Struct gtk::Label [−][src]
pub struct Label(_);
Expand description
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 ComboBox.
CSS nodes
⚠️ The following code is in plain ⚠️
label
├── [selection]
├── [link]
┊
╰── [link]
GtkLabel has a single CSS node with the name label. A wide variety
of style classes may be applied to labels, such as .title, .subtitle,
.dim-label, etc. In the ShortcutsWindow, labels are used wth the
.keycap style class.
If the label has a selection, it gets a subnode with name selection.
If the label has links, there is one subnode per link. These subnodes carry the link or visited state depending on whether they have been visited.
GtkLabel as GtkBuildable
The GtkLabel implementation of the GtkBuildable interface supports a
custom <attributes> element, which supports any number of <attribute>
elements. The <attribute> element has attributes named “name“, “value“,
“start“ and “end“ and allows you to specify PangoAttribute values for
this label.
An example of a UI definition fragment specifying Pango attributes:
⚠️ The following code is in C ⚠️
// Pressing Alt+H will activate this button
GtkWidget *button = gtk_button_new ();
GtkWidget *label = gtk_label_new_with_mnemonic ("_Hello");
gtk_container_add (GTK_CONTAINER (button), label);
There’s a convenience function to create buttons with a mnemonic label already inside:
⚠️ The following code is in C ⚠️
// Pressing Alt+H will activate this button
GtkWidget *button = gtk_button_new_with_mnemonic ("_Hello");
To create a mnemonic for a widget alongside the label, such as a
Entry, you have to point the label at the entry with
LabelExt::set_mnemonic_widget():
⚠️ The following code is in C ⚠️
// Pressing Alt+H will focus the entry
GtkWidget *entry = gtk_entry_new ();
GtkWidget *label = gtk_label_new_with_mnemonic ("_Hello");
gtk_label_set_mnemonic_widget (GTK_LABEL (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][PangoMarkupFormat].
Here’s how to create a label with a small font:
⚠️ The following code is in C ⚠️
GtkWidget *label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label), "<small>Small text</small>");
(See [complete documentation][PangoMarkupFormat] of available tags in the Pango manual.)
The markup passed to LabelExt::set_markup() must be valid; for example,
literal <, > and & characters must be escaped as <, >, and &.
If you pass text obtained from the user, file, or a network to
LabelExt::set_markup(), you’ll want to escape it with
g_markup_escape_text() or g_markup_printf_escaped().
Markup strings are just a convenient way to set the pango::AttrList on
a label; LabelExt::set_attributes() may be a simpler way to set
attributes in some cases. Be careful though; pango::AttrList tends to
cause internationalization problems, unless you’re applying attributes
to the entire string (i.e. unless you set the range of each attribute
to [0, G_MAXINT)). The reason is that specifying the start_index and
end_index for a PangoAttribute requires knowledge of the exact string
being displayed, so translations will cause problems.
Selectable labels
Labels can be made selectable with LabelExt::set_selectable().
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 # {label-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
LabelExt::set_line_wrap().
LabelExt::set_justify() 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 the property::Widget::halign and
property::Widget::valign properties.
The property::Label::width-chars and property::Label::max-width-chars properties
can be used to control the size allocation of ellipsized or wrapped
labels. For ellipsizing labels, if either is specified (and less
than the actual text size), it is used as the minimum width, and the actual
text size is used as the natural width of the label. For wrapping labels,
width-chars is used as the minimum width, if specified, and max-width-chars
is used as the natural width. Even if max-width-chars specified, wrapping
labels will be rewrapped to use all of the available width.
Note that the interpretation of property::Label::width-chars and
property::Label::max-width-chars has changed a bit with the introduction of
[width-for-height geometry management.][geometry-management]
Links
Since 2.18, GTK+ supports markup for clickable hyperlinks in addition
to regular Pango markup. The markup for links is borrowed from HTML,
using the <a> with “href“ and “title“ attributes. GTK+ renders links
similar to the way they appear in web browsers, with colored, underlined
text. The “title“ attribute is displayed as a tooltip on the link.
An example looks like this:
⚠️ The following code is in C ⚠️
const gchar *text =
"Go to the"
"<a href=\"http://www.gtk.org title=\"<i>Our</i> website\">"
"GTK+ website</a> for more...";
GtkWidget *label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label), text);
It is possible to implement custom handling for links and their tooltips with
the signal::Label::activate-link signal and the LabelExt::current_uri() function.
Implements
LabelExt, [MiscExt][trait@crate::prelude::MiscExt], WidgetExt, glib::ObjectExt, BuildableExt, WidgetExtManual, BuildableExtManual
Implementations
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
LabelExt::set_mnemonic_widget().
If LabelExt::set_mnemonic_widget() 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.
str
The text of the label, with an underscore in front of the mnemonic character
Returns
the new Label
Creates a new builder-pattern struct instance to construct Label objects.
This method returns an instance of LabelBuilder which can be used to create Label objects.
Trait Implementations
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Returns the type identifier of Self.
Auto Trait Implementations
impl RefUnwindSafe for Labelimpl UnwindSafe for LabelBlanket Implementations
Mutably borrows from an owned value. Read more
Upcasts an object to a superclass or interface T. Read more
Upcasts an object to a reference of its superclass or interface T. Read more
Tries to downcast to a subclass or interface implementor T. Read more
Tries to downcast to a reference of its subclass or interface implementor T. Read more
Tries to cast to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Tries to cast to reference to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Casts to T unconditionally. Read more
Casts to &T unconditionally. Read more
Returns true if the object is an instance of (can be cast to) T.
pub fn set_properties_from_value(
&self,
property_values: &[(&str, Value)]
) -> Result<(), BoolError>pub fn set_property<'a, N, V>(
&self,
property_name: N,
value: V
) -> Result<(), BoolError> where
V: ToValue,
N: Into<&'a str>, pub fn set_property_from_value<'a, N>(
&self,
property_name: N,
value: &Value
) -> Result<(), BoolError> where
N: Into<&'a str>, Safety Read more
Safety Read more
Safety Read more
Safety Read more
pub fn connect_notify<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec) + Send + Sync, pub fn connect_notify_local<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec), pub unsafe fn connect_notify_unsafe<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: Fn(&T, &ParamSpec), pub fn has_property<'a, N>(&self, property_name: N, type_: Option<Type>) -> bool where
N: Into<&'a str>, pub fn find_property<'a, N>(&self, property_name: N) -> Option<ParamSpec> where
N: Into<&'a str>, pub fn connect<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + Send + Sync + 'static,
N: Into<&'a str>, Same as connect but takes a SignalId instead of a signal name.
pub fn connect_local<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + 'static,
N: Into<&'a str>, Same as connect_local but takes a SignalId instead of a signal name.
pub unsafe fn connect_unsafe<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value>,
N: Into<&'a str>, Same as connect_unsafe but takes a SignalId instead of a signal name.
Emit signal by signal id.
Emit signal with details by signal id.
Emit signal by it’s name.
pub fn bind_property<'a, O, N, M>(
&'a self,
source_property: N,
target: &'a O,
target_property: M
) -> BindingBuilder<'a> where
O: ObjectType,
N: Into<&'a str>,
M: Into<&'a str>, Same as emit but takes Value for the arguments.
Same as emit_by_name but takes Value for the arguments.
Returns a SendValue clone of self.
impl<'a, T, C> FromValueOptional<'a> for T where
C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError>,
T: FromValue<'a, Checker = C>,