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ALLEGRO_EVENT

Allegro 5 API

#include <allegro5/allegro.h>
typedef union ALLEGRO_EVENT ALLEGRO_EVENT;

An ALLEGRO_EVENT is a union of all builtin event structures, i.e. it is an object large enough to hold the data of any event type. All events have the following fields in common:

Indicates the type of event.
The event source which generated the event.
When the event was generated.

By examining the type field you can then access type-specific fields. The any.source field tells you which event source generated that particular event. The any.timestamp field tells you when the event was generated. The time is referenced to the same starting point as al_get_time(3alleg5).

Each event is of one of the following types, with the usable fields given.

A joystick axis value changed.

The joystick which generated the event. This is not the same as the event source joystick.source.
The stick number, counting from zero. Axes on a joystick are grouped into "sticks".
The axis number on the stick, counting from zero.
The axis position, from -1.0 to +1.0.

A joystick button was pressed.

The joystick which generated the event.
The button which was pressed, counting from zero.

A joystick button was released.

The joystick which generated the event.
The button which was released, counting from zero.

A joystick was plugged in or unplugged. See al_reconfigure_joysticks(3alleg5) for details.

A keyboard key was pressed.

The code corresponding to the physical key which was pressed. See the "Key codes" section for the list of ALLEGRO_KEY_* constants.
The display which had keyboard focus when the event occurred.

Note: this event is about the physical keys being pressed on the keyboard. Look for ALLEGRO_EVENT_KEY_CHAR events for character input.

A keyboard key was released.

The code corresponding to the physical key which was released. See the "Key codes" section for the list of ALLEGRO_KEY_* constants.
The display which had keyboard focus when the event occurred.

A character was typed on the keyboard, or a character was auto-repeated.

The code corresponding to the physical key which was last pressed. See the "Key codes" section for the list of ALLEGRO_KEY_* constants.
A Unicode code point (character). This may be zero or negative if the event was generated for a non-visible "character", such as an arrow or Function key. In that case you can act upon the keycode field.

Some special keys will set the unichar field to their standard ASCII values: Tab=9, Return=13, Escape=27. In addition if you press the Control key together with A to Z the unichar field will have the values 1 to 26. For example Ctrl-A will set unichar to 1 and Ctrl-H will set it to 8.

As of Allegro 5.0.2 there are some inconsistencies in the treatment of Backspace (8 or 127) and Delete (127 or 0) keys on different platforms. These can be worked around by checking the keycode field.

This is a bitfield of the modifier keys which were pressed when the event occurred. See "Keyboard modifier flags" for the constants.
Indicates if this is a repeated character.
The display which had keyboard focus when the event occurred.

Note: in many input methods, characters are not entered one-for-one with physical key presses. Multiple key presses can combine to generate a single character, e.g. apostrophe + e may produce 'é'. Fewer key presses can also generate more characters, e.g. macro sequences expanding to common phrases.

One or more mouse axis values changed.

x-coordinate
y-coordinate
z-coordinate. This usually means the vertical axis of a mouse wheel, where up is positive and down is negative.
w-coordinate. This usually means the horizontal axis of a mouse wheel.
Change in the x-coordinate value since the previous ALLEGRO_EVENT_MOUSE_AXES event.
Change in the y-coordinate value since the previous ALLEGRO_EVENT_MOUSE_AXES event.
Change in the z-coordinate value since the previous ALLEGRO_EVENT_MOUSE_AXES event.
Change in the w-coordinate value since the previous ALLEGRO_EVENT_MOUSE_AXES event.
The display which had mouse focus.

Note: Calling al_set_mouse_xy(3alleg5) also will result in a change of axis values, but such a change is reported with ALLEGRO_EVENT_MOUSE_WARPED events instead.

Note: currently mouse.display may be NULL if an event is generated in response to al_set_mouse_axis(3alleg5).

A mouse button was pressed.

x-coordinate
y-coordinate
z-coordinate
w-coordinate
The mouse button which was pressed, numbering from 1.
The display which had mouse focus.

A mouse button was released.

x-coordinate
y-coordinate
z-coordinate
w-coordinate
The mouse button which was released, numbering from 1.
The display which had mouse focus.

al_set_mouse_xy(3alleg5) was called to move the mouse. This event is identical to ALLEGRO_EVENT_MOUSE_AXES otherwise.

The mouse cursor entered a window opened by the program.

x-coordinate
y-coordinate
z-coordinate
w-coordinate
The display which had mouse focus.

The mouse cursor leave the boundaries of a window opened by the program.

x-coordinate
y-coordinate
z-coordinate
w-coordinate
The display which had mouse focus.

A timer counter incremented.

The timer which generated the event.
The timer count value.

The display (or a portion thereof) has become visible.

The display which was exposed.
  display.y (int)
 
The top-left corner of the display which was exposed.
  display.height (int)
The width and height of the rectangle which was exposed.

Note: The display needs to be created with ALLEGRO_GENERATE_EXPOSE_EVENTS flag for these events to be generated.

The window has been resized.

The display which was resized.
  display.y (int)
The position of the top-level corner of the display.
The new width of the display.
The new height of the display.

You should normally respond to these events by calling al_acknowledge_resize(3alleg5). Note that further resize events may be generated by the time you process the event, so these fields may hold outdated information.

The close button of the window has been pressed.

The display which was closed.

When using Direct3D, displays can enter a "lost" state. In that state, drawing calls are ignored, and upon entering the state, bitmap's pixel data can become undefined. Allegro does its best to preserve the correct contents of bitmaps (see ALLEGRO_NO_PRESERVE_TEXTURE) and restore them when the device is "found" (see ALLEGRO_EVENT_DISPLAY_FOUND). However, this is not 100% fool proof.

To ensure that all bitmap contents are restored accurately, one must take additional steps. The best procedure to follow if bitmap constancy is important to you is as follows: first, always have the ALLEGRO_NO_PRESERVE_TEXTURE flag set to true when creating bitmaps, as it incurs pointless overhead when using this method. Second, create a mechanism in your game for easily reloading all of your bitmaps -- for example, wrap them in a class or data structure and have a "bitmap manager" that can reload them back to the desired state. Then, when you receive an ALLEGRO_EVENT_DISPLAY_FOUND event, tell the bitmap manager (or whatever your mechanism is) to restore your bitmaps.

The display which was lost.

Generated when a lost device is restored to operating state. See ALLEGRO_EVENT_DISPLAY_LOST.

The display which was found.

The window is no longer active, that is the user might have clicked into another window or "tabbed" away.

The display which was switched out of.

The window is the active one again.

The display which was switched into.

Generated when the rotation or orientation of a display changes.

The display which generated the event.
Contains one of the following values:
  • ALLEGRO_DISPLAY_ORIENTATION_0_DEGREES
  • ALLEGRO_DISPLAY_ORIENTATION_90_DEGREES
  • ALLEGRO_DISPLAY_ORIENTATION_180_DEGREES
  • ALLEGRO_DISPLAY_ORIENTATION_270_DEGREES
  • ALLEGRO_DISPLAY_ORIENTATION_FACE_UP
  • ALLEGRO_DISPLAY_ORIENTATION_FACE_DOWN

ALLEGRO_EVENT_SOURCE(3alleg5), ALLEGRO_EVENT_TYPE(3alleg5), ALLEGRO_USER_EVENT(3alleg5), ALLEGRO_GET_EVENT_TYPE(3alleg5)