ref: ff344562dbefe0e53adc900b6e7cd962ae555e94
dir: /sys/man/2/memdraw/
.TH MEMDRAW 2 .SH NAME Memimage, Memdata, Memdrawparam, memimageinit, wordaddr, byteaddr, memimagemove, allocmemimage, allocmemimaged, readmemimage, creadmemimage, writememimage, freememimage, memsetchan, loadmemimage, cloadmemimage, unloadmemimage, memfillcolor, memarc, mempoly, memellipse, memfillpoly, memimageline, memimagedraw, drawclip, drawclipnorepl, memlinebbox, memlineendsize, allocmemsubfont, openmemsubfont, freememsubfont, memsubfontwidth, getmemdefont, memimagestring, hwdraw \- drawing routines for memory-resident images .SH SYNOPSIS .nf .B #include <u.h> .B #include <libc.h> .B #include <draw.h> .B #include <memdraw.h> .PP .ft L typedef struct Memdata { ulong *base; /* allocated data pointer */ uchar *bdata; /* first byte of actual data; word-aligned */ int ref; /* number of Memimages using this data */ void* imref; /* last image that pointed at this */ int allocd; /* is this malloc'd? */ } Memdata; enum { Frepl = 1<<0, /* is replicated */ Fsimple = 1<<1, /* is 1x1 */ Fgrey = 1<<2, /* is grey */ Falpha = 1<<3, /* has explicit alpha */ Fcmap = 1<<4, /* has cmap channel */ Fbytes = 1<<5, /* has only 8-bit channels */ }; typedef struct Memimage { Rectangle r; /* rectangle in data area, local coords */ Rectangle clipr; /* clipping region */ int depth; /* number of bits of storage per pixel */ int nchan; /* number of channels */ ulong chan; /* channel descriptions */ Memdata *data; /* pointer to data */ int zero; /* data->bdata+zero==&byte containing (0,0) */ ulong width; /* width in words of a single scan line */ Memlayer *layer; /* nil if not a layer*/ ulong flags; \fI...\fP } Memimage; typedef struct Memdrawparam { Memimage *dst; Rectangle r; Memimage *src; Rectangle sr; Memimage *mask; Rectangle mr; \fI...\fP } Memdrawparam; .ta \w'\fLMemsubfont* 'u int drawdebug; .ft .PP .ft L .nf int memimageinit(void) ulong* wordaddr(Memimage *i, Point p) uchar* byteaddr(Memimage *i, Point p) void memimagemove(void *from, void *to) .PP .ft L .nf Memimage* allocmemimage(Rectangle r, ulong chan) Memimage* allocmemimaged(Rectangle r, ulong chan, Memdata *data) Memimage* readmemimage(int fd) Memimage* creadmemimage(int fd) int writememimage(int fd, Memimage *i) void freememimage(Memimage *i) int memsetchan(Memimage*, ulong) .PP .ft L .nf int loadmemimage(Memimage *i, Rectangle r, uchar *buf, int nbuf) int cloadmemimage(Memimage *i, Rectangle r, uchar *buf, int nbuf) int unloadmemimage(Memimage *i, Rectangle r, uchar *buf, int nbuf) void memfillcolor(Memimage *i, ulong color) .PP .ft L .nf void memarc(Memimage *dst, Point c, int a, int b, int thick, Memimage *src, Point sp, int alpha, int phi, Drawop op) void mempoly(Memimage *dst, Point *p, int np, int end0, int end1, int radius, Memimage *src, Point sp, Drawop op) void memellipse(Memimage *dst, Point c, int a, int b, int thick, Memimage *src, Point sp, Drawop op) void memfillpoly(Memimage *dst, Point *p, int np, int wind, Memimage *src, Point sp, Drawop op) void memimageline(Memimage *dst, Point p0, Point p1, int end0, int end1, int radius, Memimage *src, Point sp, Drawop op) void memimagedraw(Memimage *dst, Rectangle r, Memimage *src, Point sp, Memimage *mask, Point mp, Drawop op) .PP .ft L .nf int drawclip(Memimage *dst, Rectangle *dr, Memimage *src, Point *sp, Memimage *mask, Point *mp, Rectangle *sr, Rectangle *mr) int drawclipnorepl(Memimage *dst, Rectangle *dr, Memimage *src, Point *sp, Memimage *mask, Point *mp, Rectangle *sr, Rectangle *mr) Rectangle memlinebbox(Point p0, Point p1, int end0, int end1, int radius) int memlineendsize(int end) .PP .ft L .nf Memsubfont* allocmemsubfont(char *name, int n, int height, int ascent, Fontchar *info, Memimage *i) Memsubfont* openmemsubfont(char *name) void freememsubfont(Memsubfont *f) Point memsubfontwidth(Memsubfont *f, char *s) Memsubfont* getmemdefont(void) Point memimagestring(Memimage *dst, Point p, Memimage *color, Point cp, Memsubfont *f, char *cs) .PP .ft L .nf int hwdraw(Memdrawparam *param) .ft R .SH DESCRIPTION The .B Memimage type defines memory-resident rectangular pictures and the methods to draw upon them; .BR Memimage s differ from .BR Image s (see .IR draw (2)) in that they are manipulated directly in user memory rather than by RPCs to the .B /dev/draw hierarchy. The .B memdraw library is the basis for the kernel .IR draw (3) driver and also used by a number of programs that must manipulate images without a display. .PP The .BR r, .BR clipr , .BR depth , .BR nchan , and .BR chan structure elements are identical to the ones of the same name in the .B Image structure. .PP The .B flags element of the .B Memimage structure holds a number of bits of information about the image. In particular, it subsumes the purpose of the .B repl element of .B Image structures. .PP .I Memimageinit initializes various static data that the library depends on, as well as the replicated solid color images .BR memopaque , .BR memtransparent , .BR memblack , and .BR memwhite . It should be called before referring to any of these images and before calling any of the other library functions. It returns non-zero on error. .PP Each .B Memimage points at a .B Memdata structure that in turn points at the actual pixel data for the image. This allows multiple images to be associated with the same .BR Memdata . The first word of the data pointed at by the .B base element of .B Memdata points back at the .B Memdata structure, so that the memory allocator (see .IR pool (2)) can compact image memory using .IR memimagemove . .PP Because images can have different coordinate systems, the .B zero element of the .B Memimage structure contains the offset that must be added to the .B bdata element of the corresponding .B Memdata structure in order to yield a pointer to the data for the pixel (0,0). Adding .BR width machine words to this pointer moves it down one scan line. The .B depth element can be used to determine how to move the pointer horizontally. Note that this method works even for images whose rectangles do not include the origin, although one should only dereference pointers corresponding to pixels within the image rectangle. .I Wordaddr and .IR byteaddr perform these calculations, returning pointers to the word and byte, respectively, that contain the beginning of the data for a given pixel. .PP .I Allocmemimage allocates images with a given rectangle and channel descriptor (see .B strtochan in .IR graphics (2)), creating a fresh .B Memdata structure and associated storage. .I Allocmemimaged is similar but uses the supplied .I Memdata structure rather than a new one. The .I readmemimage function reads an uncompressed bitmap from the given file descriptor, while .I creadmemimage reads a compressed bitmap. .I Writememimage writes a compressed representation of .I i to file descriptor .IR fd . For more on bitmap formats, see .IR image (6). .I Freememimage frees images returned by any of these routines. The .B Memimage structure contains some tables that are used to store precomputed values depending on the channel descriptor. .I Memsetchan updates the .B chan element of the structure as well as these tables, returning \-1 if passed a bad channel descriptor. .PP .I Loadmemimage and .I cloadmemimage replace the pixel data for a given rectangle of an image with the given buffer of uncompressed or compressed data, respectively. When calling .IR cloadmemimage , the buffer must contain an integral number of compressed chunks of data that exactly cover the rectangle. .I Unloadmemimage retrieves the uncompressed pixel data for a given rectangle of an image. All three return the number of bytes consumed on success, and \-1 in case of an error. .PP .I Memfillcolor fills an image with the given color, a 32-bit number as described in .IR color (2). .PP .IR Memarc , .IR mempoly , .IR memellipse , .IR memfillpoly , .IR memimageline , and .I memimagedraw are identical to the .IR arc , .IR poly , .IR ellipse , .IR fillpoly , .IR line , and .IR gendraw , routines described in .IR draw (2), except that they operate on .BR Memimage s rather than .BR Image s. Similarly, .IR allocmemsubfont , .IR openmemsubfont , .IR freememsubfont , .IR memsubfontwidth , .IR getmemdefont , and .I memimagestring are the .B Memimage analogues of .IR allocsubfont , .IR openfont , .IR freesubfont , .IR strsubfontwidth , .IR getdefont , and .B string (see .IR subfont (2) and .IR graphics (2)), except that they operate only on .BR Memsubfont s rather than .BR Font s. .PP .I Drawclip takes the images involved in a draw operation, together with the destination rectangle .B dr and source and mask alignment points .B sp and .BR mp , and clips them according to the clipping rectangles of the images involved. It also fills in the rectangles .B sr and .B mr with rectangles congruent to the returned destination rectangle but translated so the upper left corners are the returned .B sp and .BR mp . .I Drawclipnorepl does the same as .B drawclip but avoids clamping .B sp and .B mr within the image rectangle of source and mask when replicated. .I Drawclip and .I drawclipnorepl return zero when the clipped rectangle is empty. .I Memlinebbox returns a conservative bounding box containing a line between two points with given end styles and radius. .I Memlineendsize calculates the extra length added to a line by attaching an end of a given style. .PP The .I hwdraw function is a no-op stub that may be overridden by clients of the library. .I Hwdraw is called at each call to .I memimagedraw with the current request's parameters. If it can satisfy the request, it should do so and return 1. If it cannot satisfy the request, it should return 0. This allows (for instance) the kernel to take advantage of hardware acceleration. .SH SOURCE .B /sys/src/libmemdraw .SH SEE ALSO .IR addpt (2), .IR color (2), .IR draw (2), .IR graphics (2), .IR memlayer (2), .IR stringsize (2), .IR subfont (2), .IR color (6), .IR utf (6) .SH BUGS .I Memimagestring is unusual in using a subfont rather than a font, and in having no parameter to align the source.