|
|
|
This thread is locked; no one can reply to it.
|
| Creating sub-bitmap of locked bitmap |
|
Felix-The-Ghost
Member #9,729
April 2008
 |
I'm looking to combine two for loops in my code, it would mean creating several sub-bitmaps of a bitmap that is currently locked to read pixels from. I couldn't tell from the manual if this is error prone/dangerous in any way. Is it safe? |
|
Edgar Reynaldo
Major Reynaldo
May 2007
 |
It looks safe enough to create a sub bitmap on a locked parent from the function definition. All al_create_sub_bitmap does is allocate a new ALLEGRO_BITMAP and populate it with default values. 431/* Function: al_create_sub_bitmap
432 */
433ALLEGRO_BITMAP *al_create_sub_bitmap(ALLEGRO_BITMAP *parent,
434 int x, int y, int w, int h)
435{
436 ALLEGRO_BITMAP *bitmap;
437
438 if (parent->parent) {
439 x += parent->xofs;
440 y += parent->yofs;
441 parent = parent->parent;
442 }
443
444 bitmap = al_calloc(1, sizeof *bitmap);
445 bitmap->vt = parent->vt;
446
447 /* Sub-bitmap inherits these from the parent.
448 * Leave these unchanged so they can be detected if improperly accessed
449 * directly. */
450 bitmap->_format = 0;
451 bitmap->_flags = 0;
452 bitmap->_display = (ALLEGRO_DISPLAY*)0x1;
453
454 bitmap->w = w;
455 bitmap->h = h;
456 bitmap->locked = false;
457 bitmap->cl = bitmap->ct = 0;
458 bitmap->cr_excl = w;
459 bitmap->cb_excl = h;
460 al_identity_transform(&bitmap->transform);
461 al_identity_transform(&bitmap->inverse_transform);
462 bitmap->inverse_transform_dirty = false;
463 al_identity_transform(&bitmap->proj_transform);
464 al_orthographic_transform(&bitmap->proj_transform, 0, 0, -1.0, w, h, 1.0);
465 bitmap->shader = NULL;
466 bitmap->parent = parent;
467 bitmap->xofs = x;
468 bitmap->yofs = y;
469 bitmap->memory = NULL;
470
471 bitmap->dtor_item = _al_register_destructor(_al_dtor_list, "sub_bitmap", bitmap,
472 (void (*)(void *))al_destroy_bitmap);
473
474 return bitmap;
475}
What do you need to do with the sub-bitmaps while the parent is locked? Just create them? That should be safe. My Website! | EAGLE GUI Library Demos | My Deviant Art Gallery | Spiraloid Preview | A4 FontMaker | Skyline! (Missile Defense) Eagle and Allegro 5 binaries | Older Allegro 4 and 5 binaries | Allegro 5 compile guide |
|
Felix-The-Ghost
Member #9,729
April 2008
|
|
|
