State
These functions are declared in the main Allegro header file:
#include <allegro5/allegro.h>
ALLEGRO_STATE
typedef struct ALLEGRO_STATE ALLEGRO_STATE;
Opaque type which is passed to al_store_state/al_restore_state.
The various state kept internally by Allegro can be displayed like this:
global
active system driver
current config
per thread
new bitmap params
new display params
active file interface
errno
current blending mode
current display
deferred drawing
current target bitmap
current transformation
current clipping rectangle
bitmap locking
In general, the only real global state is the active system driver. All other global state is per-thread, so if your application has multiple separate threads they never will interfere with each other. (Except if there are objects accessed by multiple threads of course. Usually you want to minimize that though and for the remaining cases use synchronization primitives described in the threads section or events described in the events section to control inter-thread communication.)
ALLEGRO_STATE_FLAGS
typedef enum ALLEGRO_STATE_FLAGS
Flags which can be passed to al_store_state/al_restore_state as bit combinations. See al_store_state for the list of flags.
al_restore_state
void al_restore_state(ALLEGRO_STATE const *state)
Restores part of the state of the current thread from the given ALLEGRO_STATE object.
See also: al_store_state, ALLEGRO_STATE_FLAGS
al_store_state
void al_store_state(ALLEGRO_STATE *state, int flags)
Stores part of the state of the current thread in the given ALLEGRO_STATE objects. The flags parameter can take any bit-combination of these flags:
- ALLEGRO_STATE_NEW_DISPLAY_PARAMETERS - new_display_format, new_display_refresh_rate, new_display_flags
- ALLEGRO_STATE_NEW_BITMAP_PARAMETERS - new_bitmap_format, new_bitmap_flags
- ALLEGRO_STATE_DISPLAY - current_display
- ALLEGRO_STATE_TARGET_BITMAP - target_bitmap
- ALLEGRO_STATE_BLENDER - blender
- ALLEGRO_STATE_TRANSFORM - current_transformation
- ALLEGRO_STATE_NEW_FILE_INTERFACE - new_file_interface
- ALLEGRO_STATE_BITMAP - same as ALLEGRO_STATE_NEW_BITMAP_PARAMETERS and ALLEGRO_STATE_TARGET_BITMAP
- ALLEGRO_STATE_ALL - all of the above
See also: al_restore_state, ALLEGRO_STATE
al_get_errno
int al_get_errno(void)
Some Allegro functions will set an error number as well as returning an error code. Call this function to retrieve the last error number set for the calling thread.
al_set_errno
void al_set_errno(int errnum)
Set the error number for for the calling thread.