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In GUI's like Windows, mouse is very
important for user interaction. But in DOS, mouse will come in to picture
only in some of the programs. If you are writing DOS games or graphics
programs, you can add mouse functionality to your code. Here is how to do
that.
If you are beginner to Turbo C graphics programming,
read our introduction to Turbo C graphics.
Mouse can be used in text mode as well as in graphics mode. Usually it is
used in graphics mode. Hence we must first change over to graphics mode. In
our program the function initgraph() is responsible for switching the mode
from text to graphics .DETECT is a macro defined in 'graphics.h'. It
requests initgraph() to automatically determine which graphics driver to
load in order to switch to the highest resolution graphics mode. The
initgraph() function takes three parameters, the graphics driver, the
graphics mode and the path to the driver file.
Once the driver has been
loaded, initgraph() sets up the numeric values of the graphics mode chosen
in the variables gd and gm respectively. Here we are assuming that the
driver files are in the directory 'c:\tc\bgi'. Hence the path passed to
initgraph() is 'c:\tc\bgi'.
The various mouse functions
can be accessed by setting up the AX register with different values (service
number) and issuing interrupt number 51. The functions are listed bellow
|
Interrupt |
Service |
Purpose |
51
|
0
|
Reset mouse and get status
Call with AX = 0
Returns: AX = FFFFh If mouse support is available
Ax = 0 If mouse support is not available |
|
51 |
1 |
Show mouse pointer
Call with AX = 1
Returns: Nothing |
|
51 |
2 |
Hide mouse pointer
Call with AX = 2
Returns: Nothing |
|
51 |
3 |
Get mouse position and button status
Call with AX = 3
Returns: BX = mouse button status
Bit Significance
0 button not pressed
1 left button is pressed
2 right button is pressed
3 center button is pressed
CX = x coordinate
DX = y coordinate |
|
51 |
4 |
Set mouse pointer position
Call with AX = 4
CX = x coordinate
DX = y coordinate
Returns: Nothing |
|
51 |
7 |
Set horizontal limits for pointer
Call with AX = 7
CX = minimum x coordinate
DX = maximum x coordinate
Returns: Nothing |
|
51 |
8 |
Set vertical limits for pointer
Call with AX = 8
CX = minimum y coordinate
DX = maximum y coordinate
Returns: Nothing |
Let us consider a program which makes
use of the above functions.
#include<graphics.h>
#include<stdio.h>
#include<conio.h>
#include<dos.h>
union REGS in,out;
int callmouse()
{
in.x.ax=1;
int86(51,&in,&out);
return 1;
}
void mouseposi(int &xpos,int &ypos,int &click)
{
in.x.ax=3;
int86(51,&in,&out);
click=out.x.bx;
xpos=out.x.cx;
ypos=out.x.dx;
}
int mousehide()
{
in.x.ax=2;
int86(51,&in,&out);
return 1;
}
void setposi(int &xpos,int &ypos)
{
in.x.ax=4;
in.x.cx=xpos;
in.x.dx=ypos;
int86(51,&in,&out);
}
int main()
{
int x,y,cl,a,b;
clrscr();
int g=DETECT,m;
initgraph(&g,&`�|7V `�|7V 0C�|7V 0�|7V x`�|7V 0`�|7V . 0`�|7V p; a=100;
b=400;
setposi(a,b);
callmouse();
do
{
mouseposi(x,y,cl);
gotoxy(10,9);
printf("\n\tMouse Position is: %d,%d",x,y);
printf("\n\tClick: %d",cl);
printf("\n\tPress any key to hide the mouse");
}while(!kbhit());
getch();
mousehide();
printf("\n\n\tPress any key to Exit");
getch();
} |
The above program makes use of the following
functions:
-
callmouse(
)
-
mouseposi(
)
-
mousehide(
)
-
setposi(
)
callmouse()
:- In this function AX is set to "1". When this
function is called in main() it displays the mouse pointer. The position of
the pointer can be changed by using the mouse.
mousehide() :- In this
function AX is set to "2".When this function is called in main() it hides
the mouse pointer. This function is useful while drawing figures, first the
mouse pointer is kept hidden, then the figure is been drawn and again the
mouse pointer is been called.
mouseposi()
:- In this function AX is set to "3". This function
returns the position of the mouse pointer. It contains three parameters,they
are xpos,ypos,click. xpos and ypos returns the position of x co-ordinate and
y co-ordinate respectively. Click is the integer variable which returns the
values 1,2,3 corresponding to the button pressed on the mouse and 0 for
buttons being not pressed. If any key is pressed kbhit returns nonzero
integer; if not it returns zero.
setposi() :- In this function AX is set to "4".
This function sets the mouse pointer to specific position . CX is been
loaded by x co-ordinate of the mouse pointer and DX is been loaded with the
y co-ordinate of the mouse pointer.
Let us consider another program
#include<graphics.h>
#include<stdio.h>
#include<conio.h>
#include<dos.h>
union REGS in,out;
int callmouse()
{
in.x.ax=1;
int86(51,&in,&out);
return 1;
}
void restrictmouseptr(int x1,int y1,int x2,int y2)
{
in.x.ax=7;
in.x.cx=x1;
in.x.dx=x2;
int86(51,&in,&out);
in.x.ax=8;
in.x.cx=y1;
in.x.dx=y2;
int86(51,&in,&out);
}
int main()
{
int x,y,cl,a,b;
clrscr();
int g=DETECT,m;
initgraph(&g,&m,"c:\tc\bgi");
rectangle(100,100,550,400);
callmouse();
restrictmouseptr(100,100,550,400);
getch();
} |
The above program makes use of
the following functions:
-
Horizontal ( )
-
Vertical( )
Horizontal() :- In this function AX is set
to "7". Its sets the horizontal barrier for the pointer which restricts the
mouse pointer to pass that limit. CX is been loaded with the minimum x
co-ordinate and Dx is been loaded with the maximum x co-ordinate.
Vertical()
:- In this function AX is set to "8".Its sets the vertical barrier for
the pointer which restricts the mouse pointer to pass that limit. CX is been
loaded with the minimum y co-ordinate and Dx is been loaded with the maximum
y co-ordinate.
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