GI.Gtk.Objects.StyleContext

StyleContext is an object that stores styling information affecting a widget defined by WidgetPath.

In order to construct the final style information, StyleContext queries information from all attached GtkStyleProviders. Style providers can be either attached explicitly to the context through styleContextAddProvider, or to the display through styleContextAddProviderForDisplay. The resulting style is a combination of all providers’ information in priority order.

For GTK+ widgets, any StyleContext returned by widgetGetStyleContext will already have a WidgetPath, a Display and RTL/LTR information set. The style context will also be updated automatically if any of these settings change on the widget.

If you are using the theming layer standalone, you will need to set a widget path and a display yourself to the created style context through styleContextSetPath and possibly styleContextSetDisplay. See the “Foreign drawing“ example in gtk4-demo.

{gtkstylecontext-classes}

Widgets can add style classes to their context, which can be used to associate different styles by class. The documentation for individual widgets lists which style classes it uses itself, and which style classes may be added by applications to affect their appearance.

GTK+ defines macros for a number of style classes.

Custom styling in UI libraries and applications

If you are developing a library with custom GtkWidgets that render differently than standard components, you may need to add a StyleProvider yourself with the STYLE_PROVIDER_PRIORITY_FALLBACK priority, either a CssProvider or a custom object implementing the StyleProvider interface. This way themes may still attempt to style your UI elements in a different way if needed so.

If you are using custom styling on an applications, you probably want then to make your style information prevail to the theme’s, so you must use a StyleProvider with the STYLE_PROVIDER_PRIORITY_APPLICATION priority, keep in mind that the user settings in XDG_CONFIG_HOME/gtk-4.0/gtk.css will still take precedence over your changes, as it uses the STYLE_PROVIDER_PRIORITY_USER priority.

Exported types

newtype StyleContext

Memory-managed wrapper type.

Constructors

StyleContext (ManagedPtr StyleContext)

Instances

Eq StyleContext

Defined in GI.Gtk.Objects.StyleContext

Methods

(==) :: StyleContext -> StyleContext -> Bool

(/=) :: StyleContext -> StyleContext -> Bool

IsGValue StyleContext

Convert StyleContext to and from GValue with toGValue and fromGValue.

Defined in GI.Gtk.Objects.StyleContext

Methods

toGValue :: StyleContext -> IO GValue

fromGValue :: GValue -> IO StyleContext

GObject StyleContext

Defined in GI.Gtk.Objects.StyleContext

Methods

gobjectType :: IO GType

HasParentTypes StyleContext

Defined in GI.Gtk.Objects.StyleContext

type ParentTypes StyleContext

Defined in GI.Gtk.Objects.StyleContext

type ParentTypes StyleContext = '[Object]

class (GObject o, IsDescendantOf StyleContext o) => IsStyleContext o

Type class for types which can be safely cast to StyleContext, for instance with toStyleContext.

Instances

(GObject o, IsDescendantOf StyleContext o) => IsStyleContext o

Defined in GI.Gtk.Objects.StyleContext

toStyleContext :: (MonadIO m, IsStyleContext o) => o -> m StyleContext

Cast to StyleContext, for types for which this is known to be safe. For general casts, use castTo.

noStyleContext :: Maybe StyleContext

A convenience alias for Nothing :: Maybe StyleContext.

Methods

Overloaded methods

addClass

styleContextAddClass

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Text

className: class name to use in styling

-> m ()

Adds a style class to context, so posterior calls to gtk_style_context_get() or any of the gtk_render_*() functions will make use of this new class for styling.

In the CSS file format, a Entry defining a “search” class, would be matched by:

 <!-- language="CSS" -->
entry.search { ... }

While any widget defining a “search” class would be matched by: > language="CSS" -- >.search { ... }

addProvider

styleContextAddProvider

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a, IsStyleProvider b)

=> a

context: a StyleContext

-> b

provider: a StyleProvider

-> Word32

priority: the priority of the style provider. The lower it is, the earlier it will be used in the style construction. Typically this will be in the range between STYLE_PROVIDER_PRIORITY_FALLBACK and STYLE_PROVIDER_PRIORITY_USER

-> m ()

Adds a style provider to context, to be used in style construction. Note that a style provider added by this function only affects the style of the widget to which context belongs. If you want to affect the style of all widgets, use styleContextAddProviderForDisplay.

Note: If both priorities are the same, a StyleProvider added through this function takes precedence over another added through styleContextAddProviderForDisplay.

addProviderForDisplay

styleContextAddProviderForDisplay

Arguments

:: (HasCallStack, MonadIO m, IsDisplay a, IsStyleProvider b)

=> a

display: a Display

-> b

provider: a StyleProvider

-> Word32

priority: the priority of the style provider. The lower it is, the earlier it will be used in the style construction. Typically this will be in the range between STYLE_PROVIDER_PRIORITY_FALLBACK and STYLE_PROVIDER_PRIORITY_USER

-> m ()

Adds a global style provider to display, which will be used in style construction for all GtkStyleContexts under display.

GTK+ uses this to make styling information from Settings available.

Note: If both priorities are the same, A StyleProvider added through styleContextAddProvider takes precedence over another added through this function.

getBorder

styleContextGetBorder

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m Border

Gets the border for a given state as a Border.

See styleContextGetProperty and STYLE_PROPERTY_BORDER_WIDTH for details.

getColor

styleContextGetColor

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m RGBA

Gets the foreground color for a given state.

See styleContextGetProperty and STYLE_PROPERTY_COLOR for details.

getDisplay

styleContextGetDisplay

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m Display

Returns: a Display.

Returns the Display to which context is attached.

getMargin

styleContextGetMargin

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m Border

Gets the margin for a given state as a Border. See gtk_style_property_get() and STYLE_PROPERTY_MARGIN for details.

getPadding

styleContextGetPadding

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m Border

Gets the padding for a given state as a Border. See gtk_style_context_get() and STYLE_PROPERTY_PADDING for details.

getParent

styleContextGetParent

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m (Maybe StyleContext)

Returns: the parent context or Nothing

Gets the parent context set via styleContextSetParent. See that function for details.

getPath

styleContextGetPath

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m WidgetPath

Returns: A WidgetPath

Returns the widget path used for style matching.

getProperty

styleContextGetProperty

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Text

property: style property name

-> m GValue

Gets a style property from context for the current state.

Note that not all CSS properties that are supported by GTK+ can be retrieved in this way, since they may not be representable as Value. GTK+ defines macros for a number of properties that can be used with this function.

When value is no longer needed, valueUnset must be called to free any allocated memory.

getScale

styleContextGetScale

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m Int32

Returns: the scale

Returns the scale used for assets.

getState

styleContextGetState

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m [StateFlags]

Returns: the state flags

Returns the state used for style matching.

This method should only be used to retrieve the StateFlags to pass to StyleContext methods, like styleContextGetPadding. If you need to retrieve the current state of a Widget, use widgetGetStateFlags.

hasClass

styleContextHasClass

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Text

className: a class name

-> m Bool

Returns: True if context has className defined

Returns True if context currently has defined the given class name.

listClasses

styleContextListClasses

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m [Text]

Returns: a List of strings with the currently defined classes. The contents of the list are owned by GTK+, but you must free the list itself with g_list_free() when you are done with it.

Returns the list of classes currently defined in context.

lookupColor

styleContextLookupColor

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Text

colorName: color name to lookup

-> m (Bool, RGBA)

Returns: True if colorName was found and resolved, False otherwise

Looks up and resolves a color name in the context color map.

new

styleContextNew

Arguments

:: (HasCallStack, MonadIO m)

=> m StyleContext

Returns: A newly created StyleContext.

Creates a standalone StyleContext, this style context won’t be attached to any widget, so you may want to call styleContextSetPath yourself.

This function is only useful when using the theming layer separated from GTK+, if you are using StyleContext to theme GtkWidgets, use widgetGetStyleContext in order to get a style context ready to theme the widget.

removeClass

styleContextRemoveClass

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Text

className: class name to remove

-> m ()

Removes className from context.

removeProvider

styleContextRemoveProvider

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a, IsStyleProvider b)

=> a

context: a StyleContext

-> b

provider: a StyleProvider

-> m ()

Removes provider from the style providers list in context.

removeProviderForDisplay

styleContextRemoveProviderForDisplay

Arguments

:: (HasCallStack, MonadIO m, IsDisplay a, IsStyleProvider b)

=> a

display: a Display

-> b

provider: a StyleProvider

-> m ()

Removes provider from the global style providers list in display.

resetWidgets

styleContextResetWidgets

Arguments

:: (HasCallStack, MonadIO m, IsDisplay a)

=> a

display: a Display

-> m ()

This function recomputes the styles for all widgets under a particular Display. This is useful when some global parameter has changed that affects the appearance of all widgets, because when a widget gets a new style, it will both redraw and recompute any cached information about its appearance. As an example, it is used when the color scheme changes in the related Settings object.

restore

styleContextRestore

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m ()

Restores context state to a previous stage. See styleContextSave.

save

styleContextSave

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> m ()

Saves the context state, so temporary modifications done through styleContextAddClass, styleContextRemoveClass, styleContextSetState, etc. can quickly be reverted in one go through styleContextRestore.

The matching call to styleContextRestore must be done before GTK returns to the main loop.

setDisplay

styleContextSetDisplay

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a, IsDisplay b)

=> a

context: a StyleContext

-> b

display: a Display

-> m ()

Attaches context to the given display.

The display is used to add style information from “global” style providers, such as the display's Settings instance.

If you are using a StyleContext returned from widgetGetStyleContext, you do not need to call this yourself.

setParent

styleContextSetParent

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a, IsStyleContext b)

=> a

context: a StyleContext

-> Maybe b

parent: the new parent or Nothing

-> m ()

Sets the parent style context for context. The parent style context is used to implement inheritance of properties.

If you are using a StyleContext returned from widgetGetStyleContext, the parent will be set for you.

setPath

styleContextSetPath

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> WidgetPath

path: a WidgetPath

-> m ()

Sets the WidgetPath used for style matching. As a consequence, the style will be regenerated to match the new given path.

If you are using a StyleContext returned from widgetGetStyleContext, you do not need to call this yourself.

setScale

styleContextSetScale

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> Int32

scale: scale

-> m ()

Sets the scale to use when getting image assets for the style.

setState

styleContextSetState

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> [StateFlags]

flags: state to represent

-> m ()

Sets the state to be used for style matching.

toString

styleContextToString

Arguments

:: (HasCallStack, MonadIO m, IsStyleContext a)

=> a

context: a StyleContext

-> [StyleContextPrintFlags]

flags: Flags that determine what to print

-> m Text

Returns: a newly allocated string representing context

Converts the style context into a string representation.

The string representation always includes information about the name, state, id, visibility and style classes of the CSS node that is backing context. Depending on the flags, more information may be included.

This function is intended for testing and debugging of the CSS implementation in GTK+. There are no guarantees about the format of the returned string, it may change.

Properties

display

No description available in the introspection data.

constructStyleContextDisplay :: (IsStyleContext o, IsDisplay a) => a -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “display” property. This is rarely needed directly, but it is used by new.

getStyleContextDisplay :: (MonadIO m, IsStyleContext o) => o -> m Display

Get the value of the “display” property. When overloading is enabled, this is equivalent to

get styleContext #display

setStyleContextDisplay :: (MonadIO m, IsStyleContext o, IsDisplay a) => o -> a -> m ()

Set the value of the “display” property. When overloading is enabled, this is equivalent to

set styleContext [ #display := value ]

parent

Sets or gets the style context’s parent. See styleContextSetParent for details.

clearStyleContextParent :: (MonadIO m, IsStyleContext o) => o -> m ()

Set the value of the “parent” property to Nothing. When overloading is enabled, this is equivalent to

clear #parent

constructStyleContextParent :: (IsStyleContext o, IsStyleContext a) => a -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “parent” property. This is rarely needed directly, but it is used by new.

getStyleContextParent :: (MonadIO m, IsStyleContext o) => o -> m (Maybe StyleContext)

Get the value of the “parent” property. When overloading is enabled, this is equivalent to

get styleContext #parent

setStyleContextParent :: (MonadIO m, IsStyleContext o, IsStyleContext a) => o -> a -> m ()

Set the value of the “parent” property. When overloading is enabled, this is equivalent to

set styleContext [ #parent := value ]

Signals

changed

type C_StyleContextChangedCallback = Ptr () -> Ptr () -> IO ()

Type for the callback on the (unwrapped) C side.

type StyleContextChangedCallback = IO ()

The changed signal is emitted when there is a change in the StyleContext.

For a StyleContext returned by widgetGetStyleContext, the styleUpdated signal/vfunc might be more convenient to use.

This signal is useful when using the theming layer standalone.

afterStyleContextChanged :: (IsStyleContext a, MonadIO m) => a -> StyleContextChangedCallback -> m SignalHandlerId

Connect a signal handler for the changed signal, to be run after the default handler. When overloading is enabled, this is equivalent to

after styleContext #changed callback

genClosure_StyleContextChanged :: MonadIO m => StyleContextChangedCallback -> m (GClosure C_StyleContextChangedCallback)

Wrap the callback into a GClosure.

mk_StyleContextChangedCallback :: C_StyleContextChangedCallback -> IO (FunPtr C_StyleContextChangedCallback)

Generate a function pointer callable from C code, from a C_StyleContextChangedCallback.

noStyleContextChangedCallback :: Maybe StyleContextChangedCallback

A convenience synonym for Nothing :: Maybe StyleContextChangedCallback.

onStyleContextChanged :: (IsStyleContext a, MonadIO m) => a -> StyleContextChangedCallback -> m SignalHandlerId

Connect a signal handler for the changed signal, to be run before the default handler. When overloading is enabled, this is equivalent to

on styleContext #changed callback

wrap_StyleContextChangedCallback :: StyleContextChangedCallback -> C_StyleContextChangedCallback

Wrap a StyleContextChangedCallback into a C_StyleContextChangedCallback.