mouse(3) - Plan 9 from User Space

| MOUSE(3) | MOUSE(3)
| NAME
| initmouse, readmouse, closemouse, moveto, cursorswitch, getrect, drawgetrect, menuhit, setcursor – mouse control
SYNOPSIS
| `#include <u.h> #include <libc.h> #include <draw.h> #include <thread.h> #include <mouse.h> #include <cursor.h>
` `Mousectl *initmouse(char *file, Image *i)
` `int readmouse(Mousectl *mc)
` `int atomouse();
` `void closemouse(Mousectl *mc)
` `void moveto(Mousectl *mc, Point pt)
` `void setcursor(Mousectl *mc, Cursor *c)
` `Rectangle getrect(int but, Mousectl *mc)
` `void drawgetrect(Rectangle r, int up)
` `int menuhit(int but, Mousectl *mc, Menu *menu, Screen *scr)`
DESCRIPTION
| These functions access and control a mouse in a multi-threaded environment. They use the message-passing `Channel` interface in the threads library (see thread(3)); programs that wish a more event-driven, single-threaded approach should use event(3).
The state of the mouse is recorded in a structure, `Mouse`, defined in `<mouse.h>`:
| `typedef struct Mouse Mouse; struct Mouse {
| int buttons; /* bit array: LMR=124 */ Point xy; ulong msec;
};
`
The `Point xy` records the position of the cursor, `buttons` the state of the buttons (three bits representing, from bit 0 up, the buttons from left to right, 0 if the button is released, 1 if it is pressed), and `msec`, a millisecond time stamp.
The routine `initmouse` returns a structure through which one may access the mouse:
| `typedef struct Mousectl Mousectl; struct Mousectl {
| Mouse; Channel *c; /* chan(Mouse)[16] */ Channel *resizec; /* chan(int)[2] */ char *file; int mfd; /* to mouse file */ int cfd; /* to cursor file */ int pid; /* of slave proc */ Image* image; /* of associated window/display */
};
`
The arguments to initmouse are a file naming the device file connected to the mouse and an Image (see draw(3)) on which the mouse will be visible. Typically the file is nil, which requests the default `/dev/mouse`; and the image is the window in which the program is running, held in the variable `screen` after a call to initdraw.
Once the `Mousectl` is set up, mouse motion will be reported by messages of type `Mouse` sent on the `Channel Mousectl.c`. Typically, a message will be sent every time a read of `/dev/mouse` succeeds, which is every time the state of the mouse changes.
When the window is resized, a message is sent on `Mousectl.resizec`. The actual value sent may be discarded; the receipt of the message tells the program that it should call `getwindow` (see graphics(3)) to reconnect to the window.
Readmouse updates the `Mouse` structure held in the `Mousectl`, blocking if the state has not changed since the last readmouse or message sent on the channel. It calls `flushimage` (see graphics(3)) before blocking, so any buffered graphics requests are displayed.
Closemouse closes the file descriptors associated with the mouse, kills the slave processes, and frees the `Mousectl` structure.
Moveto moves the mouse cursor on the display to the position specified by pt.
Setcursor sets the image of the cursor to that specified by c. If c is nil, the cursor is set to the default. The format of the cursor data is spelled out in `<cursor.h>` and described in graphics(3).
Getrect returns the dimensions of a rectangle swept by the user, using the mouse, in the manner rio(1) or sam(1) uses to create a new window. The but argument specifies which button the user must press to sweep the window; any other button press cancels the action. The returned rectangle is all zeros if the user cancels.
Getrect uses successive calls to drawgetrect to maintain the red rectangle showing the sweep-in-progress. The rectangle to be drawn is specified by rc and the up parameter says whether to draw (1) or erase (0) the rectangle.
Menuhit provides a simple menu mechanism. It uses a `Menu` structure defined in `<mouse.h>`:
| `typedef struct Menu Menu; struct Menu {
| char **item; char *(*gen)(int); int lasthit;
};
`
Menuhit behaves the same as its namesake emenuhit described in event(3), with two exceptions. First, it uses a `Mousectl` to access the mouse rather than using the event interface; and second, it creates the menu as a true window on the `Screen` scr (see window(3)), permitting the menu to be displayed in parallel with other activities on the display. If scr is null, menuhit behaves like emenuhit, creating backing store for the menu, writing the menu directly on the display, and restoring the display when the menu is removed.
SOURCE
| `/usr/lib/plan9/src/libdraw`
SEE ALSO
| graphics(3), draw(3), event(3), keyboard(3), thread(3).