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Gwyddion Drawing Library Reference Manual | ![]() |
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GwySelectionGwySelection — Data selections. |
GwySelection; GwySelectionClass; guint gwy_selection_get_object_size (GwySelection *selection); void gwy_selection_clear (GwySelection *selection); gboolean gwy_selection_get_object (GwySelection *selection, gint i, gdouble *data); gint gwy_selection_set_object (GwySelection *selection, gint i, const gdouble *data); void gwy_selection_delete_object (GwySelection *selection, gint i); gint gwy_selection_get_data (GwySelection *selection, gdouble *data); void gwy_selection_set_data (GwySelection *selection, gint nselected, const gdouble *data); guint gwy_selection_get_max_objects (GwySelection *selection); void gwy_selection_set_max_objects (GwySelection *selection, guint max_objects); gboolean gwy_selection_is_full (GwySelection *selection); void gwy_selection_changed (GwySelection *selection, gint i); void gwy_selection_finished (GwySelection *selection);
"changed" void user_function (GwySelection *gwyselection, gint arg1, gpointer user_data); "finished" void user_function (GwySelection *gwyselection, gpointer user_data);
GwySelection is an abstract class representing data selections. Particular selection types are defined by vector layer modules.
Selections behave as flat arrays of coordinates. They are however logically split into selection objects (points, lines, rectangles), characteristic for each selection type. For example, to describe a horizontal line one needs only one coordinate, for a point two coordinates are needed, rectangle or arbitrary line need four. gwy_selection_get_object_size() can be used to generically determine the number of coordinates used to describe a one selection object.
The number of selection objects in a selection can vary, gwy_selection_set_max_objects() sets the maximum possible number. Functions for getting and setting individual selection objects (gwy_selection_get_object(), gwy_selection_set_object()) or complete selection (gwy_selection_get_data(), gwy_selection_set_data()) are available.
typedef struct _GwySelection GwySelection;
The GwySelection struct describes an abstract selection as a collection of coordinates. It should not be accessed directly except selection class implementation.
typedef struct { GObjectClass parent_class; guint object_size; /* Virtual table */ void (*clear)(GwySelection *selection); gboolean(*get_object)(GwySelection *selection, gint i, gdouble *data); gint (*set_object)(GwySelection *selection, gint i, const gdouble *data); void (*delete_object)(GwySelection *selection, gint i); gint (*get_data)(GwySelection *selection, gdouble *data); void (*set_data)(GwySelection *selection, gint nselected, const gdouble *data); void (*set_max_objects)(GwySelection *selection, guint max_objects); /* TODO: maybe geometrical methods: clamp, move, scale */ /* Signals */ void (*changed)(GwySelection *selection, gint i); void (*finished)(GwySelection *selection); } GwySelectionClass;
guint gwy_selection_get_object_size (GwySelection *selection);
Gets the number of coordinates that make up a one selection object.
selection : | A selection. |
Returns : | The number of coordinates in one selection object. |
void gwy_selection_clear (GwySelection *selection);
Clears a selection.
selection : | A selection. |
gboolean gwy_selection_get_object (GwySelection *selection, gint i, gdouble *data);
Gets one selection object.
selection : | A selection. |
i : | Index of object to get. |
data : | Array to store selection object data to. Object data is an array of coordinates whose precise meaning is defined by particular selection types. |
Returns : | TRUE if there was such an object and data was filled. |
gint gwy_selection_set_object (GwySelection *selection, gint i, const gdouble *data);
Sets one selection object.
This method can be also used to append objects (if the maximum number is not exceeded). Since there cannot be holes in the object list, i must be then equal to either the number of selected objects or special value -1 meaning append to end.
selection : | A selection. |
i : | Index of object to set. |
data : | Object selection data. It's an array of coordinates whose precise meaning is defined by particular selection types. |
Returns : | The index of actually set object (useful namely when i is -1). |
void gwy_selection_delete_object (GwySelection *selection, gint i);
Deletes a one selection object.
Since there cannot be holes in the object list, the rest of selection objects is moved to close the gap.
selection : | A selection. |
i : | Index of object to delete. |
gint gwy_selection_get_data (GwySelection *selection, gdouble *data);
Gets selection data.
selection : | A selection. |
data : | Array to store selection data to. Selection data is an array of coordinates whose precise meaning is defined by particular selection types. It may be NULL. |
Returns : | The number of selected objects. This is *not* the required size of data, which must be at least gwy_selection_get_object_size() times larger. |
void gwy_selection_set_data (GwySelection *selection, gint nselected, const gdouble *data);
Sets selection data.
selection : | A selection. |
nselected : | The number of selected objects. |
data : | Selection data, that is an array nselected * gwy_selection_get_object_size() long with selected object coordinates. |
guint gwy_selection_get_max_objects (GwySelection *selection);
Gets the maximum number of selected objects.
selection : | A selection. |
Returns : | The maximum number of selected objects; |
void gwy_selection_set_max_objects (GwySelection *selection, guint max_objects);
Sets the maximum number of objects allowed to select.
When selection reaches this number of selected objects, it emits "finished" signal.
selection : | A selection. |
max_objects : | The maximum number of objects allowed to select. Note particular selection types may allow only specific values. |
gboolean gwy_selection_is_full (GwySelection *selection);
Checks whether the maximum number of objects is selected.
selection : | A selection. |
Returns : | TRUE when the maximum possible number of objects is selected, FALSE otherwise. |
void gwy_selection_changed (GwySelection *selection, gint i);
Emits "changed" signal on a selection.
selection : | A selection. |
i : | Index of object that changed. Use -1 when not applicable, e.g., when complete selection was changed, cleared, or truncated. |
void gwy_selection_finished (GwySelection *selection);
Emits "finished" signal on a selection.
selection : | A selection. |
"max-objects" guint : Read / Write
Maximum number of objects that can be selected.
Allowed values: <= 1024
Default value: 1
"object-size" guint : Read
Number of coordinates in one selection object.
Allowed values: <= 1024
Default value: 0
void user_function (GwySelection *gwyselection, gint arg1, gpointer user_data);
The ::changed signal is emitted whenever selection changes.
gwyselection : | The GwySelection which received the signal. |
arg1 : | Changed object position hint. If the value is nonnegative, only this object has changed. If it's negative, the selection has to be treated as completely changed. |
user_data : | user data set when the signal handler was connected. |
void user_function (GwySelection *gwyselection, gpointer user_data);
The ::changed signal is emitted when selection is finished.
What exactly finished means is defined by corresponding GwyVectorLayer, but normally it involves user stopped changing a selection object. Selections never emit this signal themselves.
gwyselection : | The GwySelection which received the signal. |
user_data : | user data set when the signal handler was connected. |
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