Allegro provides functions for reading the mouse state and displaying a mouse
cursor on-screen. You can read the absolute position of the mouse and the
state of the mouse buttons from global variables. Additionally, you can read
the mouse position difference as mouse mickeys, which is the number of pixels
the cursor moved since the last time this information was read.
Allegro offers three ways to display the mouse cursor:
-
Standard Allegro cursor
Allegro is responsible for drawing the mouse cursor from a timer. Use
set_mouse_sprite() and show_mouse() to define your own cursor and display
it on the screen.
You need to call scare_mouse()/unscare_mouse() to hide the mouse cursor
whenever you draw to the screen.
-
Custom operating system cursor (hardware cursor)
Allegro will let the operating system draw the mouse cursor. Use
set_mouse_sprite() and show_mouse() to define your own cursor and display
it on the screen. Not all graphics drivers are capable of this and some
may only be able to display cursors upto a certain size. Allegro will fall
back on its own cursor drawing if it cannot let the OS handle this. On some
platforms, the hardware cursor is incompatible with get_mouse_mickeys()
and it is therefor disabled by default. In such cases you need to call
enable_hardware_cursor() to enable it explicitly.
-
Default operating system cursor
Allegro will not draw its own cursor, but use the operating system default
cursor. You can use the select_mouse_cursor() function to select the cursor
shape to display. As with custom operating system cursors, you need to call
enable_hardware_cursor() before you can use this.
Not all drivers will support all functionality. See the platform specific
information for more details.
Installs the Allegro mouse handler. You must do this before using any
other mouse functions.
Return value:
Returns -1 on failure, zero if the mouse handler is already installed (in
which case this function does nothing) and the number of buttons on the
mouse if the mouse handler has successfully been installed (ie. this is
the first time a handler is installed or you have removed the previous
one).
Note that the number of mouse buttons returned by this function is more
an indication than a physical reality. With most devices there is no way
of telling how many buttons there are, and any user can override the
number of mouse buttons returned by this function with a custom
configuration file and the variable num_buttons. Even if this value is
overriden by the user, the global mouse variables will still report
whatever the hardware is sending.
See also:
remove_mouse,
poll_mouse,
mouse_x,
show_mouse,
get_mouse_mickeys,
position_mouse,
set_mouse_range,
set_mouse_speed,
Standard config variables.
Examples using this:
Available Allegro examples.
Removes the mouse handler. You don't normally need to bother calling
this, because allegro_exit() will do it for you.
See also:
install_mouse,
allegro_exit.
Wherever possible, Allegro will read the mouse input asynchronously (ie.
from inside an interrupt handler), but on some platforms that may not be
possible, in which case you must call this routine at regular intervals
to update the mouse state variables. To help you test your mouse polling
code even if you are programming on a platform that doesn't require it,
after the first time that you call this function Allegro will switch into
polling mode, so from that point onwards you will have to call this
routine in order to get any mouse input at all, regardless of whether the
current driver actually needs to be polled or not.
Return value:
Returns zero on success, or a negative number on failure (ie. no mouse
driver installed).
See also:
mouse_needs_poll,
install_mouse,
mouse_x.
Examples using this:
exlights,
exmouse,
exshade,
exspline,
extrans.
Returns TRUE if the current mouse driver is operating in polling mode.
See also:
poll_mouse,
install_mouse,
mouse_x.
After calling this function, Allegro will let the operating system draw the
mouse cursor instead of doing it itself. This is not possible with all
graphics drivers though: you'll need to check the gfx_capabilities flags
after calling show_mouse() to see if this works. On some platforms, enabling
the hardware cursor causes get_mouse_mickeys() to return only a limited
range of values, so you should not call this function if you need mouse
mickeys.
See also:
install_mouse,
show_mouse,
set_mouse_sprite,
get_mouse_mickeys,
gfx_capabilities,
disable_hardware_cursor.
After calling this function, Allegro will be responsible for drawing the
mouse cursor rather than the operating system. On some platforms calling
enable_hardware_cursor() makes the return values of get_mouse_mickeys()
unreliable. After calling this function, get_mouse_mickeys() returns
reliable results again.
See also:
install_mouse,
show_mouse,
set_mouse_sprite,
get_mouse_mickeys,
gfx_capabilities,
enable_hardware_cursor.
With this function, you can instruct Allegro to use the native system
cursors rather than Allegro's custom cursor. You will need to enable this
functionality by calling enable_hardware_cursor(). Allegro will substitute
its own default cursor if the system does not support this functionality
or if it has not been enabled. You should check the GFX_SYSTEM_CURSOR flag
in gfx_capabilities after calling show_mouse() to see wether or not Allegro
is really using the default system cursor.
The cursor argument selects the type of cursor to be displayed:
MOUSE_CURSOR_NONE
Selects an invisible mouse cursor. In that sense, it is similar to calling
show_mouse(NULL);
MOUSE_CURSOR_ALLEGRO
Selects the custom Allegro cursor.
MOUSE_CURSOR_ARROW
The operating system default arrow cursor.
MOUSE_CURSOR_BUSY
The operating system default `busy' cursor (hourglass).
MOUSE_CURSOR_QUESTION
The operating system default `question' cursor (arrow with question mark).
MOUSE_CURSOR_EDIT
The operating system default `edit' cursor (vertical bar).
Example:
/* initialize mouse sub-system */
install_mouse();
enable_hardware_cursor();
/* Set busy pointer */
select_mouse_cursor(MOUSE_CURSOR_BUSY);
show_mouse(screen);
/* Initialize stuff */
...
/* Set normal arrow pointer */
select_mouse_cursor(MOUSE_CURSOR_ARROW);
See also:
install_mouse,
show_mouse,
set_mouse_sprite,
gfx_capabilities,
enable_hardware_cursor,
set_mouse_cursor_bitmap.
This function changes the cursor image Allegro uses if select_mouse_cursor()
is called but no native OS cursor can be used, for instance because you
did not call enable_hardware_cursor().
See also:
install_mouse,
show_mouse,
set_mouse_sprite,
gfx_capabilities,
enable_hardware_cursor.
Global variables containing the current mouse position and button state.
Wherever possible these values will be updated asynchronously, but if
mouse_needs_poll() returns TRUE, you must manually call poll_mouse() to
update them with the current input state. The `mouse_x' and `mouse_y'
positions are integers ranging from zero to the bottom right corner of
the screen. The `mouse_z' variable holds the current wheel position, when
using an input driver that supports wheel mice. The `mouse_b' variable is
a bitfield indicating the state of each button: bit 0 is the left button,
bit 1 the right, and bit 2 the middle button. Additional non standard
mouse buttons might be available as higher bits in this variable. Usage
example:
if (mouse_b & 1)
printf("Left button is pressed\n");
if (!(mouse_b & 2))
printf("Right button is not pressed\n");
The `mouse_pos' variable has the current X coordinate in the upper 16 bits
and the Y in the lower 16 bits. This may be useful in tight polling loops
where a mouse interrupt could occur between your reading of the two
separate variables, since you can copy this value into a local variable
with a single instruction and then split it up at your leisure. Example:
int pos, x, y;
pos = mouse_pos;
x = pos >> 16;
y = pos & 0x0000ffff;
See also:
install_mouse,
poll_mouse,
mouse_needs_poll.
Examples using this:
exalpha,
exlights,
exmouse,
exshade,
exspline,
extrans.
Global variables containing the current mouse sprite and the focus
point. These are read-only, and only to be modified using the
set_mouse_sprite() and set_mouse_sprite_focus() functions.
See also:
set_mouse_sprite,
set_mouse_sprite_focus.
Tells Allegro to display a mouse pointer on the screen. This will only
work if the timer module has been installed. The mouse pointer will be
drawn onto the specified bitmap, which should normally be `screen' (see
later for information about bitmaps). To hide the mouse pointer, call
show_mouse(NULL).
Warning: if you draw anything onto the screen while the pointer is
visible, a mouse movement interrupt could occur in the middle of your
drawing operation. If this happens the mouse buffering and graphics drawing
code will get confused and will leave 'mouse droppings' all over the
screen. To prevent this, you must make sure you turn off the mouse
pointer whenever you draw onto the screen. This is not needed if you are
using a hardware cursor.
See also:
install_mouse,
install_timer,
set_mouse_sprite,
scare_mouse,
freeze_mouse_flag.
Examples using this:
exmouse,
expal,
exshade,
exspline.
Helper for hiding the mouse pointer prior to a drawing operation. This
will temporarily get rid of the pointer, but only if that is really
required (ie. the mouse is visible, and is displayed on the physical
screen rather than some other memory surface, and it is not a hardware
or OS cursor). The previous mouse state is stored for subsequent calls to
unscare_mouse().
See also:
unscare_mouse,
scare_mouse_area,
show_mouse.
Like scare_mouse(), but will only hide the cursor if it is inside the
specified rectangle. Otherwise the cursor will simply be frozen in place
until you call unscare_mouse(), so it cannot interfere with your drawing.
See also:
unscare_mouse,
scare_mouse,
show_mouse.
Undoes the effect of a previous call to scare_mouse() or
scare_mouse_area(), restoring the original pointer state.
See also:
scare_mouse,
scare_mouse_area.
If this flag is set, the mouse pointer won't be redrawn when the mouse
moves. This can avoid the need to hide the pointer every time you draw to
the screen, as long as you make sure your drawing doesn't overlap with
the current pointer position.
See also:
show_mouse.
Moves the mouse to the specified screen position. It is safe to call even
when a mouse pointer is being displayed.
See also:
install_mouse,
position_mouse_z,
set_mouse_range,
set_mouse_speed.
Sets the mouse wheel position variable to the specified value.
See also:
install_mouse,
position_mouse.
Sets the area of the screen within which the mouse can move. Pass the top
left corner and the bottom right corner (inclusive). If you don't call
this function the range defaults to (0, 0, SCREEN_W-1, SCREEN_H-1).
See also:
install_mouse,
set_mouse_speed,
position_mouse.
Sets the mouse speed. Larger values of xspeed and yspeed represent slower
mouse movement: the default for both is 2.
See also:
install_mouse,
set_mouse_range,
position_mouse.
You don't like my mouse pointer? No problem. Use this function to supply
an alternative of your own. If you change the pointer and then want to
get my lovely arrow back again, call set_mouse_sprite(NULL).
As a bonus, set_mouse_sprite(NULL) uses the current palette in choosing
colors for the arrow. So if your arrow mouse sprite looks ugly after
changing the palette, call set_mouse_sprite(NULL).
See also:
install_mouse,
show_mouse,
set_mouse_sprite_focus.
Examples using this:
exmouse.
The mouse focus is the bit of the pointer that represents the actual
mouse position, ie. the (mouse_x, mouse_y) position. By default this is
the top left corner of the arrow, but if you are using a different mouse
pointer you might need to alter it.
See also:
set_mouse_sprite.
Examples using this:
exmouse.
Measures how far the mouse has moved since the last call to this
function. The mouse will continue to generate movement mickeys even when
it reaches the edge of the screen, so this form of input can be useful
for games that require an infinite range of mouse movement.
See also:
install_mouse.
Examples using this:
exmouse.
Called by the interrupt handler whenever the mouse moves or one of the
buttons changes state. This function must be in locked memory, and must
execute _very_ quickly! It is passed the event flags that triggered the
call, which is a bitmask containing any of the values MOUSE_FLAG_MOVE,
MOUSE_FLAG_LEFT_DOWN, MOUSE_FLAG_LEFT_UP, MOUSE_FLAG_RIGHT_DOWN,
MOUSE_FLAG_RIGHT_UP, MOUSE_FLAG_MIDDLE_DOWN, MOUSE_FLAG_MIDDLE_UP, and
MOUSE_FLAG_MOVE_Z. Note that even if the mouse has more than three buttons,
only the first three can be trapped using a callback.
See also:
install_mouse.