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Subfonts for non ascii characters are offset by some minimum rune, typically specified within the parent font file. Because libmemdraw only deals in subfonts, if we want to have it draw non ascii runes we need some method of providing that base offset. This function is only used in one place, so update the function signature and fix the only caller.
456 lines
10 KiB
Text
456 lines
10 KiB
Text
.TH MEMDRAW 2
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.SH NAME
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Memimage,
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Memdata,
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Memdrawparam,
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memimageinit,
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wordaddr,
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byteaddr,
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memimagemove,
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allocmemimage,
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allocmemimaged,
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readmemimage,
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creadmemimage,
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writememimage,
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freememimage,
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memsetchan,
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loadmemimage,
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cloadmemimage,
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unloadmemimage,
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memfillcolor,
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memarc,
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mempoly,
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memellipse,
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memfillpoly,
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memimageline,
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memimagedraw,
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drawclip,
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drawclipnorepl,
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memlinebbox,
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memlineendsize,
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allocmemsubfont,
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openmemsubfont,
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freememsubfont,
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memsubfontwidth,
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getmemdefont,
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memimagestring,
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hwdraw \- drawing routines for memory-resident images
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.SH SYNOPSIS
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.nf
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.B #include <u.h>
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.B #include <libc.h>
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.B #include <draw.h>
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.B #include <memdraw.h>
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.PP
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.ft L
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typedef struct Memdata
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{
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ulong *base; /* allocated data pointer */
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uchar *bdata; /* first byte of actual data; word-aligned */
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int ref; /* number of Memimages using this data */
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void* imref; /* last image that pointed at this */
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int allocd; /* is this malloc'd? */
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} Memdata;
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enum {
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Frepl = 1<<0, /* is replicated */
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Fsimple = 1<<1, /* is 1x1 */
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Fgrey = 1<<2, /* is grey */
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Falpha = 1<<3, /* has explicit alpha */
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Fcmap = 1<<4, /* has cmap channel */
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Fbytes = 1<<5, /* has only 8-bit channels */
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};
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typedef struct Memimage
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{
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Rectangle r; /* rectangle in data area, local coords */
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Rectangle clipr; /* clipping region */
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int depth; /* number of bits of storage per pixel */
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int nchan; /* number of channels */
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ulong chan; /* channel descriptions */
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Memdata *data; /* pointer to data */
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int zero; /* data->bdata+zero==&byte containing (0,0) */
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ulong width; /* width in words of a single scan line */
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Memlayer *layer; /* nil if not a layer*/
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ulong flags;
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\fI...\fP
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} Memimage;
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typedef struct Memdrawparam
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{
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Memimage *dst;
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Rectangle r;
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Memimage *src;
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Rectangle sr;
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Memimage *mask;
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Rectangle mr;
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\fI...\fP
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} Memdrawparam;
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.ta \w'\fLMemsubfont* 'u
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int drawdebug;
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.ft
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.PP
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.ft L
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.nf
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int memimageinit(void)
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ulong* wordaddr(Memimage *i, Point p)
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uchar* byteaddr(Memimage *i, Point p)
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void memimagemove(void *from, void *to)
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.PP
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.ft L
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.nf
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Memimage* allocmemimage(Rectangle r, ulong chan)
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Memimage* allocmemimaged(Rectangle r, ulong chan, Memdata *data)
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Memimage* readmemimage(int fd)
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Memimage* creadmemimage(int fd)
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int writememimage(int fd, Memimage *i)
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void freememimage(Memimage *i)
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int memsetchan(Memimage*, ulong)
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.PP
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.ft L
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.nf
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int loadmemimage(Memimage *i, Rectangle r,
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uchar *buf, int nbuf)
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int cloadmemimage(Memimage *i, Rectangle r,
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uchar *buf, int nbuf)
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int unloadmemimage(Memimage *i, Rectangle r,
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uchar *buf, int nbuf)
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void memfillcolor(Memimage *i, ulong color)
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.PP
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.ft L
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.nf
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void memarc(Memimage *dst, Point c, int a, int b, int thick,
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Memimage *src, Point sp, int alpha, int phi, Drawop op)
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void mempoly(Memimage *dst, Point *p, int np, int end0,
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int end1, int radius, Memimage *src, Point sp, Drawop op)
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void memellipse(Memimage *dst, Point c, int a, int b,
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int thick, Memimage *src, Point sp, Drawop op)
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void memfillpoly(Memimage *dst, Point *p, int np, int wind,
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Memimage *src, Point sp, Drawop op)
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void memimageline(Memimage *dst, Point p0, Point p1, int end0,
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int end1, int radius, Memimage *src, Point sp, Drawop op)
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void memimagedraw(Memimage *dst, Rectangle r, Memimage *src,
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Point sp, Memimage *mask, Point mp, Drawop op)
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.PP
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.ft L
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.nf
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int drawclip(Memimage *dst, Rectangle *dr, Memimage *src,
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Point *sp, Memimage *mask, Point *mp,
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Rectangle *sr, Rectangle *mr)
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int drawclipnorepl(Memimage *dst, Rectangle *dr, Memimage *src,
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Point *sp, Memimage *mask, Point *mp,
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Rectangle *sr, Rectangle *mr)
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Rectangle memlinebbox(Point p0, Point p1, int end0, int end1,
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int radius)
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int memlineendsize(int end)
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.PP
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.ft L
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.nf
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Memsubfont* allocmemsubfont(char *name, int n, int height,
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int ascent, Fontchar *info, Memimage *i)
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Memsubfont* openmemsubfont(char *name, Rune min)
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void freememsubfont(Memsubfont *f)
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Point memsubfontwidth(Memsubfont *f, char *s)
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Memsubfont* getmemdefont(void)
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Point memimagestring(Memimage *dst, Point p, Memimage *color,
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Point cp, Memsubfont *f, char *cs)
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.PP
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.ft L
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.nf
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int hwdraw(Memdrawparam *param)
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.ft R
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.SH DESCRIPTION
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The
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.B Memimage
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type defines memory-resident rectangular pictures and the methods to draw upon them;
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.BR Memimage s
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differ from
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.BR Image s
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(see
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.IR draw (2))
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in that they are manipulated directly in user memory rather than by
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RPCs to the
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.B /dev/draw
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hierarchy.
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The
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.B memdraw
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library is the basis for the kernel
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.IR draw (3)
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driver and also used by a number of programs that must manipulate
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images without a display.
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.PP
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The
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.BR r,
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.BR clipr ,
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.BR depth ,
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.BR nchan ,
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and
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.BR chan
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structure elements are identical to
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the ones of the same name
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in the
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.B Image
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structure.
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.PP
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The
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.B flags
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element of the
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.B Memimage
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structure holds a number of bits of information about the image.
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In particular, it subsumes the
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purpose of the
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.B repl
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element of
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.B Image
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structures.
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.PP
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.I Memimageinit
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initializes various static data that the library depends on,
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as well as the replicated solid color images
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.BR memopaque ,
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.BR memtransparent ,
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.BR memblack ,
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and
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.BR memwhite .
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It should be called before referring to any of these images
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and before calling any of the other library functions. It
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returns non-zero on error.
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.PP
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Each
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.B Memimage
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points at a
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.B Memdata
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structure that in turn points at the actual pixel data for the image.
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This allows multiple images to be associated with the same
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.BR Memdata .
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The first word of the data pointed at by
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the
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.B base
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element of
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.B Memdata
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points back at the
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.B Memdata
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structure, so that the
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memory allocator (see
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.IR pool (2))
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can compact image memory
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using
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.IR memimagemove .
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.PP
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Because images can have different coordinate systems,
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the
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.B zero
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element of the
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.B Memimage
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structure contains the offset that must be added
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to the
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.B bdata
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element of the corresponding
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.B Memdata
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structure in order to yield a pointer to the data for the pixel (0,0).
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Adding
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.BR width
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machine words
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to this pointer moves it down one scan line.
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The
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.B depth
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element can be used to determine how to move the
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pointer horizontally.
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Note that this method works even for images whose rectangles
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do not include the origin, although one should only dereference
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pointers corresponding to pixels within the image rectangle.
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.I Wordaddr
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and
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.IR byteaddr
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perform these calculations,
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returning pointers to the word and byte, respectively,
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that contain the beginning of the data for a given pixel.
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.PP
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.I Allocmemimage
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allocates
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images with a given rectangle and channel descriptor
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(see
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.B strtochan
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in
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.IR graphics (2)),
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creating a fresh
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.B Memdata
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structure and associated storage.
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.I Allocmemimaged
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is similar but uses the supplied
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.I Memdata
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structure rather than a new one.
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The
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.I readmemimage
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function reads an uncompressed bitmap
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from the given file descriptor,
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while
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.I creadmemimage
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reads a compressed bitmap.
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.I Writememimage
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writes a compressed representation of
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.I i
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to file descriptor
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.IR fd .
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For more on bitmap formats, see
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.IR image (6).
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.I Freememimage
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frees images returned by any of these routines.
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The
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.B Memimage
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structure contains some tables that are used
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to store precomputed values depending on the channel descriptor.
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.I Memsetchan
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updates the
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.B chan
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element of the structure as well as these tables,
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returning \-1 if passed a bad channel descriptor.
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.PP
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.I Loadmemimage
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and
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.I cloadmemimage
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replace the pixel data for a given rectangle of an image
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with the given buffer of uncompressed or compressed
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data, respectively.
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When calling
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.IR cloadmemimage ,
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the buffer must contain an
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integral number of
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compressed chunks of data that exactly cover the rectangle.
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.I Unloadmemimage
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retrieves the uncompressed pixel data for a given rectangle of an image.
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All three return the number of bytes consumed on success,
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and \-1 in case of an error.
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.PP
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.I Memfillcolor
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fills an image with the given color, a 32-bit number as
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described in
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.IR color (2).
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.PP
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.IR Memarc ,
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.IR mempoly ,
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.IR memellipse ,
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.IR memfillpoly ,
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.IR memimageline ,
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and
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.I memimagedraw
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are identical to the
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.IR arc ,
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.IR poly ,
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.IR ellipse ,
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.IR fillpoly ,
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.IR line ,
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and
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.IR gendraw ,
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routines described in
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.IR draw (2),
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except that they operate on
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.BR Memimage s
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rather than
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.BR Image s.
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Similarly,
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.IR allocmemsubfont ,
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.IR openmemsubfont ,
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.IR freememsubfont ,
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.IR memsubfontwidth ,
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.IR getmemdefont ,
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and
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.I memimagestring
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are the
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.B Memimage
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analogues of
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.IR allocsubfont ,
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.IR openfont ,
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.IR freesubfont ,
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.IR strsubfontwidth ,
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.IR getdefont ,
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and
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.B string
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(see
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.IR subfont (2)
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and
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.IR graphics (2)),
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except that they operate
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only on
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.BR Memsubfont s
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rather than
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.BR Font s.
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.PP
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.I Drawclip
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takes the images involved in a draw operation,
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together with the destination rectangle
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.B dr
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and source
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and mask alignment points
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.B sp
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and
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.BR mp ,
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and
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clips them according to the clipping rectangles of the images involved.
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It also fills in the rectangles
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.B sr
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and
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.B mr
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with rectangles congruent to the returned destination rectangle
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but translated so the upper left corners are the returned
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.B sp
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and
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.BR mp .
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.I Drawclipnorepl
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does the same as
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.B drawclip
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but avoids clamping
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.B sp
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and
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.B mr
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within the image rectangle of source and mask when replicated.
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.I Drawclip
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and
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.I drawclipnorepl
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return zero when the clipped rectangle is empty.
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.I Memlinebbox
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returns a conservative bounding box containing a line between
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two points
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with given end styles
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and radius.
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.I Memlineendsize
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calculates the extra length added to a line by attaching
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an end of a given style.
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.PP
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The
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.I hwdraw
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function is a no-op stub that may be overridden by clients
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of the library.
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.I Hwdraw
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is called at each call to
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.I memimagedraw
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with the current request's parameters.
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If it can satisfy the request, it should do so
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and return 1.
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If it cannot satisfy the request, it should return 0.
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This allows (for instance) the kernel to take advantage
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of hardware acceleration.
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.SH SOURCE
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.B /sys/src/libmemdraw
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.SH SEE ALSO
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.IR addpt (2),
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.IR color (2),
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.IR draw (2),
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.IR graphics (2),
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.IR memlayer (2),
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.IR stringsize (2),
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.IR subfont (2),
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.IR color (6),
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.IR utf (6)
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.SH BUGS
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.I Memimagestring
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is unusual in using a subfont rather than a font,
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and in having no parameter to align the source.
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.I Writememimage
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won't write compressed images if the compressed block size of the
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resulting image is greater than 8000 bytes, in order to avoid
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exceeding the iounit when loading it into a
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.IR draw (3)
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device.
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