1al_lock_bitmap(3)          Library Functions Manual          al_lock_bitmap(3)
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NAME

6       al_lock_bitmap
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SYNOPSIS

9              #include <allegro5/allegro.h>
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11              ALLEGRO_LOCKED_REGION *al_lock_bitmap(ALLEGRO_BITMAP *bitmap,
12                 int format, int flags)
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DESCRIPTION

15       Lock  an entire bitmap for reading or writing.  If the bitmap is a dis‐
16       play bitmap it will be updated from system memory after the  bitmap  is
17       unlocked  (unless locked read only).  Returns NULL if the bitmap cannot
18       be locked, e.g. the bitmap was locked previously and not unlocked.
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20       Flags are:
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22       · ALLEGRO_LOCK_READONLY - The locked region will  not  be  written  to.
23         This  can  be  faster  if the bitmap is a video texture, as it can be
24         discarded after the lock instead of uploaded back to the card.
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26       · ALLEGRO_LOCK_WRITEONLY - The locked region will  not  be  read  from.
27         This  can be faster if the bitmap is a video texture, as no data need
28         to be read from the video card.  You are required to fill in all pix‐
29         els  before unlocking the bitmap again, so be careful when using this
30         flag.
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32       · ALLEGRO_LOCK_READWRITE - The locked region can be written to and read
33         from.
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35       `format'  indicates  the  pixel format that the returned buffer will be
36       in.  To lock in the same format as the bitmap stores it's  data  inter‐
37       nally,  call  with  al_get_bitmap_format(bitmap)  as  the format or use
38       ALLEGRO_PIXEL_FORMAT_ANY.  Locking in the native format will usually be
39       faster.
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41              Note:  While  a  bitmap  is  locked, you can not use any drawing
42              operations on it (with the sole exception of al_put_pixel(3) and
43              al_put_blended_pixel(3)).
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SEE ALSO

46       ALLEGRO_LOCKED_REGION(3), ALLEGRO_PIXEL_FORMAT(3), al_unlock_bitmap(3)
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50Allegro reference manual                                     al_lock_bitmap(3)
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