forked from AuroraMiddleware/gtk
4f0f733060
2000-01-16 Federico Mena Quintero <federico@helixcode.com> * configure.in: Removed the broken --enable-canvas-pixbuf option. Added the stuff necessary to substitute the variables in gnomecanvaspixbufConf.sh.in. * gnomecanvaspixbufConf.sh.in: New gnome-config handler for the tiny gnomecanvaspixbuf library. * Makefile.am: Build gnomecanvaspixbufConf.sh. * gdk-pixbuf/Makefile.am: Create a libgnomecanvaspixbuf and only build it if gdk-pixbuf is being built outside of gnome-libs. * doc/gdk-pixbuf-sections.txt: Added gdk_pixbuf_render_pixmap_and_mask(). * gdk-pixbuf/gdk-pixbuf-render.c (gdk_pixbuf_render_pixmap_and_mask): Renamed from gdk_pixbuf_render_pixmap(). Do not create the mask if it is not needed, and do not use a clipping mask when rendering the pixmap. Tweaked documentation a little. * HACKING: New file with hacking policies for the gdk-pixbuf module. * doc/Makefile.am (tmpl_sources): Added missing backslash. * doc/Makefile.am: Use gnomecanvaspixbuf in gnome-config when scanning for docstrings. * gdk-pixbuf/gdk-pixbuf-util.c (gdk_pixbuf_copy_area): Made sanity checks more stringent. Removed "gint" abominations. Made documentation consistent with the rest of the functions. * doc/gdk-pixbuf-sections.txt: Added gdk_pixbuf_copy_area() to the utilities section.
183 lines
5.4 KiB
Plaintext
183 lines
5.4 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. 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 image
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from a (potentially) slow network connection, or when loading an
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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, and
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call gdk_pixbuf_loader_write() to send the data to it. When done,
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gdk_pixbuf_loader_close() should be called to end the stream and
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finalize everything. The loader will emit two important signals
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throughout the process. The first, #"area_prepared", will be called
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as soon as the image has enough information to determine the size of
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the image to be used. It will pass a @GdkPixbuf in. If you want to
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use it, you can simply ref it. In addition, no actual information
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will be passed in yet, so the pixbuf can be safely filled with any
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temporary graphics (or an initial color) as needed. You can also
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call the gdk_pixbuf_loader_get_pixbuf() once this signal has been
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emitted and get the same pixbuf.
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</para>
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<para>
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The other signal, #"area_updated" gets called every
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time a region is updated. This way you can update a partially
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completed image. Note that you do not know anything about the
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completeness of an image from the area updated. For example, in an
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interlaced image, you need to make several passes before the image
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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
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#"frame_done" signal, as well as an #"animation_done" signal. The
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first lets the application know that it is dealing with an
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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 the
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frame, you need to ref it. Once the first #"frame_done" 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 goes
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through a similar lifecycle. For example #"area_prepared" is
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re-emitted. Then #"area_updated" is emitted as many times as
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necessary. Finally, #"animation_done" is emitted as soon as all
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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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<!-- ##### MACRO GDK_PIXBUF_LOADER ##### -->
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<para>
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Casts a #GtkObject to a #GdkPixbufLoader.
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</para>
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@obj: A GTK+ object.
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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_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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@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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<!-- ##### SIGNAL GdkPixbufLoader::area-updated ##### -->
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<para>
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This signal is emitted when a significant area of the image being
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loaded has been updated. Normally it means that a complete
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scanline has been read in, but it could be a different area as
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well. Applications can use this signal to know when to repaint
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areas of an image that is being loaded.
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</para>
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@gdkpixbufloader: the object which received the signal.
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@arg1:
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@arg2:
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@arg3:
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@arg4:
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<!-- # Unused Parameters # -->
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@loader: Loader which emitted the signal.
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@x: X offset of upper-left corner of the updated area.
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@y: Y offset of upper-left corner of the updated area.
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@width: Width of updated area.
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@height: Height of updated area.
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<!-- ##### SIGNAL GdkPixbufLoader::area-prepared ##### -->
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<para>
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This signal is emitted when the pixbuf loader has been fed the
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initial amount of data that is required to figure out the size and
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format of the image that it will create. After this signal is
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emitted, applications can call gdk_pixbuf_loader_get_pixbuf() to
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fetch the partially-loaded pixbuf.
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</para>
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@gdkpixbufloader: the object which received the signal.
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<!-- # Unused Parameters # -->
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@loader: Loader which emitted the signal.
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<!-- ##### SIGNAL GdkPixbufLoader::frame-done ##### -->
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<para>
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</para>
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@gdkpixbufloader: the object which received the signal.
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<!-- ##### SIGNAL GdkPixbufLoader::animation-done ##### -->
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<para>
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</para>
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@gdkpixbufloader: the object which received the signal.
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<!-- ##### SIGNAL GdkPixbufLoader::closed ##### -->
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<para>
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This signal is emitted when gdk_pixbuf_loader_close() is called.
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It can be used by different parts of an application to receive
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notification when an image loader is closed by the code that
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drives it.
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</para>
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@gdkpixbufloader: the object which received the signal.
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<!-- # Unused Parameters # -->
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@loader: Loader which emitted the signal.
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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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