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asvisual.3x

NAME

asvisual - abstraction layer on top of X Visuals, focusing on color handling libAfterImage/asvisual.h

NAMEasvisual

- Defines abstraction layer on top of X Visuals, as well as several fundamental color datatypes.

SEE ALSO

 Structures:
         ColorPair
         ASVisual
 
 Functions :
   ASVisual initialization :
         query_screen_visual(), setup_truecolor_visual(),
         setup_pseudo_visual(), setup_as_colormap(),create_asvisual(),
         destroy_asvisual()
 
   ASVisual encoding/decoding :
         visual2visual_prop(), visual_prop2visual()
 
   ASVisual convenience functions :
         create_visual_window(), create_visual_pixmap(),
         create_visual_ximage()
 
 Other libAfterImage modules :
          ascmap.h asfont.h asimage.h asvisual.h blender.h export.h
          import.h transform.h ximage.h
 

AUTHOR

 Sasha Vasko <sasha at aftercode dot net>
 

libAfterImage/alpha

FUNCTION

 Alpha channel adds visibility parameter to color value.
 Alpha channel's value of 0xFF signifies complete visibility, while 0
 makes pixel completely transparent.
 

SOURCE

 #define ALPHA_TRANSPARENT       0x00
 #define ALPHA_SEMI_TRANSPARENT  0x7F
 #define ALPHA_SOLID             0xFF
 

libAfterImage/ARGB32

NAMEARGB32

- main color datatype

FUNCTION

 ARGB32 is fundamental datatype that hold 32bit value corresponding to
 pixels color and transparency value (alpha channel) in ARGB
 colorspace. It is encoded as follows :
 Lowermost 8 bits - Blue channel
 bits 8 to 15     - Green channel
 bits 16 to 23    - Red channel
 bits 24 to 31    - Alpha channel
 

EXAMPLE

 ASTile.1
 

SOURCE

 typedef CARD32 ARGB32;
 #define ARGB32_White            0xFFFFFFFF
 #define ARGB32_Black            0xFF000000
 /* default background color is #FF000000 : */
 #define ARGB32_DEFAULT_BACK_COLOR   ARGB32_Black
 
 #define ARGB32_ALPHA_CHAN       3
 #define ARGB32_RED_CHAN         2
 #define ARGB32_GREEN_CHAN       1
 #define ARGB32_BLUE_CHAN        0
 #define ARGB32_CHANNELS         4
 
 #define MAKE_ARGB32(a,r,g,b)    ((( (CARD32)a)        <<24)| \
                                  ((((CARD32)r)&0x00FF)<<16)| \
                                  ((((CARD32)g)&0x00FF)<<8 )| \
                                  (( (CARD32)b)&0x00FF))
 
 #define MAKE_ARGB32_GREY8(a,l)  (((a)<<24)|(((l)&0x00FF)<<16)| \
                                  (((l)&0x00FF)<<8)|((l)&0x00FF))
 #define ARGB32_ALPHA8(c)        (((c)>>24)&0x00FF)
 #define ARGB32_RED8(c)          (((c)>>16)&0x00FF)
 #define ARGB32_GREEN8(c)        (((c)>>8 )&0x00FF)
 #define ARGB32_BLUE8(c)         ( (c)     &0x00FF)
 #define ARGB32_CHAN8(c,i)       (((c)>>((i)<<3))&0x00FF)
 #define MAKE_ARGB32_CHAN8(v,i)  (((v)&0x0000FF)<<((i)<<3))
 
 #ifdef __GNUC__
 #define ARGB32_ALPHA16(c)       ({ CARD32 __c = ARGB32_ALPHA8(c); __c | (__c<<8);})
 #define ARGB32_RED16(c)         ({ CARD32 __c = ARGB32_RED8(c); __c | (__c<<8);})
 #define ARGB32_GREEN16(c)       ({ CARD32 __c = ARGB32_GREEN8(c); __c | (__c<<8);})
 #define ARGB32_BLUE16(c)        ({ CARD32 __c = ARGB32_BLUE8(c); __c | (__c<<8);})
 #define ARGB32_CHAN16(c,i)      ({ CARD32 __c = ARGB32_CHAN8(c,i); __c | (__c<<8);})
 #else
 #define ARGB32_ALPHA16(c)       ((((c)>>16)&0x00FF00)|(((c)>>24)&0x0000FF))
 #define ARGB32_RED16(c)         ((((c)>>8 )&0x00FF00)|(((c)>>16)&0x0000FF))
 #define ARGB32_GREEN16(c)       (( (c)     &0x00FF00)|(((c)>>8 )&0x0000FF))
 #define ARGB32_BLUE16(c)        ((((c)<<8) &0x00FF00)|(((c)    )&0x0000FF))
 #define ARGB32_CHAN16(c,i)      ((ARGB32_CHAN8(c,i)<<8)|ARGB32_CHAN8(c,i))
 #endif
 
 #define MAKE_ARGB32_CHAN16(v,i) ((((v)&0x00FF00)>>8)<<((i)<<3))
 

libAfterImage/ARGB32_manhattan_distance()

NAMEARGB32_manhattan_distance()

- This function can be used to evaluate closeness of two colors.

SYNOPSIS

 long ARGB32_manhattan_distance (long a, long b);
 

INPUTS

a,

b - ARGB32 color values to calculate Manhattan distance in between

RETURN VALUE

 returns calculated Manhattan distance.
 

libAfterImage/ColorPart

NAMEIC_RED

- red channel IC_GREEN - green channel IC_BLUE - blue channel IC_ALPHA - alpha channel IC_NUM_CHANNELS - number of supported channels

FUNCTION

 Ids of the channels. These are basically synonyms to related ARGB32
 channel numbers
 

SOURCE

 typedef enum
 {
   IC_BLUE   = ARGB32_BLUE_CHAN ,
   IC_GREEN  = ARGB32_GREEN_CHAN,
   IC_RED    = ARGB32_RED_CHAN  ,
   IC_ALPHA  = ARGB32_ALPHA_CHAN,
   IC_NUM_CHANNELS = ARGB32_CHANNELS
 }
 ColorPart;
 

libAfterImage/ColorPair

NAMEColorPair

- convenient structure to hold pair of colors.

SOURCE

 typedef struct ColorPair
 {
   ARGB32 fore;
   ARGB32 back;
 }ColorPair;
 

libAfterImage/ASVisual

NAMEASVisual

- an abstraction layer on top of X Server Visual.

DESCRIPTION

 This structure has been introduced in order to compensate for the
 fact that X may have so many different types of Visuals. It provides
 shortcuts to most Visual data, compensated for differences in Visuals.
 For PseudoColor visual it also contains preallocated set of colors.
 This colormap allows us to write XImages very fast and without
 exhausting available X colors. This colormap consist of 8, 64, or 4096
 colors and constitutes fraction of colors available in particular
 colordepth. This colors are allocated to be evenly spread around RGB
 spectrum. Thus when converting from internal presentation - all we
 need to do is to discard unused bits, and use rest of them bits as
 an index in our colormap. Opposite conversion is much trickier and we
 engage into nasty business of having hash table mapping pixel values
 into colors, or straight table doing same in lower colordepths.
 Idea is that we do all internal processing in 32bit colordepth, and
 ASVisual provides us with means to convert it to actual X display
 format. Respectively ASVisual has methods to write out XImage lines
 and read XImage lines.
 ASVisual creation is a tricky process. Basically first we have to go
 through the list of available Visuals and choose the best suitable.
 Then based on the type of this Visual we have to setup our data
 members and method hooks. Several functions provided for that :
  query_screen_visual()    - will lookup best suitable visual
  setup_truecolor_visual() - will setup hooks if visual is TrueColor
  setup_pseudo_visual()   - will setup hooks and data if Visual is
                             PseudoColor.
  setup_as_colormap()      - will preallocate colors for PseudoColor.
 Alternative to the above is :
  create_asvisual()        - it encapsulates all of the above
                             functionality, and returns completely set
                             up ASVisual object.
 Since Visual selected for ASVisual may differ from default
 ( we choose the best suitable ), all the window creation function
 must provide colormap and some other parameters, like border color
 for example. Thus we created some convenience functions.
 These should be used instead of standard Xlib calls :
  create_visual_window() - to create window
  create_visual_pixmap() - to create pixmap
  create_visual_ximage() - to create XImage
 ASVisual could be dealolocated and its resources freed with :
  destroy_asvisual()
 

EXAMPLE

 asview.c: ASView
 

SOURCE

 typedef struct ASVisual
 {
     Display      *dpy;
 
     /* This envvar will be used to determine what X Visual 
      * (in hex) to use. If unset then best possible will 
      * be selected automagically : */
 #define ASVISUAL_ID_ENVVAR "AFTERIMAGE_VISUAL_ID"
 
     XVisualInfo   visual_info;
     /* this things are calculated based on Visual : */
     unsigned long rshift, gshift, bshift;
     unsigned long rbits,  gbits,  bbits;
     unsigned long true_depth;   /* could be 15 when X reports 16 */
     Bool          BGR_mode;
     Bool          msb_first;
     /* we must have colormap so that we can safely create windows
      * with different visuals even if we are in TrueColor mode : */
     Colormap      colormap;
     Bool          own_colormap; /* tells us to free colormap when we
                                  * done */
     unsigned long black_pixel, white_pixel;
     /* for PseudoColor mode we need some more stuff : */
     enum {
         ACM_None = 0,
         ACM_3BPP,
         ACM_6BPP,
         ACM_12BPP
     } as_colormap_type ;    /* there can only be 64 or 4096 entries
                              * so far ( 6 or 12 bpp) */
     unsigned long *as_colormap; /* array of preallocated colors for
                                  * PseudoColor mode */
     union                       /* reverse color lookup tables : */
     {
         ARGB32              *xref;
         struct ASHashTable  *hash;
     }as_colormap_reverse ;
 
     /* different useful callbacks : */
     CARD32 (*color2pixel_func)    ( struct ASVisual *asv,
                                     CARD32 encoded_color,
                                     unsigned long *pixel);
     void   (*pixel2color_func)    ( struct ASVisual *asv,
                                     unsigned long pixel,
                                     CARD32 *red, CARD32 *green,
                                     CARD32 *blue);
     void   (*ximage2scanline_func)( struct ASVisual *asv, 
                                     XImage *xim,
                                     struct ASScanline *sl, int y,
                                     unsigned char *xim_data );
     void   (*scanline2ximage_func)( struct ASVisual *asv, 
                                     XImage *xim,
                                     struct ASScanline *sl, int y,
                                     unsigned char *xim_data );
 
 #define ASGLX_Unavailable           0
 #define ASGLX_Available             (0x01<<0)
 #define ASGLX_DoubleBuffer          (0x01<<1)
 #define ASGLX_RGBA                  (0x01<<2)
 #define ASGLX_UseForImageTx         (0x01<<3)   
     ASFlagType glx_support ;    /* one of the above flags */
 
     void *glx_scratch_gc_indirect ; /* (GLXContext) */
     void *glx_scratch_gc_direct ;   /* (GLXContext) */
 
     Window scratch_window;
 
 #ifndef X_DISPLAY_MISSING
 #define ARGB2PIXEL(asv,argb,pixel)         \
     (asv)->color2pixel_func((asv),(argb),(pixel))
 #define GET_SCANLINE(asv,xim,sl,y,xim_data) \
     (asv)->ximage2scanline_func((asv),(xim),(sl),(y),(xim_data))
 #define PUT_SCANLINE(asv,xim,sl,y,xim_data) \
     (asv)->scanline2ximage_func((asv),(xim),(sl),(y),(xim_data))
 #else
 #define ARGB2PIXEL(asv,argb,pixel)         \
     do{ break; }while(0)
 #define GET_SCANLINE(asv,xim,sl,y,xim_data) \
     do{ break; }while(0)
 #define PUT_SCANLINE(asv,xim,sl,y,xim_data) \
     do{ break; }while(0)
 #endif
 }ASVisual;
 

libAfterImage/query_screen_visual()

NAMEquery_screen_visual_id()

query_screen_visual()

SYNOPSIS

 Bool query_screen_visual_id( ASVisual *asv, Display *dpy, int screen,
                           Window root, int default_depth,
                              VisualID visual_id, Colormap cmap );
 Bool query_screen_visual( ASVisual *asv, Display *dpy, int screen,
                           Window root, int default_depth );
 

INPUTS

asv

- preallocated ASVisual structure.

dpy

- valid pointer to opened X display.

screen

- screen number on which to query visuals.

root

- root window on that screen.

default_depth-

default colordepth of the screen.

visual_id

- optional ID of preferred Visual.

cmap

- optional colormap to be used.

RETURN VALUE

 True on success, False on failure
 ASVisual structure pointed by asv will have the following data
 members set on success :
 dpy, visual_info, colormap, own_colormap, black_pixel, white_pixel.
 

DESCRIPTION

 query_screen_visual_id() will go though prioritized list of possible
 Visuals and attempt to match those to what is available on the
 specified screen. If all items from list fail, then it goes about
 querying default visual.
 query_screen_visual is identical to query_screen_visual_id with
 visual_id and cmap set to 0.
 Once X Visual has been identified, we create X colormap and allocate
 white and black pixels from it.
 

libAfterImage/setup_truecolor_visual()

NAMEsetup_truecolor_visual()

SYNOPSIS

 Bool setup_truecolor_visual( ASVisual *asv );
 

INPUTS

asv

- preallocated ASVisual structure.

RETURN VALUE

 True on success, False if visual is not TrueColor.
 

DESCRIPTION

 setup_truecolor_visual() checks if Visual is indeed TrueColor and if
 so it goes about querying color masks, deducing real XImage
 colordepth, and whether we work in BGR mode. It then goes about
 setting up correct hooks to X IO functions.
 

libAfterImage/setup_pseudo_visual()

NAMEsetup_pseudo_visual()

SYNOPSIS

 void setup_pseudo_visual( ASVisual *asv  );
 

INPUTS

asv

- preallocated ASVisual structure.

DESCRIPTION

 setup_pseudo_visual() assumes that Visual is PseudoColor. It then
 tries to decide as to how many colors preallocate, and goes about
 setting up correct X IO hooks and possibly initialization of reverse
 colormap in case ASVisual already has colormap preallocated.
 

libAfterImage/setup_as_colormap()

NAMEsetup_as_colormap()

SYNOPSIS

 void setup_as_colormap( ASVisual *asv );
 

INPUTS

asv

- preallocated ASVisual structure.

DESCRIPTION

 That has to be called in order to pre-allocate sufficient number of
 colors. It uses colormap size identification supplied in ASVisual
 structure. If colors where preallocated successfully - it will also
 create reverse lookup colormap.
 

libAfterImage/create_asvisual_for_id()

NAMEcreate_asvisual_for_id()

SYNOPSIS

 ASVisual *create_asvisual_for_id( Display *dpy, int screen,
                                   int default_depth,
                                   VisualID visual_id, Colormap cmap,
                                   ASVisual *reusable_memory );
 

INPUTS

dpy

- valid pointer to opened X display.

screen

- screen number on which to query visuals.

root

- root window on that screen.

default_depth-

default colordepth of the screen.

visual_id

- ID of X visual to use.

cmap

- optional ID of the colormap to be used.

reusable_memory

- pointer to preallocated ASVisual structure.

RETURN VALUE

 Pointer to ASVisual structure initialized with enough information
 to be able to deal with current X Visual.
 

DESCRIPTION

 This function calls all the needed functions in order to setup new
 ASVisual structure for the specified screen and visual. If
 reusable_memory is not null - it will not allocate new ASVisual
 structure, but instead will use supplied one. Useful for allocating
 ASVisual on stack.
 This particular function will not do any autodetection and will use
 Visual ID supplied. That is useful when libAfterImage is used with
 an app that has its own approach to Visual handling, and since Visuals
 on all Windows, Pixmaps and colormaps must match, there is a need to
 synchronise visuals used by an app and libAfterImage.
 

libAfterImage/create_asvisual()

NAMEcreate_asvisual()

SYNOPSIS

 ASVisual *create_asvisual( Display *dpy, int screen,
                            int default_depth,
                            ASVisual *reusable_memory );
 

INPUTS

dpy

- valid pointer to opened X display.

screen

- screen number on which to query visuals.

root

- root window on that screen.

default_depth-

default colordepth of the screen.

reusable_memory

- pointer to preallocated ASVisual structure.

RETURN VALUE

 Pointer to ASVisual structure initialized with enough information
 to be able to deal with current X Visual.
 

DESCRIPTION

 This function calls all the needed functions in order to setup new
 ASVisual structure for the specified screen. If reusable_memory is
 not null - it will not allocate new ASVisual structure, but instead
 will use supplied one. Useful for allocating ASVisual on stack.
 It is different from create_asvisualfor_id() in that it will attempt
 to autodetect best possible visual for the screen. For example on some
 SUN Solaris X servers there will be both 8bpp pseudocolor and 24bpp
 truecolor, and default will be 8bpp. In this scenario libAfterImage
 will detect and use 24bpp true color visual, thus producing much better
 results.
 

libAfterImage/destroy_asvisual()

NAMEdestroy_asvisual()

SYNOPSIS

 void destroy_asvisual( ASVisual *asv, Bool reusable );
 

INPUTS

asv

- valid ASVisual structure.

reusable

- if True it will cause function to not free object itself.

DESCRIPTION

 Cleanup function. Frees all the memory and deallocates all the
 resources. If reusable is False it will also free the object, pointed
 to by asv.
 

EXAMPLE

 asview.c: ASView.2
 

libAfterImage/visual2visual_prop()

NAMEvisual2visual_prop()

SYNOPSIS

 Bool visual2visual_prop( ASVisual *asv, size_t *size,
                          unsigned long *version, unsigned long **data );
 

INPUTS

asv

- valid ASVisual structure.

RETURN VALUE

 size         - size of the encoded memory block.
 version      - version of the encoding
 data         - actual encoded memory block
 True on success, False on failure
 

DESCRIPTION

 This function will encode ASVisual structure into memory block of
 32 bit values, suitable for storing in X property.
 

libAfterImage/visual_prop2visual()

NAMEvisual_prop2visual()

SYNOPSIS

 Bool visual_prop2visual( ASVisual *asv, Display *dpy, int screen,
                          size_t size,
                          unsigned long version, unsigned long *data );
 

INPUTS

asv

- valid ASVisual structure.

dpy

- valid pointer to open X display.

screen

- screen number.

size

- encoded memory block's size.

version

- version of encoding.

data

- actual encoded memory block.

RETURN VALUE

 True on success, False on failure
 

DESCRIPTION

 visual_prop2visual() will read ASVisual data from the memory block
 encoded by visual2visual_prop(). It could be used to read data from
 X property and convert it into usable information - such as colormap,
 visual info, etc.
 Note: setup_truecolor_visual() or setup_pseudo_visual() has to be
 invoked in order to complete ASVisual setup.
 

libAfterImage/create_visual_window()

NAMEcreate_visual_window()

SYNOPSIS

 Window  create_visual_window( ASVisual *asv, Window parent,
                               int x, int y,
                               unsigned int width, unsigned int height,
                               unsigned int border_width,
                               unsigned int wclass,
                               unsigned long mask,
                               XSetWindowAttributes *attributes );
 

INPUTS

asv

- pointer to the valid ASVisual structure.

parent

- Window ID of the parent the window.

x,

y - initial position of the new window.

width,

height - initial size of the new window.

border_width

- initial border width of the new window.

wclass

- Window class - InputOnly or InputOutput.

mask

- defines what attributes are set.

attributes

- different window attributes.

RETURN VALUE

 ID of the newly created window on success. None on failure.
 

DESCRIPTION

 create_visual_window() will do sanity checks on passed parameters,
 it will then add mandatory attributes if needed, and attempt to
 create window for the specified ASVisual.
 

libAfterImage/create_visual_gc()

NAMEcreate_visual_gc()

SYNOPSIS

 GC      create_visual_gc( ASVisual *asv, Window root,
                           unsigned long mask, XGCValues *gcvalues );
 

INPUTS

asv

- pointer to the valid ASVisual structure.

root

- Window ID of the root window of destination screen

mask,

gcvalues - values for creation of new GC - see XCreateGC() for details.

RETURN VALUE

 New GC created for regular window on success. NULL on failure.
 

DESCRIPTION

 create_visual_gc() will create temporary window for the ASVisual
 specific depth and Visual and it will then create GC for such window.
 Obtained GC should be good to be used for manipulation of windows and
 Pixmaps created for the same ASVisual.
 

libAfterImage/create_visual_pixmap()

NAMEcreate_visual_pixmap()

SYNOPSIS

 Pixmap  create_visual_pixmap( ASVisual *asv, Window root,
                               unsigned int width, unsigned int height,
                               unsigned int depth );
 

INPUTS

asv

- pointer to the valid ASVisual structure.

root

- Window ID of the root window of destination screen

width,

height - size of the pixmap to create.

depth

- depth of the pixmap to create. If 0 asv->true_depth will be used.

RETURN VALUE

 ID of the newly created pixmap on success. None on failure.
 

DESCRIPTION

 create_visual_pixmap() will perform sanity checks on passed
 parameters, and attempt to create pixmap for the specified ASVisual,
 root and depth.
 

libAfterImage/create_visual_ximage()

NAMEcreate_visual_ximage()

SYNOPSIS

 XImage* create_visual_ximage( ASVisual *asv,
                               unsigned int width, unsigned int height,
                               unsigned int depth );
 

INPUTS

asv

- pointer to the valid ASVisual structure.

width,

height - size of the XImage to create.

depth

- depth of the XImage to create. If 0 asv->true_depth will be used.

RETURN VALUE

 pointer to newly created XImage on success. NULL on failure.
 

DESCRIPTION

 create_visual_ximage() will perform sanity checks on passed
 parameters, and it will attempt to create XImage of sufficient size,
 and specified colordepth. It will also setup hooks for XImage
 deallocation to be handled by custom function.