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RsvgHandle

RsvgHandle — Loads SVG data into memory.

Types and Values

Description

This is the main entry point into the librsvg library. An RsvgHandle is an object that represents SVG data in memory. Your program creates an RsvgHandle from an SVG file, or from a memory buffer that contains SVG data, or in the most general form, from a GInputStream that will provide SVG data.

Librsvg supports reading SVG 1.1 data. It also supports SVGZ files, which is just an SVG stream compressed with the GZIP algorithm.

The "base file" and resolving references to external files

When you load an SVG, librsvg needs to know the location of the "base file" for it. This is so that librsvg can determine the location of referenced entities. For example, say you have an SVG in /foo/bar/foo.svg and that it has an image element like this:

<image xlink:href="resources/foo.png" .../>

In this case, librsvg needs to know the location of the toplevel /foo/bar/foo.svg so that it can generate the appropriate reference to /foo/bar/resources/foo.png.

Security and locations of referenced files

When processing an SVG, librsvg will only load referenced files if they are in the same directory as the base file, or in a subdirectory of it. That is, if the base file is /foo/bar/baz.svg, then librsvg will only try to load referenced files (from SVG's "image" element, for example, or from content included through XML entities) if those files are in /foo/bar/* or in /foo/bar/*/.../*. This is so that malicious SVG files cannot include files that are in a directory above.


Loading an SVG with GIO

If you have a GFile that stands for an SVG file, you can simply call rsvg_handle_new_from_gfile_sync() to load an RsvgHandle from it.

Alternatively, if you have a GInputStream, you can use rsvg_handle_new_from_stream_sync().

Both of those methods allow specifying a GCancellable, so the loading process can be cancelled from another thread.

Loading an SVG from memory

If you already have SVG data in memory, you can create a memory input stream with g_memory_input_stream_new_from_data() and feed that to rsvg_handle_new_from_stream_sync(). This lets you specify the appropriate flags, for example RSVG_HANDLE_FLAG_UNLIMITED if your input data is very large.

Note that in this case, it is important that you specify the base_file for the in-memory SVG data. Librsvg uses the base_file to resolve links to external content, like raster images.


Loading an SVG without GIO

You can load an RsvgHandle from a simple filename or URI with rsvg_handle_new_from_file(). Note that this is a blocking operation; there is no way to cancel it if loading a remote URI takes a long time.

Alternatively, you can create an empty RsvgHandle with rsvg_handle_new() or rsvg_handle_new_with_flags(). The first function is equivalent to using RSVG_HANDLE_FLAGS_NONE on the second one. These functions give you back an empty RsvgHandle, which is ready for you to feed it SVG data. You can do this with rsvg_handle_write() and rsvg_handle_close().


Resolution of the rendered image (dots per inch, or DPI)

SVG images can contain dimensions like "5 cm" or "2 pt" that must be converted from physical units into device units. To do this, librsvg needs to know the actual dots per inch (DPI) of your target device. You can call rsvg_handle_set_dpi() or rsvg_handle_set_dpi_x_y() on an RsvgHandle to set the DPI before rendering it.


Rendering

The preferred way to render an already-loaded RsvgHandle is to use rsvg_handle_render_cairo(). Please see its documentation for details.

Alternatively, you can use rsvg_handle_get_pixbuf() to directly obtain a GdkPixbuf with the rendered image. This is simple, but it does not let you control the size at which the SVG will be rendered. It will just be rendered at the size which rsvg_handle_get_dimensions() would return, which depends on the dimensions that librsvg is able to compute from the SVG data.

Functions

rsvg_error_quark ()

GQuark
rsvg_error_quark (void);

The error domain for RSVG

Returns

The error domain


rsvg_cleanup ()

void
rsvg_cleanup (void);

This function should not be called from normal programs. See xmlCleanupParser() for more information.

Since: 2.36


rsvg_set_default_dpi ()

void
rsvg_set_default_dpi (double dpi);

rsvg_set_default_dpi has been deprecated since version 2.42.3 and should not be used in newly-written code.

This function used to set a global default DPI. However, it only worked if it was called before any RsvgHandle objects had been created; it would not work after that. To avoid global mutable state, please use rsvg_handle_set_dpi() instead.

Do not use this function. Create an RsvgHandle and call rsvg_handle_set_dpi() on it instead.

Parameters

dpi

Dots Per Inch (aka Pixels Per Inch)

 

Since: 2.8


rsvg_set_default_dpi_x_y ()

void
rsvg_set_default_dpi_x_y (double dpi_x,
                          double dpi_y);

rsvg_set_default_dpi_x_y has been deprecated since version 2.42.3 and should not be used in newly-written code.

This function used to set a global default DPI. However, it only worked if it was called before any RsvgHandle objects had been created; it would not work after that. To avoid global mutable state, please use rsvg_handle_set_dpi() instead.

Do not use this function. Create an RsvgHandle and call rsvg_handle_set_dpi_x_y() on it instead.

Parameters

dpi_x

Dots Per Inch (aka Pixels Per Inch)

 

dpi_y

Dots Per Inch (aka Pixels Per Inch)

 

Since: 2.8


rsvg_handle_set_dpi ()

void
rsvg_handle_set_dpi (RsvgHandle *handle,
                     double dpi);

Sets the DPI for the outgoing pixbuf. Common values are 75, 90, and 300 DPI. Passing a number <= 0 to dpi will reset the DPI to whatever the default value happens to be.

Parameters

handle

An RsvgHandle

 

dpi

Dots Per Inch (aka Pixels Per Inch)

 

Since: 2.8


rsvg_handle_set_dpi_x_y ()

void
rsvg_handle_set_dpi_x_y (RsvgHandle *handle,
                         double dpi_x,
                         double dpi_y);

Sets the DPI for the outgoing pixbuf. Common values are 75, 90, and 300 DPI. Passing a number <= 0 to dpi_x or dpi_y will reset the DPI to whatever the default value happens to be.

Parameters

handle

An RsvgHandle

 

dpi_x

Dots Per Inch (aka Pixels Per Inch)

 

dpi_y

Dots Per Inch (aka Pixels Per Inch)

 

Since: 2.8


rsvg_handle_new ()

RsvgHandle *
rsvg_handle_new (void);

Returns a new rsvg handle. Must be freed with g_object_unref . This handle can be used for dynamically loading an image. You need to feed it data using rsvg_handle_write , then call rsvg_handle_close when done. Afterwords, you can render it using Cairo or get a GdkPixbuf from it. When finished, free with g_object_unref(). No more than one image can be loaded with one handle.

Returns

A new RsvgHandle


rsvg_handle_new_with_flags ()

RsvgHandle *
rsvg_handle_new_with_flags (RsvgHandleFlags flags);

Creates a new RsvgHandle with flags flags .

Parameters

flags

flags from RsvgHandleFlags

 

Returns

a new RsvgHandle.

[transfer full]

Since: 2.36


rsvg_handle_write ()

gboolean
rsvg_handle_write (RsvgHandle *handle,
                   const guchar *buf,
                   gsize count,
                   GError **error);

Loads the next count bytes of the image. This will return TRUE if the data was loaded successful, and FALSE if an error occurred. In the latter case, the loader will be closed, and will not accept further writes. If FALSE is returned, error will be set to an error from the RsvgError domain. Errors from GIOErrorEnum are also possible.

Parameters

handle

an RsvgHandle

 

buf

pointer to svg data.

[array length=count][element-type guchar]

count

length of the buf buffer in bytes

 

error

a location to store a GError, or NULL.

[allow-none]

Returns

TRUE on success, or FALSE on error


rsvg_handle_close ()

gboolean
rsvg_handle_close (RsvgHandle *handle,
                   GError **error);

Closes handle , to indicate that loading the image is complete. This will return TRUE if the loader closed successfully. Note that handle isn't freed until g_object_unref is called.

Parameters

handle

a RsvgHandle

 

error

a location to store a GError, or NULL.

[allow-none]

Returns

TRUE on success, or FALSE on error


rsvg_handle_get_base_uri ()

const char *
rsvg_handle_get_base_uri (RsvgHandle *handle);

Gets the base uri for this RsvgHandle.

Parameters

handle

A RsvgHandle

 

Returns

the base uri, possibly null

Since: 2.8


rsvg_handle_set_base_uri ()

void
rsvg_handle_set_base_uri (RsvgHandle *handle,
                          const char *base_uri);

Set the base URI for this SVG. This can only be called before rsvg_handle_write() has been called.

Parameters

handle

A RsvgHandle

 

base_uri

The base uri

 

Since: 2.9


rsvg_handle_get_dimensions ()

void
rsvg_handle_get_dimensions (RsvgHandle *handle,
                            RsvgDimensionData *dimension_data);

Get the SVG's size. Do not call from within the size_func callback, because an infinite loop will occur.

Parameters

handle

A RsvgHandle

 

dimension_data

A place to store the SVG's size.

[out]

Since: 2.14


rsvg_handle_get_dimensions_sub ()

gboolean
rsvg_handle_get_dimensions_sub (RsvgHandle *handle,
                                RsvgDimensionData *dimension_data,
                                const char *id);

Get the size of a subelement of the SVG file. Do not call from within the size_func callback, because an infinite loop will occur.

Parameters

handle

A RsvgHandle

 

dimension_data

A place to store the SVG's size.

[out]

id

An element's id within the SVG, starting with "##", for example, "#layer1"; or NULL to use the whole SVG.

[nullable]

Since: 2.22


rsvg_handle_get_position_sub ()

gboolean
rsvg_handle_get_position_sub (RsvgHandle *handle,
                              RsvgPositionData *position_data,
                              const char *id);

Get the position of a subelement of the SVG file. Do not call from within the size_func callback, because an infinite loop will occur.

Parameters

handle

A RsvgHandle

 

position_data

A place to store the SVG fragment's position.

[out]

id

An element's id within the SVG, starting with "##", for example, "#layer1"; or NULL to use the whole SVG.

[nullable]

Since: 2.22


rsvg_handle_has_sub ()

gboolean
rsvg_handle_has_sub (RsvgHandle *handle,
                     const char *id);

Checks whether the element id exists in the SVG document.

Parameters

handle

a RsvgHandle

 

id

an element's id within the SVG, starting with "##", for example, "#layer1".

 

Returns

TRUE if id exists in the SVG document

Since: 2.22


rsvg_handle_get_title ()

const char *
rsvg_handle_get_title (RsvgHandle *handle);

rsvg_handle_get_title has been deprecated since version 2.36 and should not be used in newly-written code.

Parameters

handle

An RsvgHandle

 

Returns

This function always returns NULL.

[nullable]

Since: 2.4


rsvg_handle_get_desc ()

const char *
rsvg_handle_get_desc (RsvgHandle *handle);

rsvg_handle_get_desc has been deprecated since version 2.36 and should not be used in newly-written code.

Parameters

handle

An RsvgHandle

 

Returns

This function always returns NULL.

[nullable]

Since: 2.4


rsvg_handle_get_metadata ()

const char *
rsvg_handle_get_metadata (RsvgHandle *handle);

rsvg_handle_get_metadata has been deprecated since version 2.36 and should not be used in newly-written code.

Parameters

handle

An RsvgHandle

 

Returns

This function always returns NULL.

[nullable]

Since: 2.9


rsvg_handle_new_from_data ()

RsvgHandle *
rsvg_handle_new_from_data (const guint8 *data,
                           gsize data_len,
                           GError **error);

Loads the SVG specified by data .

Parameters

data

The SVG data.

[array length=data_len]

data_len

The length of data , in bytes

 

error

return location for errors

 

Returns

A RsvgHandle or NULL if an error occurs.

Since: 2.14


rsvg_handle_new_from_file ()

RsvgHandle *
rsvg_handle_new_from_file (const gchar *file_name,
                           GError **error);

Loads the SVG specified by file_name .

Parameters

file_name

The file name to load. If built with gnome-vfs, can be a URI.

 

error

return location for errors

 

Returns

A RsvgHandle or NULL if an error occurs.

Since: 2.14


rsvg_error_get_type ()

GType
rsvg_error_get_type (void);

rsvg_init ()

void
rsvg_init (void);

rsvg_init has been deprecated since version 2.36 and should not be used in newly-written code.

There is no need to initialize librsvg.

This function does nothing.

Since: 2.9


rsvg_term ()

void
rsvg_term (void);

rsvg_term has been deprecated since version 2.36 and should not be used in newly-written code.

There is no need to de-initialize librsvg.

This function does nothing.

Since: 2.9


rsvg_handle_free ()

void
rsvg_handle_free (RsvgHandle *handle);

rsvg_handle_free is deprecated and should not be used in newly-written code.

Use g_object_unref() instead.

Frees handle .

Parameters

handle

An RsvgHandle

 

rsvg_handle_set_size_callback ()

void
rsvg_handle_set_size_callback (RsvgHandle *handle,
                               RsvgSizeFunc size_func,
                               gpointer user_data,
                               GDestroyNotify user_data_destroy);

rsvg_handle_set_size_callback is deprecated and should not be used in newly-written code.

Set up a cairo matrix and use rsvg_handle_render_cairo() instead. You can call rsvg_handle_get_dimensions() to figure out the size of your SVG, and then scale it to the desired size via Cairo. For example, the following code renders an SVG at a specified size, scaled proportionally from whatever original size it may have had:

void
render_scaled_proportionally (RsvgHandle *handle, cairo_t cr, int width, int height)
{
    RsvgDimensionData dimensions;
    double x_factor, y_factor;
    double scale_factor;

    rsvg_handle_get_dimensions (handle, &dimensions);

    x_factor = (double) width / dimensions.width;
    y_factor = (double) height / dimensions.height;

    scale_factor = MIN (x_factor, y_factor);

    cairo_scale (cr, scale_factor, scale_factor);

    rsvg_handle_render_cairo (handle, cr);
}

Sets the sizing function for the handle . This function is called right after the size of the image has been loaded. The size of the image is passed in to the function, which may then modify these values to set the real size of the generated pixbuf. If the image has no associated size, then the size arguments are set to -1.

Parameters

handle

An RsvgHandle

 

size_func

A sizing function, or NULL.

[nullable]

user_data

User data to pass to size_func , or NULL

 

user_data_destroy

Destroy function for user_data , or NULL

 

Types and Values

enum RsvgError

An enumeration representing possible errors

Members

RSVG_ERROR_FAILED

the request failed

 

RSVG_ERROR

#define             RSVG_ERROR

struct RsvgHandle

struct RsvgHandle {
    GObject parent;
};

Lets you load SVG data and render it.

Members

GObject parent;

parent instance

 

RsvgHandlePrivate


struct RsvgHandleClass

struct RsvgHandleClass {
    GObjectClass parent;
};

Class structure for RsvgHandle.

Members

GObjectClass parent;

parent class

 

struct RsvgDimensionData

struct RsvgDimensionData {
    int width;
    int height;
    gdouble em;
    gdouble ex;
};

Members

int width;

SVG's width, in pixels

 

int height;

SVG's height, in pixels

 

gdouble em;

em

 

gdouble ex;

ex

 

struct RsvgPositionData

struct RsvgPositionData {
    int x;
    int y;
};

Position of an SVG fragment.

Members

int x;

position on the x axis

 

int y;

position on the y axis

 

RSVG_TYPE_ERROR

#define             RSVG_TYPE_ERROR
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