GnomeCanvas

Gnome User Interface Library Reference Manual
Prev		Next

Details

GnomeCanvas

struct GnomeCanvas;

GNOME_CANVAS_EPSILON

#define GNOME_CANVAS_EPSILON 1e-10

GNOME_CANVAS_COLOR()

#define GNOME_CANVAS_COLOR(r, g, b) ((((int) (r) & 0xff) << 24)	\
				     | (((int) (g) & 0xff) << 16)	\
				     | (((int) (b) & 0xff) << 8)	\
				     | 0xff)

r : g : b :

GNOME_CANVAS_COLOR_A()

#define GNOME_CANVAS_COLOR_A(r, g, b, a) ((((int) (r) & 0xff) << 24)	\
					  | (((int) (g) & 0xff) << 16)	\
					  | (((int) (b) & 0xff) << 8)	\
					  | ((int) (a) & 0xff))

r : g : b : a :

GnomeCanvasBuf

struct GnomeCanvasBuf {
	guchar *buf;			/* 24 bit RGB buffer for rendering */
	int buf_rowstride;		/* The rowstride for buf */
	ArtIRect rect;			/* The rectangle describing the
					 * rendering area.
					 */
	guint32 bg_color;		/* The background color in 0xrrggbb */

	/* Invariant: at least one of the following flags is true. */

	unsigned int is_bg : 1;		/* Set when the render rectangle area is
					 * the solid color bg_color.
					 */
	unsigned int is_buf : 1;	/* Set when the render rectangle area is
					 * represented by the buf
					 */
};

gnome_canvas_new()

GtkWidget*  gnome_canvas_new                (void);

Creates a new empty canvas. If the user wishes to use the image item inside this canvas, then the gdk_imlib visual and colormap should be pushed into Gtk+'s stack before calling this function, and they can be popped afterwards.

Returns : The newly-created canvas.

gnome_canvas_new_aa()

GtkWidget*  gnome_canvas_new_aa             (void);

Creates a new antialiased empty canvas. You want to push the GdkRgb colormap and visual for this.

Returns : The newly-created canvas.

gnome_canvas_root()

GnomeCanvasGroup* gnome_canvas_root         (GnomeCanvas *canvas);

Queries the root group of a canvas.

canvas : The canvas whose root group should be extracted.Returns : The root group of the canvas.

gnome_canvas_set_scroll_region()

void        gnome_canvas_set_scroll_region  (GnomeCanvas *canvas,
                                             double x1,
                                             double y1,
                                             double x2,
                                             double y2);

Sets the scrolling region of the canvas to the specified rectangle. The canvas will then be able to scroll only within this region. The view of the canvas is adjusted as appropriate to display as much of the new region as possible.

canvas : The canvas to set the scroll region for.x1 : Leftmost limit of the scrolling region.y1 : Upper limit of the scrolling region.x2 : Rightmost limit of the scrolling region.y2 : Lower limit of the scrolling region.

gnome_canvas_get_scroll_region()

void        gnome_canvas_get_scroll_region  (GnomeCanvas *canvas,
                                             double *x1,
                                             double *y1,
                                             double *x2,
                                             double *y2);

Queries the scroll region of the canvas.

canvas : The canvas whose scroll region should be queried.x1 : If non-NULL, returns the leftmost limit of the scrolling region.y1 : If non-NULL, returns the upper limit of the scrolling region.x2 : If non-NULL, returns the rightmost limit of the scrolling region.y2 : If non-NULL, returns the lower limit of the scrolling region.

gnome_canvas_set_pixels_per_unit()

void        gnome_canvas_set_pixels_per_unit
                                            (GnomeCanvas *canvas,
                                             double n);

Sets the zooming factor of the canvas by specifying the number of pixels that correspond to one canvas unit.

canvas : The canvas whose zoom factor should be changed.n : The number of pixels that correspond to one canvas unit.

gnome_canvas_scroll_to()

void        gnome_canvas_scroll_to          (GnomeCanvas *canvas,
                                             int cx,
                                             int cy);

Makes the canvas scroll to the specified offsets, given in canvas pixel units. The canvas will adjust the view so that it is not outside the scrolling region. This function is typically not used, as it is better to hook scrollbars to the canvas layout's scrolling adjusments.

canvas : The canvas to scroll.cx : Horizontal scrolling offset in canvas pixel units.cy : Vertical scrolling offset in canvas pixel units.

gnome_canvas_get_scroll_offsets()

void        gnome_canvas_get_scroll_offsets (GnomeCanvas *canvas,
                                             int *cx,
                                             int *cy);

Queries the scrolling offsets of the canvas.

canvas : The canvas whose scrolling offsets should be queried.cx : If non-NULL, returns the horizontal scrolling offset.cy : If non-NULL, returns the vertical scrolling offset.

gnome_canvas_update_now()

void        gnome_canvas_update_now         (GnomeCanvas *canvas);

Forces an immediate redraw or update of the canvas. If the canvas does not have any pending redraw requests, then no action is taken. This is typically only used by applications that need explicit control of when the display is updated, like games. It is not needed by normal applications.

canvas : The canvas whose view should be updated.

gnome_canvas_get_item_at()

GnomeCanvasItem* gnome_canvas_get_item_at   (GnomeCanvas *canvas,
                                             double x,
                                             double y);

Looks for the item that is under the specified position (given in world coordinates).

canvas : The canvas from which to get the itemx : X position in world coordinatesy : Y position in world coordinatesReturns : The sought item, or NULL if no item is at the specified coordinates.

gnome_canvas_request_redraw_uta()

void        gnome_canvas_request_redraw_uta (GnomeCanvas *canvas,
                                             ArtUta *uta);

Informs a canvas that the specified area, given as a microtile array, needs to be repainted.

canvas : The canvas whose area needs to be redrawn.uta : Microtile array that specifies the area to be redrawn.

gnome_canvas_request_redraw()

void        gnome_canvas_request_redraw     (GnomeCanvas *canvas,
                                             int x1,
                                             int y1,
                                             int x2,
                                             int y2);

Convenience function that informs a canvas that the specified area, specified as a rectangle, needs to be repainted. This function converts the rectangle to a microtile array and feeds it to gnome_canvas_request_redraw_uta(). The rectangle includes x1 and y1, but not x2 and y2.

canvas : The canvas whose area needs to be redrawn.x1 : Leftmost coordinate of the rectangle to be redrawn.y1 : Upper coordinate of the rectangle to be redrawn.x2 : Rightmost coordinate of the rectangle to be redrawn, plus 1.y2 : Lower coordinate of the rectangle to be redrawn, plus 1.

gnome_canvas_w2c_affine()

void        gnome_canvas_w2c_affine         (GnomeCanvas *canvas,
                                             double affine[6]);

Gets the affine transform that converts world coordinates into canvas pixel coordinates.

canvas : The canvas whose coordinates need conversion. affineaffine :

gnome_canvas_w2c()

void        gnome_canvas_w2c                (GnomeCanvas *canvas,
                                             double wx,
                                             double wy,
                                             int *cx,
                                             int *cy);

Converts world coordinates into canvas pixel coordinates. Usually only needed by item implementations.

canvas : The canvas whose coordinates need conversion.wx : World X coordinate.wy : World Y coordinate.cx : If non-NULL, returns the converted X pixel coordinate.cy : If non-NULL, returns the converted Y pixel coordinate.

gnome_canvas_w2c_d()

void        gnome_canvas_w2c_d              (GnomeCanvas *canvas,
                                             double wx,
                                             double wy,
                                             double *cx,
                                             double *cy);

Converts world coordinates into canvas pixel coordinates. Usually only needed by item implementations. This version results in double coordinates, which are useful in antialiased implementations.

gnome_canvas_c2w()

void        gnome_canvas_c2w                (GnomeCanvas *canvas,
                                             int cx,
                                             int cy,
                                             double *wx,
                                             double *wy);

Converts canvas pixel coordinates to world coordinates. Usually only needed by item implementations.

canvas : The canvas whose coordinates need conversion.cx : Canvas pixel X coordinate.cy : Canvas pixel Y coordinate.wx : If non-NULL, returns the converted X world coordinate.wy : If non-NULL, returns the converted Y world coordinate.

gnome_canvas_window_to_world()

void        gnome_canvas_window_to_world    (GnomeCanvas *canvas,
                                             double winx,
                                             double winy,
                                             double *worldx,
                                             double *worldy);

Converts window-relative coordinates into world coordinates. Use this when you need to convert from mouse coordinates into world coordinates, for example.

canvas : The canvas whose coordinates need conversion.winx : Window-relative X coordinate.winy : Window-relative Y coordinate.worldx : If non-NULL, returns the converted X world coordinate.worldy : If non-NULL, returns the converted Y world coordinate.

gnome_canvas_world_to_window()

void        gnome_canvas_world_to_window    (GnomeCanvas *canvas,
                                             double worldx,
                                             double worldy,
                                             double *winx,
                                             double *winy);

Converts world coordinates into window-relative coordinates.

canvas : The canvas whose coordinates need conversion.worldx : World X coordinate.worldy : World Y coordinate.winx : If non-NULL, returns the converted X window-relative coordinate.winy : If non-NULL, returns the converted Y window-relative coordinate.

gnome_canvas_get_color()

int         gnome_canvas_get_color          (GnomeCanvas *canvas,
                                             char *spec,
                                             GdkColor *color);

Allocates a color based on the specified X color specification. As a convenience to item implementations, it returns TRUE if the color was allocated, or FALSE if the specification was NULL. A NULL color specification is considered as "transparent" by the canvas.

canvas : The canvas in which to allocate the color.spec : X color specification, or NULL for "transparent".color : Returns the allocated color.Returns : TRUE if spec is non-NULL and the color is allocated. If spec is NULL, then returns FALSE.

gnome_canvas_set_stipple_origin()

void        gnome_canvas_set_stipple_origin (GnomeCanvas *canvas,
                                             GdkGC *gc);

Sets the stipple origin of the specified GC as is appropriate for the canvas. This is typically only needed by item implementations.

canvas : The canvas relative to which the stipple origin should be set.gc : GC on which to set the stipple origin.

GnomeCanvas

Name

Synopsis

Object Hierarchy

Description

Details

GnomeCanvas

GNOME_CANVAS_EPSILON

GNOME_CANVAS_COLOR()

GNOME_CANVAS_COLOR_A()

GnomeCanvasBuf

gnome_canvas_new()

gnome_canvas_new_aa()

gnome_canvas_root()

gnome_canvas_set_scroll_region()

gnome_canvas_get_scroll_region()

gnome_canvas_set_pixels_per_unit()

gnome_canvas_scroll_to()

gnome_canvas_get_scroll_offsets()

gnome_canvas_update_now()

gnome_canvas_get_item_at()

gnome_canvas_request_redraw_uta()

gnome_canvas_request_redraw()

gnome_canvas_w2c_affine()

gnome_canvas_w2c()

gnome_canvas_w2c_d()

gnome_canvas_c2w()

gnome_canvas_window_to_world()

gnome_canvas_world_to_window()

gnome_canvas_get_color()

gnome_canvas_set_stipple_origin()

Prev	Home	Next
GnomeCalculator	Up	GnomeCanvasItem