[A5] user keyboard input in int array ?

no-reply@allegro.cc (Inquisiteur) — Mon, 14 Mar 2011 20:50:32 +0000

Hi,

I took a glance at the keyboard tutorial. Unfortunatly I was not able to derive from it some way to gather user keyboard input in an array of int.

My goal is:

1. Display a textbox with two fields - The fields are coordinate X/Y (I know how to do that)
2. The user can input numbers in both fields (arrays)
3. While he is pushing numbers on his keyboard the X coordinate array is filled. (then the second)

Right now, and thanks to the tutorial, I know how to make the software recognize which key is pushed, however I would have to enumerate all allegro keycodes for that.

What I want is to store every number push, whatever the number is.

Can anybody englighten me ?

Thanks

no-reply@allegro.cc (Matthew Leverton) — Mon, 14 Mar 2011 22:00:08 +0000

Do you want an array like key[256] that is true if that key code is pressed, or an array that indicates a stream of characters that the user has entered?

no-reply@allegro.cc (Inquisiteur) — Mon, 14 Mar 2011 23:27:25 +0000

Thanks for your reply,

I need an array that catches a stream of numbers, not their code.

So basically:

"Please input X coordinates"

--> user input 72

Software allocate the number 72 to variable CoordX.

In fact I probably don't need an array at all...I just need to stock the user keyboard input, whatever it is (for now numbers) in some kind of int variable, I dont know what A5 function would allow me to do that.

no-reply@allegro.cc (Matthew Leverton) — Mon, 14 Mar 2011 23:34:50 +0000

Just listen for KEY_CHAR events and process the keycode:

#SelectExpand
  1int number = 0;
  2
  3while (some_loop)
  4{
  5  // assume you just received a KEY_CHAR event
  6
  7  if (keycode >= '0' && keycode <= '9')
  8  {
  9    int digit = keycode - '0';     // convert from ASCII code to integer 0-9
 10    number = number * 10 + digit;  // shift the current number left and add the new integer
 11  }
 12
 13  else if (keycode == ALLEGRO_KEY_BACKSPACE)
 14  {
 15    number = number / 10; // remove the right most digit
 16  }
 17
 18  // print number to screen
 19}

The result is that number holds an integer as entered by the keyboard.

Edit: actually I think you need to use the unichar property for the digits. i.e.:

if (unichar >= '0' && unichar <= '9')
{
  int digit = unichar - '0';
}

But the same principle applies.

no-reply@allegro.cc (Inquisiteur) — Tue, 15 Mar 2011 19:32:23 +0000

Thank you very much, I'm gonna try that today.

Update-------

For some reason I can't even have the software recognize that I am pushing a keyboard key...

I have seen two other posts in the forum about that, however they did not help me solve my issue. I have seen that this has been solved by implementing a timer, assuming I don't want a timer, is there a way to fix the code below ?

Sry to ask again for your help...

Here's the code:

#SelectExpand
  1
  2#include 
  3#include 
  4
  5int main(int argc, char *argv[]) {
  6  al_init();
  7  al_install_keyboard();
  8
  9  ALLEGRO_EVENT_QUEUE *event_queue = NULL;
 10  ALLEGRO_KEYBOARD_STATE keys;
 11  event_queue = al_create_event_queue();
 12  al_register_event_source(event_queue, al_get_keyboard_event_source());
 13
 14
 15  while(1){
 16    ALLEGRO_EVENT ev;
 17    al_wait_for_event(event_queue, &ev);
 18    al_get_keyboard_state(&keys);
 19
 20    if(ev.type == ALLEGRO_EVENT_KEY_DOWN){
 21      if(al_key_down(&keys,ALLEGRO_KEY_TAB)){
 22      printf("keyboard key pressed down");    
 23      }    
 24    }
 25  }
 26  return 0;
 27}

no-reply@allegro.cc (Matthew Leverton) — Tue, 15 Mar 2011 23:47:33 +0000

Forget about the keyboard state if you are using events.
Use ALLEGRO_EVENT_KEY_CHAR. The KEY_DOWN event doesn't do what you think.
Use ev.keyboard.unichar for printable characters; use keycode for special keys

if (ev.type == ALLEGRO_EVENT_KEY_CHAR && ev.keyboard.keycode == ALLEGRO_KEY_TAB)
{
  // tab was pressed
}

no-reply@allegro.cc (Inquisiteur) — Wed, 16 Mar 2011 14:56:14 +0000

Thanks again for your reply.

I am starting to wonder if there would be some kind of incompatibility coming from my keyboard ? I have been trying a lot of variation with absolutely no other results than a black console...

Here's the code:

#SelectExpand
  1#include 
  2#include 
  3
  4int main(int argc, char *argv[]) {
  5
  6  al_init();
  7
  8  al_install_keyboard();
  9
 10  ALLEGRO_EVENT_QUEUE *event_queue = NULL;
 11
 12  event_queue = al_create_event_queue();
 13
 14  al_register_event_source(event_queue, al_get_keyboard_event_source());
 15
 16  while(1){
 17
 18    ALLEGRO_EVENT ev;
 19
 20    al_wait_for_event(event_queue, &ev);
 21
 22    if (ev.type == ALLEGRO_EVENT_KEY_CHAR && ev.keyboard.keycode == ALLEGRO_KEY_TAB)
 23  //  if (ev.type == ALLEGRO_EVENT_KEY_DOWN)
 24    {
 25      printf("keyboard key pressed down");
 26    }
 27  }
 28}

Can anyone compile this and tell me if it works ... ?

The // if (ev.type == ALLEGRO_EVENT_KEY_DOWN) didn't work either.

The console is simply not registering any event when I am pushing the TAB, or any other button when using "if (ev.type == ALLEGRO_EVENT_KEY_DOWN)"

no-reply@allegro.cc (LennyLen) — Wed, 16 Mar 2011 15:20:07 +0000

Try adding this before your while loop:

  ALLEGRO_DISPLAY *display = al_create_display(640, 480);
  if (!display) 
      return -1;

no-reply@allegro.cc (Inquisiteur) — Wed, 16 Mar 2011 15:46:17 +0000

I can't believe this was the issue. It worked !

So basically if there are no displays to be selected, I won't be able to interact with the "allegro based" software.

Logical and weird at the same time...

Thanks to both of you guys for your time.

Regards,

Inquisiteur

no-reply@allegro.cc (Matthew Leverton) — Wed, 16 Mar 2011 23:04:37 +0000

Allegro doesn't support console mode like you might expect. It receives input from events sent to the graphical display window by the OS. So without such a window, you won't ever get any keyboard input (among other things).

no-reply@allegro.cc (Inquisiteur) — Thu, 17 Mar 2011 17:53:11 +0000

Ok, so I finally put together something that works ok for me:

#SelectExpand
  1#include 
  2#include 
  3
void command_console(ALLEGRO_EVENT_QUEUE *event_queue){

  printf("Please input X coordinates - press SPACE to confirm coordinates\n");
  7
int number = 0;
  9
while(1){
  
  ALLEGRO_EVENT c_ev;
  al_wait_for_event(event_queue, &c_ev);
 14
  if (c_ev.type == ALLEGRO_EVENT_KEY_CHAR)
  {
    if (c_ev.keyboard.unichar >= '0' && c_ev.keyboard.unichar <= '9')
    {
      int digit = (c_ev.keyboard.unichar - '0');
      number = number * 10 + digit;
      printf("Number is %d\n", number);        
    }
    else if (c_ev.keyboard.keycode == ALLEGRO_KEY_BACKSPACE)
    {
      number = number / 10;
      printf("Number is %d\n", number);
    }
    else if (c_ev.keyboard.keycode == ALLEGRO_KEY_SPACE)
    {
      printf("coordinates are %d\n", number);
    }
  }
}
}
 35///////////////////////////////////////----------------MAIN LOOP
 36int main(int argc, char *argv[]) {
 37
al_init();
 39
al_install_keyboard();
 41
if(al_is_keyboard_installed()==true)
{
  printf("keyboard installed successfully\n");
}
 46
ALLEGRO_EVENT_QUEUE *event_queue = NULL;
 48
event_queue = al_create_event_queue();

al_register_event_source(event_queue, al_get_keyboard_event_source());
 52
ALLEGRO_DISPLAY *display = al_create_display(640, 480);
if (!display) 
    return -1;
 56
ALLEGRO_EVENT ev;
al_wait_for_event(event_queue, &ev);
 59
if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_TAB)
{
    command_console(event_queue);
}
 64}

I have one last question though. When I replace:

#SelectExpand
if (ev.type == ALLEGRO_EVENT_KEY_DOWN && ev.keyboard.keycode == ALLEGRO_KEY_TAB)
{
    command_console(event_queue);
}

#SelectExpand
if (ev.type == ALLEGRO_EVENT_KEY_CHAR)
{
    command_console(event_queue);
}

The console closes down as soon as I press a character on the keyboard. So basically the function "command_console" is not launched. Why is ALLEGRO_EVENT_KEY_DOWN working and not ALLEGRO_EVENT_KEY_CHAR in this case ?

no-reply@allegro.cc (Matthew Leverton) — Thu, 17 Mar 2011 23:40:25 +0000

The key events typically look like:

KEY_DOWN
KEY_CHAR
KEY_UP

The first two happen simultaneously. You are only checking for the first one in your program. If you were to loop through all available events, you'd find a CHAR in the queue.

no-reply@allegro.cc (Inquisiteur) — Fri, 18 Mar 2011 13:38:26 +0000

Ok I see, thank you.