GwyVectorLayerSearchFunc()

gint
(*GwyVectorLayerSearchFunc) (gdouble x,
                             gdouble y,
                             gdouble *mindistance,
                             gint n,
                             const gdouble *coords,
                             const gdouble *metric);

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().

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().

gwy_vector_layer_ensure_selection()

GwySelection *
gwy_vector_layer_ensure_selection (GwyVectorLayer *layer);

Ensures a vector layer's selection exists.

If the layer has a selection set the function is identical to gwy_vector_layer_get_selection(). Otherwise a selection of appropriate type is created with default properties and returned.

gwy_vector_layer_get_selection()

GwySelection *
gwy_vector_layer_get_selection (GwyVectorLayer *layer);

Returns vector layer's selection object.

gwy_vector_layer_set_selection()

void
gwy_vector_layer_set_selection (GwyVectorLayer *layer,
                                GwySelection *selection);

Sets the vector layer's selection object.

Vector layer subclasses use specific selection types, It is an error to set the wrong selection. See gwy_vector_layer_class_get_selection_type() and gwy_vector_layer_get_selection_type() for obtaining the type generically. In most cases, however, you work with a concrete layer type and thus know the selection type.

gwy_vector_layer_get_focus()

gint
gwy_vector_layer_get_focus (GwyVectorLayer *layer);

Gets focused object index.

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.

gwy_vector_layer_get_editable()

gboolean
gwy_vector_layer_get_editable (GwyVectorLayer *layer);

Gets editability of a vector layer.

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.

gwy_vector_layer_queue_draw_parent()

gboolean
gwy_vector_layer_queue_draw_parent (GwyVectorLayer *layer);

Queue redrawing of vector layer's parent data view.

A conveninece function calling gtk_widget_queue_draw() on layer 's parent widget, provided it exists and is drawable. If there is nothing to redraw the function does nothing.

The return value can be used to decide whether to proceed with other actions which only make sense with a drawable parent widget.

gwy_vector_layer_draw()

void
gwy_vector_layer_draw (GwyVectorLayer *layer,
                       cairo_t *cr);

Draws layer to a given Cairo context.

gwy_vector_layer_get_modifiers()

GdkModifierType
gwy_vector_layer_get_modifiers (GwyVectorLayer *layer);

Gets the current modifier state of a vector layer.

This is a helper function for implementations of simple layers which then do not need to query the state themselves.

gwy_vector_layer_get_current_button()

gint
gwy_vector_layer_get_current_button (GwyVectorLayer *layer);

Gets the current pointer button interacting with a vector layer.

This is a helper function for implementations of layers.

gwy_vector_layer_get_current_object()

gint
gwy_vector_layer_get_current_object (GwyVectorLayer *layer);

Gets the index of the currently edited selection object.

gwy_vector_layer_set_current_object()

void
gwy_vector_layer_set_current_object (GwyVectorLayer *layer,
                                     gint i);

Sets the index of the currently selected selection object.

It also emits the "object-chosen" signal. Usually, the selected object is the one being edited. However, objects can also be selected then the selection is not editable.

gwy_vector_layer_update_object()

gint
gwy_vector_layer_update_object (GwyVectorLayer *layer,
                                gint i,
                                const gdouble *xy);

Updates or adds one selection object of a vector layer.

This is mainly a helper function for layer implementation. Index i may be negative for appending, as usual. Appending can also be done by passing index equal to the current number of objects. If the maximum number of objects is 1, passing negative i is the same as passing 0 (replacing the single object, if it exists). Do not pass negative i if such behaviour is not wanted.

gwy_vector_layer_find_nearest()

gint
gwy_vector_layer_find_nearest (GwyVectorLayer *layer,
                               GwyVectorLayerSearchFunc search,
                               gint subdivision,
                               gdouble x,
                               gdouble y,
                               gdouble *mindistance);

Finds the closest vector layer feature using a search function.

What type of feature is sought depends on the function calc_distance and there can be multiple features on each selection object. The function is usually something like gwy_math_find_nearest_line() and works with squared distances. However, it can compute any type of distance as needed.

The search function must accept the coordinate array exactly in the same form as they are in stored the selection data. But, for instance, the selection data of GwySelectionLine are compatible with both gwy_math_find_nearest_line() and gwy_math_find_nearest_point().

Focus is taken into account. Meaning, if focus is set only the single focused selection object is considered. Otherwise all objects are considered.

GwyVectorLayerClassPrivate

typedef struct _GwyVectorLayerClassPrivate GwyVectorLayerClassPrivate;

struct GwyVectorLayer

struct GwyVectorLayer;

struct GwyVectorLayerClass

struct GwyVectorLayerClass {
    GwyDataViewLayerClass parent_class;
    GwyVectorLayerClassPrivate *priv;

    GType selection_type;

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

    /* Virtual table */
    void (*draw)(GwyVectorLayer *layer,
                 cairo_t *cr);
    void (*invalidate_object)(GwyVectorLayer *layer,
                              cairo_region_t *cr,
                              const gdouble *xy);
    void (*selection_notify)(GwyVectorLayer *layer,
                             const GParamSpec *spec);
    void (*cancel_editing)(GwyVectorLayer *layer);
    void (*key_press)(GwyVectorLayer *layer,
                      guint keyval);
    void (*key_release)(GwyVectorLayer *layer,
                        guint keyval);
    void (*enter)(GwyVectorLayer *layer,
                  gdouble x,
                  gdouble y);
    void (*motion)(GwyVectorLayer *layer,
                   gdouble x,
                   gdouble y);
    void (*leave)(GwyVectorLayer *layer);
    void (*button_press)(GwyVectorLayer *layer,
                         gdouble x,
                         gdouble y);
    void (*button_release)(GwyVectorLayer *layer,
                           gdouble x,
                           gdouble y);
    gboolean (*set_focus)(GwyVectorLayer *layer,
                          gint i);

    void (*reserved1)(void);
    void (*reserved2)(void);
    void (*reserved3)(void);
    void (*reserved4)(void);
    void (*reserved5)(void);
};

Class of vector layers drawn on image views.

Specific vector layers need to implement the methods to provide useful functionality.

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” property

  “selection”                GwySelection *

Selection object representing the coordinates.

Owner: GwyVectorLayer

Flags: Read / Write

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.

Flags: Run First