MEMLAYER(3) MEMLAYER(3)
NAME
memdraw, memlalloc, memldelete, memlexpose, memlfree,
memlhide, memline, memlnorefresh, memload, memunload,
memlorigin, memlsetrefresh, memltofront, memltofrontn,
memltorear, memltorearn - windows of memory-resident images
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <memdraw.h>
#include <memlayer.h>
typedef struct Memscreen Memscreen;
typedef struct Memlayer Memlayer;
typedef void (*Refreshfn)(Memimage*, Rectangle, void*);
struct Memscreen
{
Memimage *frontmost; /* frontmost layer on screen */
Memimage *rearmost; /* rearmost layer on screen */
Memimage *image; /* upon which all layers are drawn */
Memimage *fill; /* if non-zero, picture to use when repainting */
};
struct Memlayer
{
Rectangle screenr; /* true position of layer on screen */
Point delta; /* add delta to go from image coords to screen */
Memscreen *screen; /* screen this layer belongs to */
Memimage *front; /* window in front of this one */
Memimage *rear; /* window behind this one*/
int clear; /* layer is fully visible */
Memimage *save; /* save area for obscured parts */
Refreshfn refreshfn; /* fn to refresh obscured parts if save==nil */
void *refreshptr;/* argument to refreshfn */
};
Memimage* memlalloc(Memscreen *s, Rectangle r, Refreshfn fn, void *arg, ulong col)
void memlnorefresh(Memimage *i, Rectangle r, void *arg)
int memlsetrefresh(Memimage *i, Refreshfn fn, void *arg)
int memldelete(Memimage *i)
int memlfree(Memimage *i)
int memlexpose(Memimage *i, Rectangle r)
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MEMLAYER(3) MEMLAYER(3)
int memlhide(Memimage *i, Rectangle r)
void memltofront(Memimage *i)
void memltofrontn(Memimage**ia, int n)
void memltorear(Memimage *i)
void memltorearn(Memimage **ia , int n)
int memlorigin(Memimage *i, Point log, Point phys)
void memdraw(Image *dst, Rectangle r,
Image *src, Point sp, Image *mask, Point mp, Drawop op)
int memload(Memimage *i, Rectangle r,
uchar *buf, int n, int iscompressed)
int memunload(Memimage *i, Rectangle r,
uchar *buf, int n)
DESCRIPTION
These functions build upon the memdraw(3) interface to main-
tain overlapping graphical windows on in-memory images.
They are used by the kernel to implement the windows inter-
face presented by draw(3) and window(3) and probably have
little use outside of the kernel.
The basic function is to extend the definition of a Memimage
(see memdraw(3)) to include overlapping windows defined by
the Memlayer type. The first fields of the Memlayer struc-
ture are identical to those in Memimage, permitting a func-
tion that expects a Memimage to be passed a Memlayer, and
vice versa. Both structures have a save field, which is nil
in a Memimage and points to `backing store' in a Memlayer.
The layer routines accept Memimages or Memlayers; if the
image is a Memimage the underlying Memimage routine is
called; otherwise the layer routines recursively subdivide
the geometry, reducing the operation into a smaller compo-
nent that ultimately can be performed on a Memimage, either
the display on which the window appears, or the backing
store.
Memlayers are associated with a Memscreen that holds the
data structures to maintain the windows and connects them to
the associated image. The fill color is used to paint the
background when a window is deleted. There is no function
to establish a Memscreen; to create one, allocate the mem-
ory, zero frontmost and rearmost, set fill to a valid fill
color or image, and set image to the Memimage (or Memlayer)
on which the windows will be displayed.
Memlalloc allocates a Memlayer of size r on Memscreen s. If
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MEMLAYER(3) MEMLAYER(3)
col is not DNofill, the new window will be initialized by
painting it that color.
The refresh function fn and associated argument arg will be
called by routines in the library to restore portions of the
window uncovered due to another window being deleted or this
window being pulled to the front of the stack. The func-
tion, when called, receives a pointer to the image (window)
being refreshed, the rectangle that has been uncovered, and
the arg recorded when the window was created. A couple of
predefined functions provide built-in management methods:
memlnorefresh does no backup at all, useful for making effi-
cient temporary windows; while a nil function specifies that
the backing store (Memlayer.save) will be used to keep the
obscured data. Other functions may be provided by the
client. Memlsetrefresh allows one to change the function
associated with the window.
Memldelete deletes the window i, restoring the underlying
display. Memlfree frees the data structures without unlink-
ing the window from the associated Memscreen or doing any
graphics.
Memlexpose restores rectangle r within the window, using the
backing store or appropriate refresh method. Memlhide goes
the other way, backing up r so that that portion of the
screen may be modified without losing the data in this win-
dow.
Memltofront pulls i to the front of the stack of windows,
making it fully visible. Memltofrontn pulls the n windows
in the array ia to the front as a group, leaving their
internal order unaffected. Memltorear and memltorearn push
the windows to the rear.
Memlorigin changes the coordinate systems associated with
the window i. The points log and phys represent the upper
left corner (min) of the window's internal coordinate system
and its physical location on the screen. Changing log
changes the interpretation of coordinates within the window;
for example, setting it to (0, 0) makes the upper left cor-
ner of the window appear to be the origin of the coordinate
system, regardless of its position on the screen. Changing
phys changes the physical location of the window on the
screen. When a window is created, its logical and physical
coordinates are the same, so
memlorigin(i, i->r.min, i->r.min)
would be a no-op.
Memdraw and memline are implemented in the layer library but
provide the main entry points for drawing on memory-resident
windows. They have the signatures of memimagedraw and
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MEMLAYER(3) MEMLAYER(3)
memimageline (see memdraw(3)) but accept Memlayer or
Memimage arguments both.
Memload and memunload are similarly layer-savvy versions of
loadmemimage and unloadmemimage. The iscompressed flag to
memload specifies whether the n bytes of data in buf are in
compressed image format (see image(7)).
SOURCE
/usr/local/plan9/src/libmemlayer
SEE ALSO
graphics(3), memdraw(3), stringsize(3), window(3), draw(3)
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