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Graphics.UI.Gtk.Display.Label

Portability | portable (depends on GHC)
Stability | provisional
Maintainer | gtk2hs-users@lists.sourceforge.net

Contents

Detail
  Mnemonics
  Markup (styled text)
  Selectable labels
  Text layout
Class Hierarchy
Types
Constructors
Methods
Attributes

Description
A widget that displays a small to medium amount of text
Synopsis

data Label
class MiscClass o => LabelClass o
castToLabel :: GObjectClass obj => obj -> Label
toLabel :: LabelClass o => o -> Label
labelNew :: Maybe String -> IO Label
labelNewWithMnemonic :: String -> IO Label
labelSetText :: LabelClass self => self -> String -> IO ()
labelSetLabel :: LabelClass self => self -> String -> IO ()
labelSetTextWithMnemonic :: LabelClass self => self -> String -> IO ()
labelSetMarkup :: LabelClass self => self -> Markup -> IO ()
labelSetMarkupWithMnemonic :: LabelClass self => self -> Markup -> IO ()
labelSetMnemonicWidget :: (LabelClass self, WidgetClass widget) => self -> widget -> IO ()
labelGetMnemonicWidget :: LabelClass self => self -> IO (Maybe Widget)
type KeyVal = Word32
labelGetMnemonicKeyval :: LabelClass self => self -> IO KeyVal
labelSetUseMarkup :: LabelClass self => self -> Bool -> IO ()
labelGetUseMarkup :: LabelClass self => self -> IO Bool
labelSetUseUnderline :: LabelClass self => self -> Bool -> IO ()
labelGetUseUnderline :: LabelClass self => self -> IO Bool
labelGetText :: LabelClass self => self -> IO String
labelGetLabel :: LabelClass self => self -> IO String
labelSetPattern :: LabelClass l => l -> [Int] -> IO ()

data Justification

= JustifyLeft
| JustifyRight
| JustifyCenter
| JustifyFill

labelSetJustify :: LabelClass self => self -> Justification -> IO ()
labelGetJustify :: LabelClass self => self -> IO Justification
labelGetLayout :: LabelClass self => self -> IO PangoLayout
labelSetLineWrap :: LabelClass self => self -> Bool -> IO ()
labelGetLineWrap :: LabelClass self => self -> IO Bool
labelSetSelectable :: LabelClass self => self -> Bool -> IO ()
labelGetSelectable :: LabelClass self => self -> IO Bool
labelSelectRegion :: LabelClass self => self -> Int -> Int -> IO ()
labelGetSelectionBounds :: LabelClass self => self -> IO (Maybe (Int, Int))
labelGetLayoutOffsets :: LabelClass self => self -> IO (Int, Int)
labelSetEllipsize :: LabelClass self => self -> EllipsizeMode -> IO ()
labelGetEllipsize :: LabelClass self => self -> IO EllipsizeMode
labelSetWidthChars :: LabelClass self => self -> Int -> IO ()
labelGetWidthChars :: LabelClass self => self -> IO Int
labelSetMaxWidthChars :: LabelClass self => self -> Int -> IO ()
labelGetMaxWidthChars :: LabelClass self => self -> IO Int
labelSetSingleLineMode :: LabelClass self => self -> Bool -> IO ()
labelGetSingleLineMode :: LabelClass self => self -> IO Bool
labelSetAngle :: LabelClass self => self -> Double -> IO ()
labelGetAngle :: LabelClass self => self -> IO Double
labelLabel :: LabelClass self => Attr self String
labelUseMarkup :: LabelClass self => Attr self Bool
labelUseUnderline :: LabelClass self => Attr self Bool
labelJustify :: LabelClass self => Attr self Justification
labelWrap :: LabelClass self => Attr self Bool
labelSelectable :: LabelClass self => Attr self Bool
labelMnemonicWidget :: (LabelClass self, WidgetClass widget) => ReadWriteAttr self (Maybe Widget) widget
labelCursorPosition :: LabelClass self => ReadAttr self Int
labelSelectionBound :: LabelClass self => ReadAttr self Int
labelEllipsize :: LabelClass self => Attr self EllipsizeMode
labelWidthChars :: LabelClass self => Attr self Int
labelSingleLineMode :: LabelClass self => Attr self Bool
labelAngle :: LabelClass self => Attr self Double
labelMaxWidthChars :: LabelClass self => Attr self Int
labelLineWrap :: LabelClass self => Attr self Bool
labelText :: LabelClass self => Attr self String

Detail
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`.
Mnemonics

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

Markup (styled text)

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 `"&lt;"`, `"&gt;"`, and `"&amp;`". If you pass text obtained from the user, file, or a network to `labelSetMarkup`, you'll want to escape it with Graphics.UI.Gtk.Pango.Layout.escapeMarkup.

Selectable labels
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.
Text layout

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.

Class Hierarchy

     |  GObject
     |   +----Object
     |         +----Widget
     |               +----Misc
     |                     +----Label
     |                           +----AccelLabel
     |                           +----TipsQuery

Types
data Label

Instances

GObjectClass Label
LabelClass Label
MiscClass Label
WidgetClass Label
ObjectClass Label

class MiscClass o => LabelClass o

Instances

LabelClass TipsQuery
LabelClass AccelLabel
LabelClass Label

castToLabel :: GObjectClass obj => obj -> Label
toLabel :: LabelClass o => o -> Label
Constructors
labelNew :: Maybe String -> IO Label
Creates a new label with the given text inside it. You can pass `Nothing` to get an empty label widget.
labelNewWithMnemonic

:: 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.

Methods
labelSetText :: LabelClass self => self -> String -> IO ()
Sets the text within the `Label` widget. It overwrites any text that was there before. This will also clear any previously set mnemonic accelerators.
labelSetLabel :: LabelClass self => self -> String -> IO ()
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.
labelSetTextWithMnemonic :: LabelClass self => self -> String -> IO ()
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`.
labelSetMarkup

:: LabelClass self |
=> self |
-> Markup | `str` - a markup string (see Pango markup format)
-> IO () |
Parses `str` which is marked up with the Pango text markup language, as defined in Graphics.UI.Gtk.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.

labelSetMarkupWithMnemonic

:: LabelClass self |
=> self |
-> Markup | `str` - a markup string (see Pango markup format)
-> IO () |

Parses `str` which is marked up with the Pango text markup language, as defined in Graphics.UI.Gtk.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`.

labelSetMnemonicWidget

:: (LabelClass self, WidgetClass widget) |
=> self |
-> widget | `widget` - the target `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.

labelGetMnemonicWidget

:: LabelClass self |
=> self |
-> IO (Maybe Widget) | returns the target of the label's mnemonic, or `Nothing` if none has been set and the default algorithm will be used.
Retrieves the target of the mnemonic (keyboard shortcut) of this label. See `labelSetMnemonicWidget`.

type KeyVal = Word32
Key values are the codes which are sent whenever a key is pressed or released.
labelGetMnemonicKeyval :: LabelClass self => self -> IO KeyVal
If the label has been set so that it has an mnemonic key this function returns the keyval used for the mnemonic accelerator.
labelSetUseMarkup

:: LabelClass self |
=> self |
-> Bool | `setting` - `True` if the label's text should be parsed for markup.
-> IO () |
Sets whether the text of the label contains markup in Pango's text markup language. See `labelSetMarkup`.

labelGetUseMarkup

:: LabelClass self |
=> self |
-> IO Bool | returns `True` if the label's text will be parsed for markup.
Returns whether the label's text is interpreted as marked up with the Pango text markup language. See `labelSetUseMarkup`.

labelSetUseUnderline :: LabelClass self => self -> Bool -> IO ()
If `True`, an underline in the text indicates the next character should be used for the mnemonic accelerator key.
labelGetUseUnderline :: LabelClass self => self -> IO Bool
Returns whether an embedded underline in the label indicates a mnemonic. See `labelSetUseUnderline`.
labelGetText :: LabelClass self => self -> IO String
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`)
labelGetLabel :: LabelClass self => self -> IO String
Gets the text from a label widget including any embedded underlines indicating mnemonics and Pango markup. (See `labelGetText`).
labelSetPattern :: LabelClass l => l -> [Int] -> IO ()
Underline parts of the text, odd indices of the list represent underlined parts.
data Justification

Justification for label and maybe other widgets (text?)
Constructors

JustifyLeft |
JustifyRight |
JustifyCenter |
JustifyFill |

Instances

Enum Justification
Eq Justification
Show Justification

labelSetJustify :: LabelClass self => self -> Justification -> IO ()
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.
labelGetJustify :: LabelClass self => self -> IO Justification
Returns the justification of the label. See `labelSetJustify`.
labelGetLayout :: LabelClass self => self -> IO PangoLayout
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`.
labelSetLineWrap

:: LabelClass self |
=> self |
-> Bool | `wrap` - the setting
-> 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.

labelGetLineWrap

:: LabelClass self |
=> self |
-> IO Bool | returns `True` if the lines of the label are automatically wrapped.
Returns whether lines in the label are automatically wrapped. See `labelSetLineWrap`.

labelSetSelectable

:: LabelClass self |
=> self |
-> Bool | `setting` - `True` to allow selecting text in the label
-> IO () |
Selectable labels allow the user to select text from the label, for copy-and-paste.

labelGetSelectable

:: LabelClass self |
=> self |
-> IO Bool | returns `True` if the user can copy text from the label
Gets whether the text selectable.

labelSelectRegion

:: LabelClass self |
=> self |
-> Int | `startOffset` - start offset
-> Int | `endOffset` - end offset
-> 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.

labelGetSelectionBounds :: LabelClass self => self -> IO (Maybe (Int, Int))
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.
labelGetLayoutOffsets :: LabelClass self => self -> IO (Int, Int)
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.
labelSetEllipsize

:: LabelClass self |
=> self |
-> EllipsizeMode | `mode` - a `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

labelGetEllipsize

:: LabelClass self |
=> self |
-> IO EllipsizeMode | returns `EllipsizeMode`

Returns the ellipsizing position of the label. See `labelSetEllipsize`.

- Available since Gtk+ version 2.6

labelSetWidthChars

:: LabelClass self |
=> self |
-> Int | `nChars` - the new desired width, in characters.
-> IO () |

Sets the desired width in characters of `label` to `nChars`.

- Available since Gtk+ version 2.6

labelGetWidthChars

:: LabelClass self |
=> self |
-> IO Int | returns the width of the label in characters.

Retrieves the desired width of `label`, in characters. See `labelSetWidthChars`.

- Available since Gtk+ version 2.6

labelSetMaxWidthChars

:: LabelClass self |
=> self |
-> Int | `nChars` - the new desired maximum width, in characters.
-> IO () |

Sets the desired maximum width in characters of `label` to `nChars`.

- Available since Gtk+ version 2.6

labelGetMaxWidthChars

:: LabelClass self |
=> self |
-> IO Int | returns the maximum width of the label in characters.

Retrieves the desired maximum width of `label`, in characters. See `labelSetWidthChars`.

- Available since Gtk+ version 2.6

labelSetSingleLineMode

:: LabelClass self |
=> self |
-> Bool | `singleLineMode` - `True` if the label should be in single line mode
-> IO () |

Sets whether the label is in single line mode.

- Available since Gtk+ version 2.6

labelGetSingleLineMode

:: LabelClass self |
=> self |
-> IO Bool | returns `True` when the label is in single line mode.

Returns whether the label is in single line mode.

- Available since Gtk+ version 2.6

labelSetAngle

:: LabelClass self |
=> self |
-> Double | `angle` - the angle that the baseline of the label makes with the horizontal, in degrees, measured counterclockwise
-> 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

labelGetAngle

:: LabelClass self |
=> self |
-> IO Double | returns the angle of rotation for the label

Gets the angle of rotation for the label. See gtk_label_set_angle.

- Available since Gtk+ version 2.6

Attributes
labelLabel :: LabelClass self => Attr self String
The text of the label.
labelUseMarkup :: LabelClass self => Attr self Bool
The text of the label includes XML markup. See pango_parse_markup(). Default value: `False`
labelUseUnderline :: LabelClass self => Attr self Bool
If set, an underline in the text indicates the next character should be used for the mnemonic accelerator key. Default value: `False`
labelJustify :: LabelClass self => Attr self Justification
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. See `Misc`::xalign for that. Default value: `JustifyLeft`
labelWrap :: LabelClass self => Attr self Bool
If set, wrap lines if the text becomes too wide. Default value: `False`
labelSelectable :: LabelClass self => Attr self Bool
Whether the label text can be selected with the mouse. Default value: `False`
labelMnemonicWidget :: (LabelClass self, WidgetClass widget) => ReadWriteAttr self (Maybe Widget) widget
The widget to be activated when the label's mnemonic key is pressed.
labelCursorPosition :: LabelClass self => ReadAttr self Int
The current position of the insertion cursor in chars. Allowed values: >= 0 Default value: 0
labelSelectionBound :: LabelClass self => ReadAttr self Int
The position of the opposite end of the selection from the cursor in chars. Allowed values: >= 0 Default value: 0
labelEllipsize :: LabelClass self => Attr self EllipsizeMode

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`

labelWidthChars :: LabelClass self => Attr self Int
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
labelSingleLineMode :: LabelClass self => Attr self Bool
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`
labelAngle :: LabelClass self => Attr self Double
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
labelMaxWidthChars :: LabelClass self => Attr self Int
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
labelLineWrap :: LabelClass self => Attr self Bool
'lineWrap' property. See `labelGetLineWrap` and `labelSetLineWrap`
labelText :: LabelClass self => Attr self String
'text' property. See `labelGetText` and `labelSetText`
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