NAME
asvisual- 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
NAME
ARGB32- 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/ColorPart
NAME
IC_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
NAME
ColorPair- convenient structure to hold pair of colors.
SOURCE
libAfterImage/ARGB32_manhattan_distance()
NAME
ARGB32_manhattan_distance()- This function can be used to evaluate closeness of two colors.
SYNOPSIS
long ARGB32_manhattan_distance (long a, long b);
INPUTS
RETURN VALUE
returns calculated Manhattan distance.
libAfterImage/ASVisual
NAME
ASVisual- 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()
NAME
query_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
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()
NAME
setup_truecolor_visual()SYNOPSIS
Bool setup_truecolor_visual( ASVisual *asv );
INPUTS
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()
NAME
setup_pseudo_visual()SYNOPSIS
void setup_pseudo_visual( ASVisual *asv );
INPUTS
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()
NAME
setup_as_colormap()SYNOPSIS
void setup_as_colormap( ASVisual *asv );
INPUTS
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()
NAME
create_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
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.
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