Rsvg.Handle
Description: Reference for Rsvg.Handle

### Class

# RsvgHandle

#### Description [src]

    class Rsvg.Handle : GObject.Object
    {
      /* No available fields */
    }

`RsvgHandle` loads an SVG document into memory.

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 can load SVG images and render them to Cairo surfaces, using a mixture of SVG’s static mode and secure static mode. Librsvg does not do animation nor scripting, and can load references to external data only in some situations; see below.

Librsvg supports reading SVG 1.1 data, and is gradually adding support for features in SVG 2. Librsvg also supports SVGZ files, which are 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 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/<anything>` or in `/foo/bar/<anything>\/.../<anything>`. This is so that malicious SVG files cannot include files that are in a directory above.

The full set of rules for deciding which URLs may be loaded is as follows; they are applied in order. A referenced URL will not be loaded as soon as one of these rules fails:

1. All `data:` URLs may be loaded. These are sometimes used to include raster image data, encoded as base-64, directly in an SVG file.

2. URLs with queries (“?”) or fragment identifiers (“#”) are not allowed.

3. All URL schemes other than data: in references require a base URL. For example, this means that if you load an SVG with `rsvg_handle_new_from_data()` without calling `rsvg_handle_set_base_uri()`, then any referenced files will not be allowed (e.g. raster images to be loaded from other files will not work).

4. If referenced URLs are absolute, rather than relative, then they must have the same scheme as the base URL. For example, if the base URL has a `file` scheme, then all URL references inside the SVG must also have the `file` scheme, or be relative references which will be resolved against the base URL.

5. If referenced URLs have a `resource` scheme, that is, if they are included into your binary program with GLib’s resource mechanism, they are allowed to be loaded (provided that the base URL is also a `resource`, per the previous rule).

6. Otherwise, non-`file` schemes are not allowed. For example, librsvg will not load `http` resources, to keep malicious SVG data from “phoning home”.

7. URLs with a `file` scheme are rejected if they contain a hostname, as in `file://hostname/some/directory/foo.svg`. Windows UNC paths with a hostname are also rejected. This is to prevent documents from trying to access resources on other machines.

8. A relative URL must resolve to the same directory as the base URL, or to one of its subdirectories. Librsvg will canonicalize filenames, by removing “..” path components and resolving symbolic links, to decide whether files meet these conditions.

# Loading an SVG with GIO

This is the easiest and most resource-efficient way of loading SVG data into an `RsvgHandle`.

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 a byte buffer 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()`.

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. Also, note that this method does not let you specify `RsvgHandleFlags`.

Otherwise, loading an SVG without GIO is not recommended, since librsvg will need to buffer your entire data internally before actually being able to parse it. The deprecated way of doing this is by creating a handle with `rsvg_handle_new()` or `rsvg_handle_new_with_flags()`, and then using `rsvg_handle_write()` and `rsvg_handle_close()` to feed the handle with SVG data. Still, please try to use the GIO stream functions instead.

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

SVG images can contain dimensions like “`5cm`” or “`2pt`” 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.

For historical reasons, the default DPI is 90. Current CSS assumes a default DPI of 96, so you may want to set the DPI of a `RsvgHandle` immediately after creating it with `rsvg_handle_set_dpi()`.

# Rendering

The preferred way to render a whole SVG document is to use `rsvg_handle_render_document()`. Please see its documentation for details.

# API ordering

Due to the way the librsvg API evolved over time, an `RsvgHandle` object is available for use as soon as it is constructed. However, not all of its methods can be called at any time. For example, an `RsvgHandle` just constructed with `rsvg_handle_new()` is not loaded yet, and it does not make sense to call `rsvg_handle_render_document()` on it just at that point.

The documentation for the available methods in `RsvgHandle` may mention that a particular method is only callable on a “fully loaded handle”. This means either:

- The handle was loaded with `rsvg_handle_write()` and `rsvg_handle_close()`, and those functions returned no errors.

- The handle was loaded with `rsvg_handle_read_stream_sync()` and that function returned no errors.

Before librsvg 2.46, the library did not fully verify that a handle was in a fully loaded state for the methods that require it. To preserve compatibility with old code which inadvertently called the API without checking for errors, or which called some methods outside of the expected order, librsvg will just emit a `g_critical()` message in those cases.

New methods introduced in librsvg 2.46 and later will check for the correct ordering, and panic if they are called out of order. This will abort the program as if it had a failed assertion.

#### Ancestors

- GObject

#### Constructors

###### rsvg_handle_new

Returns a new rsvg handle. Must be freed with `g_object_unref()`. This handle can be used to load an image.

###### rsvg_handle_new_from_data

Loads the SVG specified by `data`. Note that this function creates an `RsvgHandle` without a base URL, and without any `RsvgHandleFlags`. If you need these, use `rsvg_handle_new_from_stream_sync()` instead by creating a `GMemoryInputStream` from your data.

since: 2.14

###### rsvg_handle_new_from_file

Loads the SVG specified by `file_name`. Note that this function, like `rsvg_handle_new()`, does not specify any loading flags for the resulting handle. If you require the use of `RsvgHandleFlags`, use `rsvg_handle_new_from_gfile_sync()`.

since: 2.14

###### rsvg_handle_new_from_gfile_sync

Creates a new `RsvgHandle` for `file`.

since: 2.32

###### rsvg_handle_new_from_stream_sync

Creates a new `RsvgHandle` for `stream`.

since: 2.32

###### rsvg_handle_new_with_flags

Creates a new `RsvgHandle` with flags `flags`. After calling this function, you can feed the resulting handle with SVG data by using `rsvg_handle_read_stream_sync()`.

since: 2.36

#### Instance methods

###### rsvg_handle_close

This is used after calling `rsvg_handle_write()` to indicate that there is no more data to consume, and to start the actual parsing of the SVG document. The only reason to call this function is if you use use `rsvg_handle_write()` to feed data into the `handle`; if you use the other methods like `rsvg_handle_new_from_file()` or `rsvg_handle_read_stream_sync()`, then you do not need to call this function.

deprecated: 2.46.

###### rsvg_handle_free

Frees `handle`.

deprecated: Unknown

###### rsvg_handle_get_base_uri

Gets the base uri for this `RsvgHandle`.

since: 2.8

###### rsvg_handle_get_desc

No description available.

deprecated: 2.36. since: 2.4

###### rsvg_handle_get_dimensions

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

deprecated: 2.52. since: 2.14

###### rsvg_handle_get_dimensions_sub

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.

deprecated: 2.46. since: 2.22

###### rsvg_handle_get_geometry_for_element

Computes the ink rectangle and logical rectangle of a single SVG element.

since: 2.46

###### rsvg_handle_get_geometry_for_layer

Computes the ink rectangle and logical rectangle of an SVG element, or the whole SVG, as if the whole SVG were rendered to a specific viewport.

since: 2.46

###### rsvg_handle_get_intrinsic_dimensions

In simple terms, queries the `width`, `height`, and `viewBox` attributes in an SVG document.

since: 2.46

###### rsvg_handle_get_intrinsic_size_in_pixels

Converts an SVG document’s intrinsic dimensions to pixels, and returns the result.

since: 2.52

###### rsvg_handle_get_metadata

No description available.

deprecated: 2.36. since: 2.9

###### rsvg_handle_get_pixbuf

Returns the pixbuf loaded by `handle`. The pixbuf returned will be reffed, so the caller of this function must assume that ref.

deprecated: 2.58.

###### rsvg_handle_get_pixbuf_and_error

Returns the pixbuf loaded by `handle`. The pixbuf returned will be reffed, so the caller of this function must assume that ref.

since: 2.59

###### rsvg_handle_get_pixbuf_sub

Creates a `GdkPixbuf` the same size as the entire SVG loaded into `handle`, but only renders the sub-element that has the specified `id` (and all its sub-sub-elements recursively). If `id` is `NULL`, this function renders the whole SVG.

since: 2.14

###### rsvg_handle_get_position_sub

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.

deprecated: 2.46. since: 2.22

###### rsvg_handle_get_title

No description available.

deprecated: 2.36. since: 2.4

###### rsvg_handle_has_sub

Checks whether the element `id` exists in the SVG document.

since: 2.22

###### rsvg_handle_internal_set_testing

Do not call this function. This is intended for librsvg’s internal test suite only.

###### rsvg_handle_read_stream_sync

Reads `stream` and writes the data from it to `handle`.

since: 2.32

###### rsvg_handle_render_cairo

Draws a loaded SVG handle to a Cairo context. Please try to use `rsvg_handle_render_document()` instead, which allows you to pick the size at which the document will be rendered.

deprecated: 2.52. since: 2.14

###### rsvg_handle_render_cairo_sub

Renders a single SVG element in the same place as for a whole SVG document (a “subset” of the document). Please try to use `rsvg_handle_render_layer()` instead, which allows you to pick the size at which the document with the layer will be rendered.

deprecated: 2.52. since: 2.14

###### rsvg_handle_render_document

Renders the whole SVG document fitted to a viewport.

since: 2.46

###### rsvg_handle_render_element

Renders a single SVG element to a given viewport.

since: 2.46

###### rsvg_handle_render_layer

Renders a single SVG element in the same place as for a whole SVG document.

since: 2.46

###### rsvg_handle_set_base_gfile

Set the base URI for `handle` from `file`.

since: 2.32

###### rsvg_handle_set_base_uri

Set the base URI for this SVG.

since: 2.9

###### rsvg_handle_set_cancellable_for_rendering

Sets a cancellable object that can be used to interrupt rendering while the handle is being rendered in another thread. For example, you can set a cancellable from your main thread, spawn a thread to do the rendering, and interrupt the rendering from the main thread by calling g_cancellable_cancel().

since: 2.59.0

###### rsvg_handle_set_dpi

Sets the DPI at which the `handle` will be rendered. Common values are 75, 90, and 300 DPI.

since: 2.8

###### rsvg_handle_set_dpi_x_y

Sets the DPI at which the `handle` will be rendered. Common values are 75, 90, and 300 DPI.

since: 2.8

###### rsvg_handle_set_size_callback

Sets the sizing function for the `handle`, which can be used to override the size that librsvg computes for SVG images. The `size_func` is called from the following functions:.

deprecated: 2.14.

###### rsvg_handle_set_stylesheet

Sets a CSS stylesheet to use for an SVG document.

since: 2.48

###### rsvg_handle_write

Loads the next `count` bytes of the image. You can call this function multiple times until the whole document is consumed; then you must call `rsvg_handle_close()` to actually parse the document.

deprecated: 2.46.

##### Methods inherited from GObject (43)

Please see GObject for a full list of methods.

#### Properties

###### Rsvg.Handle:base-uri

Base URI, to be used to resolve relative references for resources. See the section “Security and locations of referenced files” for details.

###### Rsvg.Handle:desc

SVG’s description.

deprecated: 2.36.

###### Rsvg.Handle:dpi-x

Horizontal resolution in dots per inch.

###### Rsvg.Handle:dpi-y

Horizontal resolution in dots per inch.

###### Rsvg.Handle:em

Exact width, in pixels, of the rendered SVG before calling the size callback as specified by `rsvg_handle_set_size_callback()`.

deprecated: 2.46.

###### Rsvg.Handle:ex

Exact height, in pixels, of the rendered SVG before calling the size callback as specified by `rsvg_handle_set_size_callback()`.

deprecated: 2.46.

###### Rsvg.Handle:flags

Flags from `RsvgHandleFlags`.

since: 2.36

###### Rsvg.Handle:height

Height, in pixels, of the rendered SVG after calling the size callback as specified by `rsvg_handle_set_size_callback()`.

deprecated: 2.46.

###### Rsvg.Handle:metadata

SVG’s metadata.

deprecated: 2.36.

###### Rsvg.Handle:title

SVG’s title.

deprecated: 2.36.

###### Rsvg.Handle:width

Width, in pixels, of the rendered SVG after calling the size callback as specified by `rsvg_handle_set_size_callback()`.

deprecated: 2.46.

#### Signals

##### Signals inherited from GObject (1)

###### GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

#### Class structure

    struct RsvgHandleClass {
      GObjectClass parent;

    }

Class structure for `RsvgHandle`.

###### Class members

`parent: GObjectClass`

  Parent class.