gtkmm: Gdk::Visual Class Reference

A Gdk::Visual describes a particular video hardware display format. More...

#include <gdkmm/visual.h>

Inheritance diagram for Gdk::Visual:

Public Member Functions

 Visual (Visual&& src) noexcept
 
Visualoperator= (Visual&& src) noexcept
 
 ~Visual () noexceptoverride
 
GdkVisual* gobj ()
 Provides access to the underlying C GObject. More...

 
const GdkVisual* gobj () const
 Provides access to the underlying C GObject. More...

 
GdkVisual* gobj_copy ()
 Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs. More...

 
Glib::RefPtr< Screenget_screen ()
 Gets the screen to which this visual belongs. More...

 
Glib::RefPtr< const Screenget_screen () const
 Gets the screen to which this visual belongs. More...

 
VisualType get_visual_type () const
 Returns the type of visual this is (PseudoColor, TrueColor, etc). More...

 
int get_depth () const
 Returns the bit depth of this visual. More...

 
ByteOrder get_byte_order ()
 Returns the byte order of this visual. More...

 
int get_colormap_size () const
 Returns the size of a colormap for this visual. More...

 
int get_bits_per_rgb () const
 Returns the number of significant bits per red, green and blue value. More...

 
void get_red_pixel_details (guint32& mask, int&shift, int& precision) const
 Obtains values that are needed to calculate red pixel values in TrueColor and DirectColor. More...

 
void get_green_pixel_details (guint32& mask, int&shift, int& precision) const
 Obtains values that are needed to calculate green pixel values in TrueColor and DirectColor. More...

 
void get_blue_pixel_details (guint32& mask, int&shift, int& precision) const
 Obtains values that are needed to calculate blue pixel values in TrueColor and DirectColor. More...

 
- Public Member Functions inherited from Glib::Object
 Object (const Object &)=delete
 
Objectoperator= (const Object &)=delete
 
 Object (Object &&src) noexcept
 
Objectoperator= (Object &&src) noexcept
 
void * get_data (const QueryQuark &key)
 
void set_data (const Quark &key, void *data)
 
void set_data (const Quark &key, void *data, DestroyNotify notify)
 
void remove_data (const QueryQuark &quark)
 
void * steal_data (const QueryQuark &quark)
 
Glib::RefPtr< Glib::Objectwrap (GObject *object, bool take_copy=false)
 
- Public Member Functions inherited from Glib::ObjectBase
 ObjectBase (const ObjectBase &)=delete
 
ObjectBaseoperator= (const ObjectBase &)=delete
 
void set_property_value (const Glib::ustring &property_name, const Glib::ValueBase &value)
 
void get_property_value (const Glib::ustring &property_name, Glib::ValueBase &value) const
 
void set_property (const Glib::ustring &property_name, const PropertyType &value)
 
void get_property (const Glib::ustring &property_name, PropertyType &value) const
 
void connect_property_changed (const Glib::ustring &property_name, const sigc::slot< void > &slot)
 
void connect_property_changed (const Glib::ustring &property_name, sigc::slot< void > &&slot)
 
sigc::connection connect_property_changed_with_return (const Glib::ustring &property_name, const sigc::slot< void > &slot)
 
sigc::connection connect_property_changed_with_return (const Glib::ustring &property_name, sigc::slot< void > &&slot)
 
void freeze_notify ()
 
void thaw_notify ()
 
virtual void reference () const
 
virtual void unreference () const
 
GObject * gobj ()
 
const GObject * gobj () const
 
GObject * gobj_copy () const
 
- Public Member Functions inherited from sigc::trackable
 trackable () noexcept
 
 trackable (const trackable &src) noexcept
 
 trackable (trackable &&src)
 
 ~trackable ()
 
void add_destroy_notify_callback (void *data, func_destroy_notify func) const
 
void notify_callbacks ()
 
trackableoperator= (const trackable &src)
 
trackableoperator= (trackable &&src)
 
void remove_destroy_notify_callback (void *data) const
 

Static Public Member Functions

static GType get_type ()
 Get the GType for this class, for use with the underlying GObject type system. More...

 
static Glib::RefPtr< Visualget_system ()
 Get the system’s default visual for the default GDK screen. More...

 
static Glib::RefPtr< Visualget_best ()
 Get the visual with the most available colors for the default GDK screen. More...

 
static Glib::RefPtr< Visualget_best (int depth)
 Get the best visual with depth depth for the default GDK screen. More...

 
static Glib::RefPtr< Visualget_best (VisualType visual_type)
 Get the best visual of the given visual_type for the default GDK screen. More...

 
static Glib::RefPtr< Visualget_best (int depth, VisualType visual_type)
 Combines get_best_with_depth() and get_best_with_type(). More...

 
static int get_best_depth ()
 Get the best available depth for the default GDK screen. More...

 
static VisualType get_best_type ()
 Return the best available visual type for the default GDK screen. More...

 

Protected Member Functions

 Visual ()
 
- Protected Member Functions inherited from Glib::Object
 Object ()
 
 Object (const Glib::ConstructParams &construct_params)
 
 Object (GObject *castitem)
 
 ~Object () noexceptoverride
 
- Protected Member Functions inherited from Glib::ObjectBase
 ObjectBase ()
 
 ObjectBase (const char *custom_type_name)
 
 ObjectBase (const std::type_info &custom_type_info)
 
 ObjectBase (ObjectBase &&src) noexcept
 
ObjectBaseoperator= (ObjectBase &&src) noexcept
 
virtual ~ObjectBase () noexcept=0
 
void initialize (GObject *castitem)
 
void initialize_move (GObject *castitem, Glib::ObjectBase *previous_wrapper)
 

Related Functions

(Note that these are not member functions.)

Glib::RefPtr< Gdk::Visualwrap (GdkVisual* object, bool take_copy=false)
 A Glib::wrap() method for this object. More...

 

Additional Inherited Members

- Public Types inherited from Glib::Object
typedef void(*)(gpointer data DestroyNotify)
 
- Public Types inherited from sigc::trackable
typedef internal::func_destroy_notify func_destroy_notify
 

Detailed Description

A Gdk::Visual describes a particular video hardware display format.

It includes information about the number of bits used for each color, the way the bits are translated into an RGB value for display, and the way the bits are stored in memory. For example, a piece of display hardware might support 24-bit color, 16-bit color, or 8-bit color; meaning 24/16/8-bit pixel sizes. For a given pixel size, pixels can be in different formats; for example the "red" element of an RGB pixel may be in the top 8 bits of the pixel, or may be in the lower 4 bits.

There are several standard visuals. The visual returned by Gdk::Screen::get_system_visual() is the system's default visual.

A number of methods are provided for determining the "best" available visual. For the purposes of making this determination, higher bit depths are considered better, and for visuals of the same bit depth, GDK_VISUAL_PSEUDO_COLOR is preferred at 8bpp, otherwise, the visual types are ranked in the order of (highest to lowest) GDK_VISUAL_DIRECT_COLOR, GDK_VISUAL_TRUE_COLOR, GDK_VISUAL_PSEUDO_COLOR, GDK_VISUAL_STATIC_COLOR, GDK_VISUAL_GRAYSCALE, then GDK_VISUAL_STATIC_GRAY.

Constructor & Destructor Documentation

Gdk::Visual::Visual ( Visual&&  src)
noexcept
Gdk::Visual::~Visual ( )
overridenoexcept
Gdk::Visual::Visual ( )
protected

Member Function Documentation

static Glib::RefPtr<Visual> Gdk::Visual::get_best ( )
static

Get the visual with the most available colors for the default GDK screen.

The return value should not be freed.

Returns
Best visual.
static Glib::RefPtr<Visual> Gdk::Visual::get_best ( int  depth)
static

Get the best visual with depth depth for the default GDK screen.

Color visuals and visuals with mutable colormaps are preferred over grayscale or fixed-colormap visuals. The return value should not be freed. nullptr may be returned if no visual supports depth.

Parameters
depthA bit depth.
Returns
Best visual for the given depth.
static Glib::RefPtr<Visual> Gdk::Visual::get_best ( VisualType  visual_type)
static

Get the best visual of the given visual_type for the default GDK screen.

Visuals with higher color depths are considered better. The return value should not be freed. nullptr may be returned if no visual has type visual_type.

Parameters
visual_typeA visual type.
Returns
Best visual of the given type.
static Glib::RefPtr<Visual> Gdk::Visual::get_best ( int  depth,
VisualType  visual_type 
)
static

Combines get_best_with_depth() and get_best_with_type().

Parameters
depthA bit depth.
visual_typeA visual type.
Returns
Best visual with both depth and visual_type, or nullptr if none.
static int Gdk::Visual::get_best_depth ( )
static

Get the best available depth for the default GDK screen.

“Best” means “largest,” i.e. 32 preferred over 24 preferred over 8 bits per pixel.

Returns
Best available depth.
static VisualType Gdk::Visual::get_best_type ( )
static

Return the best available visual type for the default GDK screen.

Returns
Best visual type.
int Gdk::Visual::get_bits_per_rgb ( ) const

Returns the number of significant bits per red, green and blue value.

Not all GDK backend provide a meaningful value for this function.

Since gtkmm 2.22:

Deprecated: 3.22. Use get_red_pixel_details() and its variants to learn about the pixel layout of TrueColor and DirectColor visuals

Returns
The number of significant bits per color value for visual.
void Gdk::Visual::get_blue_pixel_details ( guint32 &  mask,
int &  shift,
int &  precision 
) const

Obtains values that are needed to calculate blue pixel values in TrueColor and DirectColor.

The “mask” is the significant bits within the pixel. The “shift” is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary.

Since gtkmm 2.22:
Parameters
maskA pointer to a #guint32 to be filled in, or nullptr.
shiftA pointer to a int to be filled in, or nullptr.
precisionA pointer to a int to be filled in, or nullptr.
ByteOrder Gdk::Visual::get_byte_order ( )

Returns the byte order of this visual.

The information returned by this function is only relevant when working with XImages, and not all backends return meaningful information for this.

Since gtkmm 2.22:

Deprecated: 3.22: This information is not useful

Returns
A Gdk::ByteOrder stating the byte order of visual.
int Gdk::Visual::get_colormap_size ( ) const

Returns the size of a colormap for this visual.

You have to use platform-specific APIs to manipulate colormaps.

Since gtkmm 2.22:

Deprecated: 3.22: This information is not useful, since GDK does not provide APIs to operate on colormaps.

Returns
The size of a colormap that is suitable for visual.
int Gdk::Visual::get_depth ( ) const

Returns the bit depth of this visual.

Since gtkmm 2.22:
Returns
The bit depth of this visual.
void Gdk::Visual::get_green_pixel_details ( guint32 &  mask,
int &  shift,
int &  precision 
) const

Obtains values that are needed to calculate green pixel values in TrueColor and DirectColor.

The “mask” is the significant bits within the pixel. The “shift” is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary.

Since gtkmm 2.22:
Parameters
maskA pointer to a #guint32 to be filled in, or nullptr.
shiftA pointer to a int to be filled in, or nullptr.
precisionA pointer to a int to be filled in, or nullptr.
void Gdk::Visual::get_red_pixel_details ( guint32 &  mask,
int &  shift,
int &  precision 
) const

Obtains values that are needed to calculate red pixel values in TrueColor and DirectColor.

The “mask” is the significant bits within the pixel. The “shift” is the number of bits left we must shift a primary for it to be in position (according to the "mask"). Finally, "precision" refers to how much precision the pixel value contains for a particular primary.

Since gtkmm 2.22:
Parameters
maskA pointer to a #guint32 to be filled in, or nullptr.
shiftA pointer to a int to be filled in, or nullptr.
precisionA pointer to a int to be filled in, or nullptr.
Glib::RefPtr<Screen> Gdk::Visual::get_screen ( )

Gets the screen to which this visual belongs.

Since gtkmm 2.2:
Returns
The screen to which this visual belongs.
Glib::RefPtr<const Screen> Gdk::Visual::get_screen ( ) const

Gets the screen to which this visual belongs.

Since gtkmm 2.2:
Returns
The screen to which this visual belongs.
static Glib::RefPtr<Visual> Gdk::Visual::get_system ( )
static

Get the system’s default visual for the default GDK screen.

This is the visual for the root window of the display. The return value should not be freed.

Returns
System visual.
static GType Gdk::Visual::get_type ( )
static

Get the GType for this class, for use with the underlying GObject type system.

VisualType Gdk::Visual::get_visual_type ( ) const

Returns the type of visual this is (PseudoColor, TrueColor, etc).

Since gtkmm 2.22:
Returns
A Gdk::VisualType stating the type of visual.
GdkVisual* Gdk::Visual::gobj ( )
inline

Provides access to the underlying C GObject.

const GdkVisual* Gdk::Visual::gobj ( ) const
inline

Provides access to the underlying C GObject.

GdkVisual* Gdk::Visual::gobj_copy ( )

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

Visual& Gdk::Visual::operator= ( Visual&&  src)
noexcept

Friends And Related Function Documentation

Glib::RefPtr< Gdk::Visual > wrap ( GdkVisual *  object,
bool  take_copy = false 
)
related

A Glib::wrap() method for this object.

Parameters
objectThe C instance.
take_copyFalse if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns
A C++ instance that wraps this C instance.