Hello,
I'm having problems with my system crashing when I call destroy_bitmap() when the bitmap is a system or video bitmap, but not when it is a memory bitmap. This is roughly what I am doing, I'm in 32bpp and my bitmaps are 32bpp, allegro is fully initialised and ready to go:

void someclass::LoadFunction()
{
 BITMAP* tmp;
 this->Image=load_bmp(filename,NULL);
 if(WantSystemBitmap)
 {
  tmp=create_system_bitmap(Image->w,Image->h);
  blit(Image,tmp,0,0,0,0,Image->w,Image->h);
  if(tmp)
  {
    destroy_bitmap(Image);
    Image=tmp;
  }
 }

Everything works fine and the graphic is displayed in the game.

4. On quitting I do this (allegro is still initialised, so no problems there).
if(Image) destroy_bitmap(Image);

Anyone got a clue as to what could be causing it to crash? the bitmap definitely exists on the call to destroy and can still be viewed ok, it's memory address is the same as when it was initially created. It has no sub-bitmaps, etc. It only crashes when it is a system bitmap, so I guess it must be something to do with the creation of the bitmap, but I can't see a fault.

I'll try it, but I don't see how it would work any better.

I'm getting lots of wierd things happening. If I display the same bitmap but have enabled paging/triple buffering these graphics all point to the wrong images. It's as if creating my 2 or 3 video bitmaps for the screen buffers is affecting system/video bitmaps I create from the above method in my first post, in that instead of pointing to the correct image they are pointing to another image.

Neil.

I think (I'll look at the code tonight), but I'm first creating 3 (or 2 for paged) video bitmaps to cover the screen bitmaps, then I'm creating the smaller bitmaps from the memory bitmaps.

Thomas, was my code right or should I be doing it the way Synaps Jump recommended, as I can't see anything wrong with my code.

I should say, that when I'm getting errors with the video/system bitmaps seemingly looking at the wrong bitmap (though memory bitmaps work), only happens when I'm using sub-bitmaps of video or system bitmaps.

I can let you see my code if you wish, but it's spread over a couple of files

One final nail in my video/system bitmap is when I try and delete my surface bitmap, e.g. destroy_bitmap(page[0]) it crashes with a pointer error, but I've checked and I haven't got the screen locked for drawing and just a few seconds before this my game loop was showing the video pages fine.

Now, another problem I'm having that I noticed on a very simple example that just used textprintf_ex() was there was lots of white noise in blocks over my screen when I use video bitmaps for the surface. I'm simply using the code as shown in the allegro help file.

Was this perchance related to using the Allegro mousecursor and not calling show_mouse(NULL) before destroying the bitmaps? Only now (post 4.2.0) has it been mentioned in the docs.

AE.

Indeed!

In that case, your malloc() clears the returned memory. This isn't guarenteed and you can't count on it, even for memory bitmaps. Always clear bitmaps you just allocated.

Correct. You draw onto the pages you allocate. This is mentioned in the docs, but I can understand if you missed it:

Well, what I sortof meant to say was, if you think there are things that can be improved in the manual to make some of these caveats more obvious, feel free to say so.