forked from AuroraMiddleware/gtk
206 lines
4.6 KiB
Plaintext
206 lines
4.6 KiB
Plaintext
<!-- ##### SECTION Title ##### -->
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GdkPixbufLoader
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<!-- ##### SECTION Short_Description ##### -->
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Application-driven progressive image loading.
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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#GdkPixbufLoader provides a way for applications to drive the
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process of loading an image, by letting them send the image data
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directly to the loader instead of having the loader read the data
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from a file. Applications can use this functionality instead of
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gdk_pixbuf_new_from_file() or gdk_pixbuf_animation_new_from_file()
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when they need to parse image data in
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small chunks. For example, it should be used when reading an
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image from a (potentially) slow network connection, or when
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loading an extremely large file.
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</para>
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<para>
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To use #GdkPixbufLoader to load an image, just create a new one,
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and call gdk_pixbuf_loader_write() to send the data to it. When
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done, gdk_pixbuf_loader_close() should be called to end the stream
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and finalize everything. The loader will emit three important
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signals throughout the process. The first, "<link
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linkend="GdkPixbufLoader-size-prepared">size_prepared</link>",
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will be called as soon as the image has enough information to
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determine the size of the image to be used. If you want to scale
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the image while loading it, you can call gdk_pixbuf_loader_set_size()
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in response to this signal.
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</para>
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<para>The second signal, "<link
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linkend="GdkPixbufLoader-area-prepared">area_prepared</link>",
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will be called as soon as the pixbuf of the desired has been
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allocated. You can obtain it by calling gdk_pixbuf_loader_get_pixbuf().
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If you want to use it, simply ref it.
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In addition, no actual information will be passed in yet, so the
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pixbuf can be safely filled with any temporary graphics (or an
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initial color) as needed. You can also call
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gdk_pixbuf_loader_get_pixbuf() later and get the same pixbuf.
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</para>
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<para>
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The last signal, "<link
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linkend="GdkPixbufLoader-area-updated">area_updated</link>" gets
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called every time a region is updated. This way you can update a
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partially completed image. Note that you do not know anything
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about the completeness of an image from the area updated. For
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example, in an interlaced image, you need to make several passes
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before the image is done loading.
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</para>
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<refsect2>
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<title>Loading an animation</title>
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<para>
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Loading an animation is almost as easy as loading an
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image. Once the first "<link
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linkend="GdkPixbufLoader-area-prepared">area_prepared</link>" signal
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has been emitted, you can call gdk_pixbuf_loader_get_animation()
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to get the #GdkPixbufAnimation struct and gdk_pixbuf_animation_get_iter()
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to get an #GdkPixbufAnimationIter for displaying it.
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</para>
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</refsect2>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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gdk_pixbuf_new_from_file(), gdk_pixbuf_animation_new_from_file()
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</para>
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<!-- ##### SECTION Stability_Level ##### -->
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<!-- ##### STRUCT GdkPixbufLoader ##### -->
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<para>
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The <structname>GdkPixbufLoader</structname> struct contains only private
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fields.
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</para>
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<!-- ##### SIGNAL GdkPixbufLoader::area-prepared ##### -->
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<para>
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</para>
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@gdkpixbufloader:
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<!-- ##### SIGNAL GdkPixbufLoader::area-updated ##### -->
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<para>
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</para>
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@gdkpixbufloader:
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@arg1:
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@arg2:
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@arg3:
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@arg4:
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<!-- ##### SIGNAL GdkPixbufLoader::closed ##### -->
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<para>
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</para>
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@gdkpixbufloader:
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<!-- ##### SIGNAL GdkPixbufLoader::size-prepared ##### -->
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<para>
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</para>
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@gdkpixbufloader:
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@arg1:
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@arg2:
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<!-- ##### FUNCTION gdk_pixbuf_loader_new ##### -->
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<para>
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</para>
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_new_with_type ##### -->
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<para>
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</para>
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@image_type:
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@error:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_new_with_mime_type ##### -->
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<para>
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</para>
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@mime_type:
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@error:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_get_format ##### -->
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<para>
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</para>
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@loader:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_write ##### -->
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<para>
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</para>
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@loader:
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@buf:
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@count:
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@error:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_set_size ##### -->
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<para>
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</para>
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@loader:
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@width:
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@height:
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<!-- ##### FUNCTION gdk_pixbuf_loader_get_pixbuf ##### -->
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<para>
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</para>
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@loader:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_get_animation ##### -->
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<para>
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</para>
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@loader:
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@Returns:
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<!-- ##### FUNCTION gdk_pixbuf_loader_close ##### -->
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<para>
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</para>
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@loader:
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@error:
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@Returns:
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<!--
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Local variables:
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mode: sgml
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sgml-parent-document: ("../gdk-pixbuf.sgml" "book" "refsect2" "")
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End:
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-->
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