107 lines
4.0 KiB
Plaintext
107 lines
4.0 KiB
Plaintext
README for GDK-DirectFB
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This is the GDK backend that allows GTK to work on top of DirectFB.
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Important:
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The current code does not pass through directfb passed on the gtk
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apps command line on to directfb you need to set the environment variable
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DFBARGS.
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Example:
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export DFBARGS=system=sdl
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DirectFB is a hardware abstraction layer on top of the Linux
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frame buffer that provides drawing functions, a window stack and
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support for input devices. The code you find here is a backend for
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GDK, the drawing kit used by GTK+.
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As DirectFB provides drawing functions, a windowing stack and manages
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input devices, this is a lightweight GDK port. Some parts of GDK
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require higher level drawing functions that are supported by
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cairo on DirectFB.
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GDK also uses some feature like bitmaps that do not map well to
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modern graphics hardware and are for that reason not yet supported in
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this snapshot. See the file TODO for a list of missing features.
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If you want GTK+ to draw window decorations for you, edit the file
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gtk/gtkwindow-decorate.c and uncomment the line that says
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#define DECORATE_WINDOWS.
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GTK+ application compiled with this version of GTK+ understand some
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additional command-line options special to the DirectFB GDK backend:
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--transparent-unfocused Makes unfocused windows translucent.
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--argb-font Use ARGB surfaces for fonts, needed for some
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broken hardware.
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--glyph-surface-cache Lets you tune the size of the glyph cache,
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the default is to cache glyphs from 8 faces.
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--enable-color-keying This option turns on a hack that does the
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following:
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(1) It overrides the color used to draw the window background to
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gdk_directfb_bg_color as defined in gdkprivate-directfb.h.
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Note that the alpha value only takes effect if the window has
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an alpha channel.
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(2) It also draws all rectangles that are drawn in
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gdk_directfb_bg_color_key in this color (gdk_directfb_bg_color).
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This feature can be used to create windows with translucent background.
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Additionally all DirectFB command-line options as described in the
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directfbrc man-page are supported.
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This version of GTK+ also introduces two new functions that are special
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to the DirectFB version. You need to include gdk/gdkdirectfb.h to be
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able to use them.
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gdk_directfb_window_set_opacity (GdkWindow *window, guchar opacity));
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This function sets the overall opacity for toplevel GDK windows.
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gdk_directfb_visual_by_format (DFBSurfacePixelFormat pixel_format);
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This function returns a GdkVisual for a DirectFB pixelformat and
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thus gives you control over the window surface. If for example
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you want to create a window with alpha channel you can use some
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code like the following:
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visual = gdk_directfb_visual_by_format (DSPF_ARGB);
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cmap = gdk_colormap_new (visual, FALSE);
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gtk_widget_push_colormap (cmap);
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window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
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gtk_widget_pop_colormap ();
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g_object_unref (cmap);
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Don't use these functions if you want to be able to compile your
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application against GTK+-X11 or other GTK+ versions.
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If you are developing a GTK+ application for GTK+-DirectFB make sure
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you use the gtk+-directfb-2.0.pc file when calling pkg-config to get
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the correct compiler and linker flags for GTK+-DirectFB:
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pkg-config --cflags gtk+-directfb-2.0
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pkg-config --libs gtk+-directfb-2.0
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See the file TODO for a list of unimplemented features.
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Detailed and up-to-date instructions on how to build a complete
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set of GTK-DFB libraries is avalable in the WIKI of the DirectFB project
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at the address
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http://www.directfb.org/wiki/index.php/Projects:GTK_on_DirectFB
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This library is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published
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by the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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