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GocItem

GocItem — Base canvas item.

Properties

GocCanvas * canvas Read
GocGroup * parent Read

Types and Values

  GocItem
struct GocItemClass

Object Hierarchy

    GObject
    ╰── GocItem
        ├── GocStyledItem
        ├── GocComponent
        ├── GocGraph
        ├── GocGroup
        ├── GocImage
        ├── GocPixbuf
        ╰── GocWidget

Description

GocItem is the virtual base object for canvas items.

Functions

goc_item_bounds_changed ()

void
goc_item_bounds_changed (GocItem *item);

This function needs to be called each time the bounds of item change. It is normally called from inside the implementation of items derived classes.

Parameters

item

GocItem

 

goc_item_destroy ()

void
goc_item_destroy (GocItem *item);

Destroys item , removes it from its parent group and updates the canvas accordingly.

Parameters

item

GocItem

 

goc_item_distance ()

double
goc_item_distance (GocItem *item,
                   double x,
                   double y,
                   GocItem **near_item);

Evaluates the distance between the point with canvas coordinates x ,y and the nearest point of item . near_item is set with either item or its appropriate child.

Parameters

item

GocItem

 

x

horizontal position

 

y

vertical position

 

near_item

where to store the nearest item

 

Returns

the evaluated distance.


goc_item_draw ()

void
goc_item_draw (GocItem const *item,
               cairo_t *cr);

Renders item using cr . There is no need to call this function directly. Invalidating the item is the way to go.

Parameters

item

GocItem

 

cr

cairo_t

 

goc_item_draw_region ()

gboolean
goc_item_draw_region (GocItem const *item,
                      cairo_t *cr,
                      double x0,
                      double y0,
                      double x1,
                      double y1);

Renders item using cr , limiting all drawings to the region limited by x0 , y0 , x1 , and y1 . If this function returns FALSE, goc_item_draw should be called. There is no need to call this function directly. Invalidating the item is the way to go.

Parameters

item

GocItem

 

cr

cairo_t

 

x0

the lowest horizontal bound of the region to draw

 

y0

the lowest vertical bound of the region to draw

 

x1

the highest horizontal bound of the region to draw

 

y1

the highest vertical bound of the region to draw

 

Returns

TRUE if successful.


goc_item_get_bounds ()

void
goc_item_get_bounds (GocItem const *item,
                     double *x0,
                     double *y0,
                     double *x1,
                     double *y1);

Retrieves the bounds of item in canvas coordinates.

Parameters

item

GocItem

 

x0

where to store the lowest horizontal bound

 

y0

where to store the lowest vertical bound

 

x1

where to store the highest horizontal bound

 

y1

where to store the highest vertical bound

 

goc_item_get_operator ()

cairo_operator_t
goc_item_get_operator (GocItem *item);

Parameters

item

GocItem

 

Returns

the operator used when drawing the item.


goc_item_get_parent ()

GocGroup *
goc_item_get_parent (GocItem *item);

Parameters

item

GocItem

 

Returns

The item parent GocGroup.

[transfer none]


goc_item_get_style_context ()

GtkStyleContext *
goc_item_get_style_context (const GocItem *item);

Parameters

item

GocItem

 

Returns

The style context to use for the item.

[transfer none]


goc_item_get_window ()

GdkWindow *
goc_item_get_window (GocItem *item);

Parameters

item

GocItem

 

Returns

The GdkWindow associated with the item if any or NULL. Only GocWidget owns a GdkWindow.

[transfer none]


goc_item_grab ()

void
goc_item_grab (GocItem *item);

Grabs the item. This function will fail if another item is grabbed.

Parameters

item

GocItem

 

goc_item_hide ()

void
goc_item_hide (GocItem *item);

Hides item .

Parameters

item

GocItem

 

goc_item_invalidate ()

void
goc_item_invalidate (GocItem *item);

Force a redraw of item bounding region.

Parameters

item

GocItem

 

goc_item_is_visible ()

gboolean
goc_item_is_visible (GocItem *item);

Parameters

item

GocItem

 

Returns

TRUE if item is visible.


goc_item_lower ()

void
goc_item_lower (GocItem *item,
                int n);

Lowers item by n steps inside its parent GocGroup (or less if the list is too short) in the item list so that it is displayed more deeply in the items stack.

Parameters

item

GocItem

 

n

the rank change

 

goc_item_lower_to_bottom ()

void
goc_item_lower_to_bottom (GocItem *item);

Lowers item to bottom inside its parent GocGroup so that it will be at least partly hidden by any overlapping item.

Parameters

item

GocItem

 

goc_item_new ()

GocItem *
goc_item_new (GocGroup *parent,
              GType type,
              const gchar *first_arg_name,
              ...);

Creates a new item of type type in group group . Properties can be set just the same way they are in g_object_new.

Parameters

parent

parent GocGroup for the new item

 

type

GType of the new item

 

first_arg_name

property name or NULL

 

...

value for the first property, followed optionally by more name/value pairs, followed by NULL

 

Returns

the newly created GocItem.

[transfer none]


goc_item_raise ()

void
goc_item_raise (GocItem *item,
                int n);

Raises item by n steps inside its parent GocGroup (or less if the list is too short) in the item list so that it is displayed nearer the top of the items stack.

Parameters

item

GocItem

 

n

the rank change

 

goc_item_raise_to_top ()

void
goc_item_raise_to_top (GocItem *item);

Raises item to front so that it becomes the toplevel item inside its parent GocGroup.

Parameters

item

GocItem

 

goc_item_set ()

void
goc_item_set (GocItem *item,
              const gchar *first_arg_name,
              ...);

Set properties and updates the canvas. Using g_object_set instead would set the properties, but not update the canvas.

Parameters

item

GocItem

 

first_arg_name

property name or NULL

 

...

value for the first property, followed optionally by more name/value pairs, followed by NULL

 

goc_item_set_operator ()

void
goc_item_set_operator (GocItem *item,
                       cairo_operator_t op);

Set the operator used when drawing the item.

Parameters

item

GocItem

 

op

cairo_operator_t

 

goc_item_set_transform ()

void
goc_item_set_transform (GocItem *item,
                        cairo_matrix_t *m);

Set the matrix used to transform the item.

Parameters

item

GocItem

 

m

cairo_matrix_t

 

goc_item_set_visible ()

void
goc_item_set_visible (GocItem *item,
                      gboolean visible);

Either hides or shows item as appropriate..

Parameters

item

GocItem

 

visible

whether the item should be visible

 

goc_item_show ()

void
goc_item_show (GocItem *item);

Makes item visible.

Parameters

item

GocItem

 

goc_item_ungrab ()

void
goc_item_ungrab (GocItem *item);

Ungrabs the item. This function will fail if item is not grabbed.

Parameters

item

GocItem

 

Types and Values

GocItem

typedef struct _GocItem GocItem;


struct GocItemClass

struct GocItemClass {
	GObjectClass	 base;

	double			(*distance) (GocItem *item,
					     double x, double y, GocItem **near_item);
	void			(*draw) (GocItem const *item, cairo_t *cr);
	gboolean		(*draw_region) (GocItem const *item, cairo_t *cr,
						double x0, double y0, double x1, double y1);
	void			(*update_bounds) (GocItem *item);
	/* events related functions */
	gboolean		(*button_pressed) (GocItem *item, int button, double x, double y);
	gboolean		(*button2_pressed) (GocItem *item, int button, double x, double y);
	gboolean		(*button_released) (GocItem *item, int button, double x, double y);
	gboolean		(*motion) (GocItem *item, double x, double y);
	gboolean		(*enter_notify) (GocItem *item, double x, double y);
	gboolean		(*leave_notify) (GocItem *item, double x, double y);
	void			(*realize) (GocItem *item);
	void			(*unrealize) (GocItem *item);
	void			(*notify_scrolled) (GocItem *item);
#ifdef GOFFICE_WITH_GTK
	gboolean		(*key_pressed) (GocItem *item, GdkEventKey* ev);
	gboolean		(*key_released) (GocItem *item, GdkEventKey* ev);
	GdkWindow*		(*get_window) (GocItem *item);
#endif
};

The base class for all canvas items.

Members

GObjectClass base;

the parent class

 

distance ()

returns the distance between the item and the point defined by x and y . When the distance is larger than a few pixels, the result is not relevant, so an approximate value or even G_MAXDOUBLE might be returned.

 

draw ()

draws the item to the cairo context.

 

draw_region ()

draws the item in the region defined by x0 , y0 , x1 and y1 . Should return TRUE when successfull. If FALSE is returned, draw will be called. There is no need to implement both methods for an item. Large items should implement draw_region .

 

update_bounds ()

updates the bounds stored in GocItem as fields x0, y0, x1,and y1.

 

button_pressed ()

callback for a button press event.

 

button2_pressed ()

callback for a double click event.

 

button_released ()

callback for a button release event.

 

motion ()

callback for a motion event.

 

enter_notify ()

callback for an enter notify event.

 

leave_notify ()

callback for a leave notify event.

 

realize ()

callback for a realizes event.

 

unrealize ()

callback for an unrealize event.

 

notify_scrolled ()

callback for a notify scrolled event. This is useful to reposition children of the GtkLayout parent of the canvas to their new position.

 

key_pressed ()

callback for a key press event.

 

key_released ()

callback for a key release event.

 

get_window ()

returns the GdkWindow for the item if any.

 

Property Details

The “canvas” property

  “canvas”                   GocCanvas *

The canvas object on which the item resides.

Flags: Read


The “parent” property

  “parent”                   GocGroup *

The group in which the item resides.

Flags: Read

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