305 lines
6.8 KiB
Text
305 lines
6.8 KiB
Text
.TH MEMLAYER 2
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.SH NAME
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memdraw, memlalloc, memldelete, memlexpose, memlfree, memlhide, memline, memlnorefresh, memload, memunload, memlorigin, memlsetrefresh, memltofront, memltofrontn, memltorear, memltorearn \- windows of 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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.br
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.B #include <libc.h>
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.br
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.B #include <draw.h>
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.br
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.B #include <memdraw.h>
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.br
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.B #include <memlayer.h>
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.PP
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.ft L
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typedef struct Memscreen Memscreen;
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typedef struct Memlayer Memlayer;
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typedef void (*Refreshfn)(Memimage*, Rectangle, void*);
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.ta 4n +\w'\fLRefreshfn 'u +\w'\fL*frontmost; 'u
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struct Memscreen
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{
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Memimage *frontmost; /* frontmost layer on screen */
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Memimage *rearmost; /* rearmost layer on screen */
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Memimage *image; /* upon which all layers are drawn */
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Memimage *fill; /* if non-zero, picture to use when repainting */
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};
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struct Memlayer
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{
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Rectangle screenr; /* true position of layer on screen */
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Point delta; /* add delta to go from image coords to screen */
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Memscreen *screen; /* screen this layer belongs to */
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Memimage *front; /* window in front of this one */
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Memimage *rear; /* window behind this one*/
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int clear; /* layer is fully visible */
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Memimage *save; /* save area for obscured parts */
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Refreshfn refreshfn; /* fn to refresh obscured parts if save==nil */
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void *refreshptr; /* argument to refreshfn */
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};
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.ft
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.ta \w'\fLMemimage* 'u
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.PP
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.B
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Memimage* memlalloc(Memscreen *s, Rectangle r, Refreshfn fn, void *arg, ulong col)
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.PP
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.B void memlnorefresh(Memimage *i, Rectangle r, void *arg)
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.PP
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.B
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int memlsetrefresh(Memimage *i, Refreshfn fn, void *arg)
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.PP
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.B
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void memldelete(Memimage *i)
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.PP
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.B
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void memlfree(Memimage *i)
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.PP
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.B
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void memlexpose(Memimage *i, Rectangle r)
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.PP
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.B
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void memlhide(Memimage *i, Rectangle r)
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.PP
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.B
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void memltofront(Memimage *i)
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.PP
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.B
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void memltofrontn(Memimage**ia, int n)
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.PP
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.B
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void memltorear(Memimage *i)
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.PP
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.B
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void memltorearn(Memimage **ia , int n)
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.PP
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.B
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int memlorigin(Memimage *i, Point log, Point phys)
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.PP
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.B
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void memdraw(Memimage *dst, Rectangle r,
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.br
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.B
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Memimage *src, Point sp, Memimage *mask, Point mp, Drawop op)
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.fi
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.B
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int memload(Memimage *i, Rectangle r,
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.br
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.B
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uchar *buf, int n, int iscompressed)
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.PP
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.B
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int memunload(Memimage *i, Rectangle r,
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.br
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.B
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uchar *buf, int n)
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.PP
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.SH DESCRIPTION
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These functions build upon the
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.IR memdraw (2)
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interface to maintain overlapping graphical windows on in-memory images.
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They are used by the kernel to implement the windows interface presented by
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.IR draw (3)
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and
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.IR window (2)
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and probably have little use outside of the kernel.
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.PP
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The basic function is to extend the definition of a
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.B Memimage
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(see
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.IR memdraw (2))
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to include overlapping windows defined by the
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.B Memlayer
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type.
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The first fields of the
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.B Memlayer
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structure are identical to those in
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.BR Memimage ,
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permitting a function that expects a
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.B Memimage
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to be passed a
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.BR Memlayer ,
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and vice versa.
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Both structures have a
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.B save
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field, which is nil in a
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.B Memimage
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and points to `backing store' in a
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.BR Memlayer .
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The layer routines accept
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.B Memimages
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or
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.BR Memlayers ;
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if the image is a
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.B Memimage
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the underlying
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.B Memimage
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routine is called; otherwise the layer routines recursively
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subdivide the geometry, reducing the operation into a smaller
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component that ultimately can be performed on a
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.BR Memimage ,
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either the display on which the window appears, or the backing store.
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.PP
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.B Memlayers
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are associated with a
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.B Memscreen
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that holds the data structures to maintain the windows and connects
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them to the associated
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.BR image .
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The
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.B fill
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color is used to paint the background when a window is deleted.
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There is no function to establish a
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.BR Memscreen ;
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to create one, allocate the memory, zero
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.B frontmost
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and
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.BR rearmost ,
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set
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.B fill
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to a valid fill color or image, and set
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.B image
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to the
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.B Memimage
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(or
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.BR Memlayer )
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on which the windows will be displayed.
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.PP
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.I Memlalloc
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allocates a
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.B Memlayer
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of size
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.I r
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on
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.B Memscreen
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.IR s .
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If
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.I col
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is not
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.BR DNofill ,
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the new window will be initialized by painting it that color.
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.PP
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The refresh function
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.I fn
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and associated argument
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.I arg
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will be called by routines in the library to restore portions of the window
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uncovered due to another window being deleted or this window being pulled to the front of the stack.
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The function, when called,
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receives a pointer to the image (window) being refreshed, the rectangle that has been uncovered,
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and the
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.I arg
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recorded when the window was created.
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A couple of predefined functions provide built-in management methods:
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.I memlnorefresh
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does no backup at all, useful for making efficient temporary windows;
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while a
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.I nil
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function specifies that the backing store
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.RB ( Memlayer.save )
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will be used to keep the obscured data.
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Other functions may be provided by the client.
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.I Memlsetrefresh
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allows one to change the function associated with the window.
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.PP
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.I Memldelete
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deletes the window
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.IR i ,
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restoring the underlying display.
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.I Memlfree
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frees the data structures without unlinking the window from the associated
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.B Memscreen
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or doing any graphics.
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.PP
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.I Memlexpose
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restores rectangle
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.I r
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within the window, using the backing store or appropriate refresh method.
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.I Memlhide
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goes the other way, backing up
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.I r
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so that portion of the screen may be modified without losing the data in this window.
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.PP
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.I Memltofront
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pulls
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.I i
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to the front of the stack of windows, making it fully visible.
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.I Memltofrontn
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pulls the
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.I n
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windows in the array
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.I ia
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to the front as a group, leaving their internal order unaffected.
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.I Memltorear
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and
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.I memltorearn
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push the windows to the rear.
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.PP
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.I Memlorigin
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changes the coordinate systems associated with the window
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.IR i .
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The points
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.I log
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and
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.I phys
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represent the upper left corner
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.RB ( min )
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of the window's internal coordinate system and its physical location on the screen.
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Changing
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.I log
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changes the interpretation of coordinates within the window; for example, setting it to
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(0,\ 0) makes the upper left corner of the window appear to be the origin of the coordinate
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system, regardless of its position on the screen.
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Changing
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.I phys
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changes the physical location of the window on the screen.
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When a window is created, its logical and physical coordinates are the same, so
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.EX
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memlorigin(i, i->r.min, i->r.min)
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.EE
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would be a no-op.
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.PP
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.I Memdraw
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and
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.I memline
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are implemented in the layer library but provide the main entry points for drawing on
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memory-resident windows.
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They have the signatures of
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.I memimagedraw
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and
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.I memimageline
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(see
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.IR memdraw (2))
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but accept
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.B Memlayer
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or
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.B Memimage
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arguments both.
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.PP
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.I Memload
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and
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.I memunload
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are similarly layer-savvy versions of
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.I loadmemimage
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and
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.IR unloadmemimage .
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The
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.I iscompressed
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flag to
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.I memload
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specifies whether the
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.I n
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bytes of data in
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.I buf
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are in compressed image format
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(see
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.IR image (6)).
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.SH SOURCE
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.B /sys/src/libmemlayer
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.SH SEE ALSO
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.IR graphics (2),
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.IR memdraw (2),
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.IR stringsize (2),
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.IR window (2),
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.IR draw (3)
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