NAME
rio, label, window, wloc – window system

SYNOPSIS
rio [ –i 'cmd' ] [ –k 'kbdcmd' ] [ –s ] [ –f font ]

label name

window [ –m ] [ –r minx miny maxx maxy ] [ –dx n ] [ –dy n ] [ –minx n ] [ –miny n ] [ –maxx n ] [ –maxy n ] [ –cd dir ] [ –hide ] [ –scroll ] [ –noscroll ] [ cmd arg ... ]

wloc

DESCRIPTION
Rio manages asynchronous layers of text, or windows, on a raster display. It also serves a variety of files for communicating with and controlling windows; these are discussed in section rio(4).

Commands
The rio command starts a new instance of the window system. Its –i option names a startup script, which typically contains several window commands generated by wloc. The –k option causes rio to run the command kbdcmd at startup and allow it to provide characters as keyboard input; the keyboard program described in bitsyload(1) is the usual choice.

The –s option initializes windows so that text scrolls; the default is not to scroll. The font argument names a font used to display text, both in rio's menus and as a default for any programs running in its windows; it also establishes the environment variable $font. If –f is not given, rio uses the imported value of $font if set; otherwise it imports the default font from the underlying graphics server, usually the terminal's operating system.

The label command changes a window's identifying name.

The window command creates a window. By default, it creates a shell window and sizes and places it automatically. The geometry arguments control the size (dx, dy) and placement (minx, miny, maxx, maxy); the units are pixels with the upper left corner of the screen at (0, 0). The hide option causes the window to be created off–screen. The scroll and noscroll options set the scroll mode. The cd option sets the working directory. The optional command and arguments define which program to run in the window.

By default, window uses /dev/wctl (see rio(4)) to create the window and run the command. Therefore, the window and command will be created by rio and run in a new file name space, just as if the window had been created using the interactive menu. However, the –m option uses the file server properties of rio to mount (see bind(1)) the new window's name space within the name space of the program calling window. This means, for example, that running window in a CPU window will create another window whose command runs on the terminal, where rio is running; while window –m will create another window whose command runs on the CPU server.

The wloc command prints the coordinates and label of each window in its instance of rio and is used to construct arguments for window.

Window control
Each window behaves as a separate terminal with at least one process associated with it. When a window is created, a new process (usually a shell; see rc(1)) is established and bound to the window as a new process group. Initially, each window acts as a simple terminal that displays character text; the standard input and output of its processes are attached to /dev/cons. Other special files, accessible to the processes running in a window, may be used to make the window a more general display. Some of these are mentioned here; the complete set is discussed in rio(4).

One window is current, and is indicated with a dark border and text; characters typed on the keyboard are available in the /dev/cons file of the process in the current window. Characters written on /dev/cons appear asynchronously in the associated window whether or not the window is current.

Windows are created, deleted and rearranged using the mouse. Clicking (pressing and releasing) mouse button 1 in a non–current window makes that window current and brings it in front of any windows that happen to be overlapping it. When the mouse cursor points to the background area or is in a window that has not claimed the mouse for its own use, pressing mouse button 3 activates a menu of window operations provided by rio. Releasing button 3 then selects an operation. At this point, a gunsight or cross cursor indicates that an operation is pending. The button 3 menu operations are:
New      Create a window. Press button 3 where one corner of the new rectangle should appear (cross cursor), and move the mouse, while holding down button 3, to the diagonally opposite corner. Releasing button 3 creates the window, and makes it current. Very small windows may not be created. Resize   Change the size and location of a window. First click button 3 in the window to be changed (gunsight cursor). Then sweep out a window as for the New operation. The window is made current.
Move     Move a window to another location. After pressing and holding button 3 over the window to be moved (gunsight cursor), indicate the new position by dragging the rectangle to the new location. The window is made current. Windows may be moved partially off–screen.
Delete   Delete a window. Click in the window to be deleted (gunsight cursor). Deleting a window causes a hangup note to be sent to all processes in the window's process group (see notify(2)).
Hide     Hide a window. Click in the window to be hidden (gunsight cursor); it will be moved off–screen. Each hidden window is given a menu entry in the button 3 menu according to the value of the file /dev/label, which rio maintains (see rio(4)).
label     Restore a hidden window.

Windows may also be arranged by dragging their borders. Pressing button 1 or 2 over a window's border allows one to move the corresponding edge or corner, while button 3 moves the whole window.

Text windows
Characters typed on the keyboard or written to /dev/cons collect in the window to form a long, continuous document.

There is always some selected text, a contiguous string marked on the screen by reversing its color. If the selected text is a null string, it is indicated by a hairline cursor between two characters. The selected text may be edited by mousing and typing. Text is selected by pointing and clicking button 1 to make a null– string selection, or by pointing, then sweeping with button 1 pressed. Text may also be selected by double–clicking: just inside a matched delimiter–pair with one of {[(<«`'" on the left and }])>»`'" on the right, it selects all text within the pair; at the beginning or end of a line, it selects the line; within or at the edge of an alphanumeric word, it selects the word.

Characters typed on the keyboard replace the selected text; if this text is not empty, it is placed in a snarf buffer common to all windows but distinct from that of sam(1).

Programs access the text in the window at a single point maintained automatically by rio. The output point is the location in the text where the next character written by a program to /dev/cons will appear; afterwards, the output point is the null string beyond the new character. The output point is also the location in the text of the next character that will be read (directly from the text in the window, not from an intervening buffer) by a program from /dev/cons. When such a read will occur is, however, under control of rio and the user.

In general there is text in the window after the output point, usually placed there by typing but occasionally by the editing operations described below. A pending read of /dev/cons will block until the text after the output point contains a newline, whereupon the read may acquire the text, up to and including the newline. After the read, as described above, the output point will be at the beginning of the next line of text. In normal circumstances, therefore, typed text is delivered to programs a line at a time. Changes made by typing or editing before the text is read will not be seen by the program reading it. If the program in the window does not read the terminal, for example if it is a long–running computation, there may accumulate multiple lines of text after the output point; changes made to all this text will be seen when the text is eventually read. This means, for example, that one may edit out newlines in unread text to forestall the associated text being read when the program finishes computing. This behavior is very different from most systems.

Even when there are newlines in the output text, rio will not honor reads if the window is in hold mode, which is indicated by a white cursor and blue text and border. The ESC character toggles hold mode. Some programs, such as mail(1), automatically turn on hold mode to simplify the editing of multi–line text; type ESC when done to allow mail to read the text.

An EOT character (control–D) behaves exactly like newline except that it is not delivered to a program when read. Thus on an empty line an EOT serves to deliver an end–of–file indication: the read will return zero characters. Like newlines, unread EOTs may be successfully edited out of the text. The BS character (control–H) erases the character before the selected text. The ETB character (control–W) erases any nonalphanumeric characters, then the alphanumeric word just before the selected text. `Alphanumeric' here means non–blanks and non–punctuation. The NAK character (control–U) erases the text after the output point, and not yet read by a program, but not more than one line. All these characters are typed on the keyboard and hence replace the selected text; for example, typing a BS with a word selected places the word in the snarf buffer, removes it from the screen, and erases the character before the word.

An ACK character (control–F) or Insert character triggers file name completion for the preceding string (see complete(2)).

Typing a left or right arrow moves the cursor one character in that direction. Typing an SOH character (control–A) moves the cursor to the beginning of the current line; an ENQ character (control–E) moves to the end.

Text may be moved vertically within the window. A scroll bar on the left of the window shows in its clear portion what fragment of the total output text is visible on the screen, and in its gray part what is above or below view; it measures characters, not lines. Mousing inside the scroll bar moves text: clicking button 1 with the mouse pointing inside the scroll bar brings the line at the top of the window to the cursor's vertical location; button 3 takes the line at the cursor to the top of the window; button 2, treating the scroll bar as a ruler, jumps to the indicated portion of the stored text. Holding a button pressed in the scroll bar will cause the text to scroll continuously until the button is released. Also, a page down or down–arrow scrolls forward half a window, and page up or up–arrow scrolls back. Typing the home key scrolls to the top of the window; typing the end key scrolls to the bottom.

The DEL character sends an interrupt note to all processes in the window's process group. Unlike the other characters, the DEL, VIEW, and up– and down–arrow keys do not affect the selected text. The left (right) arrow key moves the selection to one character before (after) the current selection.

Normally, written output to a window blocks when the text reaches the end of the screen; a button 2 menu item toggles scrolling.

Other editing operations are selected from a menu on button 2. The cut operation deletes the selected text from the screen and puts it in the snarf buffer; snarf copies the selected text to the buffer without deleting it; paste replaces the selected text with the contents of the buffer; and send copies the snarf buffer to just after the output point, adding a final newline if missing. Paste will sometimes and send will always place text after the output point; the text so placed will behave exactly as described above. Therefore when pasting text containing newlines after the output point, it may be prudent to turn on hold mode first.

The plumb menu item sends the contents of the selection (not the snarf buffer) to the plumber(4). If the selection is empty, it sends the white–space–delimited text containing the selection (typing cursor). A typical use of this feature is to tell the editor to find the source of an error by plumbing the file and line information in a compiler's diagnostic.

Raw text windows
Opening or manipulating certain files served by rio suppresses some of the services supplied to ordinary text windows. While the file /dev/mouse is open, any mouse operations are the responsibility of another program running in the window. Thus, rio refrains from maintaining the scroll bar, supplying text editing or menus, interpreting the VIEW key as a request to scroll, and also turns scrolling on.

The file /dev/consctl controls interpretation of keyboard input. In particular, a raw mode may be set: in a raw–input window, no typed keyboard characters are special, they are not echoed to the screen, and all are passed to a program immediately upon reading, instead of being gathered into lines.

Graphics windows
A program that holds /dev/mouse and /dev/consctl open after putting the console in raw mode has complete control of the window: it interprets all mouse events, gets all keyboard characters, and determines what appears on the screen.

FILES
/lib/font/bit/*       font directories
/mnt/wsys            Files served by rio (also unioned in /dev in a window's name space, before the terminal's real /dev files)
/srv/rio.user.pid       Server end of rio.
/srv/riowctl.user.pid   Named pipe for wctl messages.

SOURCE
/sys/src/cmd/rio
/rc/bin/label
/rc/bin/window
/rc/bin/wloc

SEE ALSO
rio(4), rc(1), cpu(1), sam(1), mail(1), proof(1), graphics(2), frame(2), window(2), notify(2), cons(3), draw(3), mouse(3), keyboard(6)

BUGS
The standard input of window is redirected to the newly created window, so there is no way to pipe the output of a program to the standard input of the new window. In some cases, plumb(1) can be used to work around this limitation.
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