Newbie Question--Inputing Data

Matt Ward

Hi there,
I'm new to these forums and Allegro itself.
I am creating a program in which I am using Allegro to graph basic math functions. I am accomplishing this by a simple loop of putpixel()'s in which I step the x value up each loop. My y value for putpixel() is obtained through the formula y=(a+(x*b)+(x*x*c)+(x*x*x*d)+(x*x*x*x*e)) where a, b, c, d, and e are doubles. I would really like to allow the user to enter values for these doubles so that they can choose the shape of the graph, but I can't seem to figure out how to that. I know the C++ reserved word cin does not work in Allegro. Is there something similar that I could use in Allegro? I have looked through a bunch of tutorials and FAQ's and I haven't found anything. Could someone either show me what command I should use or point me in the right direction.
Thanks,
Matt

spork222

You'd have to use either key[KEY_whatever] or readkey() (most likely readkey) to obtain user input key by key then take that data and use it for something. Sorry I can't help more than that; I haven't actually done this myself, just how to do it.:'(

Matt Ward

Thanks for your help spork.
Looking at both key[] and readkey(), it appears they both only accept input from one key. If I wanted to type a number like 1.34 (or any other double), wouldn't it just accept the first key pressed? Is there a way to tie multiple "pressings"? (excuse my non-C++ jargon :-[ )

Another thought, in my college C++ class, we learned to import data from other programs using #include <fstream>. Although that doesn't work, is there away for Allegro to access data from other programs?

Thanks Again!
Matt

LennyLen

Quote:

If I wanted to type a number like 1.34 (or any other double), wouldn't it just accept the first key pressed? Is there a way to tie multiple "pressings"?

Read the input key by key and save it in a buffer. Then when the user has hit ENTER (or whtever you want to use to terminate input), convert the contents of the buffer to a numeric format.

miran

Or use the Allegro GUI routines, most notably d_edit_proc()

TeamTerradactyl

Matt Ward said:

...import data from other programs using #include <fstream>. Although that doesn't work...

What's not working with fstream? Using it in your code concurrently with Allegro, or fstream "doesn't work at all"?

1#include <iostream>
2#include <fstream>
3 
4using namespace std;
5 
6int main(void)
7{
8   int input;
9   int result;
10 
11   // ifstream means input from file
12   ifstream fin;
13   // ostream means output to file
14   ofstream fout;
15 
16   fin.open("input_file.txt");
17   fout.open("output_file.txt");
18 
19   // Grab data until the end of file (EOF) is reached
20   fin >> input;
21   while (!fin.eof())
22   {
23      if (input < 100)
24         result = input + 100;
25      else
26         result = input;
27 
28      fout << result;
29      fin >> input;
30   }
31   fin.close();
32   fout.close();
33 
34   return 0;
35}

Dorianin

i had a couple of functions that did exactly what your talking about....

...but i just spent 15 minutes looking through my dev files and i think it may be deleted.(check,oh gods, check before delete!)...

someone here should know it, since i got it from the code gallery, although the link seems to be broken...

..there was a couple of lines of hexidecimal magic, to take the actual ascii value of the keypress and put it into a string, inside a loop that went till enter.

...try the code gallery, theres only 3 files there...you should recognize the one...:)

Three Harris

I am not sure but I think this is the snipit you want.

1#include <allegro.h>
2 
3#define BUFFERSIZE 128
4#define WHITE makecol(255, 255, 255)
5#define BLACK makecol(0,0,0)
6 
7int main()
8{
/* typical Allegro initialization */
allegro_init();
install_keyboard();
set_gfx_mode(GFX_AUTODETECT_WINDOWED,640,480,0,0);

char    edittext[BUFFERSIZE];
int     caret  = 0;
BITMAP *buffer = create_bitmap(200,20);
//clean out string
int i;
for(i=0;i<BUFFERSIZE;i++)
  edittext<i> = '\0';
//text loop
do {
  if(keypressed()) {
    int  newkey   = readkey();
    char ASCII    = newkey & 0xff;
    char scancode = newkey >> 8;
    /* a character key was pressed; add it to the string */
    if(ASCII >= 32 && ASCII <= 126) {
      if(caret < BUFFERSIZE - 1) {
        edittext[caret] = ASCII;
        caret++;
        edittext[caret] = '\0';
      }
    }
    else if(scancode == KEY_BACKSPACE) {
      if (caret > 0) caret--;
      edittext[caret] = '\0';
    }
  }
  /* all drawing goes here */
  clear_to_color(buffer,WHITE);
  textout_ex(buffer,font,edittext,5,(buffer->h / 2) - 4,BLACK,-1);
  vline(buffer,(caret*8) + 6,(buffer->h / 2) - 6,(buffer->h / 2) + 5,BLACK);
  vline(buffer,(caret*8) + 7,(buffer->h / 2) - 6,(buffer->h / 2) + 5,BLACK);
  blit(buffer,screen,0,0,25,15,300,200);
} while(!key[KEY_ENTER]);
47 
destroy_bitmap(buffer);
allegro_exit();
return 0;
51}
52END_OF_MAIN();

Neil Walker

Why code when the allegro wiki is there for you

http://awiki.tomasu.org/bin/view/Main/TextInputC

there's a c++ version as well.

Three Harris

Quote:

Why code

That is basicly identical code.

[edit] But I didn't have that link so thanks.

Thread #588812. Printed from Allegro.cc

1	#include <iostream>
2	#include <fstream>
3
4	using namespace std;
5
6	int main(void)
7	{
8	int input;
9	int result;
10
11	// ifstream means input from file
12	ifstream fin;
13	// ostream means output to file
14	ofstream fout;
15
16	fin.open("input_file.txt");
17	fout.open("output_file.txt");
18
19	// Grab data until the end of file (EOF) is reached
20	fin >> input;
21	while (!fin.eof())
22	{
23	if (input < 100)
24	result = input + 100;
25	else
26	result = input;
27
28	fout << result;
29	fin >> input;
30	}
31	fin.close();
32	fout.close();
33
34	return 0;
35	}

1	#include <allegro.h>
2
3	#define BUFFERSIZE 128
4	#define WHITE makecol(255, 255, 255)
5	#define BLACK makecol(0,0,0)
6
7	int main()
8	{
9	/* typical Allegro initialization */
10	allegro_init();
11	install_keyboard();
12	set_gfx_mode(GFX_AUTODETECT_WINDOWED,640,480,0,0);
13
14	char edittext[BUFFERSIZE];
15	int caret = 0;
16	BITMAP *buffer = create_bitmap(200,20);
17	//clean out string
18	int i;
19	for(i=0;i<BUFFERSIZE;i++)
20	edittext<i> = '\0';
21	//text loop
22	do {
23	if(keypressed()) {
24	int newkey = readkey();
25	char ASCII = newkey & 0xff;
26	char scancode = newkey >> 8;
27	/* a character key was pressed; add it to the string */
28	if(ASCII >= 32 && ASCII <= 126) {
29	if(caret < BUFFERSIZE - 1) {
30	edittext[caret] = ASCII;
31	caret++;
32	edittext[caret] = '\0';
33	}
34	}
35	else if(scancode == KEY_BACKSPACE) {
36	if (caret > 0) caret--;
37	edittext[caret] = '\0';
38	}
39	}
40	/* all drawing goes here */
41	clear_to_color(buffer,WHITE);
42	textout_ex(buffer,font,edittext,5,(buffer->h / 2) - 4,BLACK,-1);
43	vline(buffer,(caret*8) + 6,(buffer->h / 2) - 6,(buffer->h / 2) + 5,BLACK);
44	vline(buffer,(caret*8) + 7,(buffer->h / 2) - 6,(buffer->h / 2) + 5,BLACK);
45	blit(buffer,screen,0,0,25,15,300,200);
46	} while(!key[KEY_ENTER]);
47
48	destroy_bitmap(buffer);
49	allegro_exit();
50	return 0;
51	}
52	END_OF_MAIN();