Provided by: libafterimage-dev_2.2.12-12build1_amd64 bug

NAME

       afterimage - overview of libAfterImage image library libAfterImage/libAfterImage

NAMElibAfterImage

       - generic imaging library originally designed for AfterStep X Window Manager.

PURPOSE

       libAfterImage  is  the  imaging library implemented for AfterStep X Window Manager. It has
       been generalized to be suitable for any application in need of robust graphics engine.

       It provides facilities for loading images from files of different formats,  compressed  in
       memory  storage  of  images,  scaling,  tinting/shading,  flipping  and superimposition of
       arbitrary number of images over each other. In addition it  allows  for  linear  gradients
       drawing,  and  antialiased/smoothed text drawing using both  FreeType library and X Window
       fonts.

       Primary goals of this library are to achieve  exceptional  quality  of  images  and  text,
       making code fast and small at the same time.  Additional steps are taken to compensate for
       screen colordepth limitation, and different error diffusion algorithms are used to provide
       for smooth images even in low colordepth modes.

HISTORY

       libAfterImage has been implemented as an attempt to address several issues. First one, and
       most important is that X Window System completely lacks any tools for image  manipulation,
       except  for very rudimentary operations. With Introduction of Render extensions in XFree86
       4.0 that situation is changing, but still is far from perfect. There need is therefore  to
       implement  client  side  image  manipulation.  That inturn creates a problem of image data
       transfer between Server and client.

       To avoid that full-time image storage on the client  side  is  needed.   Which  is  memory
       extensive. So there appears to be a need for some in-memory compression.

       On the other side there is an image quality issue. Its easy to write a scaling function by
       simply dropping out or duplicating pixels, but quality is awfull. What is needed  is  very
       fast  averaging/interpolation code. That brings us to the issue of 8 bits per channel. Add
       two pixels together and you get overflow. So all the math has to be performed in different
       colorspace  and  then  converted  back.  On  the other side, such a conversion may discard
       valuable bits, so some compensation method has to be implemented.

       On the text drawing side of things, there are numerous problems just  as  well.  Native  X
       fonts look ugly as soon as you try to show any decently sized text. That is supposed to be
       solved with said Render extensions to XFree86, but as experiense has shown, things  aren't
       as  easy  as  it looks, besides one wants his app to run well under any X Server. FreeType
       library provides a solution, but not always available. Another problem is that if you keep
       all your images on the client side, you want to draw text on client side as well.

       The solution is to provide transparent interface that could use both X fonts and FreeType,
       cache glyphs on the client side and possibly perform smoothing of ugly X fonts.

       There is no library solving all this problems in one  fell  swoop,  except  for  monstrous
       ones, like ImLib.

       Hence libAfterImage has come to life.

DESCRIPTION

       libAfterStep provides sevarl facilities.

       1.  X Visual abstruction layer via ASVisual. This layer handles color management, transfer
       of data to and from X Server, and other screen related stuff.

       2. Scanline handling facility via ASScanline. ASScanline is the most widely used structure
       since image handling is implemented on per-scanline basis.

       3.  Image  storage,  trasformation and rendering via ASImage. ASImage provides for generic
       container used for  any  image  or  text  manipulation.  It  incorporates  such  a  robust
       facilities  as  in-memory RLE compression, separate channel storage of 4 channels ( Alpha,
       Red, Green, and Blue ) with 8 bit per channel.

       4. Simplified font handling facility via ASFont and ASFointManager.  All the font handling
       is done using ASFont structure, no matter what type of font is used. Any font supported by
       X11 and FreeType can be used.

       5. Transparent image file reading  for  many  different  formats.  Included  built-in  XPM
       reading  code and XCF ( GIMP's native format ).  Overall supported: via external libraries
       : XPM, JPEG, PNG, TIFF, GIF via built in code : XPM, XCF, PNM, PPM,  BMP,  ICO,  CUR  Note
       that  XPM  can be supported both via built-in code or via libXpm, depending on compilation
       configuration.  Actuall image file format is autodetected from the file  contents  -  file
       name extension is not used and can be anything at all.

       6.  Image  export  into many popular file formats. Currently implemented : XPM, JPEG, PNG,
       GIF. Work is underway to implement support for TIFF, XCF, BMP, ICO.

       7. Image quantization to arbitrary size colormap.

       8. libAfterImage could be used without X window system, which is coninient for such  thing
       as  web  development.  XML Image manipulation tool, that could be used in such activity is
       included (see ascompose.c)

       9. Image reference counting

USES

       libAfterBase - AfterStep basic functionality library.  That  Includes  Hash  tables,  file
       search  methods, message output, generic types.  However effort has been made to allow for
       standalone configuration as well. If libAfterBase is  not  found  at  compilation  time  -
       libAfterImage will use extract from libAfterBase included with libAfterImage.

SEE ALSO

       Examples API Reference

TODO

       Implement support for Targa and PCX image format and maybe some other formats as well.

       Implement complete support for I18N internationalization.

       Implement color<->pixel conversion for all colordepths.

AUTHOR

       Sasha Vasko <sasha at aftercode dot net>
       libAfterImage/Examples

EXAMPLE

       ASView   -  image loading from the file and displaying in window.  ASScale - image loading
       from file and scaling to arbitrary size.  ASTile  - image loading from  file,  tiling  and
       tinting to arbitrary
                 size and color.  ASMerge - imgae loading and merging with another image.  ASGrad
       - mutlipoint gradient drawing.  ASFlip  - image loading from file and rotation.  ASText  -
       trexturized semitransparent antialised text drawing.

SEE ALSO

       API Reference
       libAfterImage/API Reference

CHILDREN

       Headers :
                ascmap.h asfont.h asimage.h asvisual.h blender.h export.h
                import.h transform.h ximage.h Structures :
                ColorPair
                ASScanline
                ASVisual
                ASImage
                ASImageManager
                ASImageBevel
                ASImageDecoder
                ASImageOutput
                ASImageLayer
                ASGradient
                ASFontManager
                ASFont
                ASGlyph
                ASGlyphRange
                ASColormap
                ASImageExportParams
                ASVectorPalette

       Functions :
         ASScanline handling:
               prepare_scanline(), free_scanline()

         ASVisual initialization :
               query_screen_visual(), setup_truecolor_visual(),
               setup_pseudo_visual(), setup_as_colormap(),
                create_asvisual(), create_asvisual_for_id(),
               destroy_asvisual()

         ASVisual encoding/decoding :
               visual2visual_prop(), visual_prop2visual()

         ASVisual convenience functions :
               create_visual_window(), create_visual_pixmap(),
               create_visual_ximage(), create_visual_gc()

         Colorspace conversion :
                rgb2value(), rgb2saturation(), rgb2hue(), rgb2luminance(),
                rgb2hsv(), rgb2hls(), hsv2rgb(), hls2rgb(),
                degrees2hue16(), hue162degrees(), normalize_degrees_val()

         Image quantization :
                colormap_asimage(), destroy_colormap()

         merge_scanline methods :
                alphablend_scanlines(), allanon_scanlines(),
                tint_scanlines(), add_scanlines(), sub_scanlines(),
                diff_scanlines(), darken_scanlines(), lighten_scanlines(),
                screen_scanlines(), overlay_scanlines(), hue_scanlines(),
                saturate_scanlines(), value_scanlines(),
                colorize_scanlines(), dissipate_scanlines().

         ASImage handling :
                asimage_init(), asimage_start(), create_asimage(),
                clone_asimage(), destroy_asimage()

         ASImage channel data manipulations :
                get_asimage_chanmask(), move_asimage_channel(),
                copy_asimage_channel(), copy_asimage_lines()

         ImageManager Reference counting and managing :
                create_image_manager(), destroy_image_manager(),
                store_asimage(), fetch_asimage(), dup_asimage(),
                release_asimage(), release_asimage_by_name()

         Layers helper functions :
                init_image_layers(), create_image_layers(),
                destroy_image_layers()

         Encoding :
                asimage_add_line(),    asimage_add_line_mono(),
                asimage_print_line()

         Decoding :
                start_image_decoding(), stop_image_decoding(),
                asimage_decode_line (), set_decoder_shift(),
                set_decoder_bevel_geom(), set_decoder_back_color()

         ASImage from scientific data :
                set_asimage_vector(), colorize_asimage_vector(),
                create_asimage_from_vector()

         Output :
                start_image_output(), set_image_output_back_color(),
                toggle_image_output_direction(), stop_image_output()

         X11 conversions :
                ximage2asimage(), pixmap2asimage(), asimage2ximage(),
                asimage2mask_ximage(), asimage2pixmap(), asimage2mask()

         Transformations :
                scale_asimage(), tile_asimage(), merge_layers(),
                   make_gradient(),
                flip_asimage(), mirror_asimage(), pad_asimage(),
                blur_asimage_gauss(), fill_asimage(), adjust_asimage_hsv()

         Import :
                file2ASImage(), file2pixmap()
         Export :
               ASImage2file()

         Text Drawing :
                create_font_manager(), destroy_font_manager(),
                open_freetype_font(), open_X11_font(), get_asfont(),
                release_font(), print_asfont(), print_asglyph(),
                draw_text(), draw_fancy_text()