GooCanvas Reference Manual: GooCanvasStyle

## GooCanvasStyle GooCanvasStyle — support for cascading style properties for canvas items. |

## Synopsis

    struct              GooCanvasStyle;
    struct              GooCanvasStyleProperty;

    GooCanvasStyle *    goo_canvas_style_new                (void);
    GooCanvasStyle *    goo_canvas_style_copy               (GooCanvasStyle *style);

    GooCanvasStyle *    goo_canvas_style_get_parent         (GooCanvasStyle *style);
    void                goo_canvas_style_set_parent         (GooCanvasStyle *style,
                                                             GooCanvasStyle *parent);

    GValue *            goo_canvas_style_get_property       (GooCanvasStyle *style,
                                                             GQuark property_id);
    void                goo_canvas_style_set_property       (GooCanvasStyle *style,
                                                             GQuark property_id,
                                                             const GValue *value);

    gboolean            goo_canvas_style_set_fill_options   (GooCanvasStyle *style,
                                                             cairo_t *cr);
    gboolean            goo_canvas_style_set_stroke_options (GooCanvasStyle *style,
                                                             cairo_t *cr);

    extern GQuark       goo_canvas_style_antialias_id;
    extern GQuark       goo_canvas_style_fill_pattern_id;
    extern GQuark       goo_canvas_style_fill_rule_id;
    extern GQuark       goo_canvas_style_font_desc_id;
    extern GQuark       goo_canvas_style_hint_metrics_id;
    extern GQuark       goo_canvas_style_line_cap_id;
    extern GQuark       goo_canvas_style_line_dash_id;
    extern GQuark       goo_canvas_style_line_join_id;
    extern GQuark       goo_canvas_style_line_join_miter_limit_id;
    extern GQuark       goo_canvas_style_line_width_id;
    extern GQuark       goo_canvas_style_operator_id;
    extern GQuark       goo_canvas_style_stroke_pattern_id;

## Object Hierarchy

      GObject
       +----GooCanvasStyle

## Description

GooCanvasStyle provides support for cascading style properties for canvas items. It is intended to be used when implementing new canvas items.

### Note

The cascading styles canvas feature may be removed in a future version of GooCanvas.

Style properties are identified by a unique GQuark, and contain arbitrary data stored in a GValue.

GooCanvasStyle also provides a few convenience functions such as `goo_canvas_style_set_stroke_options()` and `goo_canvas_style_set_fill_options()` which efficiently apply an item's standard style properties to the given cairo_t.

## Details

### struct GooCanvasStyle

    struct GooCanvasStyle {
      GooCanvasStyle *parent;
      GArray *properties;
    };

GooCanvasStyle holds the style properties of a canvas item, as well as a pointer to the parent style.

GooCanvasStyle *`parent`; | the parent style.
GArray *`properties`; | an array of GooCanvasStyleProperty property settings.

### struct GooCanvasStyleProperty

    struct GooCanvasStyleProperty {
      GQuark id;
      GValue value;
    };

GooCanvasStyleProperty represents a property setting.

GQuark `id`; | the unique property identifier.
GValue `value`; | the value of the property.

### goo_canvas_style_new ()

    GooCanvasStyle *    goo_canvas_style_new                (void);

Creates a new GooCanvasStyle.

Returns : | a new GooCanvasStyle. [transfer full]

### goo_canvas_style_copy ()

    GooCanvasStyle *    goo_canvas_style_copy               (GooCanvasStyle *style);

Copies the given GooCanvasStyle, by copying all of its properties. Though the parent of the new style is left unset.

`style` : | a GooCanvasStyle.
Returns : | a copy of the given GooCanvasStyle. [transfer full]

### goo_canvas_style_get_parent ()

    GooCanvasStyle *    goo_canvas_style_get_parent         (GooCanvasStyle *style);

Gets the parent of the style.

`style` : | a style.
Returns : | the parent of the given style, or `NULL`. [transfer none]

### goo_canvas_style_set_parent ()

    void                goo_canvas_style_set_parent         (GooCanvasStyle *style,
                                                             GooCanvasStyle *parent);

Sets the parent of the style.

`style` : | a style.
`parent` : | the new parent.

### goo_canvas_style_get_property ()

    GValue *            goo_canvas_style_get_property       (GooCanvasStyle *style,
                                                             GQuark property_id);

Gets the value of a property.

This searches though all the GooCanvasStyle's own list of property settings and also all ancestor GooCanvasStyle objects.

Note that it returns a pointer to the internal GValue setting, which should not be changed.

`style` : | a style.
`property_id` : | the property identifier.
Returns : | the property value, or `NULL` if it isn't set.

### goo_canvas_style_set_property ()

    void                goo_canvas_style_set_property       (GooCanvasStyle *style,
                                                             GQuark property_id,
                                                             const GValue *value);

Sets a property in the style, replacing any current setting.

Note that this will override the property setting in ancestor GooCanvasStyle objects.

`style` : | a style.
`property_id` : | the property identifier.
`value` : | the value of the property.

### goo_canvas_style_set_fill_options ()

    gboolean            goo_canvas_style_set_fill_options   (GooCanvasStyle *style,
                                                             cairo_t *cr);

Sets the standard cairo fill options using the given style.

`style` : | a style.
`cr` : | a cairo context.
Returns : | `TRUE` if a paint source is set, or `FALSE` if the fill should be skipped.

### goo_canvas_style_set_stroke_options ()

    gboolean            goo_canvas_style_set_stroke_options (GooCanvasStyle *style,
                                                             cairo_t *cr);

Sets the standard cairo stroke options using the given style.

`style` : | a style.
`cr` : | a cairo context.
Returns : | `TRUE` if a paint source is set, or `FALSE` if the stroke should be skipped.

### goo_canvas_style_antialias_id

    extern GQuark goo_canvas_style_antialias_id;

Unique GQuark identifier used for the standard antialias property.

### goo_canvas_style_fill_pattern_id

    extern GQuark goo_canvas_style_fill_pattern_id;

Unique GQuark identifier used for the standard fill pattern property.

### goo_canvas_style_fill_rule_id

    extern GQuark goo_canvas_style_fill_rule_id;

Unique GQuark identifier used for the standard fill rule property.

### goo_canvas_style_font_desc_id

    extern GQuark goo_canvas_style_font_desc_id;

Unique GQuark identifier used for the standard font description property.

### goo_canvas_style_hint_metrics_id

    extern GQuark goo_canvas_style_hint_metrics_id;

Unique GQuark identifier used for the standard hint metrics property.

### goo_canvas_style_line_cap_id

    extern GQuark goo_canvas_style_line_cap_id;

Unique GQuark identifier used for the standard line cap property.

### goo_canvas_style_line_dash_id

    extern GQuark goo_canvas_style_line_dash_id;

Unique GQuark identifier used for the standard line dash property.

### goo_canvas_style_line_join_id

    extern GQuark goo_canvas_style_line_join_id;

Unique GQuark identifier used for the standard line join property.

### goo_canvas_style_line_join_miter_limit_id

    extern GQuark goo_canvas_style_line_join_miter_limit_id;

Unique GQuark identifier used for the standard miter limit property.

### goo_canvas_style_line_width_id

    extern GQuark goo_canvas_style_line_width_id;

Unique GQuark identifier used for the standard line width property.

### goo_canvas_style_operator_id

    extern GQuark goo_canvas_style_operator_id;

Unique GQuark identifier used for the standard operator property.

### goo_canvas_style_stroke_pattern_id

    extern GQuark goo_canvas_style_stroke_pattern_id;

Unique GQuark identifier used for the standard stroke pattern property.