libAfterImage/imencdec.h
NAME
imencdecdefines main structures and function for image storing, extraction and conversion to/from usable formats.
DESCRIPTION
this header defines structures and functions to be used by outside applications for reading and writing into ASImages. ASImage pixel data maybe stored in sevral different formats, and should not be accessed directly, but only through encoder/decoder facility.
SEE ALSO
Structures :
ASImageBevel
ASImageDecoder
ASImageOutput
Functions :
Encoding :
asimage_add_line(), asimage_add_line_mono(),
asimage_print_line(), get_asimage_chanmask(),
move_asimage_channel(), copy_asimage_channel(),
copy_asimage_lines()
Decoding
start_image_decoding(), stop_image_decoding(),
asimage_decode_line (), set_decoder_shift(),
set_decoder_back_color()
Output :
start_image_output(), set_image_output_back_color(),
toggle_image_output_direction(), stop_image_output()
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/ASImageBevel
NAME
ASImageBeveldescribes bevel to be drawn around the image.
DESCRIPTION
Bevel is used to create 3D effect while drawing buttons, or any other image that needs to be framed. Bevel is drawn using 2 primary colors: one for top and left sides - hi color, and another for bottom and right sides - low color. There are additionally 3 auxiliary colors: hihi is used for the edge of top-left corner, hilo is used for the edge of top-right and bottom-left corners, and lolo is used for the edge of bottom-right corner. Colors are specified as ARGB and contain alpha component, thus allowing for semitransparent bevels. Bevel consists of outline and inline. Outline is drawn outside of the image boundaries and its size adds to image size as the result. Alpha component of the outline is constant. Inline is drawn on top of the image and its alpha component is fading towards the center of the image, thus creating illusion of smooth disappearing edge.
SOURCE
typedef struct ASImageBevel { #define BEVEL_SOLID_INLINE (0x01<<0) ASFlagType type ; /* reserved for future use */ /* primary bevel colors */ ARGB32 hi_color ; /* top and left side color */ ARGB32 lo_color ; /* bottom and right side color */ /* these will be placed in the corners */ ARGB32 hihi_color ; /* color of the top-left corner */ ARGB32 hilo_color ; /* color of the top-right and * bottom-left corners */ ARGB32 lolo_color ; /* color of the bottom-right corner */ /* outlines define size of the line drawn around the image */ unsigned short left_outline ; unsigned short top_outline ; unsigned short right_outline ; unsigned short bottom_outline ; /* inlines define size of the semitransparent line drawn * inside the image */ unsigned short left_inline ; unsigned short top_inline ; unsigned short right_inline ; unsigned short bottom_inline ; }ASImageBevel;
libAfterImage/ASImageDecoder
NAME
ASImageDecoderdescribes the status of reading any particular ASImage, as well as providing detail on how it should be done.
DESCRIPTION
ASImageDecoder works as an abstraction layer and as the way to automate several operations. Most of the transformations in libAfterImage are performed as operations on ASScanline data structure, that holds all or some of the channels of single image scanline. In order to automate data extraction from ASImage into ASScanline ASImageDecoder has been designed. It has following features : 1) All missing scanlines, or channels of scanlines will be filled with supplied back_color 2) It is possible to leave out some channels of the image, extracting only subset of channels. It is done by setting only needed flags in filter member. 3) It is possible to extract sub-image of the image by setting offset_x and offset_y to top-left corner of sub-image, out_width - to width of the sub-image and calling decode_image_scanline method as many times as height of the sub-image. 4) It is possible to apply bevel to extracted sub-image, by setting bevel member to specific ASImageBevel structure. Extracted Scanlines will be stored in buffer and it will be updated after each call to decode_image_scanline().
SOURCE
/* low level driver (what data to use - native, XImage or ARGB): */ typedef void (*decode_asscanline_func)( struct ASImageDecoder *imdec, unsigned int skip, int y ); /* high level driver (bevel or not bevel): */ typedef void (*decode_image_scanline_func) (struct ASImageDecoder *imdec); typedef struct ASImageDecoder { struct ASVisual *asv; struct ASImage *im ; ASFlagType filter; /* flags that mask set of * channels to be extracted * from the image */ ARGB32 back_color; /* we fill missing scanlines * with this default - black*/ unsigned int offset_x, /* left margin on source image * before which we skip everything */ out_width; /* actual length of the output * scanline */ unsigned int offset_y, /* top margin */ out_height; ASImageBevel *bevel; /* bevel to wrap everything * around with */ /* offsets of the drawn bevel baseline on resulting image : */ int bevel_left, bevel_top, bevel_right, bevel_bottom ; /* scanline buffer containing current scanline */ struct ASScanline buffer; /* matches the out_width */ /* internal data : */ unsigned short bevel_h_addon, bevel_v_addon ; int next_line ; struct ASScanline *xim_buffer; /* matches the size of the * original XImage */ decode_asscanline_func decode_asscanline ; decode_image_scanline_func decode_image_scanline ; }ASImageDecoder;
libAfterImage/asimage/quality
FUNCTION
Defines level of output quality/speed ratio
NAME
ASIMAGE_QUALITY_POORthere will be no dithering and interpolation used while transforming
ASIMAGE_QUALITY_FASTthere will be no dithering and used while transforming but interpolation will be used.
ASIMAGE_QUALITY_GOODsimplified dithering is performed in addition to interpolation.
ASIMAGE_QUALITY_TOPfull dithering and interpolation.
ASIMAGE_QUALITY_DEFAULTrequests current default setting - typically same as ASIMAGE_QUALITY_GOOD.
MAX_GRADIENT_DITHER_LINESdefines number of lines to use for dithering, while rendering gradients, in order to create smooth effect. Higher number will slow things down, but will create better gradients.
SOURCE
#define ASIMAGE_QUALITY_POOR 0 #define ASIMAGE_QUALITY_FAST 1 #define ASIMAGE_QUALITY_GOOD 2 #define ASIMAGE_QUALITY_TOP 3 #define ASIMAGE_QUALITY_DEFAULT -1 #define MAX_GRADIENT_DITHER_LINES ASIMAGE_QUALITY_TOP+1
libAfterImage/asimage/ASImageOutput
NAME
ASImageOutputdescribes the output state of the transformation result. It is used to transparently write results into ASImage or XImage with different levels of quality.
DESCRIPTION
libAfterImage allows for transformation result to be stored in both ASImage ( useful for long term storage and subsequent processing ) and XImage ( useful for transfer of the result onto the X Server). At the same time there are 4 different quality levels of output implemented. They differ in the way special technics, like error diffusion and interpolation are applyed, and allow for fine grained selection of quality/speed ratio. ASIMAGE_QUALITY_GOOD should be good enough for most applications. The following additional output features are implemented : 1) Filling of the missing channels with supplied values. 2) Error diffusion to improve quality while converting from internal 24.8 format to 8 bit format. 3) Tiling of the output. If tiling_step is greater then 0, then each scanlines will be copied into lines found tiling_step one from another, upto the edge of the image. 4) Reverse order of output. Output image will be mirrored along y axis if bottom_to_top is set to True.
NOTES
The output_image_scanline method should be called for each scanline to be stored. Convenience functions listed below should be used to safely alter state of the output instead of direct manipulation of the data members. (makes you pity you don't write in C++ doesn't it ?) Also There is a trick in the way how output_image_scanline handles empty scanlines while writing ASImage. If back_color of empty scanline matches back_color of ASImageOutput - then particular line is erased! If back_colors are same - then particular line of ASImage gets filled with the back_color of ASScanline. First approach is useful when resulting image will be used in subsequent call to merge_layers - in such case knowing back_color of image is good enough and we don't need to store lines with the same color. In case where ASImage will be converted into Pixmap/XImage - second approach is preferable, since that conversion does not take into consideration image's back color - we may want to change it in the future.
SEE ALSO
start_image_output() set_image_output_back_color() toggle_image_output_direction() stop_image_output()
SOURCE
typedef void (*encode_image_scanline_func)( struct ASImageOutput *imout, struct ASScanline *to_store ); typedef void (*output_image_scanline_func)( struct ASImageOutput *, struct ASScanline *, int ); typedef struct ASImageOutput { struct ASVisual *asv; struct ASImage *im ; ASAltImFormats out_format ; CARD32 chan_fill[4]; int buffer_shift; /* -1 means - buffer is empty, * 0 - no shift, * 8 - use 8 bit precision */ int next_line ; /* next scanline to be written */ unsigned int tiling_step; /* each line written will be * repeated with this step until * we exceed image size */ unsigned int tiling_range; /* Limits region in which we need * to tile. If set to 0 then image * height is used */ int bottom_to_top; /* -1 if we should output in * bottom to top order, * +1 otherwise*/ int quality ; /* see above */ output_image_scanline_func output_image_scanline ; /* high level interface - division, * error diffusion as well * as encoding */ encode_image_scanline_func encode_image_scanline ; /* low level interface - * encoding only */ /* internal data members : */ struct ASScanline buffer[2], *used, *available; }ASImageOutput;
libAfterImage/asimage/start_image_decoding()
NAME
start_image_decoding()- allocates and initializes decoder structure.
SYNOPSIS
ASImageDecoder *start_image_decoding( ASVisual *asv,ASImage *im, ASFlagType filter, int offset_x, int offset_y, unsigned int out_width, unsigned int out_height, ASImageBevel *bevel );
INPUTS
RETURN VALUE
start_image_decoding() returns pointer to newly allocated ASImageDecoder structure on success, NULL on failure.
DESCRIPTION
Normal process of reading image data from ASImage consists of 3 steps : 1) start decoding by calling start_image_decoding. 2) call decode_image_scanline() method of returned structure, for each scanline upto desired height of the target image. Decoded data will be returned in buffer member of the ASImageDecoder structure. 3) finish decoding and deallocated all the used memory by calling stop_image_decoding()
libAfterImage/asimage/set_decoder_bevel_geom()
NAME
set_decoder_bevel_geom()- changes default placement of the bevel on decoded image.
SYNOPSIS
void set_decoder_bevel_geom( ASImageDecoder *imdec, int x, int y, unsigned int width, unsigned int height );
INPUTS
DESCRIPTION
For example if you only need to render small part of the button, that is being rendered from transparency image. NOTE This call modifies bevel_h_addon and bevel_v_addon of ASImageDecoder structure.
libAfterImage/asimage/set_decoder_shift()
NAME
set_decoder_shift()- changes the shift value of decoder - 8 or 0.
SYNOPSIS
void set_decoder_shift( ASImageDecoder *imdec, int shift );
INPUTS
DESCRIPTION
This function should be used instead of directly modifyeing value of shift memebr of ASImageDecoder structure.
libAfterImage/asimage/set_decoder_back_color()
NAME
set_decoder_back_color()- changes the back color to be used while decoding the image.
SYNOPSIS
void set_decoder_back_color( ASImageDecoder *imdec, ARGB32 back_color );
INPUTS
DESCRIPTION
This function should be used instead of directly modifyeing value of back_color memebr of ASImageDecoder structure.
libAfterImage/asimage/stop_image_decoding()
NAME
stop_image_decoding()- finishes decoding, frees all allocated memory.
SYNOPSIS
void stop_image_decoding( ASImageDecoder **pimdec );
INPUTS
RETURN VALUE
pimdec - pointer to ASImageDecoder will be reset to NULL.
SEE ALSO
start_image_decoding()
libAfterImage/asimage/start_image_output()
NAME
start_image_output()- initializes output structure
SYNOPSIS
ASImageOutput *start_image_output ( struct ASVisual *asv, ASImage *im, ASAltImFormats format, int shift, int quality );
INPUTS
DESCRIPTION
start_image_output() creates and initializes new ASImageOutput structure based on supplied parameters. Created structure can be subsequently used to write scanlines into destination image. It is effectively hiding differences of XImage and ASImage and other available output formats. outpt_image_scanline() method of the structure can be used to write out single scanline. Each written scanlines moves internal pointer to the next image line, and possibly writes several scanlines at once if tiling_step member is not 0.
libAfterImage/asimage/set_image_output_back_color()
NAME
set_image_output_back_color()- changes background color of output
SYNOPSIS
void set_image_output_back_color ( ASImageOutput *imout, ARGB32 back_color );
INPUTS
libAfterImage/asimage/toggle_image_output_direction()
NAME
toggle_image_output_direction()- reverses vertical direction of output
SYNOPSIS
void toggle_image_output_direction( ASImageOutput *imout );
INPUTS
DESCRIPTION
reverses vertical direction output. If previously scanlines has been written from top to bottom, for example, after this function is called they will be written in opposite direction. Current line does not change, unless it points to the very first or the very last image line. In this last case it will be moved to the opposing end of the image.
libAfterImage/asimage/stop_image_output()
NAME
stop_image_output()- finishes output, frees all the allocated memory.
SYNOPSIS
void stop_image_output( ASImageOutput **pimout );
INPUTS
RETURN VALUE
pimout - pointer to ASImageOutput will be reset to NULL.
DESCRIPTION
Completes image output process. Flushes all the internal buffers. Deallocates all the allocated memory. Resets pointer to NULL to avoid dereferencing invalid pointers.
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