GwyVectorLayer

GwyVectorLayer — Base class for GwyDataView vector (interactive) layers

Functions

GType	gwy_vector_layer_class_get_selection_type ()
#define	gwy_vector_layer_get_selection_type()
void	gwy_vector_layer_set_selection_key ()
const gchar *	gwy_vector_layer_get_selection_key ()
GwySelection *	gwy_vector_layer_ensure_selection ()
gint	gwy_vector_layer_get_focus ()
gboolean	gwy_vector_layer_set_focus ()
gboolean	gwy_vector_layer_get_editable ()
void	gwy_vector_layer_set_editable ()
void	gwy_vector_layer_draw ()
gboolean	gwy_vector_layer_button_press ()
gboolean	gwy_vector_layer_button_release ()
gboolean	gwy_vector_layer_motion_notify ()
gboolean	gwy_vector_layer_key_press ()
gboolean	gwy_vector_layer_key_release ()
void	gwy_vector_layer_object_chosen ()

Properties

gboolean	editable	Read / Write
int	focus	Read / Write
char *	selection-key	Read / Write

Signals

void

object-chosen

Run First

Types and Values

struct	GwyVectorLayer
struct	GwyVectorLayerClass

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GtkObject
            ╰── GwyDataViewLayer
                ╰── GwyVectorLayer

Includes

#include <libgwydgets/gwydgets.h>

Description

GwyVectorLayer is a base class for GwyDataViewLayers displaying selections and handling user input. It is a GwyDataView component and it is not normally usable outside of it.

The layer takes the selection to display from its parent GwyDataView's container. The key under which the selection is found is set with gwy_vector_layer_set_selection_key(). The selection either can be put there beforehand (the corresponding selection type can be obtained with gwy_vector_layer_class_get_selection_type()) or gwy_vector_layer_ensure_selection() can be used to create it if it doesn't exist.

GwyVectorLayer provides two independent means to restrict user interaction with displayed selection: editability and focus. When a layer is set noneditable (see gwy_vector_layer_set_editable()), the user cannot modify displayed objects, however "object-chosen" is emitted normally. Focus (see gwy_vector_layer_set_focus()) on the other hand limits all possible interactions to a single selection object. It is possible although not very useful to combine both restrictions.

The other methods are rarely useful outside GwyDataView and/or layer implementation.

Functions

gwy_vector_layer_class_get_selection_type ()

GType
gwy_vector_layer_class_get_selection_type
                               (GwyVectorLayerClass *klass);

Returns the selection type of a vector layer class.

Note this is a class method, to get the type from an instance one can use gwy_vector_layer_get_selection_type(). To get the type from layer's GType one has to use g_type_class_peek().

Parameters

klass

A vector layer class.

Returns

The type of selection used by layers of class klass .

gwy_vector_layer_get_selection_type()

#define             gwy_vector_layer_get_selection_type(layer)

Gets the selection type of a vector layer.

This is a convenience wrapper around gwy_vector_layer_class_get_selection_type().

Parameters

layer

A vector layer.

gwy_vector_layer_set_selection_key ()

void
gwy_vector_layer_set_selection_key (GwyVectorLayer *layer,
                                    const gchar *key);

Sets the selection object to use by a vector layer.

Parameters

layer	A vector layer.
key	Container string key identifying the selection object.

gwy_vector_layer_get_selection_key ()

const gchar *
gwy_vector_layer_get_selection_key (GwyVectorLayer *layer);

Gets the key identifying selection this vector layer displays.

Parameters

layer

A vector layer.

Returns

The string key, or NULL if it isn't set.

gwy_vector_layer_ensure_selection ()

GwySelection *
gwy_vector_layer_ensure_selection (GwyVectorLayer *layer);

Ensures a vector layer's selection exist in data container.

This method can be called only when layer is plugged into a data view and it has a selection key set. If the data container contains a selection under the specified key the selection is returned. If there is none, a selection of appropriate type is created and put to the container first.

Provided the above conditions are met this method is suitable for just obtaining the selection object a vector layer uses too.

Parameters

layer

A vector layer.

Returns

The layer's selection (no reference is added).

gwy_vector_layer_get_focus ()

gint
gwy_vector_layer_get_focus (GwyVectorLayer *layer);

Gets focused object index.

Parameters

layer

A vector data view layer.

Returns

Focued object index, or -1 if no object is focused.

gwy_vector_layer_set_focus ()

gboolean
gwy_vector_layer_set_focus (GwyVectorLayer *layer,
                            gint focus);

Focues on one selection object.

When a selection object is focused, it becomes the only one user can interact with. More precisely, "object-chosen" signal is emitted only for this object, and if the layer is editable only this object can be modified by the user.

Parameters

layer	A vector data view layer.
focus	Index of object to focus on, use -1 to unfocus (allow interaction with any object).

Returns

TRUE if the object was focused, FALSE on failure. Failure can be caused by user currently moving another object, wrong object index, or the feature being unimplemented in layer .

gwy_vector_layer_get_editable ()

gboolean
gwy_vector_layer_get_editable (GwyVectorLayer *layer);

Gets editability of a vector layer.

Parameters

layer

A vector data view layer.

Returns

TRUE if layer is edtiable, FALSE if it is not editable.

gwy_vector_layer_set_editable ()

void
gwy_vector_layer_set_editable (GwyVectorLayer *layer,
                               gboolean editable);

Sets a vector layer editability.

It is an error to attempt to set a layer non-editabile while it is being edited.

When a layer is set noneditable, the user cannot change the selection. However, "object-chosen" signal is still emitted.

Parameters

layer	A vector data view layer.
editable	TRUE to set layer editable, FALSE to set it noneditable.

gwy_vector_layer_draw ()

void
gwy_vector_layer_draw (GwyVectorLayer *layer,
                       GdkDrawable *drawable,
                       GwyRenderingTarget target);

Draws layer on given drawable (which should be a GwyDataView window).

Parameters

layer	A vector data view layer.
drawable	A drawable to draw on.
target	Rendering target.

gwy_vector_layer_button_press ()

gboolean
gwy_vector_layer_button_press (GwyVectorLayer *layer,
                               GdkEventButton *event);

Sends a mouse button press event to a layer.

This method primarily exists for GwyDataView to forward events to layers. You should rarely need it.

Parameters

layer	A vector data view layer.
event	A Gdk mouse button event.

Returns

TRUE if the event was handled. In practice, it returns FALSE.

gwy_vector_layer_button_release ()

gboolean
gwy_vector_layer_button_release (GwyVectorLayer *layer,
                                 GdkEventButton *event);

Sends a mouse button release event to a layer.

This method primarily exists for GwyDataView to forward events to layers. You should rarely need it.

Parameters

layer	A vector data view layer.
event	A Gdk mouse button event.

Returns

TRUE if the event was handled. In practice, it returns FALSE.

gwy_vector_layer_motion_notify ()

gboolean
gwy_vector_layer_motion_notify (GwyVectorLayer *layer,
                                GdkEventMotion *event);

Sends a mouse pointer motion notification event to a layer.

This method primarily exists for GwyDataView to forward events to layers. You should rarely need it.

Parameters

layer	A vector data view layer.
event	A Gdk mouse pointer motion notification event. It can be a hint.

Returns

TRUE if the event was handled. In practice, it returns FALSE.

gwy_vector_layer_key_press ()

gboolean
gwy_vector_layer_key_press (GwyVectorLayer *layer,
                            GdkEventKey *event);

Sends a key press event to a layer.

This method primarily exists for GwyDataView to forward events to layers. You should rarely need it.

Parameters

layer	A vector data view layer.
event	A Gdk key event.

Returns

TRUE if the event was handled. In practice, it returns FALSE.

gwy_vector_layer_key_release ()

gboolean
gwy_vector_layer_key_release (GwyVectorLayer *layer,
                              GdkEventKey *event);

Sends a key release event to a layer.

This method primarily exists for GwyDataView to forward events to layers. You should rarely need it.

Parameters

layer	A vector data view layer.
event	A Gdk key event.

Returns

TRUE if the event was handled. In practice, it returns FALSE.

gwy_vector_layer_object_chosen ()

void
gwy_vector_layer_object_chosen (GwyVectorLayer *layer,
                                gint id);

Emits "object-chosen" signal on a vector layer.

This function is primarily intended for layer implementations.

Parameters

layer	A vector data view layer.
id	Index of the chosen object.

Types and Values

struct GwyVectorLayer

struct GwyVectorLayer;

struct GwyVectorLayerClass

struct GwyVectorLayerClass {
    GwyDataViewLayerClass parent_class;

    GType selection_type;

    /* Signals */
    gboolean (*object_chosen)(GwyVectorLayer *layer,
                              gint id);

    /* Virtual table */
    void (*draw)(GwyVectorLayer *layer,
                 GdkDrawable *drawable,
                 GwyRenderingTarget target);
    gboolean (*button_press)(GwyVectorLayer *layer,
                             GdkEventButton *event);
    gboolean (*button_release)(GwyVectorLayer *layer,
                               GdkEventButton *event);
    gboolean (*motion_notify)(GwyVectorLayer *layer,
                              GdkEventMotion *event);
    gboolean (*key_press)(GwyVectorLayer *layer,
                          GdkEventKey *event);
    gboolean (*key_release)(GwyVectorLayer *layer,
                            GdkEventKey *event);
    gboolean (*set_focus)(GwyVectorLayer *layer,
                          gint object);

    void (*reserved1)(void);
    void (*reserved2)(void);
    void (*reserved3)(void);
    void (*reserved4)(void);
};

Property Details

The “editable” property

  “editable”                 gboolean

Whether selection objects are editable.

Owner: GwyVectorLayer

Flags: Read / Write

Default value: TRUE

The “focus” property

  “focus”                    int

The id of focused object, or -1 if all objects are active.

Owner: GwyVectorLayer

Flags: Read / Write

Allowed values: >= -1

Default value: -1

The “selection-key” property

  “selection-key”            char *

The key identifying selection object in data container.

Owner: GwyVectorLayer

Flags: Read / Write

Default value: NULL

Signal Details

The “object-chosen” signal

void
user_function (GwyVectorLayer *gwyvectorlayer,
               int             arg1,
               gpointer        user_data)

The ::object-chosen signal is emitted when user starts interacting with a selection object, even before modifying it. It is emitted even if the layer is not editable, but it is not emitted when focus is set and the user attempts to choose a different object.

Parameters

gwyvectorlayer	The GwyVectorLayer which received the signal.
arg1	The number (index) of the chosen selection object.
user_data	user data set when the signal handler was connected.

Flags: Run First

See Also

Standard vector layers