Asimage- internal structures and methods used for image manipulation in libafterimage libafterimage/asimage.h
defines main structures and function for image manipulation.
libAfterImage provides powerful functionality to load, store and transform images. It allows for smaller memory utilization by utilizing run-length encoding of the image data. There could be different levels of compression selected, allowing to choose best speed/memory ratio.
Structures :
ASImage
ASImageManager
ASImageBevel
ASImageDecoder
ASImageOutput
ASImageLayer
ASGradient
Functions :
asimage_init(), asimage_start(), create_asimage(),
clone_asimage(), destroy_asimage()
ImageManager Reference counting and managing :
create_image_manager(), destroy_image_manager(),
store_asimage(), fetch_asimage(), query_asimage(),
dup_asimage(), release_asimage(),
release_asimage_by_name(), forget_asimage(),
safe_asimage_destroy()
Gradients helper functions :
flip_gradient(), destroy_asgradient()
Layers helper functions :
init_image_layers(), create_image_layers(),
destroy_image_layers()
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
Sasha Vasko <sasha at aftercode dot net> libAfterImage/ASAltImFormats
identifies what output format should be used for storing the transformation result. Also identifies what data is currently stored in alt member of ASImage structure.
typedef enum {
ASA_ASImage = 0,
ASA_XImage,
ASA_MaskXImage,
/* temporary XImages to be allocated from static pool of memory :*/
ASA_ScratchXImage,
ASA_ScratchMaskXImage,
ASA_ScratchXImageAndAlpha,
ASA_ARGB32,
ASA_Vector, /* This cannot be used for transformation's result
* format */
ASA_Formats
}ASAltImFormats;
libAfterImage/ASImage
is the main structure to hold image data.
Images are stored internally split into ARGB channels, each split into scanline. Actuall data is stored using ASStorage container. Inside ASImage data structure we only store IDs pointing to data in ASStorage ASStorage implements reference counting, data compression, automatic memory defragmentation and other nice things.
asimage_init() asimage_start() create_asimage() destroy_asimage()
struct ASImageAlternative; struct ASImageManager;
/* magic number identifying ASFont data structure */ #define MAGIC_ASIMAGE 0xA3A314AE
typedef struct ASImage {
unsigned long magic ;
unsigned int width, height; /* size of the image in pixels */
/* arrays of storage ids of stored scanlines of particular channel: */
ASStorageID *alpha,
*red,
*green,
*blue;
ASStorageID *channels[IC_NUM_CHANNELS];
/* merely a shortcut so we can
* somewhat simplify code in loops */
ARGB32 back_color ; /* background color of the image, so
* we could discard everything that
* matches it, and then restore it
* back. */
struct ASImageAlternative
{ /* alternative forms of ASImage storage : */
XImage *ximage ; /* pointer to XImage created as the
* result of transformations whenever
* we request it to output into
* XImage ( see to_xim parameter ) */
XImage *mask_ximage ; /* XImage of depth 1 that could be
* used to store mask of the image */
ARGB32 *argb32 ; /* array of widthxheight ARGB32
* values */
double *vector ; /* scientific data that should be used
* in conjunction with
* ASScientificPalette to produce
* actuall ARGB data */
}alt;
struct ASImageManager *imageman; /* if not null - then image could be
* referenced by some other code */
int ref_count ;/* this will tell us what us how many
* times */
char *name ; /* readonly copy of image name
* this name is a hash value used to
* store image in the image-man's hash,
* and gets freed automagically on image
* removal from hash */
#define ASIM_DATA_NOT_USEFUL (0x01<<0) #define ASIM_VECTOR_TOP2BOTTOM (0x01<<1) #define ASIM_XIMAGE_8BIT_MASK (0x01<<2) #define ASIM_NO_COMPRESSION (0x01<<3) /* Do not use compression to
* save some computation time
*/
#define ASIM_ALPHA_IS_BITMAP (0x01<<4) #define ASIM_RGB_IS_BITMAP (0x01<<5) #define ASIM_XIMAGE_NOT_USEFUL (0x01<<6) #define ASIM_NAME_IS_FILENAME (0x01<<7)
ASFlagType flags ; /* combination of the above flags */
} ASImage;
libAfterImage/ASImageManager
structure to be used to maintain list of loaded images for given set of search paths and gamma. Images are named and reference counted.
typedef struct ASImageManager {
ASHashTable *image_hash ;
/* misc stuff that may come handy : */
char *search_path[MAX_SEARCH_PATHS+1];
double gamma ;
}ASImageManager;
libAfterImage/LIMITS
effectively limits size of the allowed images to be loaded from files. That is needed to be able to filter out corrupt files. MAX_BEVEL_OUTLINE Limit on bevel outline to be drawn around the image. MAX_SEARCH_PATHS Number of search paths to be used while loading images from files.
#define MAX_IMPORT_IMAGE_SIZE 8000 #define MAX_BEVEL_OUTLINE 100 #define MAX_SEARCH_PATHS 8 /* prudently limiting ourselfs */
libAfterImage/ASVectorPalette
contains palette allowing us to map double values in vector image data into actuall ARGB values.
typedef struct ASVectorPalette {
unsigned int npoints ;
double *points ;
CARD16 *channels[IC_NUM_CHANNELS] ; /* ARGB data for key points. */
ARGB32 default_color;
}ASVectorPalette;
libAfterImage/asimage/ASImageLayer
specifies parameters of the image superimposition.
libAfterImage allows for simultaneous superimposition (overlaying) of arbitrary number of images. To facilitate this ASImageLayer structure has been created in order to specify parameters of each image participating in overlaying operation. Images need not to be exact same size. For each image its position on destination is specified via dst_x and dst_y data members. Each image maybe tiled and clipped to fit into rectangle specified by clip_x, clip_y, clip_width, clip_height ( in image coordinates - not destination ). If image is missing, then area specified by dst_x, dst_y, clip_width, clip_height will be filled with solid_color. Entire image will be tinted using tint parameter prior to overlaying. Bevel specified by bevel member will be drawn over image prior to overlaying. Specific overlay method has to be specified. merge_scanlines method is pointer to a function, that accepts 2 ASScanlines as arguments and performs overlaying of first one with the second one. There are 15 different merge_scanline methods implemented in libAfterImage, including alpha-blending, tinting, averaging, HSV and HSL colorspace operations, etc.
ASImageLayer s could be organized into chains using next pointers. Since there could be a need to rearrange layers and maybe bypass some layers - we need to provide for flexibility, while at the same time allowing for simplicity of arrays. As the result next pointers could be used to link together continuous arrays of layer, like so : array1: [layer1(next==NULL)][layer2(next!=NULL)]
____________________________|
V
array2: [layer3(next==NULL)][layer4(next==NULL)][layer5(next!=NULL)]
________________________________________________|
V
array3: [layer6(next==NULL)][layer7(next==layer7)]
^______|
While iterating through such a list we check for two conditions - exceeding count of layers and layer pointing to self. When any of that is met - we stopping iteration.
merge_layers() blender.h
typedef struct ASImageLayer {
ASImage *im;
ARGB32 solid_color ; /* If im == NULL, then fill
* the area with this color. */
int dst_x, dst_y; /* placement in overall
* composition */
/* clip area could be partially outside of the image -
* image gets tiled in it */
int clip_x, clip_y;
unsigned int clip_width, clip_height;
ARGB32 tint ; /* if 0 - no tint */
struct ASImageBevel *bevel ; /* border to wrap layer with
* (for buttons, etc.)*/
/* if image is clipped then we need to specify offsets of bevel as
* related to clipped rectangle. Normally it should be :
* 0, 0, im->width, im->height. And if width/height left 0 - it will
* default to this values. Note that clipped image MUST be entirely
* inside the bevel rectangle. !!!*/
int bevel_x, bevel_y;
unsigned int bevel_width, bevel_height;
int merge_mode ; /* reserved for future use */
merge_scanlines_func merge_scanlines ; /* overlay method */
struct ASImageLayer *next; /* optional pointer to next
* layer. If it points to
* itself - then end of the
* chain.*/
void *data; /* hook to hung data on */
}ASImageLayer;
libAfterImage/asimage/GRADIENT_TYPE_flags
Combination of this flags defines the way gradient is rendered.
when set it will cause gradient's direction to be rotated by 45 degrees GRADIENT_TYPE_ORIENTATION will cause gradient direction to be rotated by 90 degrees. When combined with GRADIENT_TYPE_DIAG - rotates gradient direction by 135 degrees.
#define GRADIENT_TYPE_DIAG (0x01<<0) #define GRADIENT_TYPE_ORIENTATION (0x01<<1) #define GRADIENT_TYPE_MASK (GRADIENT_TYPE_ORIENTATION| \
GRADIENT_TYPE_DIAG)
libAfterImage/asimage/GRADIENT_TYPE
This are named combinations of above flags to define type of gradient.
normal left-to-right gradient. GRADIENT_TopLeft2BottomRight diagonal top-left to bottom-right. GRADIENT_Top2Bottom vertical top to bottom gradient. GRADIENT_BottomLeft2TopRight diagonal bottom-left to top-right.
#define GRADIENT_Left2Right 0 #define GRADIENT_TopLeft2BottomRight GRADIENT_TYPE_DIAG #define GRADIENT_Top2Bottom GRADIENT_TYPE_ORIENTATION #define GRADIENT_BottomLeft2TopRight (GRADIENT_TYPE_DIAG| \
GRADIENT_TYPE_ORIENTATION)
libAfterImage/ASGradient
describes how gradient is to be drawn.
libAfterImage includes functionality to draw multipoint gradients in 4 different directions left->right, top->bottom and diagonal lefttop->rightbottom and bottomleft->topright. Each gradient described by type, number of colors (or anchor points), ARGB values for each color and offsets of each point from the beginning of gradient in fractions of entire length. There should be at least 2 anchor points. very first point should have offset of 0. and last point should have offset of 1. Gradients are drawn in ARGB colorspace, so it is possible to have semitransparent gradients.
make_gradient()
typedef struct ASGradient {
int type; /* see GRADIENT_TYPE above */
int npoints; /* number of anchor points */
ARGB32 *color; /* ARGB color values for each anchor point*/
double *offset; /* offset of each point from the beginning in
* fractions of entire length */
}ASGradient;
libAfterImage/asimage/flip
This are flags that define rotation angle.
defines rotation of 90 degrees counterclockwise. FLIP_UPSIDEDOWN defines rotation of 180 degrees counterclockwise. combined they define rotation of 270 degrees counterclockwise.
#define FLIP_VERTICAL (0x01<<0) #define FLIP_UPSIDEDOWN (0x01<<1) #define FLIP_MASK (FLIP_UPSIDEDOWN|FLIP_VERTICAL)
libAfterImage/asimage/flip_gradient()
- rotates gradient in 90 degree increments.
ASGradient *flip_gradient( ASGradient *orig, int flip );
- pointer to original ASGradient structure to be rotated.
- value defining desired rotation.
Same as original gradient if flip is 0. New gradient structure in any other case.
Rotates ( flips ) gradient data in 90 degree increments. When needed order of points is reversed. libAfterImage/asimage/tint
We use 32 bit ARGB values to define how tinting should be done. The formula for tinting particular channel data goes like that: tinted_data = (image_data * tint)/128 So if tint channel value is greater then 127 - same channel will be brighter in destination image; if it is lower then 127 - same channel will be darker in destination image. Tint channel value of 127 ( or 0x7F hex ) does not change anything. Alpha channel is tinted as well, allowing for creation of semitransparent images. Calculations are performed in 24.8 format - with 8 bit precision. Result is saturated to avoid overflow, and precision is carried over to next pixel ( error diffusion ), when con verting 24.8 to 8 bit format.
special value that disables tinting TINT_LEAVE_SAME also disables tinting.
#define TINT_NONE 0 #define TINT_LEAVE_SAME (0x7F7F7F7F) #define TINT_HALF_DARKER (0x3F3F3F3F) #define TINT_HALF_BRIGHTER (0xCFCFCFCF) #define TINT_RED (0x7F7F0000) #define TINT_GREEN (0x7F007F00) #define TINT_BLUE (0x7F00007F)
libAfterImage/asimage/compression
Defines the level of compression to attempt on ASImage scanlines.
defined as 0 - disables compression. ASIM_COMPRESSION_FULL defined as 100 - highest compression level. Anything in between 0 and 100 will cause only part of the scanline to be compressed. This is obsolete. Now all images are compressed if possible. libAfterImage/asimage/asimage_init()
frees datamembers of the supplied ASImage structure, and initializes it to all 0.
void asimage_init (ASImage * im, Bool free_resources);
- pointer to valid ASImage structure
- if True will make function attempt to free all non-NULL pointers. libAfterImage/asimage/flush_asimage_cache()
destroys XImage and mask XImage kept from previous conversions to/from X Pixmap.
void flush_asimage_cache (ASImage * im );
- pointer to valid ASImage structure libAfterImage/asimage/asimage_start()
Allocates memory needed to store scanline of the image of supplied size. Assigns all the data members valid values. Makes sure that ASImage structure is ready to store image data.
void asimage_start (ASImage * im, unsigned int width,
unsigned int height,
unsigned int compression);
- pointer to valid ASImage structure
- width of the image
- height of the image
- level of compression to perform on image data. compression has to be in range of 0-100 with 100 signifying highest level of compression.
In order to resize ASImage structure after asimage_start() has been called, asimage_init() must be invoked to free all the memory, and then asimage_start() has to be called with new dimensions. libAfterImage/asimage/create_asimage()
Performs memory allocation for the new ASImage structure, as well as initialization of allocated structure based on supplied parameters.
ASImage *create_asimage( unsigned int width,
unsigned int height,
unsigned int compression);
- desired image width
- desired image height
- compression level in new ASImage( see asimage_start() for more ).
Pointer to newly allocated and initialized ASImage structure on Success. NULL in case of any kind of error - that should never happen. libAfterImage/asimage/clone_asimage()
ASImage *clone_asimage(ASImage *src, ASFlagType filter );
- original ASImage.
- bitmask of channels to be copied from one image to another.
New ASImage, as a copy of original image.
Creates exact clone of the original ASImage, with same compression, back_color and rest of the attributes. Only ASImage data will be carried over. Any attached alternative forms of images (XImages, etc.) will not be copied. Any channel with unset bit in filter will not be copied. Image name, ASImageManager and ref_count will not be copied - use store_asimage() afterwards and make sure you use different name, to avoid clashes with original image. libAfterImage/asimage/destroy_asimage()
frees all the memory allocated for specified ASImage.
void destroy_asimage( ASImage **im );
- pointer to valid ASImage structure.
If there was XImage attached to it - it will be deallocated as well.
asview.c: ASView.5 libAfterImage/asimage/asimage_replace()
will replace ASImage's data using data from another ASImage
Bool asimage_replace (ASImage *im, ASImage *from);
- pointer to valid ASImage structure.
- pointer to ASImage from which to take the data.
this function updates image without reallocating structure itself, which means that all pointers to it will still be valid. If that function succeeds - [from] ASImage will become unusable and should be deallocated using free() call. libAfterImage/asimage/set_asimage_vector()
This function replaces contents of the vector member of ASImage structure with new double precision data.
set_asimage_vector( ASImage *im, register double *vector );
- pointer to valid ASImage structure.
- scientific data to attach to the image.
Data must have size of width*height ahere width and height are size of the ASImage. libAfterImage/asimage/vectorize_asimage()
This function replaces contents of the vector member of ASImage structure with new double precision data, generated from native ARGB32 image contents. Color palette is generated by indexing color values using max_colors, dither and opaque_threshold parameters.
ASVectorPalette* vectorize_asimage( ASImage *im,
unsigned int max_colors,
unsigned int dither,
int opaque_threshold );
- pointer to valid ASImage structure.
- maximum size of the colormap.
- number of bits to strip off the color data ( 0...7 )
- alpha channel threshold at which pixel should be treated as opaque
pointer to the ASVectorPalette structure that could be used for reverse conversion from double values to ARGB32.
alt.vector member of the supplied ASImage will be replaced and will contain WIDTHxHEIGHT double values representing generated scientific data. libAfterImage/asimage/create_image_manager()
create ASImage management and reference counting object.
ASImageManager *create_image_manager( ASImageManager *reusable_memory,
double gamma, ... );
- optional pointer to a block of memory to be used to store ASImageManager object.
gamma - value of gamma correction to be used while loading images from files.
- NULL terminated list of up to 8 PATH strings to list locations at which images could be found.
Creates ASImageManager object in memory and initializes it with requested gamma value and PATH list. This Object will contain a hash table referencing all the loaded images. When such object is used while loading images from the file - gamma and PATH values will be used, so that all the loaded and referenced images will have same parameters. File name will be used as the image name, and if same file is attempted to be loaded again - instead reference will be incremented, and previously loaded image will be retyrned. All the images stored in ASImageManager's table will contain a back pointer to it, and they must be deallocated only by calling release_asimage(). destroy_asimage() will refuse to deallocate such an image. libAfterImage/asimage/destroy_image_manager()
destroy management obejct.
void destroy_image_manager( struct ASImageManager *imman,
Bool reusable );
- pointer to ASImageManager object to be deallocated
- if True, then memory that holds object itself will not be deallocated. Useful when object is created on stack.
Destroys all the referenced images, PATH values and if reusable is False, also deallocates object's memory. libAfterImage/asimage/store_asimage()
add ASImage to the reference.
Bool store_asimage( ASImageManager* imageman, ASImage *im,
const char *name );
- pointer to valid ASImageManager object.
- pointer to the image to be stored.
- unique name of the image.
Adds specifyed image to the ASImageManager's list of referenced images. Stored ASImage could be deallocated only by release_asimage(), or when ASImageManager object itself is destroyed. libAfterImage/asimage/relocate_asimage()
relocate ASImage into a different image manager.
void relocate_asimage( ASImageManager* to_imageman, ASImage *im );
- pointer to valid ASImageManager object.
- pointer to the image to be stored.
Moves image from one ASImageManager's list of referenced images into another ASImageManager. Reference count will be kept the same. libAfterImage/asimage/fetch_asimage()
query_asimage()
ASImage *fetch_asimage( ASImageManager* imageman, const char *name ); ASImage *query_asimage( ASImageManager* imageman, const char *name );
- pointer to valid ASImageManager object.
- unique name of the image.
Looks for image with the name in ASImageManager's list and if found, returns pointer to it. Note that query_asimage() does not increment reference count, while fetch_asimage() does. Therefore if fetch_asimage() is used - release_asimage() should be called , when image is no longer in use. libAfterImage/asimage/dup_asimage()
increment reference count of stored ASImage.
ASImage *dup_asimage( ASImage* im );
- pointer to already referenced image. libAfterImage/asimage/release_asimage()
decrement reference count for given ASImage. release_asimage_by_name() decrement reference count for ASImage identifyed by its name.
int release_asimage( ASImage *im ); int release_asimage_by_name( ASImageManager *imman, char *name );
- pointer to already referenced image.
- pointer to valid ASImageManager object.
- unique name of the image.
Decrements reference count on the ASImage object and destroys it if reference count is below zero. libAfterImage/asimage/forget_asimage()
remove ASImage from ASImageManager's hash by pointer. forget_asimage_name() remove ASImage from ASImageManager's hash by its name.
void forget_asimage( ASImage *im ); void forget_asimage_name( ASImageManager *imman, const char *name );
pointer to already referenced image.
pointer to valid ASImageManager object.
unique name of the image. libAfterImage/safe_asimage_destroy()
either release or destroy asimage, checking if it is attached to ASImageManager.
int safe_asimage_destroy( ASImage *im );
pointer to and ASImage structure. libAfterImage/print_asimage_manager()
prints list of images referenced in given ASImageManager structure. libAfterImage/asimage/destroy_asgradient()
- destroy ASGradient structure, deallocating all associated memory libAfterImage/asimage/init_image_layers()
- initialize set of ASImageLayer structures.
void init_image_layers( register ASImageLayer *l, int count );
- pointer to valid ASImageLayer structure.
- number of elements to initialize.
Initializes array on ASImageLayer structures to sensible defaults. Basically - all zeros and merge_scanlines == alphablend_scanlines. libAfterImage/asimage/create_image_layers()
- allocate and initialize set of ASImageLayer's.
ASImageLayer *create_image_layers( int count );
- number of ASImageLayer structures in allocated array.
Pointer to newly allocated and initialized array of ASImageLayer structures on Success. NULL in case of any kind of error - that should never happen.
Performs memory allocation for the new array of ASImageLayer structures, as well as initialization of allocated structure to sensible defaults - merge_func will be set to alphablend_scanlines. libAfterImage/asimage/destroy_image_layers()
- destroy set of ASImageLayer structures.
void destroy_image_layers( register ASImageLayer *l,
int count,
Bool reusable );
- pointer to pointer to valid array of ASImageLayer structures.
- number of structures in array.
- if True - then array itself will not be deallocates - which is usable when it was allocated on stack.
frees all the memory allocated for specified array of ASImageLayer s. If there was ASImage and/or ASImageBevel attached to it - it will be deallocated as well. libAfterImage/asimage/asimage_add_line()
size_t asimage_add_line ( ASImage * im, ColorPart color,
CARD32 * data, unsigned int y);
- pointer to valid ASImage structure
- color channel's number
- raw channel data of 32 bits per pixel - only lowest 8 bits gets encoded.
- image row starting with 0
asimage_add_line() return size of the encoded channel scanline in bytes. On failure it will return 0.
Encodes raw data of the single channel into ASImage channel scanline. based on compression level selected for this ASImage all or part of the scanline will be RLE encoded. libAfterImage/asimage/asimage_add_line_mono()
size_t asimage_add_line_mono ( ASImage * im, ColorPart color,
CARD8 value, unsigned int y);
- pointer to valid ASImage structure
- color channel's number
- value for the channel
- image row starting with 0
asimage_add_line_mono() return size of the encoded channel scanline in bytes. On failure it will return 0.
encodes ASImage channel scanline to have same color components value in every pixel. Useful for vertical gradients for example. libAfterImage/asimage/get_asimage_chanmask()
ASFlagType get_asimage_chanmask( ASImage *im);
- valid ASImage object.
goes throu all the scanlines of the ASImage and toggles bits representing those components that have at least some data. libAfterImage/asimage/move_asimage_channel()
void move_asimage_channel( ASImage *dst, int channel_dst,
ASImage *src, int channel_src );
- ASImage which will have its channel substituted;
- what channel to move data to;
- ASImage which will donate its channel to dst;
- what source image channel to move data from.
MOves channel data from one ASImage to another, while discarding what was already in destination's channel.
Source image (donor) will loose its channel data, as it will be moved to destination ASImage. Also there is a condition that both images must be of the same width - otherwise function returns without doing anything. If height is different - the minimum of two will be used. libAfterImage/asimage/copy_asimage_channel()
void copy_asimage_channel( ASImage *dst, int channel_dst,
ASImage *src, int channel_src );
- ASImage which will have its channel substituted;
- what channel to copy data to;
- ASImage which will donate its channel to dst;
- what source image channel to copy data from.
Same as move_asimage_channel() but makes copy of channel's data instead of simply moving it from one image to another. libAfterImage/asimage/copy_asimage_lines()
void copy_asimage_lines( ASImage *dst, unsigned int offset_dst,
ASImage *src, unsigned int offset_src,
unsigned int nlines, ASFlagType filter );
- ASImage which will have its channel substituted;
- scanline in destination image to copy to;
- ASImage which will donate its channel to dst;
- scanline in source image to copy data from;
- number of scanlines to be copied;
- specifies what channels should be copied.
Makes copy of scanline data for continuos set of scanlines, affecting only those channels marked in filter. NOTE Images must be of the same width. libAfterImage/asimage/verbosity
This are flags that define what should be printed by asimage_print_line():
VRB_LINE_SUMMARY - print only summary for each scanline
VRB_LINE_CONTENT - print summary and data for each scanline
VRB_CTRL_EXPLAIN - print summary, data and control codes for each
scanline
#define VRB_LINE_SUMMARY (0x01<<0) #define VRB_LINE_CONTENT (0x01<<1) #define VRB_CTRL_EXPLAIN (0x01<<2) #define VRB_EVERYTHING (VRB_LINE_SUMMARY|VRB_CTRL_EXPLAIN| \
VRB_LINE_CONTENT)
libAfterImage/asimage/asimage_print_line()
unsigned int asimage_print_line ( ASImage * im, ColorPart color,
unsigned int y,
unsigned long verbosity);
- pointer to valid ASImage structure
- color channel's number
- image row starting with 0
- verbosity level - any combination of flags is allowed
amount of memory used by this particular channel of specified scanline.
asimage_print_line() prints data stored in specified image scanline channel. That may include simple summary of how much memory is used, actual visible data, and/or RLE control codes. That helps one to see how effectively data is encoded.
Useful mostly for debugging purposes. libAfterImage/asimage/get_asimage_channel_rects()
- translate image into a list of rectangles.
XRectangle*
get_asimage_channel_rects( ASImage *src, int channel,
unsigned int threshold,
unsigned int *rects_count_ret );
- ASImage which will donate its channel to dst;
- what source image channel to copy data from;
- threshold to compare channel values against;
- returns count of generated rectangles.
This function will translate contents of selected channel (usually alpha) into a list of rectangles, ecompasing regions with values above the threshold. This is useful to generate shape of the window to be used with X Shape extension.