Package ch.bailu.gtk.gio

Klasse Resource

java.lang.Object
ch.bailu.gtk.type.Type
ch.bailu.gtk.type.Pointer
ch.bailu.gtk.type.Record
ch.bailu.gtk.gio.Resource
Alle implementierten Schnittstellen:
PointerInterface
public class Resource extends Record
Applications and libraries often contain binary or textual data that is
really part of the application, rather than user data. For instance
[`GtkBuilder`](https://docs.gtk.org/gtk4/class.Builder.html) `.ui` files,
splashscreen images, [class@Gio.Menu] markup XML, CSS files, icons, etc.
These are often shipped as files in `$datadir/appname`, or manually
included as literal strings in the code.

The `GResource` API and the
[`glib-compile-resources`](glib-compile-resources.html) program provide a
convenient and efficient alternative to this which has some nice properties.
You maintain the files as normal files, so it’s easy to edit them, but during
the build the files are combined into a binary bundle that is linked into the
executable. This means that loading the resource files are efficient (as they
are already in memory, shared with other instances) and simple (no need to
check for things like I/O errors or locate the files in the filesystem). It
also makes it easier to create relocatable applications.

Resource files can also be marked as compressed. Such files will be included
in the resource bundle in a compressed form, but will be automatically
uncompressed when the resource is used. This is very useful e.g. for larger
text files that are parsed once (or rarely) and then thrown away.

Resource files can also be marked to be preprocessed, by setting the value of the
`preprocess` attribute to a comma-separated list of preprocessing options.
The only options currently supported are:

- `xml-stripblanks` which will use the [`xmllint`](man:xmllint(1)) command
to strip ignorable whitespace from the XML file. For this to work,
the `XMLLINT` environment variable must be set to the full path to
the xmllint executable, or xmllint must be in the `PATH`; otherwise
the preprocessing step is skipped.

- `to-pixdata` (deprecated since gdk-pixbuf 2.32) which will use the
`gdk-pixbuf-pixdata` command to convert images to the [`GdkPixdata`](https://docs.gtk.org/gdk-pixbuf/class.Pixdata.html)
format, which allows you to create pixbufs directly using the data inside
the resource file, rather than an (uncompressed) copy of it. For this, the
`gdk-pixbuf-pixdata` program must be in the `PATH`, or the
`GDK_PIXBUF_PIXDATA` environment variable must be set to the full path to
the `gdk-pixbuf-pixdata` executable; otherwise the resource compiler will
abort. `to-pixdata` has been deprecated since gdk-pixbuf 2.32, as
`GResource` supports embedding modern image formats just as well. Instead
of using it, embed a PNG or SVG file in your `GResource`.

- `json-stripblanks` which will use the
[`json-glib-format`](man:json-glib-format(1)) command to strip ignorable
whitespace from the JSON file. For this to work, the `JSON_GLIB_FORMAT`
environment variable must be set to the full path to the
`json-glib-format` executable, or it must be in the `PATH`; otherwise the
preprocessing step is skipped. In addition, at least version 1.6 of
`json-glib-format` is required.

Resource files will be exported in the `GResource` namespace using the
combination of the given `prefix` and the filename from the `file` element.
The `alias` attribute can be used to alter the filename to expose them at a
different location in the resource namespace. Typically, this is used to
include files from a different source directory without exposing the source
directory in the resource namespace, as in the example below.

Resource bundles are created by the
[`glib-compile-resources`](glib-compile-resources.html) program
which takes an XML file that describes the bundle, and a set of files that
the XML references. These are combined into a binary resource bundle.

An example resource description:
```xml
<?xml version="1.0" encoding="UTF-8"?>
<gresources>
<gresource prefix="/org/gtk/Example">
<file>data/splashscreen.png</file>
<file compressed="true">dialog.ui</file>
<file preprocess="xml-stripblanks">menumarkup.xml</file>
<file alias="example.css">data/example.css</file>
</gresource>
</gresources>
```

This will create a resource bundle with the following files:
```
/org/gtk/Example/data/splashscreen.png
/org/gtk/Example/dialog.ui
/org/gtk/Example/menumarkup.xml
/org/gtk/Example/example.css
```

Note that all resources in the process share the same namespace, so use
Java-style path prefixes (like in the above example) to avoid conflicts.

You can then use [`glib-compile-resources`](glib-compile-resources.html) to
compile the XML to a binary bundle that you can load with
[func@Gio.Resource.load]. However, it’s more common to use the
`--generate-source` and `--generate-header` arguments to create a source file
and header to link directly into your application.
This will generate `get_resource()`, `register_resource()` and
`unregister_resource()` functions, prefixed by the `--c-name` argument passed
to [`glib-compile-resources`](glib-compile-resources.html). `get_resource()`
returns the generated `GResource` object. The register and unregister
functions register the resource so its files can be accessed using
[func@Gio.resources_lookup_data].

Once a `GResource` has been created and registered all the data in it can be
accessed globally in the process by using API calls like
[func@Gio.resources_open_stream] to stream the data or
[func@Gio.resources_lookup_data] to get a direct pointer to the data. You can
also use URIs like `resource:///org/gtk/Example/data/splashscreen.png` with
[iface@Gio.File] to access the resource data.

Some higher-level APIs, such as [`GtkApplication`](https://docs.gtk.org/gtk4/class.Application.html),
will automatically load resources from certain well-known paths in the
resource namespace as a convenience. See the documentation for those APIs
for details.

There are two forms of the generated source, the default version uses the
compiler support for constructor and destructor functions (where available)
to automatically create and register the `GResource` on startup or library
load time. If you pass `--manual-register`, two functions to
register/unregister the resource are created instead. This requires an
explicit initialization call in your application/library, but it works on all
platforms, even on the minor ones where constructors are not supported.
(Constructor support is available for at least Win32, Mac OS and Linux.)

Note that resource data can point directly into the data segment of e.g. a
library, so if you are unloading libraries during runtime you need to be very
careful with keeping around pointers to data from a resource, as this goes
away when the library is unloaded. However, in practice this is not generally
a problem, since most resource accesses are for your own resources, and
resource data is often used once, during parsing, and then released.

# Overlays

When debugging a program or testing a change to an installed version, it is
often useful to be able to replace resources in the program or library,
without recompiling, for debugging or quick hacking and testing purposes.
Since GLib 2.50, it is possible to use the `G_RESOURCE_OVERLAYS` environment
variable to selectively overlay resources with replacements from the
filesystem. It is a `G_SEARCHPATH_SEPARATOR`-separated list of substitutions
to perform during resource lookups. It is ignored when running in a setuid
process.

A substitution has the form

```
/org/gtk/libgtk=/home/desrt/gtk-overlay
```

The part before the `=` is the resource subpath for which the overlay
applies. The part after is a filesystem path which contains files and
subdirectories as you would like to be loaded as resources with the
equivalent names.

In the example above, if an application tried to load a resource with the
resource path `/org/gtk/libgtk/ui/gtkdialog.ui` then `GResource` would check
the filesystem path `/home/desrt/gtk-overlay/ui/gtkdialog.ui`. If a file was
found there, it would be used instead. This is an overlay, not an outright
replacement, which means that if a file is not found at that path, the
built-in version will be used instead. Whiteouts are not currently
supported.

Substitutions must start with a slash, and must not contain a trailing slash
before the `=`. The path after the slash should ideally be absolute, but
this is not strictly required. It is possible to overlay the location of a
single resource with an individual file.

https://docs.gtk.org/gio/struct.Resource.html

  • Konstruktordetails

  • Methodendetails

    • getClassHandler

      public static ClassHandler getClassHandler()

    • newFromDataResource

      public static Resource newFromDataResource(@Nonnull Bytes data) throws AllocationError
      Creates a [struct@Gio.Resource] from a reference to the binary resource bundle.

      This will keep a reference to @data while the resource lives, so
      the data should not be modified or freed.

      If you want to use this resource in the global resource namespace you need
      to register it with [func@Gio.resources_register].

      Note: @data must be backed by memory that is at least pointer aligned.
      Otherwise this function will internally create a copy of the memory since
      GLib 2.56, or in older versions fail and exit the process.

      If @data is empty or corrupt, %G_RESOURCE_ERROR_INTERNAL will be returned.
      Parameter:
      data - A [struct@GLib.Bytes]
      Gibt zurück:
      a new [struct@Gio.Resource], or `NULL` on error
      Löst aus:
      AllocationError

    • register

      public void register()
      Registers the resource with the process-global set of resources.

      Once a resource is registered the files in it can be accessed
      with the global resource lookup functions like
      [func@Gio.resources_lookup_data].

    • unregister

      public void unregister()
      Unregisters the resource from the process-global set of resources.

    • enumerateChildren

      public Strs enumerateChildren(@Nonnull Str path, int lookup_flags) throws AllocationError
      Returns all the names of children at the specified @path in the resource.

      The return result is a `NULL` terminated list of strings which should
      be released with [func@GLib.strfreev].

      If @path is invalid or does not exist in the [struct@Gio.Resource],
      %G_RESOURCE_ERROR_NOT_FOUND will be returned.

      @lookup_flags controls the behaviour of the lookup.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      an array of constant strings
      Löst aus:
      AllocationError

    • enumerateChildren

      public Strs enumerateChildren(String path, int lookup_flags) throws AllocationError
      Returns all the names of children at the specified @path in the resource.

      The return result is a `NULL` terminated list of strings which should
      be released with [func@GLib.strfreev].

      If @path is invalid or does not exist in the [struct@Gio.Resource],
      %G_RESOURCE_ERROR_NOT_FOUND will be returned.

      @lookup_flags controls the behaviour of the lookup.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      an array of constant strings
      Löst aus:
      AllocationError

    • getInfo

      public boolean getInfo(@Nonnull Str path, int lookup_flags, @Nullable Int64 size, @Nullable Int flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      if found returns information about it.

      @lookup_flags controls the behaviour of the lookup.

      The only error this can return is %G_RESOURCE_ERROR_NOT_FOUND, if @path was
      not found in @resource.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      size - a location to place the length of the contents of the file, or `NULL` if the length is not needed
      flags - a location to place the flags about the file, or `NULL` if the length is not needed
      Gibt zurück:
      `TRUE` if the file was found, `FALSE` if there were errors
      Löst aus:
      AllocationError

    • getInfo

      public boolean getInfo(String path, int lookup_flags, @Nullable Int64 size, @Nullable Int flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      if found returns information about it.

      @lookup_flags controls the behaviour of the lookup.

      The only error this can return is %G_RESOURCE_ERROR_NOT_FOUND, if @path was
      not found in @resource.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      size - a location to place the length of the contents of the file, or `NULL` if the length is not needed
      flags - a location to place the flags about the file, or `NULL` if the length is not needed
      Gibt zurück:
      `TRUE` if the file was found, `FALSE` if there were errors
      Löst aus:
      AllocationError

    • hasChildren

      public boolean hasChildren(@Nonnull Str path)
      Returns whether the specified @path in the resource
      has children.
      Parameter:
      path - A pathname inside the resource
      Gibt zurück:
      %TRUE if @path has children

    • hasChildren

      public boolean hasChildren(String path)
      Returns whether the specified @path in the resource
      has children.
      Parameter:
      path - A pathname inside the resource
      Gibt zurück:
      %TRUE if @path has children

    • lookupData

      public Bytes lookupData(@Nonnull Str path, int lookup_flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      returns a [struct@GLib.Bytes] that lets you directly access the data in
      memory.

      The data is always followed by a zero byte, so you
      can safely use the data as a C string. However, that byte
      is not included in the size of the [struct@GLib.Bytes].

      For uncompressed resource files this is a pointer directly into
      the resource bundle, which is typically in some read-only data section
      in the program binary. For compressed files, memory is allocated on
      the heap and the data is automatically uncompressed.

      @lookup_flags controls the behaviour of the lookup.

      This can return error %G_RESOURCE_ERROR_NOT_FOUND if @path was not found in
      @resource, or %G_RESOURCE_ERROR_INTERNAL if decompression of a compressed
      resource failed.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      [struct@GLib.Bytes] or `NULL` on error
      Löst aus:
      AllocationError

    • lookupData

      public Bytes lookupData(String path, int lookup_flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      returns a [struct@GLib.Bytes] that lets you directly access the data in
      memory.

      The data is always followed by a zero byte, so you
      can safely use the data as a C string. However, that byte
      is not included in the size of the [struct@GLib.Bytes].

      For uncompressed resource files this is a pointer directly into
      the resource bundle, which is typically in some read-only data section
      in the program binary. For compressed files, memory is allocated on
      the heap and the data is automatically uncompressed.

      @lookup_flags controls the behaviour of the lookup.

      This can return error %G_RESOURCE_ERROR_NOT_FOUND if @path was not found in
      @resource, or %G_RESOURCE_ERROR_INTERNAL if decompression of a compressed
      resource failed.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      [struct@GLib.Bytes] or `NULL` on error
      Löst aus:
      AllocationError

    • openStream

      public InputStream openStream(@Nonnull Str path, int lookup_flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      returns a [class@Gio.InputStream] that lets you read the data.

      @lookup_flags controls the behaviour of the lookup.

      The only error this can return is %G_RESOURCE_ERROR_NOT_FOUND, if @path was
      not found in @resource.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      [class@Gio.InputStream] or `NULL` on error
      Löst aus:
      AllocationError

    • openStream

      public InputStream openStream(String path, int lookup_flags) throws AllocationError
      Looks for a file at the specified @path in the resource and
      returns a [class@Gio.InputStream] that lets you read the data.

      @lookup_flags controls the behaviour of the lookup.

      The only error this can return is %G_RESOURCE_ERROR_NOT_FOUND, if @path was
      not found in @resource.
      Parameter:
      path - A path name inside the resource
      lookup_flags - A [flags@Gio.ResourceLookupFlags]
      Gibt zurück:
      [class@Gio.InputStream] or `NULL` on error
      Löst aus:
      AllocationError

    • ref

      public Resource ref()
      Atomically increments the reference count of @resource by one.

      This function is threadsafe and may be called from any thread.
      Gibt zurück:
      The passed in [struct@Gio.Resource]

    • unref

      public void unref()
      Atomically decrements the reference count of @resource by one.

      If the reference count drops to 0, all memory allocated by the resource is
      released. This function is threadsafe and may be called from any
      thread.

    • load

      public static Resource load(@Nonnull Str filename) throws AllocationError
      Loads a binary resource bundle and creates a [struct@Gio.Resource]
      representation of it, allowing you to query it for data.

      If you want to use this resource in the global resource namespace you need
      to register it with [func@Gio.resources_register].

      If @filename is empty or the data in it is corrupt,
      %G_RESOURCE_ERROR_INTERNAL will be returned. If @filename doesn’t exist, or
      there is an error in reading it, an error from [ctor@GLib.MappedFile.new]
      will be returned.
      Parameter:
      filename - the path of a filename to load, in the GLib filename encoding
      Gibt zurück:
      a new [struct@Gio.Resource], or `NULL` on error
      Löst aus:
      AllocationError

    • getTypeID

      public static long getTypeID()

    • getParentTypeID

      public static long getParentTypeID()

    • getTypeSize

      public static TypeSystem.TypeSize getTypeSize()

    • getParentTypeSize

      public static TypeSystem.TypeSize getParentTypeSize()

    • getInstanceSize

      public static int getInstanceSize()