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Mon Nov 13 16:58:43 2000 Owen Taylor <otaylor@redhat.com> * {gtk,gdk,gdk-pixbuf}/Makefile.am: cd to srcdir before calling gtkdoc-fixref, distribute index.sgml. * gtk/gtk-docs.sgml gtk/Makefile.am gtk/gtk-sections.txt gtk/gtk.types: Update
133 lines
3.9 KiB
Plaintext
133 lines
3.9 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() 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 two important
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signals throughout the process. The first, "<link
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linkend="GdkPixbufLoader-area-prepared">area_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. It will pass a
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@GdkPixbuf in. If you want to use it, you can simply ref it. In
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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 the
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gdk_pixbuf_loader_get_pixbuf() once this signal has been emitted
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and get the same pixbuf.
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</para>
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<para>
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The other 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 a little more complex then loading an
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image. In addition to the above signals, there is also a "<link
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linkend="GdkPixbufLoader-frame-done">frame_done</link>" signal,
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as well as an "<link
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linkend="GdkPixbufLoader-animation-done">animation_done</link>"
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signal. The first lets the application know that it is dealing
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with an animation, instead of a static image. It also passes a
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#GdkPixbufFrame in the signal. As before, if you want to keep
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the frame, you need to ref it. Once the first "<link
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linkend="GdkPixbufLoader-frame-done">frame_done</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. Each subsequent frame
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goes through a similar lifecycle. For example "<link
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linkend="GdkPixbufLoader-area-prepared">area_prepared</link>" is
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re-emitted. Then "<link
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linkend="GdkPixbufLoader-area-updated">area_updated</link>" is
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emitted as many times as necessary. Finally, "<link
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linkend="GdkPixbufLoader-animation-done">animation_done</link>"
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is emitted as soon as all frames are done.
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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()
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</para>
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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_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_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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