gi-gdk-4.0.4: Gdk bindings
CopyrightWill Thompson and Iñaki García Etxebarria
LicenseLGPL-2.1
MaintainerIñaki García Etxebarria
Safe HaskellSafe-Inferred
LanguageHaskell2010

GI.Gdk.Objects.DrawContext

Description

Base class for objects implementing different rendering methods.

GdkDrawContext is the base object used by contexts implementing different rendering methods, such as CairoContext or GLContext. It provides shared functionality between those contexts.

You will always interact with one of those subclasses.

A GdkDrawContext is always associated with a single toplevel surface.

Synopsis

Exported types

newtype DrawContext Source #

Memory-managed wrapper type.

class (GObject o, IsDescendantOf DrawContext o) => IsDrawContext o Source #

Type class for types which can be safely cast to DrawContext, for instance with toDrawContext.

Instances

Instances details
(GObject o, IsDescendantOf DrawContext o) => IsDrawContext o Source # 
Instance details

Defined in GI.Gdk.Objects.DrawContext

toDrawContext :: (MonadIO m, IsDrawContext o) => o -> m DrawContext Source #

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

Methods

beginFrame

drawContextBeginFrame Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: the GdkDrawContext used to draw the frame

-> Region

region: minimum region that should be drawn

-> m () 

Indicates that you are beginning the process of redrawing region on the context's surface.

Calling this function begins a drawing operation using context on the surface that context was created from. The actual requirements and guarantees for the drawing operation vary for different implementations of drawing, so a CairoContext and a GLContext need to be treated differently.

A call to this function is a requirement for drawing and must be followed by a call to drawContextEndFrame, which will complete the drawing operation and ensure the contents become visible on screen.

Note that the region passed to this function is the minimum region that needs to be drawn and depending on implementation, windowing system and hardware in use, it might be necessary to draw a larger region. Drawing implementation must use drawContextGetFrameRegion to query the region that must be drawn.

When using GTK, the widget system automatically places calls to drawContextBeginFrame and drawContextEndFrame via the use of Gsk.Renderers, so application code does not need to call these functions explicitly.

endFrame

drawContextEndFrame Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: a GdkDrawContext

-> m () 

Ends a drawing operation started with drawContextBeginFrame.

This makes the drawing available on screen. See drawContextBeginFrame for more details about drawing.

When using a GLContext, this function may call glFlush() implicitly before returning; it is not recommended to call glFlush() explicitly before calling this function.

getDisplay

drawContextGetDisplay Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: a GdkDrawContext

-> m (Maybe Display)

Returns: the GdkDisplay

Retrieves the GdkDisplay the context is created for

getFrameRegion

drawContextGetFrameRegion Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: a GdkDrawContext

-> m (Maybe Region)

Returns: a Cairo region

Retrieves the region that is currently being repainted.

After a call to drawContextBeginFrame this function will return a union of the region passed to that function and the area of the surface that the context determined needs to be repainted.

If context is not in between calls to drawContextBeginFrame and drawContextEndFrame, Nothing will be returned.

getSurface

drawContextGetSurface Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: a GdkDrawContext

-> m (Maybe Surface)

Returns: a GdkSurface

Retrieves the surface that context is bound to.

isInFrame

drawContextIsInFrame Source #

Arguments

:: (HasCallStack, MonadIO m, IsDrawContext a) 
=> a

context: a GdkDrawContext

-> m Bool

Returns: True if the context is between drawContextBeginFrame and drawContextEndFrame calls.

Returns True if context is in the process of drawing to its surface.

This is the case between calls to drawContextBeginFrame and drawContextEndFrame. In this situation, drawing commands may be effecting the contents of the context's surface.

Properties

display

The GdkDisplay used to create the GdkDrawContext.

constructDrawContextDisplay :: (IsDrawContext o, MonadIO m, IsDisplay a) => a -> m (GValueConstruct o) Source #

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

getDrawContextDisplay :: (MonadIO m, IsDrawContext o) => o -> m (Maybe Display) Source #

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

get drawContext #display

surface

The GdkSurface the context is bound to.

constructDrawContextSurface :: (IsDrawContext o, MonadIO m, IsSurface a) => a -> m (GValueConstruct o) Source #

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

getDrawContextSurface :: (MonadIO m, IsDrawContext o) => o -> m (Maybe Surface) Source #

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

get drawContext #surface