size="expand"

Parameters

Parameter reference
Type Description / Code Result
boolsince 1.0 Creates a checkbox to set a boolean value. Allowed values are true or false (default value: true).
<param name="name" type="boolean" gui-text="Some label text">false</param>
INX sample-boolean.png
color Creates a control to select an RGBA color value. Values should be given in hexadecimal notation, e.g. 0xff0000ff for red with full opacity (default value: 0x000000ff)
<param name="name" type="color" gui-text="Some label text">0x000000ff</param>

Use appearance="colorbutton" for a simple button that opens a simplified color picker. Otherwise a full ColorNotebook will be rendered.

Implementation note: colors values are internally treated as 32-bit unsigned integers (unsigned long). Acceptable default values include everything the standard library function strtoul understandssince 1.0. Earlier Inkscape version only handled decimal numbers. The value passed to the extension script will also be a decimal number.

default
appearance="colorbutton"
float Creates a input to enter a floating point number. Limit the input range with the min and max attributes; set the number of decimal places with the precision attribute. (defaults: min="0", max="10" and precision="1"; default value: 0)
<param name="name" type="float" precision="3" min="0" max="9999" 
gui-text="Some label text">1.234</param>

Use the attribute appearance="full" to create a slider with which the value can be adjusted dynamically over the full range.

default
appearance="full"
int Creates a textbox input to enter an integer number. Limit the input range with the min and max attributes. (defaults: min="0" and max="10"; default value: 0)
<param name="name" type="int" min="1" max="100" gui-text="Some label text">1</param>

Use the attribute appearance="full" to create a slider with which the value can be adjusted dynamically over the full range.

default
appearance="full"
notebook Creates a set of pages (aka tab control). The user can switch between individual pages. Each page can contain an arbitrary set of other Widgets and Parameters. Individual pages are created with the <page> element.

The returned value for notebook parameters is the value of the name attribute of the selected <page>. By default the first page is selected.

<param name="name" type="notebook">
    <page name="page_1" gui-text="First page"></page>
    <page name="page_2" gui-text="Second page"></page>
</param>
INX sample-notebook.png
optiongroup Creates a control that allows to select one option one option from a set of multiple choices. The different choices are created with <option> elements.

The returned value for optiongroup type parameters is the value of the value attribute of the selected <option>. By default the first <option> is selected.

<param name="name" type="optiongroup" appearance="radio/combo"
gui-text="Some label text">
   <option value="1">First option</option>
   <option value="2">Second option</option>
</param>

Set the attribute appearance="radio"since 1.0 to render radio buttons (default). Set the attribute appearance="combo"since 1.0 to display a drop-down list instead.

appearance="radio"
appearance="combo"
pathsince 1.0 Creates a control to choose a path. Paths can either be entered manually or by using the file chooser that can be opened using the ellipsis button.

The mode attribute allows to set behavior of the file chooser (i.e. if files or folders can be selected, if they need to exist previously and if multiple selections are possible). The filetypes attribute holds a comma-separated list of file extensions and restricts the selectable file types in file picker mode.

<param type="path" name="varname" gui-text="label" mode="$mode" [filetypes="$filetypes"]/>

Possible values for the mode attribute:

  • file - select a single existing file
  • files - select multiple existing files
  • folder - select a single existing folder
  • folders - select multiple existing folders
  • file_new - select a single new file name
  • file_new - select a single new folder name

Implementation note: Existence of paths are not checked before passing them to the extension, so extension authors need to implement suitable error handling, especially in case of manual path entry. For multiple selections the individual paths are joined using the pipe character ("|") and passed to the extension as a single string.

INX path.png
string Creates a input to enter a string. Limit the number of characters the user is allowed to enter with the max-length attribute. (defaults: no character limit; default value: empty string)
<param name="name" type="string" gui-text="Some text label">Some default text</param>

Set the attribute appearance="multiline"since 1.0 to render a multi-line input. Line-breaks will be encoded as literal \n in the value passed to the extension.

  • default (top)
  • appearance="multiline" (bottom)

Translation of widgets and parameters

Deprecated Functionality

These widgets and parameters have been deprecated and should not be used anymore. Extension authors are encouraged to update their existing extensions wherever possible. Documentation is kept for authors that need to make their extensions backwards-compatible but please be aware that deprecated functionality will be removed eventually and without further notice.

Deprecated Parameters
Type Description / Code Result
booleandepr. 1.0 Replace with <param type="bool" …/> parameter.

Creates a checkbox to set a boolean value. Allowed values are true or false (default value: true).

<param name="name" type="boolean" gui-text="Some label text">false</param>
INX sample-boolean.png
descriptiondepr. 1.0 Replace with <label>…</label> widget.

Creates a text element. Specifying the attribute xml:space="preserve" preserves whitespace in the text content of the description and enables multiline text.

<param name="name" type="description">Some text here.</param>

When additionally setting the attribute appearance="header" the text is styled as a heading and can be used as another possibility to group parameters.

<param name="name" type="description" appearance="header">Header</param>

All description type parameters are purely informational (they do not return any value). They are intended to be used to provide additional information / help on other parameters (Consider using the gui-description attribute for short help texts that are specific to a single parameter, though).


INX sample-description.png
default appearance



INX sample-description header.png
with appearance="header"


 


enumdepr. 1.0 Replace with <optiongroup appearance="combo" …> parameter.

Creates a drop-down list from which one predefined value can be chosen. The different choices are created with <item> elements. The first <item> is selected by default. The returned value for enum type parameters is the value of the value attribute of the selected <item>.

<param name="name" type="enum" gui-text="Some label text">
   <item value="1">First option</item>
   <item value="2">Second option</item>
</param>
INX sample-enum.png

Other deprecations

  • Parameters of type optiongroup:
  • appearance="minimal"depr. 1.0

Deprecated localization functionality of parametersdepr. 1.0

To mark parameters to be included into the translation files variants of all relevant attributes and tag names existed that started with an underscore.

While the underscored variants are still accepted for backwards-compatibility, translations are handled differently since Inkscape 1.0, which solved a number of limitations of the prior implementation, while also making the INX specification significantly cleaner. See Translation of widgets and parameters for details.