Visuals: GDK 2 Reference Manual

## Visuals Visuals |

## Functions

void | gdk_query_depths ()
void | gdk_query_visual_types ()
GList * | gdk_list_visuals ()
gint | gdk_visual_get_best_depth ()
GdkVisualType | gdk_visual_get_best_type ()
GdkVisual * | gdk_visual_get_system ()
GdkVisual * | gdk_visual_get_best ()
GdkVisual * | gdk_visual_get_best_with_depth ()
GdkVisual * | gdk_visual_get_best_with_type ()
GdkVisual * | gdk_visual_get_best_with_both ()
#define | gdk_visual_ref()
#define | gdk_visual_unref()
GdkScreen * | gdk_visual_get_screen ()
gint | gdk_visual_get_bits_per_rgb ()
void | gdk_visual_get_blue_pixel_details ()
GdkByteOrder | gdk_visual_get_byte_order ()
gint | gdk_visual_get_colormap_size ()
gint | gdk_visual_get_depth ()
void | gdk_visual_get_green_pixel_details ()
void | gdk_visual_get_red_pixel_details ()
GdkVisualType | gdk_visual_get_visual_type ()

## Types and Values

| GdkVisual
enum | GdkVisualType
enum | GdkByteOrder

## Includes

    #include <gdk/gdk.h>

## Description

## Functions

### gdk_query_depths ()

    void
    gdk_query_depths (gint **depths,
                      gint *count);

This function returns the available bit depths for the default screen. It's equivalent to listing the visuals (`gdk_list_visuals()`) and then looking at the depth field in each visual, removing duplicates.

The array returned by this function should not be freed.

#### Parameters

depths | return location for available depths. | [out][array]
count | return location for number of available depths. | [out]

### gdk_query_visual_types ()

    void
    gdk_query_visual_types (GdkVisualType **visual_types,
                            gint *count);

This function returns the available visual types for the default screen. It's equivalent to listing the visuals (`gdk_list_visuals()`) and then looking at the type field in each visual, removing duplicates.

The array returned by this function should not be freed.

#### Parameters

visual_types | return location for the available visual types |
count | return location for the number of available visual types |

### gdk_list_visuals ()

    GList *
    gdk_list_visuals (void);

Lists the available visuals for the default screen. (See `gdk_screen_list_visuals()`) A visual describes a hardware image data format. For example, a visual might support 24-bit color, or 8-bit color, and might expect pixels to be in a certain format.

Call `g_list_free()` on the return value when you're finished with it.

#### Returns

a list of visuals; the list must be freed, but not its contents.

[transfer container][element-type GdkVisual]

### gdk_visual_get_best_depth ()

    gint
    gdk_visual_get_best_depth (void);

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

### gdk_visual_get_best_type ()

    GdkVisualType
    gdk_visual_get_best_type (void);

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

#### Returns

best visual type

### gdk_visual_get_system ()

    GdkVisual *
    gdk_visual_get_system (void);

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.

[transfer none]

### gdk_visual_get_best ()

    GdkVisual *
    gdk_visual_get_best (void);

Get the visual with the most available colors for the default GDK screen. The return value should not be freed.

#### Returns

best visual.

[transfer none]

### gdk_visual_get_best_with_depth ()

    GdkVisual *
    gdk_visual_get_best_with_depth (gint depth);

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. `NULL` may be returned if no visual supports `depth` .

#### Parameters

depth | a bit depth |

#### Returns

best visual for the given depth.

[transfer none]

### gdk_visual_get_best_with_type ()

    GdkVisual *
    gdk_visual_get_best_with_type (GdkVisualType visual_type);

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. `NULL` may be returned if no visual has type `visual_type` .

#### Parameters

visual_type | a visual type |

#### Returns

best visual of the given type.

[transfer none]

### gdk_visual_get_best_with_both ()

    GdkVisual *
    gdk_visual_get_best_with_both (gint depth,
                                   GdkVisualType visual_type);

Combines `gdk_visual_get_best_with_depth()` and `gdk_visual_get_best_with_type()`.

#### Parameters

depth | a bit depth |
visual_type | a visual type |

#### Returns

best visual with both `depth` and `visual_type` , or `NULL` if none.

[transfer none]

### gdk_visual_ref()

    #define gdk_visual_ref(v) g_object_ref(v)

`gdk_visual_ref` is deprecated and should not be used in newly-written code.

### gdk_visual_unref()

    #define gdk_visual_unref(v) g_object_unref(v)

`gdk_visual_unref` is deprecated and should not be used in newly-written code.

### gdk_visual_get_screen ()

    GdkScreen *
    gdk_visual_get_screen (GdkVisual *visual);

Gets the screen to which this visual belongs

#### Parameters

visual | a GdkVisual |

#### Returns

the screen to which this visual belongs.

[transfer none]

Since: 2.2

### gdk_visual_get_bits_per_rgb ()

    gint
    gdk_visual_get_bits_per_rgb (GdkVisual *visual);

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

#### Parameters

visual | a GdkVisual |

#### Returns

The number of significant bits per color value for `visual` .

Since: 2.22

### gdk_visual_get_blue_pixel_details ()

    void
    gdk_visual_get_blue_pixel_details (GdkVisual *visual,
                                       guint32 *mask,
                                       gint *shift,
                                       gint *precision);

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.

#### Parameters

visual | a GdkVisual |
mask | A pointer to a guint32 to be filled in, or `NULL`. | [out][allow-none]
shift | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]
precision | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]

Since: 2.22

### gdk_visual_get_byte_order ()

    GdkByteOrder
    gdk_visual_get_byte_order (GdkVisual *visual);

Returns the byte order of this visual.

#### Parameters

visual | A GdkVisual. |

#### Returns

A GdkByteOrder stating the byte order of `visual` .

Since: 2.22

### gdk_visual_get_colormap_size ()

    gint
    gdk_visual_get_colormap_size (GdkVisual *visual);

Returns the size of a colormap for this visual.

#### Parameters

visual | A GdkVisual. |

#### Returns

The size of a colormap that is suitable for `visual` .

Since: 2.22

### gdk_visual_get_depth ()

    gint
    gdk_visual_get_depth (GdkVisual *visual);

Returns the bit depth of this visual.

#### Parameters

visual | A GdkVisual. |

#### Returns

The bit depth of this visual.

Since: 2.22

### gdk_visual_get_green_pixel_details ()

    void
    gdk_visual_get_green_pixel_details (GdkVisual *visual,
                                        guint32 *mask,
                                        gint *shift,
                                        gint *precision);

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.

#### Parameters

visual | a GdkVisual |
mask | A pointer to a guint32 to be filled in, or `NULL`. | [out][allow-none]
shift | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]
precision | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]

Since: 2.22

### gdk_visual_get_red_pixel_details ()

    void
    gdk_visual_get_red_pixel_details (GdkVisual *visual,
                                      guint32 *mask,
                                      gint *shift,
                                      gint *precision);

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.

#### Parameters

visual | A GdkVisual. |
mask | A pointer to a guint32 to be filled in, or `NULL`. | [out][allow-none]
shift | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]
precision | A pointer to a gint to be filled in, or `NULL`. | [out][allow-none]

Since: 2.22

### gdk_visual_get_visual_type ()

    GdkVisualType
    gdk_visual_get_visual_type (GdkVisual *visual);

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

#### Parameters

visual | A GdkVisual. |

#### Returns

A GdkVisualType stating the type of `visual` .

Since: 2.22

## Types and Values

### GdkVisual

    typedef struct {
      GObject parent_instance;

      GdkVisualType GSEAL (type);
      gint GSEAL (depth);
      GdkByteOrder GSEAL (byte_order);
      gint GSEAL (colormap_size);
      gint GSEAL (bits_per_rgb);

      guint32 GSEAL (red_mask);
      gint GSEAL (red_shift);
      gint GSEAL (red_prec);

      guint32 GSEAL (green_mask);
      gint GSEAL (green_shift);
      gint GSEAL (green_prec);

      guint32 GSEAL (blue_mask);
      gint GSEAL (blue_shift);
      gint GSEAL (blue_prec);
    } GdkVisual;

### enum GdkVisualType

#### Members

GDK_VISUAL_STATIC_GRAY |  |
GDK_VISUAL_GRAYSCALE |  |
GDK_VISUAL_STATIC_COLOR |  |
GDK_VISUAL_PSEUDO_COLOR |  |
GDK_VISUAL_TRUE_COLOR |  |
GDK_VISUAL_DIRECT_COLOR |  |

### enum GdkByteOrder

#### Members

GDK_LSB_FIRST |  |
GDK_MSB_FIRST |  |