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><H1
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><A
NAME="MOUSE"
></A
>12. Interfacing with the mouse</H1
><P
>Now that you have seen how to get keys, lets do the same thing from mouse.
Usually each UI allows the user to interact with both keyboard and mouse. </P
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MOUSEBASICS"
></A
>12.1. The Basics</H2
><P
>Before you do any thing else, the events you want to receive have to be enabled
with <TT
CLASS="LITERAL"
>mousemask()</TT
>.</P
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><PRE
CLASS="PROGRAMLISTING"
> mousemask( mmask_t newmask, /* The events you want to listen to */
mmask_t *oldmask) /* The old events mask */</PRE
></FONT
></TD
></TR
></TABLE
><P
>The first parameter to above function is a bit mask of events you would like to
listen. By default, all the events are turned off. The bit mask <TT
CLASS="LITERAL"
> ALL_MOUSE_EVENTS</TT
> can be used to get all the events.</P
><P
>The following are all the event masks:</P
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><PRE
CLASS="PROGRAMLISTING"
> Name Description
---------------------------------------------------------------------
BUTTON1_PRESSED mouse button 1 down
BUTTON1_RELEASED mouse button 1 up
BUTTON1_CLICKED mouse button 1 clicked
BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
BUTTON2_PRESSED mouse button 2 down
BUTTON2_RELEASED mouse button 2 up
BUTTON2_CLICKED mouse button 2 clicked
BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
BUTTON3_PRESSED mouse button 3 down
BUTTON3_RELEASED mouse button 3 up
BUTTON3_CLICKED mouse button 3 clicked
BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
BUTTON4_PRESSED mouse button 4 down
BUTTON4_RELEASED mouse button 4 up
BUTTON4_CLICKED mouse button 4 clicked
BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
BUTTON_SHIFT shift was down during button state change
BUTTON_CTRL control was down during button state change
BUTTON_ALT alt was down during button state change
ALL_MOUSE_EVENTS report all button state changes
REPORT_MOUSE_POSITION report mouse movement</PRE
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><H2
CLASS="SECT2"
><A
NAME="GETTINGEVENTS"
></A
>12.2. Getting the events</H2
><P
>Once a class of mouse events have been enabled, getch() class of functions
return KEY_MOUSE every time some mouse event happens. Then the mouse event can
be retrieved with <TT
CLASS="LITERAL"
>getmouse()</TT
>.</P
><P
>The code approximately looks like this:</P
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><PRE
CLASS="PROGRAMLISTING"
> MEVENT event;
ch = getch();
if(ch == KEY_MOUSE)
if(getmouse(&event) == OK)
. /* Do some thing with the event */
.
.</PRE
></FONT
></TD
></TR
></TABLE
><P
>
getmouse() returns the event into the pointer given to it. It's a structure
which contains</P
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><FONT
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><PRE
CLASS="PROGRAMLISTING"
> typedef struct
{
short id; /* ID to distinguish multiple devices */
int x, y, z; /* event coordinates */
mmask_t bstate; /* button state bits */
} </PRE
></FONT
></TD
></TR
></TABLE
><P
>The <TT
CLASS="LITERAL"
>bstate</TT
> is the main variable we are
interested in. It tells the button state of the mouse.</P
><P
>Then with a code snippet like the following, we can find out what happened.</P
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><PRE
CLASS="PROGRAMLISTING"
> if(event.bstate & BUTTON1_PRESSED)
printw("Left Button Pressed");</PRE
></FONT
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><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MOUSETOGETHER"
></A
>12.3. Putting it all Together</H2
><P
>That's pretty much interfacing with mouse. Let's create the same menu and enable
mouse interaction. To make things simpler, key handling is removed.</P
><DIV
CLASS="EXAMPLE"
><A
NAME="BMOME"
></A
><P
><B
>Example 11. Access the menu with mouse !!! </B
></P
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><PRE
CLASS="PROGRAMLISTING"
><SPAN
CLASS="INLINEMEDIAOBJECT"
>#include <ncurses.h>
#define WIDTH 30
#define HEIGHT 10
int startx = 0;
int starty = 0;
char *choices[] = { "Choice 1",
"Choice 2",
"Choice 3",
"Choice 4",
"Exit",
};
int n_choices = sizeof(choices) / sizeof(char *);
void print_menu(WINDOW *menu_win, int highlight);
void report_choice(int mouse_x, int mouse_y, int *p_choice);
int main()
{ int c, choice = 0;
WINDOW *menu_win;
MEVENT event;
/* Initialize curses */
initscr();
clear();
noecho();
cbreak(); //Line buffering disabled. pass on everything
/* Try to put the window in the middle of screen */
startx = (80 - WIDTH) / 2;
starty = (24 - HEIGHT) / 2;
attron(A_REVERSE);
mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
refresh();
attroff(A_REVERSE);
/* Print the menu for the first time */
menu_win = newwin(HEIGHT, WIDTH, starty, startx);
print_menu(menu_win, 1);
/* Get all the mouse events */
mousemask(ALL_MOUSE_EVENTS, NULL);
while(1)
{ c = wgetch(menu_win);
switch(c)
{ case KEY_MOUSE:
if(getmouse(&event) == OK)
{ /* When the user clicks left mouse button */
if(event.bstate & BUTTON1_PRESSED)
{ report_choice(event.x + 1, event.y + 1, &choice);
if(choice == -1) //Exit chosen
goto end;
mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
refresh();
}
}
print_menu(menu_win, choice);
break;
}
}
end:
endwin();
return 0;
}
void print_menu(WINDOW *menu_win, int highlight)
{
int x, y, i;
x = 2;
y = 2;
box(menu_win, 0, 0);
for(i = 0; i < n_choices; ++i)
{ if(highlight == i + 1)
{ wattron(menu_win, A_REVERSE);
mvwprintw(menu_win, y, x, "%s", choices[i]);
wattroff(menu_win, A_REVERSE);
}
else
mvwprintw(menu_win, y, x, "%s", choices[i]);
++y;
}
wrefresh(menu_win);
}
/* Report the choice according to mouse position */
void report_choice(int mouse_x, int mouse_y, int *p_choice)
{ int i,j, choice;
i = startx + 2;
j = starty + 3;
for(choice = 0; choice < n_choices; ++choice)
if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice]))
{ if(choice == n_choices - 1)
*p_choice = -1;
else
*p_choice = choice + 1;
break;
}
}</SPAN
></PRE
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><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="MISCMOUSEFUNCS"
></A
>12.4. Miscellaneous Functions</H2
><P
>The functions mouse_trafo() and wmouse_trafo() can be used to convert to mouse
co-ordinates to screen relative co-ordinates. See curs_mouse(3X) man page for details.</P
><P
>The mouseinterval function sets the maximum time (in thousands of a
second) that can elapse between press and release events in order for
them to be recognized as a click. This function returns the previous
interval value. The default is one fifth of a second.</P
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