[C++] Bitmap Scroller: Strings And Things.

[Clyde]

I thought I had this on the 4th attempt, It crashes when it gets to a tag / command. Could you have a peek and help me fix it once and for all

Cheers and big thanks,
Clyde.

[Hotshot]

interesting and i would love to help ya but to honest..I leave to expert such as jim and hellfire to help ya

Keep going Clyde You are getting there    You will be overjoy when it is finish

[hellfire]

The reason why your code crashes is that your scrolltext contains a "[" character which is not available in your font.
When you're trying to draw it in update_scroller using draw_gfx_buffer, the data in "scroll->font->frame[ (int)frame ]" is not properly initialized.
I'd suggest to create enough space for all possible characters and initialize the unused ones to an empty "gfx_buffer".

This bug was rather easy to find:
Just build as "debug" and run with debugger (F5).
It drops out in draw_gfx_buffer where "srce" points to some odd adress and its' content is garbage.
In the call stack you can see that draw_gfx_buffer was called from update_scroller where "scroll->message[letter_pos]" is '['.
Without the debugger you can spend hours to find such simple bugs. You should really try it!

Another, more general, thing is you shouldn't do things like that:

Code Select Expand


screen_buffer= graphics("bitMap scRo77eR TAgS", "", 640,480);
...
gfx_buffer *graphics( char *title, char *title2, int wwidth, int height )
{
  if (title2=="") title2="would you prefer full screen dude?";

You're comparing two char* which are adresses to some location in memory (so they're just numbers).
As the compiler is clever enough to create only a single string when it occurs multiple times, your two occurrences of "" actually point to the same adress in memory - so this code works but that's merely accidental

If you want to handle empty strings use 0:

Code Select Expand

screen_buffer= graphics("bitMap scRo77eR TAgS", 0, 640,480);

gfx_buffer *graphics( char *title, char *title2, int wwidth, int height )
{
  if (title2==0) title2="would you prefer full screen dude?";


[Clyde]

thanks hellfire
wasnt aware of the 0. I also forgot about checking against the total frames.

the tag detection / scroller isnt working as intended; I tried it with different symbols (pause), and it still displayed that in the message. so will need to revisit a new one of this in the future.