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Graphics.UI.Gtk.Display.Label | Portability | portable (depends on GHC) | Stability | provisional | Maintainer | gtk2hs-users@lists.sourceforge.net |
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Description |
A widget that displays a small to medium amount of text
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Synopsis |
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Detail
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The Label widget displays a small amount of text. As the name implies,
most labels are used to label another widget such as a Button, a
MenuItem, or a OptionMenu.
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Mnemonics
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Labels may contain mnemonics. Mnemonics are underlined characters in the
label, used for keyboard navigation. Mnemonics are created by providing a
string with an underscore before the mnemonic character, such as
"_File", to the functions labelNewWithMnemonic or
labelSetTextWithMnemonic.
Mnemonics automatically activate any activatable widget the label is
inside, such as a Button; if the label is not inside the mnemonic's target
widget, you have to tell the label about the target using
labelSetMnemonicWidget. Here's a simple example where the label is inside
a button: There's a convenience function to create buttons with a mnemonic
label already inside: To create a mnemonic for a widget alongside the label,
such as a Entry, you have to point the label at the entry with
labelSetMnemonicWidget:
-- Pressing Alt+H will activate this button
button <- buttonNew
label <- labelNewWithMnemonic "_Hello"
containerAdd button label
-- Pressing Alt+H will activate this button
button <- buttonNewWithMnemonic "_Hello"
-- Pressing Alt+H will focus the entry
entry <- entryNew
label <- labelNewWithMnemonic "_Hello"
labelSetMnemonicWidget label entry
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Markup (styled text)
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To make it easy to format text in a label (changing colors, fonts, etc.),
label text can be provided in a simple markup format. Here's how to create a
label with a small font: (See complete documentation of available tags in
the Pango manual.)
label <- labelNew Nothing
labelSetMarkup label "<small>Small text</small>"
The markup passed to labelSetMarkup must be valid; for example, literal
</>/& characters must be escaped as "<", ">", and
"&". If you pass
text obtained from the user, file, or a network to labelSetMarkup, you'll
want to escape it with escapeMarkup.
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Selectable labels
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Labels can be made selectable with labelSetSelectable. Selectable
labels allow the user to copy the label contents to the clipboard. Only
labels that contain useful-to-copy information - such as error messages -
should be made selectable.
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Text layout
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A label can contain any number of paragraphs, but will have performance
problems if it contains more than a small number. Paragraphs are separated
by newlines or other paragraph separators understood by Pango.
Labels can automatically wrap text if you call labelSetLineWrap.
labelSetJustify sets how the lines in a label align with one another.
If you want to set how the label as a whole aligns in its available space,
see Graphics.UI.Gtk.Abstract.Misc.miscSetAlignment.
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Class Hierarchy
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| GObject
| +----Object
| +----Widget
| +----Misc
| +----Label
| +----AccelLabel
| +----TipsQuery
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Types
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Constructors
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Creates a new label with the given text inside it. You can pass Nothing
to get an empty label widget.
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:: String | str - The text of the label, with an underscore in front
of the mnemonic character
| -> IO Label | | Creates a new Label, containing the text in str.
If characters in str are preceded by an underscore, they are
underlined. If you need a literal underscore character in a label, use
'__' (two underscores). The first underlined character represents a
keyboard accelerator called a mnemonic. The mnemonic key can be used to
activate another widget, chosen automatically, or explicitly using
labelSetMnemonicWidget.
If labelSetMnemonicWidget is not called, then the first activatable
ancestor of the Label will be chosen as the mnemonic widget. For instance,
if the label is inside a button or menu item, the button or menu item will
automatically become the mnemonic widget and be activated by the mnemonic.
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Methods
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Sets the text within the Label widget. It overwrites any text that was
there before.
This will also clear any previously set mnemonic accelerators.
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Sets the text of the label. The label is interpreted as including
embedded underlines and/or Pango markup depending on the markup and
underline properties.
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Sets the label's text from the given string. If characters in the string are
preceded by an underscore, they are underlined indicating that they
represent a keyboard accelerator called a mnemonic. The mnemonic key can be
used to activate another widget, chosen automatically, or explicitly using
labelSetMnemonicWidget.
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:: LabelClass self | | => self | str - a markup string (see Pango markup format)
| -> Markup | | -> IO () | | Parses str which is marked up with the Pango text markup language,
as defined in Graphics.Rendering.Pango.Markup,
setting the label's text and attribute list based on the parse results. If
the str is external data, you may need to escape it.
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labelSetMarkupWithMnemonic | Source |
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:: LabelClass self | | => self | str - a markup string (see Pango markup format)
| -> Markup | | -> IO () | | Parses str which is marked up with the Pango text markup language,
as defined in Graphics.Rendering.Pango.Markup,
setting the label's text and attribute list based on the parse results. If
characters in str are preceded by an underscore, they are underlined
indicating that they represent a keyboard accelerator called a mnemonic.
The mnemonic key can be used to activate another widget, chosen
automatically, or explicitly using labelSetMnemonicWidget.
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:: (LabelClass self, WidgetClass widget) | | => self | widget - the target Widget
| -> widget | | -> IO () | | If the label has been set so that it has an mnemonic key (using i.e.
labelSetMarkupWithMnemonic, labelSetTextWithMnemonic,
labelNewWithMnemonic or the "use_underline" property) the label can be
associated with a widget that is the target of the mnemonic. When the label
is inside a widget (like a Button or a Notebook tab) it is automatically
associated with the correct widget, but sometimes (i.e. when the target is a
Entry next to the label) you need to set it explicitly using this
function.
The target widget will be accelerated by emitting "mnemonic_activate"
on it. The default handler for this signal will activate the widget if there
are no mnemonic collisions and toggle focus between the colliding widgets
otherwise.
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:: LabelClass self | | => self | returns the target of the label's mnemonic, or
Nothing if none has been set and the default
algorithm will be used.
| -> IO (Maybe Widget) | | Retrieves the target of the mnemonic (keyboard shortcut) of this label.
See labelSetMnemonicWidget.
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Key values are the codes which are sent whenever a key is pressed or
released.
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If the label has been set so that it has an mnemonic key this function
returns the keyval used for the mnemonic accelerator.
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:: LabelClass self | | => self | setting - True if the label's text should be parsed for
markup.
| -> Bool | | -> IO () | | Sets whether the text of the label contains markup in Pango's text markup
language. See labelSetMarkup.
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:: LabelClass self | | => self | returns True if the label's text will be parsed for markup.
| -> IO Bool | | Returns whether the label's text is interpreted as marked up with the
Pango text markup language. See labelSetUseMarkup.
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If True, an underline in the text indicates the next character should be
used for the mnemonic accelerator key.
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Returns whether an embedded underline in the label indicates a mnemonic.
See labelSetUseUnderline.
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Gets the text from a label widget, as displayed on the screen. This
does not include any embedded underlines indicating mnemonics or Pango
markup. (See labelGetLabel)
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Gets the text from a label widget including any embedded underlines
indicating mnemonics and Pango markup. (See labelGetText).
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:: LabelClass self | | => self | attr PangoAttribute
| -> [PangoAttribute] | | -> IO () | | Sets a PangoAttrList; the attributes in the list are applied to the label
text.
Note: The attributes set with this function will be applied and merged with
any other attributes previously effected by way of the labelUseUnderline or
labelUseMarkup properties. While it is not recommended to mix markup strings
with manually set attributes, if you must; know that the attributes will be
applied to the label after the markup string is parsed.
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Underline parts of the text, odd indices of the list represent underlined
parts.
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Justification for label and maybe other widgets (text?)
| Constructors | JustifyLeft | | JustifyRight | | JustifyCenter | | JustifyFill | |
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Sets the alignment of the lines in the text of the label relative to each
other. JustifyLeft is the default value when the widget is first created
with labelNew. If you instead want to set the alignment of the label as a
whole, use Graphics.UI.Gtk.Abstract.Misc.miscSetAlignment instead.
labelSetJustify has no effect on labels containing only a single line.
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Returns the justification of the label. See labelSetJustify.
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Gets the PangoLayout used to display the label. The layout is useful to
e.g. convert text positions to pixel positions, in combination with
labelGetLayoutOffsets.
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:: LabelClass self | | => self | wrap - the setting
| -> Bool | | -> IO () | | Toggles line wrapping within the Label widget. True makes it break
lines if text exceeds the widget's size. False lets the text get cut off
by the edge of the widget if it exceeds the widget size.
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:: LabelClass self | | => self | returns True if the lines of the label are automatically
wrapped.
| -> IO Bool | | Returns whether lines in the label are automatically wrapped. See
labelSetLineWrap.
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:: LabelClass self | | => self | setting - True to allow selecting text in the label
| -> Bool | | -> IO () | | Selectable labels allow the user to select text from the label, for
copy-and-paste.
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:: LabelClass self | | => self | returns True if the user can copy text from the label
| -> IO Bool | | Gets whether the text selectable.
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:: LabelClass self | | => self | startOffset - start offset
| -> Int | endOffset - end offset
| -> Int | | -> IO () | | Selects a range of characters in the label, if the label is selectable.
See labelSetSelectable. If the label is not selectable, this function has
no effect. If startOffset or endOffset are -1, then the end of the label
will be substituted.
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Gets the selected range of characters in the label, if any. If there is
a range selected the result is the start and end of the selection as
character offsets.
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Obtains the coordinates where the label will draw the PangoLayout
representing the text in the label; useful to convert mouse events into
coordinates inside the PangoLayout, e.g. to take some action if some part
of the label is clicked. Of course you will need to create a EventBox to
receive the events, and pack the label inside it, since labels are a
'NoWindow' widget.
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:: LabelClass self | | => self | mode - a EllipsizeMode
| -> EllipsizeMode | | -> IO () | | Sets the mode used to ellipsize (add an ellipsis: "...") to the text if
there is not enough space to render the entire string.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | nChars - the new desired width, in characters.
| -> Int | | -> IO () | | Sets the desired width in characters of label to nChars.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | returns the width of the label in characters.
| -> IO Int | | Retrieves the desired width of label, in characters. See
labelSetWidthChars.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | nChars - the new desired maximum width, in characters.
| -> Int | | -> IO () | | Sets the desired maximum width in characters of label to nChars.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | returns the maximum width of the label in characters.
| -> IO Int | | Retrieves the desired maximum width of label, in characters. See
labelSetWidthChars.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | singleLineMode - True if the label should be in single line
mode
| -> Bool | | -> IO () | | Sets whether the label is in single line mode.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | returns True when the label is in single line mode.
| -> IO Bool | | Returns whether the label is in single line mode.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | angle - the angle that the baseline of the label makes with
the horizontal, in degrees, measured counterclockwise
| -> Double | | -> IO () | | Sets the angle of rotation for the label. An angle of 90 reads from from
bottom to top, an angle of 270, from top to bottom. The angle setting for
the label is ignored if the label is selectable, wrapped, or ellipsized.
- Available since Gtk+ version 2.6
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:: LabelClass self | | => self | returns the angle of rotation for the label
| -> IO Double | | Gets the angle of rotation for the label. See gtk_label_set_angle.
- Available since Gtk+ version 2.6
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Attributes
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The text of the label.
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The text of the label includes XML markup. See pango_parse_markup().
Default value: False
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If set, an underline in the text indicates the next character should be
used for the mnemonic accelerator key.
Default value: False
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The alignment of the lines in the text of the label relative to each
other. This does NOT affect the alignment of the label within its
allocation.
Default value: JustifyLeft
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If set, wrap lines if the text becomes too wide.
Default value: False
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If line wrapping is on (see the labelWrap property) this controls how the line wrapping is done.
The default is WrapWholeWords, which means wrap on word boundaries.
Default value: WrapWholeWords
- Available since Gtk+ version 2.10
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Whether the label text can be selected with the mouse.
Default value: False
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The widget to be activated when the label's mnemonic key is pressed.
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The mnemonic accelerator key for this label.
Default value: 16777215
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A string with _ characters in positions correspond to characters in the text to underline.
Default value: \
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The current position of the insertion cursor in chars.
Allowed values: >= 0
Default value: 0
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The position of the opposite end of the selection from the cursor in
chars.
Allowed values: >= 0
Default value: 0
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The preferred place to ellipsize the string, if the label does not have
enough room to display the entire string, specified as a EllipsizeMode.
Note that setting this property to a value other than EllipsizeNone has
the side-effect that the label requests only enough space to display the
ellipsis "...". In particular, this means that ellipsizing labels don't
work well in notebook tabs, unless the tab's tab-expand property is set to
True. Other means to set a label's width are
Graphics.UI.Gtk.Abstract.Widget.widgetSetSizeRequest and
labelSetWidthChars.
Default value: EllipsizeNone
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The desired width of the label, in characters. If this property is set to
-1, the width will be calculated automatically, otherwise the label will
request either 3 characters or the property value, whichever is greater. If
the width-chars property is set to a positive value, then the
max-width-chars property is ignored.
Allowed values: >= -1
Default value: -1
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Whether the label is in single line mode. In single line mode, the height
of the label does not depend on the actual text, it is always set to ascent
+ descent of the font. This can be an advantage in situations where resizing
the label because of text changes would be distracting, e.g. in a statusbar.
Default value: False
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The angle that the baseline of the label makes with the horizontal, in
degrees, measured counterclockwise. An angle of 90 reads from from bottom to
top, an angle of 270, from top to bottom. Ignored if the label is
selectable, wrapped, or ellipsized.
Allowed values: [0,360]
Default value: 0
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A list of style attributes to apply to the text of the label.
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The desired maximum width of the label, in characters. If this property
is set to -1, the width will be calculated automatically, otherwise the
label will request space for no more than the requested number of
characters. If the width-chars property is set to a positive value, then the
max-width-chars property is ignored.
Allowed values: >= -1
Default value: -1
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'lineWrap' property. See labelGetLineWrap and labelSetLineWrap
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'text' property. See labelGetText and labelSetText
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Produced by Haddock version 2.6.0 |