Class: Gdk::DrawContext

Inherits:
Object
  • Object
show all
Defined in:
(unknown)

Overview

Base class for objects implementing different rendering methods.

GdkDrawContext is the base object used by contexts implementing different
rendering methods, such as [classGdk.CairoContext] or [classGdk.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.

Direct Known Subclasses

CairoContext, GLContext, VulkanContext

Instance Method Summary collapse

Instance Method Details

#begin_frame(region) ⇒ nil

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 [classGdk.CairoContext] and a [classGdk.GLContext]
need to be treated differently.

A call to this function is a requirement for drawing and must be
followed by a call to [methodGdk.DrawContext.end_frame], 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 [methodGdk.DrawContext.get_frame_region] to
query the region that must be drawn.

When using GTK, the widget system automatically places calls to
gdk_draw_context_begin_frame() and gdk_draw_context_end_frame() via the
use of GskRenderers, so application code
does not need to call these functions explicitly.

Parameters:

  • region (cairo::Region) —

    minimum region that should be drawn

Returns:

  • (nil)

#display ⇒ Gdk::Display

The GdkDisplay used to create the GdkDrawContext.

Returns:

#display=(display) ⇒ Gdk::Display

The GdkDisplay used to create the GdkDrawContext.

Parameters:

Returns:

#end_frame ⇒ nil

Ends a drawing operation started with gdk_draw_context_begin_frame().

This makes the drawing available on screen.
See [methodGdk.DrawContext.begin_frame] for more details about drawing.

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

Returns:

  • (nil)

#frame_region ⇒ cairo::Region

Retrieves the region that is currently being repainted.

After a call to [methodGdk.DrawContext.begin_frame] 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 [methodGdk.DrawContext.begin_frame]
and [methodGdk.DrawContext.end_frame], nil will be returned.

Returns:

  • (cairo::Region) —

    a Cairo region

#is_in_frame ⇒ Boolean

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

This is the case between calls to [methodGdk.DrawContext.begin_frame]
and [methodGdk.DrawContext.end_frame]. In this situation, drawing commands
may be effecting the contents of the context's surface.

Returns:

  • (Boolean) —

    true if the context is between [methodGdk.DrawContext.begin_frame]
    and [methodGdk.DrawContext.end_frame] calls.

#surface ⇒ Gdk::Surface

The GdkSurface the context is bound to.

Returns:

#surface=(surface) ⇒ Gdk::Surface

The GdkSurface the context is bound to.

Parameters:

Returns: