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gint | (*GwyVectorLayerSearchFunc) () |
#define | gwy_vector_layer_get_selection_type() |
GType | gwy_vector_layer_class_get_selection_type () |
void | gwy_vector_layer_set_selection_key () |
const gchar * | gwy_vector_layer_get_selection_key () |
GwySelection * | gwy_vector_layer_ensure_selection () |
GwySelection * | gwy_vector_layer_get_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 () |
GdkModifierType | gwy_vector_layer_get_modifiers () |
gint | gwy_vector_layer_get_current_button () |
gint | gwy_vector_layer_get_current_object () |
void | gwy_vector_layer_set_current_object () |
gint | gwy_vector_layer_update_object () |
gint | gwy_vector_layer_find_nearest () |
GObject ╰── GInitiallyUnowned ╰── GwyDataViewLayer ╰── GwyVectorLayer ├── GwyLayerAxis ├── GwyLayerCross ├── GwyLayerEllipse ├── GwyLayerLattice ├── GwyLayerLine ├── GwyLayerPath ├── GwyLayerPoint ├── GwyLayerQuad ╰── GwyLayerRectangle
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.
gint (*GwyVectorLayerSearchFunc) (gdouble x
,gdouble y
,gdouble *mindistance
,gint n
,const gdouble *coords
,const gdouble *metric
);
#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()
.
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()
.
void gwy_vector_layer_set_selection_key (GwyVectorLayer *layer
,const gchar *key
);
Sets the selection object to use by a vector layer.
const gchar *
gwy_vector_layer_get_selection_key (GwyVectorLayer *layer
);
Gets the key identifying selection this vector layer displays.
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.
GwySelection *
gwy_vector_layer_get_selection (GwyVectorLayer *layer
);
Returns vector layer's selection object.
gint
gwy_vector_layer_get_focus (GwyVectorLayer *layer
);
Gets focused object index.
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.
gboolean
gwy_vector_layer_get_editable (GwyVectorLayer *layer
);
Gets editability of a vector layer.
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.
void gwy_vector_layer_draw (GwyVectorLayer *layer
,cairo_t *cr
);
Draws layer
to a given Cairo context.
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.
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.
gint
gwy_vector_layer_get_current_object (GwyVectorLayer *layer
);
Gets the index of the currently edited selection 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.
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.
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.
layer |
A vector data view layer. |
|
search |
Function to which calculates the distance to the closest feature. |
|
subdivision |
How many features each selection object is considered to consist of. |
|
x |
X-coodinate of the point to search. |
|
y |
Y-coodinate of the point to search. |
|
mindistance |
Location where to store the minimum distance, or |
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 (*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); };
“editable”
property “editable” gboolean
Whether selection objects are editable.
Owner: GwyVectorLayer
Flags: Read / Write
Default value: TRUE
“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
“object-chosen”
signalvoid 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.
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