GI.Gdk.Interfaces.Paintable

GdkPaintable is a simple interface used by GTK to represent content that can be painted.

The content of a GdkPaintable can be painted anywhere at any size without requiring any sort of layout. The interface is inspired by similar concepts elsewhere, such as ClutterContent, HTML/CSS Paint Sources, or SVG Paint Servers.

A GdkPaintable can be snapshot at any time and size using paintableSnapshot. How the paintable interprets that size and if it scales or centers itself into the given rectangle is implementation defined, though if you are implementing a GdkPaintable and don't know what to do, it is suggested that you scale your paintable ignoring any potential aspect ratio.

The contents that a GdkPaintable produces may depend on the [classgdkSnapshot] passed to it. For example, paintables may decide to use more detailed images on higher resolution screens or when OpenGL is available. A GdkPaintable will however always produce the same output for the same snapshot.

A GdkPaintable may change its contents, meaning that it will now produce a different output with the same snapshot. Once that happens, it will call paintableInvalidateContents which will emit the signalgdkPaintable[invalidateContents] signal. If a paintable is known to never change its contents, it will set the PaintableFlagsContents flag. If a consumer cannot deal with changing contents, it may call paintableGetCurrentImage which will return a static paintable and use that.

A paintable can report an intrinsic (or preferred) size or aspect ratio it wishes to be rendered at, though it doesn't have to. Consumers of the interface can use this information to layout thepaintable appropriately. Just like the contents, the size of a paintable can change. A paintable will indicate this by calling paintableInvalidateSize which will emit the signalgdkPaintable[invalidateSize] signal. And just like for contents, if a paintable is known to never change its size, it will set the PaintableFlagsSize flag.

Besides API for applications, there are some functions that are only useful for implementing subclasses and should not be used by applications: paintableInvalidateContents, paintableInvalidateSize, [funcgdk.Paintable.new_empty].

Exported types

newtype Paintable

Memory-managed wrapper type.

Constructors

Paintable (ManagedPtr Paintable)

Instances

Eq Paintable

Defined in GI.Gdk.Interfaces.Paintable

Methods

(==) :: Paintable -> Paintable -> Bool

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

GObject Paintable

Defined in GI.Gdk.Interfaces.Paintable

ManagedPtrNewtype Paintable

Defined in GI.Gdk.Interfaces.Paintable

Methods

toManagedPtr :: Paintable -> ManagedPtr Paintable

TypedObject Paintable

Defined in GI.Gdk.Interfaces.Paintable

Methods

glibType :: IO GType

HasParentTypes Paintable

Defined in GI.Gdk.Interfaces.Paintable

IsGValue (Maybe Paintable)

Convert Paintable to and from GValue. See toGValue and fromGValue.

Defined in GI.Gdk.Interfaces.Paintable

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe Paintable -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe Paintable)

type ParentTypes Paintable

Defined in GI.Gdk.Interfaces.Paintable

type ParentTypes Paintable = '[Object]

class (GObject o, IsDescendantOf Paintable o) => IsPaintable o

Type class for types which can be safely cast to Paintable, for instance with toPaintable.

Instances

(GObject o, IsDescendantOf Paintable o) => IsPaintable o

Defined in GI.Gdk.Interfaces.Paintable

toPaintable :: (MonadIO m, IsPaintable o) => o -> m Paintable

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

Methods

Click to display all available methods, including inherited ones

Methods

bindProperty, bindPropertyFull, computeConcreteSize, forceFloating, freezeNotify, getv, invalidateContents, invalidateSize, isFloating, notify, notifyByPspec, ref, refSink, runDispose, snapshot, stealData, stealQdata, thawNotify, unref, watchClosure.

Getters

getCurrentImage, getData, getFlags, getIntrinsicAspectRatio, getIntrinsicHeight, getIntrinsicWidth, getProperty, getQdata.

Setters

setData, setDataFull, setProperty.

computeConcreteSize

paintableComputeConcreteSize

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> Double

specifiedWidth: the width paintable could be drawn into or 0.0 if unknown

-> Double

specifiedHeight: the height paintable could be drawn into or 0.0 if unknown

-> Double

defaultWidth: the width paintable would be drawn into if no other constraints were given

-> Double

defaultHeight: the height paintable would be drawn into if no other constraints were given

-> m (Double, Double)

Compute a concrete size for the GdkPaintable.

Applies the sizing algorithm outlined in the CSS Image spec to the given paintable. See that link for more details.

It is not necessary to call this function when both specifiedWidth and specifiedHeight are known, but it is useful to call this function in GtkWidget:measure implementations to compute the other dimension when only one dimension is given.

getCurrentImage

paintableGetCurrentImage

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m Paintable

Returns: An immutable paintable for the current contents of paintable

Gets an immutable paintable for the current contents displayed by paintable.

This is useful when you want to retain the current state of an animation, for example to take a screenshot of a running animation.

If the paintable is already immutable, it will return itself.

getFlags

paintableGetFlags

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m [PaintableFlags]

Returns: The GdkPaintableFlags for this paintable

Get flags for the paintable.

This is oftentimes useful for optimizations.

See [flagsgdk.PaintableFlags] for the flags and what they mean.

getIntrinsicAspectRatio

paintableGetIntrinsicAspectRatio

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m Double

Returns: the intrinsic aspect ratio of paintable or 0 if none.

Gets the preferred aspect ratio the paintable would like to be displayed at.

The aspect ratio is the width divided by the height, so a value of 0.5 means that the paintable prefers to be displayed twice as high as it is wide. Consumers of this interface can use this to preserve aspect ratio when displaying the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to paintableSnapshot.

Usually when a paintable returns nonzero values from paintableGetIntrinsicWidth and paintableGetIntrinsicHeight the aspect ratio should conform to those values, though that is not required.

If the paintable does not have a preferred aspect ratio, it returns 0. Negative values are never returned.

getIntrinsicHeight

paintableGetIntrinsicHeight

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m Int32

Returns: the intrinsic height of paintable or 0 if none.

Gets the preferred height the paintable would like to be displayed at.

Consumers of this interface can use this to reserve enough space to draw the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to paintableSnapshot.

If the paintable does not have a preferred height, it returns 0. Negative values are never returned.

getIntrinsicWidth

paintableGetIntrinsicWidth

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m Int32

Returns: the intrinsic width of paintable or 0 if none.

Gets the preferred width the paintable would like to be displayed at.

Consumers of this interface can use this to reserve enough space to draw the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to paintableSnapshot.

If the paintable does not have a preferred width, it returns 0. Negative values are never returned.

invalidateContents

paintableInvalidateContents

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m ()

Called by implementations of GdkPaintable to invalidate their contents.

Unless the contents are invalidated, implementations must guarantee that multiple calls of paintableSnapshot produce the same output.

This function will emit the Paintable::invalidateContents signal.

If a paintable reports the PaintableFlagsContents flag, it must not call this function.

invalidateSize

paintableInvalidateSize

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a)

=> a

paintable: a GdkPaintable

-> m ()

Called by implementations of GdkPaintable to invalidate their size.

As long as the size is not invalidated, paintable must return the same values for its intrinsic width, height and aspect ratio.

This function will emit the Paintable::invalidateSize signal.

If a paintable reports the PaintableFlagsSize flag, it must not call this function.

newEmpty

paintableNewEmpty

Arguments

:: (HasCallStack, MonadIO m)

=> Int32

intrinsicWidth: The intrinsic width to report. Can be 0 for no width.

-> Int32

intrinsicHeight: The intrinsic height to report. Can be 0 for no height.

-> m Paintable

Returns: a GdkPaintable

Returns a paintable that has the given intrinsic size and draws nothing.

This is often useful for implementing the Paintable.get_current_image() virtual function when the paintable is in an incomplete state (like a Gtk.MediaStream before receiving the first frame).

snapshot

paintableSnapshot

Arguments

:: (HasCallStack, MonadIO m, IsPaintable a, IsSnapshot b)

=> a

paintable: a GdkPaintable

-> b

snapshot: a GdkSnapshot to snapshot to

-> Double

width: width to snapshot in

-> Double

height: height to snapshot in

-> m ()

Snapshots the given paintable with the given width and height.

The paintable is drawn at the current (0,0) offset of the snapshot. If width and height are not larger than zero, this function will do nothing.

Signals

invalidateContents

type PaintableInvalidateContentsCallback = IO ()

Emitted when the contents of the paintable change.

Examples for such an event would be videos changing to the next frame or the icon theme for an icon changing.

afterPaintableInvalidateContents :: (IsPaintable a, MonadIO m) => a -> ((?self :: a) => PaintableInvalidateContentsCallback) -> m SignalHandlerId

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

after paintable #invalidateContents callback

By default the object invoking the signal is not passed to the callback. If you need to access it, you can use the implit ?self parameter. Note that this requires activating the ImplicitParams GHC extension.

onPaintableInvalidateContents :: (IsPaintable a, MonadIO m) => a -> ((?self :: a) => PaintableInvalidateContentsCallback) -> m SignalHandlerId

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

on paintable #invalidateContents callback

invalidateSize

type PaintableInvalidateSizeCallback = IO ()

Emitted when the intrinsic size of the paintable changes.

This means the values reported by at least one of paintableGetIntrinsicWidth, paintableGetIntrinsicHeight or paintableGetIntrinsicAspectRatio has changed.

Examples for such an event would be a paintable displaying the contents of a toplevel surface being resized.

afterPaintableInvalidateSize :: (IsPaintable a, MonadIO m) => a -> ((?self :: a) => PaintableInvalidateSizeCallback) -> m SignalHandlerId

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

after paintable #invalidateSize callback

By default the object invoking the signal is not passed to the callback. If you need to access it, you can use the implit ?self parameter. Note that this requires activating the ImplicitParams GHC extension.

onPaintableInvalidateSize :: (IsPaintable a, MonadIO m) => a -> ((?self :: a) => PaintableInvalidateSizeCallback) -> m SignalHandlerId

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

on paintable #invalidateSize callback