mirror of
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d2aa626845
Fri Oct 4 21:21:47 2002 Soeren Sandmann <sandmann@daimi.au.dk>
* gtk/gtkhandlebox.c (gtk_handle_box_paint): remove unused
codepath.
* gtk/gtkmenuitem.c (gtk_real_menu_item_{de,}select): call
gtk_widget_queue_draw() instead of gtk_widget_draw().
99 lines
3.8 KiB
Plaintext
99 lines
3.8 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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Module Interface
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<!-- ##### SECTION Short_Description ##### -->
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Extending &gdk-pixbuf;
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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If &gdk-pixbuf; has been compiled with GModule support, it can be extended by
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modules which can load (and perhaps also save) new image and animation
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formats. Each loadable module must export a
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#GdkPixbufModuleFillInfoFunc function named <function>fill_info</function> and
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a #GdkPixbufModuleFillVtableFunc function named
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<function>fill_vtable</function>.
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</para>
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<para>
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In order to make format-checking work before actually loading the modules
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(which may require dlopening image libraries), modules export their
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signatures (and other information) via the <function>fill_info</function>
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function. An external utility, <command>gdk-pixbuf-query-loaders</command>, uses
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this to create a text file containing a list of all available loaders and
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their signatures. This file is then read at runtime by &gdk-pixbuf; to obtain
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the list of available loaders and their signatures.
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</para>
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<para>
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Modules may only implement a subset of the functionality available via
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#GdkPixbufModule. If a particular functionality is not implemented, the
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<function>fill_vtable</function> function will simply not set the corresponding
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function pointers of the #GdkPixbufModule structure. If a module supports
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incremental loading (i.e. provides #begin_load, #stop_load and
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#load_increment), it doesn't have to implement #load, since &gdk-pixbuf; can
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supply a generic #load implementation wrapping the incremental loading.
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</para>
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<para>
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Installing a module is a two-step process:
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<itemizedlist>
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<listitem><para>copy the module file(s) to the loader directory (normally
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<filename><replaceable>libdir</replaceable>/gtk-2.0/<replaceable>version</replaceable>/loaders</filename>,
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unless overridden by the environment variable
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<envar>GDK_PIXBUF_MODULEDIR</envar>)
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</para></listitem>
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<listitem><para>call <command>gdk-pixbuf-query-loaders</command> to update the
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module file (normally
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<filename><replaceable>sysconfdir</replaceable>/gtk-2.0/gdk-pixbuf.loaders</filename>,
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unless overridden by the environment variable
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<envar>GDK_PIXBUF_MODULE_FILE</envar>)
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</para></listitem>
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</itemizedlist>
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</para>
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<para>
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The &gdk-pixbuf; interfaces needed for implementing modules are contained in
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<filename>gdk-pixbuf-io.h</filename> (and
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<filename>gdk-pixbuf-animation.h</filename> if the module supports animations).
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They are not covered by the same stability guarantees as the regular
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&gdk-pixbuf; API. To underline this fact, they are protected by
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<literal>#ifdef GDK_PIXBUF_ENABLE_BACKEND</literal>.
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</para>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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</para>
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<!-- ##### STRUCT GdkPixbufModule ##### -->
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<para>
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A #GdkPixbufModule contains the necessary functions to load and save
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images in a certain file format.
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</para>
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<para>
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A #GdkPixbufModule can be loaded dynamically from a #GModule.
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Each loadable module must contain a #GdkPixbufModuleFillVtableFunc function
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named <function>fill_vtable</function>, which will get called when the module
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is loaded and must set the function pointers of the #GdkPixbufModule.
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</para>
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@module_name: the name of the module, usually the same as the
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usual file extension for images of this type, eg. "xpm", "jpeg" or "png".
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@module_path: the path from which the module is loaded.
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@module: the loaded #GModule.
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@info: a #GdkPixbufFormat holding information about the module.
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@load: loads an image from a file.
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@load_xpm_data: loads an image from data in memory.
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@begin_load: begins an incremental load.
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@stop_load: stops an incremental load.
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@load_increment: continues an incremental load.
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@load_animation: loads an animation from a file.
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@save: saves a #GdkPixbuf to a file.
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@_reserved1:
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@_reserved2:
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@_reserved3:
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@_reserved4:
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@_reserved5:
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@_reserved6:
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