GooCanvas

typedef struct _GooCanvas GooCanvas;

The GooCanvas struct contains private data only.

struct GooCanvasClass

struct GooCanvasClass {
  GooCanvasItem* (* create_item)	    (GooCanvas          *canvas,
					     GooCanvasItemModel *model);

  /* Signals. */
  void           (* item_created)	    (GooCanvas          *canvas,
					     GooCanvasItem      *item,
					     GooCanvasItemModel *model);
};

create_item: a virtual method that subclasses may override to create custom canvas items for item models. item_created: signal emitted when a new canvas item has been created. Applications can connect to this to setup signal handlers for the new item.

The GooCanvasClass struct contains one virtual method that subclasses may override.

goo_canvas_new ()

GtkWidget *         goo_canvas_new                      (void);

Creates a new GooCanvas widget.

A GooCanvasGroup is created automatically as the root item of the canvas, though this can be overriden with goo_canvas_set_root_item() or goo_canvas_set_root_item_model().

goo_canvas_get_root_item ()

GooCanvasItem *     goo_canvas_get_root_item            (GooCanvas *canvas);

Gets the root item of the canvas, usually a GooCanvasGroup.

goo_canvas_set_root_item ()

void                goo_canvas_set_root_item            (GooCanvas *canvas,
                                                         GooCanvasItem *item);

Sets the root item of the canvas. Any existing canvas items are removed.

goo_canvas_get_root_item_model ()

GooCanvasItemModel * goo_canvas_get_root_item_model     (GooCanvas *canvas);

Gets the root item model of the canvas.

goo_canvas_set_root_item_model ()

void                goo_canvas_set_root_item_model      (GooCanvas *canvas,
                                                         GooCanvasItemModel *model);

Sets the root item model of the canvas.

A hierarchy of canvas items will be created, corresponding to the hierarchy of items in the model. Any current canvas items will be removed.

goo_canvas_get_static_root_item ()

GooCanvasItem *     goo_canvas_get_static_root_item     (GooCanvas *canvas);

Gets the static root item of the canvas.

Static items are exactly the same as ordinary canvas items, except that they do not move or change size when the canvas is scrolled or the scale changes.

Static items are added to the static root item in exactly the same way that ordinary items are added to the root item.

goo_canvas_set_static_root_item ()

void                goo_canvas_set_static_root_item     (GooCanvas *canvas,
                                                         GooCanvasItem *item);

Sets the static root item. Any existing static items are removed.

Static items are exactly the same as ordinary canvas items, except that they do not move or change size when the canvas is scrolled or the scale changes.

Static items are added to the static root item in exactly the same way that ordinary items are added to the root item.

goo_canvas_get_static_root_item_model ()

GooCanvasItemModel * goo_canvas_get_static_root_item_model
                                                        (GooCanvas *canvas);

Gets the static root item model of the canvas.

Static item models are exactly the same as ordinary item models, except that the corresponding items do not move or change size when the canvas is scrolled or the scale changes.

Static items models are added to the static root item model in exactly the same way that ordinary item models are added to the root item model.

goo_canvas_set_static_root_item_model ()

void                goo_canvas_set_static_root_item_model
                                                        (GooCanvas *canvas,
                                                         GooCanvasItemModel *model);

Sets the static root item model. Any existing static item models are removed.

Static item models are exactly the same as ordinary item models, except that the corresponding items do not move or change size when the canvas is scrolled or the scale changes.

Static items models are added to the static root item model in exactly the same way that ordinary item models are added to the root item model.

goo_canvas_get_bounds ()

void                goo_canvas_get_bounds               (GooCanvas *canvas,
                                                         gdouble *left,
                                                         gdouble *top,
                                                         gdouble *right,
                                                         gdouble *bottom);

Gets the bounds of the canvas, in canvas units.

By default, canvas units are pixels, though the "units" property can be used to change the units to points, inches or millimeters.

goo_canvas_set_bounds ()

void                goo_canvas_set_bounds               (GooCanvas *canvas,
                                                         gdouble left,
                                                         gdouble top,
                                                         gdouble right,
                                                         gdouble bottom);

Sets the bounds of the GooCanvas, in canvas units.

By default, canvas units are pixels, though the "units" property can be used to change the units to points, inches or millimeters.

goo_canvas_get_scale ()

gdouble             goo_canvas_get_scale                (GooCanvas *canvas);

Gets the current scale of the canvas.

The scale specifies the magnification factor of the canvas, e.g. if an item has a width of 2 pixels and the scale is set to 3, it will be displayed with a width of 2 x 3 = 6 pixels.

goo_canvas_set_scale ()

void                goo_canvas_set_scale                (GooCanvas *canvas,
                                                         gdouble scale);

Sets the scale of the canvas.

The scale specifies the magnification factor of the canvas, e.g. if an item has a width of 2 pixels and the scale is set to 3, it will be displayed with a width of 2 x 3 = 6 pixels.

goo_canvas_get_item ()

GooCanvasItem *     goo_canvas_get_item                 (GooCanvas *canvas,
                                                         GooCanvasItemModel *model);

Gets the canvas item associated with the given GooCanvasItemModel. This is only useful when goo_canvas_set_root_item_model() has been used to set a model for the canvas.

For simple applications you can use goo_canvas_get_item() to set up signal handlers for your items, e.g.

   item = goo_canvas_get_item (GOO_CANVAS (canvas), my_item);
   g_signal_connect (item, "button_press_event",
                     (GtkSignalFunc) on_my_item_button_press, NULL);

More complex applications may want to use the "item-created" signal to hook up their signal handlers.

goo_canvas_get_item_at ()

GooCanvasItem *     goo_canvas_get_item_at              (GooCanvas *canvas,
                                                         gdouble x,
                                                         gdouble y,
                                                         gboolean is_pointer_event);

Gets the item at the given point.

goo_canvas_get_items_at ()

GList *             goo_canvas_get_items_at             (GooCanvas *canvas,
                                                         gdouble x,
                                                         gdouble y,
                                                         gboolean is_pointer_event);

Gets all items at the given point.

goo_canvas_get_items_in_area ()

GList *             goo_canvas_get_items_in_area        (GooCanvas *canvas,
                                                         const GooCanvasBounds *area,
                                                         gboolean inside_area,
                                                         gboolean allow_overlaps,
                                                         gboolean include_containers);

Gets a list of items inside or outside a given area.

goo_canvas_scroll_to ()

void                goo_canvas_scroll_to                (GooCanvas *canvas,
                                                         gdouble left,
                                                         gdouble top);

Scrolls the canvas, placing the given point as close to the top-left of the view as possible.

goo_canvas_render ()

void                goo_canvas_render                   (GooCanvas *canvas,
                                                         cairo_t *cr,
                                                         const GooCanvasBounds *bounds,
                                                         gdouble scale);

Renders all or part of a canvas to the given cairo context.

This example code could be used in a GtkPrintOperation "draw-page" callback to print each page in a multi-page document (assuming the pages appear one after the other vertically in the canvas). Note the call to cairo_translate() to translate the output to the correct position on the printed page.

   GooCanvasBounds bounds;
   bounds.x1 = 0;
   bounds.x2 = A4_PAGE_WIDTH;
   bounds.y1 = A4_PAGE_HEIGHT * page_num;
   bounds.y2 = A4_PAGE_HEIGHT * (page_num + 1);

   cr = gtk_print_context_get_cairo_context (print_context);
   cairo_translate (cr, 0, -A4_PAGE_HEIGHT * page_num);
   goo_canvas_render (GOO_CANVAS (canvas), cr, &bounds, 0.0);

goo_canvas_convert_to_pixels ()

void                goo_canvas_convert_to_pixels        (GooCanvas *canvas,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from the canvas coordinate space to pixels.

The canvas coordinate space is specified in the call to goo_canvas_set_bounds().

The pixel coordinate space specifies pixels from the top-left of the entire canvas window, according to the current scale setting. See goo_canvas_set_scale().

goo_canvas_convert_from_pixels ()

void                goo_canvas_convert_from_pixels      (GooCanvas *canvas,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from pixels to the canvas coordinate space.

The pixel coordinate space specifies pixels from the top-left of the entire canvas window, according to the current scale setting. See goo_canvas_set_scale().

The canvas coordinate space is specified in the call to goo_canvas_set_bounds().

goo_canvas_convert_to_item_space ()

void                goo_canvas_convert_to_item_space    (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from the canvas coordinate space to the given item's coordinate space, applying all transformation matrices including the item's own transformation matrix, if it has one.

goo_canvas_convert_from_item_space ()

void                goo_canvas_convert_from_item_space  (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from the given item's coordinate space to the canvas coordinate space, applying all transformation matrices including the item's own transformation matrix, if it has one.

goo_canvas_convert_bounds_to_item_space ()

void                goo_canvas_convert_bounds_to_item_space
                                                        (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         GooCanvasBounds *bounds);

Converts the given bounds in the canvas coordinate space to a bounding box in item space. This is useful in the item paint() methods to convert the bounds to be painted to the item's coordinate space.

goo_canvas_convert_units_to_pixels ()

void                goo_canvas_convert_units_to_pixels  (GooCanvas *canvas,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from the canvas's units to pixels, ignoring scaling and ignoring the coordinate space specified in the call to goo_canvas_set_bounds().

Since 2.0.1

goo_canvas_convert_units_from_pixels ()

void                goo_canvas_convert_units_from_pixels
                                                        (GooCanvas *canvas,
                                                         gdouble *x,
                                                         gdouble *y);

Converts a coordinate from pixels to the canvas's units, ignoring scaling and ignoring the coordinate space specified in the call to goo_canvas_set_bounds().

Since 2.0.1

goo_canvas_pointer_grab ()

GdkGrabStatus       goo_canvas_pointer_grab             (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         GdkEventMask event_mask,
                                                         GdkCursor *cursor,
                                                         guint32 time);

Attempts to grab the pointer for the given item.

goo_canvas_pointer_ungrab ()

void                goo_canvas_pointer_ungrab           (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         guint32 time);

Ungrabs the pointer, if the given item has the pointer grab.

goo_canvas_grab_focus ()

void                goo_canvas_grab_focus               (GooCanvas *canvas,
                                                         GooCanvasItem *item);

Grabs the keyboard focus for the given item.

goo_canvas_keyboard_grab ()

GdkGrabStatus       goo_canvas_keyboard_grab            (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         gboolean owner_events,
                                                         guint32 time);

Attempts to grab the keyboard for the given item.

goo_canvas_keyboard_ungrab ()

void                goo_canvas_keyboard_ungrab          (GooCanvas *canvas,
                                                         GooCanvasItem *item,
                                                         guint32 time);

Ungrabs the keyboard, if the given item has the keyboard grab.

goo_canvas_create_cairo_context ()

cairo_t *           goo_canvas_create_cairo_context     (GooCanvas *canvas);

Creates a cairo context, initialized with the default canvas settings.

goo_canvas_create_item ()

GooCanvasItem *     goo_canvas_create_item              (GooCanvas *canvas,
                                                         GooCanvasItemModel *model);

This function is only intended to be used when implementing new canvas items, typically container items such as GooCanvasGroup.

It creates a new canvas item for the given item model, and recursively creates items for any children.

It uses the create_item() virtual method if it has been set. Subclasses of GooCanvas can define this method if they want to use custom views for items.

It emits the "item-created" signal after creating the view, so application code can connect signal handlers to the new view if desired.

goo_canvas_unregister_item ()

void                goo_canvas_unregister_item          (GooCanvas *canvas,
                                                         GooCanvasItemModel *model);

This function is only intended to be used when implementing new canvas items.

It should be called in the finalize method of GooCanvasItem objects, to remove the canvas item from the GooCanvas's hash table.

goo_canvas_register_widget_item ()

void                goo_canvas_register_widget_item     (GooCanvas *canvas,
                                                         GooCanvasWidget *witem);

This function should only be used by GooCanvasWidget and subclass implementations.

It registers a widget item with the canvas, so that the canvas can do the necessary actions to move and resize the widget as needed.

goo_canvas_unregister_widget_item ()

void                goo_canvas_unregister_widget_item   (GooCanvas *canvas,
                                                         GooCanvasWidget *witem);

This function should only be used by GooCanvasWidget and subclass implementations.

It unregisters a widget item from the canvas, when the item is no longer in the canvas.

goo_canvas_update ()

void                goo_canvas_update                   (GooCanvas *canvas);

This function is only intended to be used by subclasses of GooCanvas or GooCanvasItem implementations.

It updates any items that need updating.

If the bounds of items change, they will request a redraw of the old and new bounds so the display is updated correctly.

goo_canvas_request_update ()

void                goo_canvas_request_update           (GooCanvas *canvas);

This function is only intended to be used by subclasses of GooCanvas or GooCanvasItem implementations.

It schedules an update of the GooCanvas. This will be performed in the idle loop, after all pending events have been handled, but before the canvas has been repainted.

goo_canvas_request_redraw ()

void                goo_canvas_request_redraw           (GooCanvas *canvas,
                                                         const GooCanvasBounds *bounds);

This function is only intended to be used by subclasses of GooCanvas or GooCanvasItem implementations.

Requests that the given bounds be redrawn. The bounds must be in the canvas coordinate space.

goo_canvas_request_item_redraw ()

void                goo_canvas_request_item_redraw      (GooCanvas *canvas,
                                                         const GooCanvasBounds *bounds,
                                                         gboolean is_static);

This function is only intended to be used by subclasses of GooCanvas or GooCanvasItem implementations.

Requests that the given bounds be redrawn. If is_static is TRUE the bounds are assumed to be in the static item coordinate space, otherwise they are assumed to be in the canvas coordinate space.

If is_static is FALSE this function behaves the same as goo_canvas_request_redraw().

goo_canvas_get_default_line_width ()

gdouble             goo_canvas_get_default_line_width   (GooCanvas *canvas);

Gets the default line width, which depends on the current units setting.

The "anchor" property

  "anchor"                   GooCanvasAnchorType   : Read / Write

Where to place the canvas when it is smaller than the widget's allocated area.

Default value: GOO_CANVAS_ANCHOR_NORTH_WEST

The "automatic-bounds" property

  "automatic-bounds"         gboolean              : Read / Write

If the bounds are automatically calculated based on the bounds of all the items in the canvas.

Default value: FALSE

The "background-color" property

  "background-color"         gchar*                : Write

The color to use for the canvas background.

Default value: NULL

The "background-color-gdk-rgba" property

  "background-color-gdk-rgba" GdkRGBA*              : Write

The color to use for the canvas background, specified as a GdkRGBA.

Since 2.0.1

The "background-color-rgb" property

  "background-color-rgb"     guint                 : Write

The color to use for the canvas background, specified as a 24-bit integer value, 0xRRGGBB.

Default value: 0

The "bounds-from-origin" property

  "bounds-from-origin"       gboolean              : Read / Write

If the automatic bounds are calculated from the origin.

Default value: TRUE

The "bounds-padding" property

  "bounds-padding"           gdouble               : Read / Write

The padding added to the automatic bounds.

Allowed values: >= 0

Default value: 0

The "clear-background" property

  "clear-background"         gboolean              : Read / Write

If the background is cleared before the canvas is painted.

Default value: TRUE

The "integer-layout" property

  "integer-layout"           gboolean              : Read / Write

If all item layout is done to the nearest integer.

Default value: FALSE

The "redraw-when-scrolled" property

  "redraw-when-scrolled"     gboolean              : Read / Write

If the canvas is completely redrawn when scrolled, to reduce the flicker of static items.

Default value: FALSE

The "resolution-x" property

  "resolution-x"             gdouble               : Read / Write

The horizontal resolution of the display, in dots per inch.

Allowed values: >= 0

Default value: 96

The "resolution-y" property

  "resolution-y"             gdouble               : Read / Write

The vertical resolution of the display, in dots per inch.

Allowed values: >= 0

Default value: 96

The "scale" property

  "scale"                    gdouble               : Read / Write

The magnification factor of the canvas.

Allowed values: >= 0

Default value: 1

The "scale-x" property

  "scale-x"                  gdouble               : Read / Write

The horizontal magnification factor of the canvas.

Allowed values: >= 0

Default value: 1

The "scale-y" property

  "scale-y"                  gdouble               : Read / Write

The vertical magnification factor of the canvas.

Allowed values: >= 0

Default value: 1

The "units" property

  "units"                    GtkUnit               : Read / Write

The units to use for the canvas.

Default value: GTK_UNIT_NONE

The "x1" property

  "x1"                       gdouble               : Read / Write

The x coordinate of the left edge of the canvas bounds, in canvas units.

Default value: 0

The "x2" property

  "x2"                       gdouble               : Read / Write

The x coordinate of the right edge of the canvas bounds, in canvas units.

Default value: 1000

The "y1" property

  "y1"                       gdouble               : Read / Write

The y coordinate of the top edge of the canvas bounds, in canvas units.

Default value: 0

The "y2" property

  "y2"                       gdouble               : Read / Write

The y coordinate of the bottom edge of the canvas bounds, in canvas units.

Default value: 1000

The "item-created" signal

void                user_function                      (GooCanvas          *canvas,
                                                        GooCanvasItem      *item,
                                                        GooCanvasItemModel *model,
                                                        gpointer            user_data)      : Run Last

This is emitted when a new canvas item is created, in model/view mode.

Applications can set up signal handlers for the new items here.