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al_lock_bitmap(3alleg5) Allegro reference manual() | al_lock_bitmap(3alleg5) Allegro reference manual() |
NAME¶
al_lock_bitmap - Allegro 5 APISYNOPSIS¶
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#include <allegro5/allegro.h> ALLEGRO_LOCKED_REGION *al_lock_bitmap(ALLEGRO_BITMAP *bitmap, int format, int flags)
DESCRIPTION¶
Lock an entire bitmap for reading or writing. If the bitmap is a display bitmap it will be updated from system memory after the bitmap is unlocked (unless locked read only). Returns NULL if the bitmap cannot be locked, e.g. the bitmap was locked previously and not unlocked. Flags are:- •
- ALLEGRO_LOCK_READONLY - The locked region will not be written to. This can be faster if the bitmap is a video texture, as it can be discarded after the lock instead of uploaded back to the card.
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- ALLEGRO_LOCK_WRITEONLY - The locked region will not be read from. This can be faster if the bitmap is a video texture, as no data need to be read from the video card. You are required to fill in all pixels before unlocking the bitmap again, so be careful when using this flag.
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- ALLEGRO_LOCK_READWRITE - The locked region can be written to and read from. Use this flag if a partial number of pixels need to be written to, even if reading is not needed.
Note: While a bitmap is locked, you can not use any drawing operations on
it (with the sole exception of al_put_pixel(3alleg5) and
al_put_blended_pixel(3alleg5)).