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GtkCellAreaContext

GtkCellAreaContext — Stores geometrical information for a series of rows in a GtkCellArea

Properties

GtkCellArea * area Read / Write / Construct Only
gint minimum-height Read
gint minimum-width Read
gint natural-height Read
gint natural-width Read

Types and Values

Object Hierarchy

    GObject
    ╰── GtkCellAreaContext

Includes

#include <gtk/gtk.h>

Description

The GtkCellAreaContext object is created by a given GtkCellArea implementation via its GtkCellAreaClass.create_context() virtual method and is used to store cell sizes and alignments for a series of GtkTreeModel rows that are requested and rendered in the same context.

GtkCellLayout widgets can create any number of contexts in which to request and render groups of data rows. However, it’s important that the same context which was used to request sizes for a given GtkTreeModel row also be used for the same row when calling other GtkCellArea APIs such as gtk_cell_area_render() and gtk_cell_area_event().

Functions

gtk_cell_area_context_get_area ()

GtkCellArea *
gtk_cell_area_context_get_area (GtkCellAreaContext *context);

Fetches the GtkCellArea this context was created by.

This is generally unneeded by layouting widgets; however, it is important for the context implementation itself to fetch information about the area it is being used for.

For instance at GtkCellAreaContextClass.allocate() time it’s important to know details about any cell spacing that the GtkCellArea is configured with in order to compute a proper allocation.

Parameters

context

a GtkCellAreaContext

 

Returns

the GtkCellArea this context was created by.

[transfer none]

Since: 3.0


gtk_cell_area_context_allocate ()

void
gtk_cell_area_context_allocate (GtkCellAreaContext *context,
                                gint width,
                                gint height);

Allocates a width and/or a height for all rows which are to be rendered with context .

Usually allocation is performed only horizontally or sometimes vertically since a group of rows are usually rendered side by side vertically or horizontally and share either the same width or the same height. Sometimes they are allocated in both horizontal and vertical orientations producing a homogeneous effect of the rows. This is generally the case for GtkTreeView when “fixed-height-mode” is enabled.

Since 3.0

Parameters

context

a GtkCellAreaContext

 

width

the allocated width for all GtkTreeModel rows rendered with context , or -1.

 

height

the allocated height for all GtkTreeModel rows rendered with context , or -1.

 

gtk_cell_area_context_reset ()

void
gtk_cell_area_context_reset (GtkCellAreaContext *context);

Resets any previously cached request and allocation data.

When underlying GtkTreeModel data changes its important to reset the context if the content size is allowed to shrink. If the content size is only allowed to grow (this is usually an option for views rendering large data stores as a measure of optimization), then only the row that changed or was inserted needs to be (re)requested with gtk_cell_area_get_preferred_width().

When the new overall size of the context requires that the allocated size changes (or whenever this allocation changes at all), the variable row sizes need to be re-requested for every row.

For instance, if the rows are displayed all with the same width from top to bottom then a change in the allocated width necessitates a recalculation of all the displayed row heights using gtk_cell_area_get_preferred_height_for_width().

Since 3.0

Parameters

context

a GtkCellAreaContext

 

gtk_cell_area_context_get_preferred_width ()

void
gtk_cell_area_context_get_preferred_width
                               (GtkCellAreaContext *context,
                                gint *minimum_width,
                                gint *natural_width);

Gets the accumulative preferred width for all rows which have been requested with this context.

After gtk_cell_area_context_reset() is called and/or before ever requesting the size of a GtkCellArea, the returned values are 0.

Parameters

context

a GtkCellAreaContext

 

minimum_width

location to store the minimum width, or NULL.

[out][allow-none]

natural_width

location to store the natural width, or NULL.

[out][allow-none]

Since: 3.0


gtk_cell_area_context_get_preferred_height ()

void
gtk_cell_area_context_get_preferred_height
                               (GtkCellAreaContext *context,
                                gint *minimum_height,
                                gint *natural_height);

Gets the accumulative preferred height for all rows which have been requested with this context.

After gtk_cell_area_context_reset() is called and/or before ever requesting the size of a GtkCellArea, the returned values are 0.

Parameters

context

a GtkCellAreaContext

 

minimum_height

location to store the minimum height, or NULL.

[out][allow-none]

natural_height

location to store the natural height, or NULL.

[out][allow-none]

Since: 3.0


gtk_cell_area_context_get_preferred_height_for_width ()

void
gtk_cell_area_context_get_preferred_height_for_width
                               (GtkCellAreaContext *context,
                                gint width,
                                gint *minimum_height,
                                gint *natural_height);

Gets the accumulative preferred height for width for all rows which have been requested for the same said width with this context.

After gtk_cell_area_context_reset() is called and/or before ever requesting the size of a GtkCellArea, the returned values are -1.

Parameters

context

a GtkCellAreaContext

 

width

a proposed width for allocation

 

minimum_height

location to store the minimum height, or NULL.

[out][allow-none]

natural_height

location to store the natural height, or NULL.

[out][allow-none]

Since: 3.0


gtk_cell_area_context_get_preferred_width_for_height ()

void
gtk_cell_area_context_get_preferred_width_for_height
                               (GtkCellAreaContext *context,
                                gint height,
                                gint *minimum_width,
                                gint *natural_width);

Gets the accumulative preferred width for height for all rows which have been requested for the same said height with this context.

After gtk_cell_area_context_reset() is called and/or before ever requesting the size of a GtkCellArea, the returned values are -1.

Parameters

context

a GtkCellAreaContext

 

height

a proposed height for allocation

 

minimum_width

location to store the minimum width, or NULL.

[out][allow-none]

natural_width

location to store the natural width, or NULL.

[out][allow-none]

Since: 3.0


gtk_cell_area_context_get_allocation ()

void
gtk_cell_area_context_get_allocation (GtkCellAreaContext *context,
                                      gint *width,
                                      gint *height);

Fetches the current allocation size for context .

If the context was not allocated in width or height, or if the context was recently reset with gtk_cell_area_context_reset(), the returned value will be -1.

Parameters

context

a GtkCellAreaContext

 

width

location to store the allocated width, or NULL.

[out][allow-none]

height

location to store the allocated height, or NULL.

[out][allow-none]

Since: 3.0


gtk_cell_area_context_push_preferred_width ()

void
gtk_cell_area_context_push_preferred_width
                               (GtkCellAreaContext *context,
                                gint minimum_width,
                                gint natural_width);

Causes the minimum and/or natural width to grow if the new proposed sizes exceed the current minimum and natural width.

This is used by GtkCellAreaContext implementations during the request process over a series of GtkTreeModel rows to progressively push the requested width over a series of gtk_cell_area_get_preferred_width() requests.

Parameters

context

a GtkCellAreaContext

 

minimum_width

the proposed new minimum width for context

 

natural_width

the proposed new natural width for context

 

Since: 3.0


gtk_cell_area_context_push_preferred_height ()

void
gtk_cell_area_context_push_preferred_height
                               (GtkCellAreaContext *context,
                                gint minimum_height,
                                gint natural_height);

Causes the minimum and/or natural height to grow if the new proposed sizes exceed the current minimum and natural height.

This is used by GtkCellAreaContext implementations during the request process over a series of GtkTreeModel rows to progressively push the requested height over a series of gtk_cell_area_get_preferred_height() requests.

Parameters

context

a GtkCellAreaContext

 

minimum_height

the proposed new minimum height for context

 

natural_height

the proposed new natural height for context

 

Since: 3.0

Types and Values

struct GtkCellAreaContextClass

struct GtkCellAreaContextClass {
  void    (* allocate)                       (GtkCellAreaContext *context,
                                              gint                width,
                                              gint                height);
  void    (* reset)                          (GtkCellAreaContext *context);
  void    (* get_preferred_height_for_width) (GtkCellAreaContext *context,
                                              gint                width,
                                              gint               *minimum_height,
                                              gint               *natural_height);
  void    (* get_preferred_width_for_height) (GtkCellAreaContext *context,
                                              gint                height,
                                              gint               *minimum_width,
                                              gint               *natural_width);
};

Members

allocate ()

This tells the context that an allocation width or height (or both) have been decided for a group of rows. The context should store any allocations for internally aligned cells at this point so that they dont need to be recalculated at gtk_cell_area_render() time.

 

reset ()

Clear any previously stored information about requested and allocated sizes for the context.

 

get_preferred_height_for_width ()

Returns the aligned height for the given width that context must store while collecting sizes for it’s rows.

 

get_preferred_width_for_height ()

Returns the aligned width for the given height that context must store while collecting sizes for it’s rows.

 

GtkCellAreaContext

typedef struct _GtkCellAreaContext GtkCellAreaContext;

Property Details

The “area” property

  “area”                     GtkCellArea *

The GtkCellArea this context was created by

Flags: Read / Write / Construct Only

Since: 3.0


The “minimum-height” property

  “minimum-height”           gint

The minimum height for the GtkCellArea in this context for all GtkTreeModel rows that this context was requested for using gtk_cell_area_get_preferred_height().

Flags: Read

Allowed values: >= -1

Default value: -1

Since: 3.0


The “minimum-width” property

  “minimum-width”            gint

The minimum width for the GtkCellArea in this context for all GtkTreeModel rows that this context was requested for using gtk_cell_area_get_preferred_width().

Flags: Read

Allowed values: >= -1

Default value: -1

Since: 3.0


The “natural-height” property

  “natural-height”           gint

The natural height for the GtkCellArea in this context for all GtkTreeModel rows that this context was requested for using gtk_cell_area_get_preferred_height().

Flags: Read

Allowed values: >= -1

Default value: -1

Since: 3.0


The “natural-width” property

  “natural-width”            gint

The natural width for the GtkCellArea in this context for all GtkTreeModel rows that this context was requested for using gtk_cell_area_get_preferred_width().

Flags: Read

Allowed values: >= -1

Default value: -1

Since: 3.0

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