GooCanvasItemSimple

GooCanvasItemSimple — the base class for the standard canvas items.

Functions

void goo_canvas_item_simple_check_style ()
gdouble goo_canvas_item_simple_get_line_width ()
void goo_canvas_item_simple_get_path_bounds ()
void goo_canvas_item_simple_user_bounds_to_device ()
void goo_canvas_item_simple_user_bounds_to_parent ()
gboolean goo_canvas_item_simple_check_in_path ()
void goo_canvas_item_simple_paint_path ()
void goo_canvas_item_simple_changed ()
void goo_canvas_item_simple_set_model ()

Properties

GooCairoAntialias antialias Read / Write
GooCairoFillRule clip-fill-rule Read / Write
gchar * clip-path Write
gchar * fill-color Write
GdkRGBA * fill-color-gdk-rgba Read / Write
guint fill-color-rgba Read / Write
GooCairoPattern * fill-pattern Read / Write
GdkPixbuf * fill-pixbuf Write
GooCairoFillRule fill-rule Read / Write
gchar * font Read / Write
PangoFontDescription * font-desc Read / Write
GooCairoHintMetrics hint-metrics Read / Write
GooCairoLineCap line-cap Read / Write
GooCanvasLineDash * line-dash Read / Write
GooCairoLineJoin line-join Read / Write
gdouble line-join-miter-limit Read / Write
gdouble line-width Read / Write
GooCairoOperator operator Read / Write
gchar * stroke-color Write
GdkRGBA * stroke-color-gdk-rgba Read / Write
guint stroke-color-rgba Read / Write
GooCairoPattern * stroke-pattern Read / Write
GdkPixbuf * stroke-pixbuf Write

Types and Values

struct GooCanvasItemSimple
struct GooCanvasItemSimpleData
struct GooCanvasItemSimpleClass

Object Hierarchy

    GObject
    ╰── GooCanvasItemSimple
        ├── GooCanvasWidget
        ├── GooCanvasRect
        ├── GooCanvasGroup
        ├── GooCanvasPath
        ├── GooCanvasEllipse
        ├── GooCanvasText
        ├── GooCanvasPolyline
        ├── GooCanvasImage
        ╰── GooCanvasGrid

Implemented Interfaces

GooCanvasItemSimple implements GooCanvasItem.

Description

GooCanvasItemSimple is used as a base class for all of the standard canvas items. It can also be used as the base class for new custom canvas items.

It provides default implementations for many of the GooCanvasItem methods.

For very simple items, all that is needed is to implement the create_path() method. (GooCanvasEllipse, GooCanvasRect and GooCanvasPath do this.)

More complicated items need to implement the update(), paint() and is_item_at() methods instead. (GooCanvasImage, GooCanvasPolyline, GooCanvasText and GooCanvasWidget do this.) They may also need to override some of the other GooCanvasItem methods such as set_canvas(), set_parent() or allocate_area() if special code is needed. (GooCanvasWidget does this to make sure the GtkWidget is embedded in the GooCanvas widget correctly.)

Functions

goo_canvas_item_simple_check_style ()

void
goo_canvas_item_simple_check_style (GooCanvasItemSimple *item);

This function is intended to be used by subclasses of GooCanvasItemSimple, typically in their update() or get_requested_area() methods.

It ensures that the item's style is setup correctly. If the item has its own GooCanvasStyle it makes sure the parent is set correctly. If it doesn't have its own style it uses the parent item's style.

Parameters

item

a GooCanvasItemSimple.

  

goo_canvas_item_simple_get_line_width ()

gdouble
goo_canvas_item_simple_get_line_width (GooCanvasItemSimple *item);

Gets the item's line width.

Parameters

item

a GooCanvasItemSimple.

  

Returns

the item's line width.

goo_canvas_item_simple_get_path_bounds ()

void
goo_canvas_item_simple_get_path_bounds
                               (GooCanvasItemSimple *item,
                                cairo_t *cr,
                                GooCanvasBounds *bounds);

This function is intended to be used by subclasses of GooCanvasItemSimple, typically in their update() or get_requested_area() methods.

It calculates the bounds of the current path, using the item's style settings, and stores the results in the given GooCanvasBounds struct.

The returned bounds contains the bounding box of the path in device space, converted to user space coordinates. To calculate the bounds completely in user space, use cairo_identity_matrix() to temporarily reset the current transformation matrix to the identity matrix.

Parameters

item

a GooCanvasItemSimple.

  

cr

a cairo context.

  

bounds

the GooCanvasBounds struct to store the resulting bounding box.

  

goo_canvas_item_simple_user_bounds_to_device ()

void
goo_canvas_item_simple_user_bounds_to_device
                               (GooCanvasItemSimple *item,
                                cairo_t *cr,
                                GooCanvasBounds *bounds);

This function is intended to be used by subclasses of GooCanvasItemSimple, typically in their update() or get_requested_area() methods.

It converts the item's bounds to a bounding box in the canvas (device) coordinate space.

Parameters

item

a GooCanvasItemSimple.

  

cr

a cairo context.

  

bounds

the bounds of the item, in the item's coordinate space.

  

goo_canvas_item_simple_user_bounds_to_parent ()

void
goo_canvas_item_simple_user_bounds_to_parent
                               (GooCanvasItemSimple *item,
                                cairo_t *cr,
                                GooCanvasBounds *bounds);

This function is intended to be used by subclasses of GooCanvasItemSimple, typically in their get_requested_area() method.

It converts the item's bounds to a bounding box in its parent's coordinate space. If the item has no transformation matrix set then no conversion is needed.

Parameters

item

a GooCanvasItemSimple.

  

cr

a cairo context.

  

bounds

the bounds of the item, in the item's coordinate space.

  

goo_canvas_item_simple_check_in_path ()

gboolean
goo_canvas_item_simple_check_in_path (GooCanvasItemSimple *item,
                                      gdouble x,
                                      gdouble y,
                                      cairo_t *cr,
                                      GooCanvasPointerEvents pointer_events);

This function is intended to be used by subclasses of GooCanvasItemSimple.

It checks if the given point is in the current path, using the item's style settings.

Parameters

item

a GooCanvasItemSimple.

  

x

the x coordinate of the point.

  

y

the y coordinate of the point.

  

cr

a cairo context.

  

pointer_events

specifies which parts of the path to check.

  

Returns

TRUE if the given point is in the current path.

goo_canvas_item_simple_paint_path ()

void
goo_canvas_item_simple_paint_path (GooCanvasItemSimple *item,
                                   cairo_t *cr);

This function is intended to be used by subclasses of GooCanvasItemSimple.

It paints the current path, using the item's style settings.

Parameters

item

a GooCanvasItemSimple.

  

cr

a cairo context.

  

goo_canvas_item_simple_changed ()

void
goo_canvas_item_simple_changed (GooCanvasItemSimple *item,
                                gboolean recompute_bounds);

This function is intended to be used by subclasses of GooCanvasItemSimple.

It is used as a callback for the "changed" signal of the item models. It requests an update or redraw of the item as appropriate.

Parameters

item

a GooCanvasItemSimple.

  

recompute_bounds

if the item's bounds need to be recomputed.

  

goo_canvas_item_simple_set_model ()

void
goo_canvas_item_simple_set_model (GooCanvasItemSimple *item,
                                  GooCanvasItemModel *model);

This function should be called by subclasses of GooCanvasItemSimple in their set_model() method.

Parameters

item

a GooCanvasItemSimple.

  

model

the model that item will view.

  

Types and Values

struct GooCanvasItemSimple

struct GooCanvasItemSimple {
  GooCanvas *canvas;
  GooCanvasItem *parent;
  GooCanvasItemModelSimple *model;
  GooCanvasItemSimpleData *simple_data;
  GooCanvasBounds bounds;
  guint need_update			: 1;
  guint need_entire_subtree_update      : 1;
};

The GooCanvasItemSimple struct contains the basic data needed to implement canvas items.

Members

GooCanvas *canvas;

the canvas.

  

GooCanvasItem *parent;

the parent item.

  

GooCanvasItemModelSimple *model;

the item's model, if it has one.

  

GooCanvasItemSimpleData *simple_data;

data that is common to both the model and view classes. If the canvas item has a model, this will point to the model's GooCanvasItemSimpleData, otherwise the canvas item will have its own GooCanvasItemSimpleData.

  

GooCanvasBounds bounds;

the bounds of the item, in device space.

  

guint need_update : 1;

if the item needs to recompute its bounds and redraw.

  

guint need_entire_subtree_update : 1;

if all descendants need to be updated.

  

struct GooCanvasItemSimpleData

struct GooCanvasItemSimpleData {
  GooCanvasStyle *style;
  cairo_matrix_t *transform;
  GArray *clip_path_commands;
  gchar *tooltip;

  gdouble visibility_threshold;
  guint visibility			: 2;
  guint pointer_events			: 4;
  guint can_focus                       : 1;
  guint own_style                       : 1;
  guint clip_fill_rule			: 4;
  guint is_static			: 1;
};

This is the data common to both the model and view classes.

Members

GooCanvasStyle *style;

the style to draw with.

  

cairo_matrix_t *transform;

the transformation matrix of the item, or NULL.

  

GArray *clip_path_commands;

an array of GooCanvasPathCommand specifying the clip path of the item, or NULL.

  

gchar *tooltip;

the item's tooltip.

  

gdouble visibility_threshold;

the threshold scale setting at which to show the item (if the visibility setting is set to VISIBLE_ABOVE_THRESHOLD).

  

guint visibility : 2;

the GooCanvasItemVisibility setting specifying whether the item is visible, invisible, or visible above a given canvas scale setting.

  

guint pointer_events : 4;

the GooCanvasPointerEvents setting specifying the events the item should receive.

  

guint can_focus : 1;

if the item can take the keyboard focus.

  

guint own_style : 1;

if the item has its own style, rather than using its parent's.

  

guint clip_fill_rule : 4;

the cairo_fill_rule_t setting specifying the fill rule used for the clip path.

  

guint is_static : 1;

if the item is static.

  

struct GooCanvasItemSimpleClass

struct GooCanvasItemSimpleClass {
  void		 (* simple_create_path) (GooCanvasItemSimple   *simple,
					 cairo_t               *cr);

  void           (* simple_update) (GooCanvasItemSimple   *simple,
					 cairo_t               *cr);
  void           (* simple_paint) (GooCanvasItemSimple   *simple,
					 cairo_t               *cr,
					 const GooCanvasBounds *bounds);
  gboolean       (* simple_is_item_at)  (GooCanvasItemSimple   *simple,
					 gdouble                x,
					 gdouble                y,
					 cairo_t               *cr,
					 gboolean               is_pointer_event);
};

The GooCanvasItemSimpleClass struct contains several methods that subclasses can override.

Simple items need only implement the create_path() method. More complex items must override the update(), paint() and is_item_at() methods instead.

Members

simple_create_path ()

simple subclasses that draw basic shapes and paths only need to override this one method. It creates the path for the item. All updating, painting and hit-testing is provided automatically by the GooCanvasItemSimple class. (This method is used by the builtin GooCanvasEllipse, GooCanvasRect and GooCanvasPath items.) More complicated subclasses must override simple_update , simple_paint and simple_is_item_at instead.

  

simple_update ()

subclasses should override this to calculate their new bounds, in user space.

  

simple_paint ()

subclasses should override this to paint their item.

  

simple_is_item_at ()

subclasses should override this to do hit-testing.

  

Property Details

The “antialias” property

  “antialias”                GooCairoAntialias

The antialiasing mode to use.

Flags: Read / Write

Default value: CAIRO_ANTIALIAS_GRAY

The “clip-fill-rule” property

  “clip-fill-rule”           GooCairoFillRule

The fill rule used to determine which parts of the item are clipped.

Flags: Read / Write

Default value: CAIRO_FILL_RULE_WINDING

The “clip-path” property

  “clip-path”                gchar *

The sequence of commands describing the clip path of the item, specified as a string using the same syntax as in the Scalable Vector Graphics (SVG) path element.

Flags: Write

Default value: NULL

The “fill-color” property

  “fill-color”               gchar *

The color to use to paint the interior of the item. To disable painting set the 'fill-pattern' property to NULL.

Flags: Write

Default value: NULL

The “fill-color-gdk-rgba” property

  “fill-color-gdk-rgba”      GdkRGBA *

The color to use to paint the interior of the item, specified as a GdkRGBA. To disable painting set the 'fill-pattern' property to NULL.

Flags: Read / Write

Since: 2.0.1

The “fill-color-rgba” property

  “fill-color-rgba”          guint

The color to use to paint the interior of the item, specified as a 32-bit integer value. To disable painting set the 'fill-pattern' property to NULL.

Flags: Read / Write

Default value: 0

The “fill-pattern” property

  “fill-pattern”             GooCairoPattern *

The pattern to use to paint the interior of the item, or NULL to disable painting.

Flags: Read / Write

The “fill-pixbuf” property

  “fill-pixbuf”              GdkPixbuf *

The pixbuf to use to paint the interior of the item. To disable painting set the 'fill-pattern' property to NULL.

Flags: Write

The “fill-rule” property

  “fill-rule”                GooCairoFillRule

The fill rule used to determine which parts of the item are filled.

Flags: Read / Write

Default value: CAIRO_FILL_RULE_WINDING

The “font” property

  “font”                     gchar *

The base font to use for the text.

Flags: Read / Write

Default value: NULL

The “font-desc” property

  “font-desc”                PangoFontDescription *

The attributes specifying which font to use.

Flags: Read / Write

The “hint-metrics” property

  “hint-metrics”             GooCairoHintMetrics

The hinting to be used for font metrics.

Flags: Read / Write

Default value: CAIRO_HINT_METRICS_OFF

The “line-cap” property

  “line-cap”                 GooCairoLineCap

The line cap style to use.

Flags: Read / Write

Default value: CAIRO_LINE_CAP_BUTT

The “line-dash” property

  “line-dash”                GooCanvasLineDash *

The dash pattern to use.

Flags: Read / Write

The “line-join” property

  “line-join”                GooCairoLineJoin

The line join style to use.

Flags: Read / Write

Default value: CAIRO_LINE_JOIN_MITER

The “line-join-miter-limit” property

  “line-join-miter-limit”    gdouble

The smallest angle to use with miter joins, in degrees. Bevel joins will be used below this limit.

Flags: Read / Write

Allowed values: >= 0

Default value: 10

The “line-width” property

  “line-width”               gdouble

The line width to use for the item's perimeter.

Flags: Read / Write

Allowed values: >= 0

Default value: 2

The “operator” property

  “operator”                 GooCairoOperator

The compositing operator to use.

Flags: Read / Write

Default value: CAIRO_OPERATOR_OVER

The “stroke-color” property

  “stroke-color”             gchar *

The color to use for the item's perimeter. To disable painting set the 'stroke-pattern' property to NULL.

Flags: Write

Default value: NULL

The “stroke-color-gdk-rgba” property

  “stroke-color-gdk-rgba”    GdkRGBA *

The color to use for the item's perimeter, specified as a GdkRGBA. To disable painting set the 'stroke-pattern' property to NULL.

Flags: Read / Write

Since: 2.0.1

The “stroke-color-rgba” property

  “stroke-color-rgba”        guint

The color to use for the item's perimeter, specified as a 32-bit integer value. To disable painting set the 'stroke-pattern' property to NULL.

Flags: Read / Write

Default value: 0

The “stroke-pattern” property

  “stroke-pattern”           GooCairoPattern *

The pattern to use to paint the perimeter of the item, or NULL disable painting.

Flags: Read / Write

The “stroke-pixbuf” property

  “stroke-pixbuf”            GdkPixbuf *

The pixbuf to use to draw the item's perimeter. To disable painting set the 'stroke-pattern' property to NULL.

Flags: Write

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