User input http://www.allegro.cc/forums/view/283416 Allegro.cc Forum Thread matthew@allegro.cc (Matthew Leverton) Thu, 17 Jul 2003 21:01:12 +0000

Im trying to make a save/load box in my editor but how do i get input from the user so the user can write wich file to load/save

]]> no-reply@allegro.cc (Hubb the great) Thu, 17 Jul 2003 14:39:50 +0000

I'm working on a similar thing, I can show you
the code when I've finished it...

]]> no-reply@allegro.cc (redMarvin) Thu, 17 Jul 2003 14:57:07 +0000

There is so many ways to do that!
One simple way is to use allegro gui functions.
Or write your own and take input from key[] or readkey()

Read the manual and use your imagination!

]]> no-reply@allegro.cc (psundlin) Thu, 17 Jul 2003 14:57:53 +0000

The most easy way (IMO) would be to use aDime

It's pretty easy to use, so you don't need to bother with the allegro gui.

]]> no-reply@allegro.cc (spellcaster) Thu, 17 Jul 2003 15:10:13 +0000

This is a real crappy well example and it's
not for long finished and contains at least
one bug but as I'm quite new to c++ and
allegro this is the best I've achieved since
my last post:

1 bool string_is_finished=false;
2 char string[256];
3 int cursor;
4 for (cursor=0; cursor<255; string[cursor++]=0);
5 cursor=0;
6 while(!string_is_finished)
7 {
8 if(keypressed())
9 {
10 if(key[KEY_ENTER])
11 {
12 string_is_finished=true;
13 }
14 if (key[KEY_BACKSPACE])
15 {
16 if (cursor>-1)
17 {
18 string[cursor]=0;
19 rest(25);
20 clear_keybuf();
21 if(cursor>0){cursor--;}
22 }
23 }
24 if(!(key[KEY_ENTER]||key[KEY_BACKSPACE]))
25 {
26 string[cursor]=readkey()&0xff;
27 cursor++;
28 }
29 clear_bitmap(screen);
30 textout(screen,font,string,100,50,15);
31 }
32 }

btw: if you or another one do improvement on this
code, please post it so I can learn/use it...

]]> no-reply@allegro.cc (redMarvin) Thu, 17 Jul 2003 20:14:48 +0000

C:

1// edittext.c
2#include <allegro.h>
3 
4int main()
5{
6 BITMAP* buffer = NULL;
7 char edittext[128];
8 int caret = 0;
9 
10 /* typical Allegro initialization */
11 allegro_init();
12 install_keyboard();
13 set_gfx_mode(GFX_AUTODETECT, 320, 240, 0, 0);
14 
15 buffer = create_bitmap(320, 240);
16 
17 do
18 {
19 if(keypressed())
20 {
21 int newkey = readkey();
22 char ASCII = newkey & 0xff;
23 char scancode = newkey >> 8;
24 
25 /* a character key was pressed; add it to the string */
26 if(ASCII >= 32 && ASCII <= 126)
27 {
28 edittext[caret] = ASCII;
29 caret++;
30 edittext[caret] = '\0';
31 }
32 else if(scancode == KEY_BACKSPACE)
33 {
34 caret--;
35 edittext[caret] = '\0';
36 }
37 }
38
39 /* all drawing goes here */
40 clear(buffer);
41 textout(buffer, font, edittext, 0, 10, makecol(255, 255, 255));
42 vline(buffer, caret * 8, 8, 18, makecol(255, 255, 255));
43 blit(buffer, screen, 0, 0, 0, 0, 320, 240);
44 
45 }
46 while(!key[KEY_ESC]);
47
48 destroy_bitmap(buffer);
49 
50 return 0;
51}
52END_OF_MAIN()

C++:

1// edittext.cpp
2#include <allegro.h>
3#include <string>
4using namespace std;
5 
6#define WHITE makecol(255, 255, 255)
7 
8int main()
9{
10 // typical Allegro initialization
11 allegro_init();
12 install_keyboard();
13 set_gfx_mode(GFX_AUTODETECT, 320, 240, 0, 0);
14 
15 // all variables are here
16 BITMAP* buffer = create_bitmap(320, 240); // initialize the double buffer
17 string edittext; // an empty string for editting
18 string::iterator iter = edittext.begin(); // string iterator
19 int caret = 0; // tracks the text caret
20 bool insert = true; // true of should text be inserted
21
22 // the game loop
23 do
24 {
25 while(keypressed())
26 {
27 int newkey = readkey();
28 char ASCII = newkey & 0xff;
29 char scancode = newkey >> 8;
30 
31 // a character key was pressed; add it to the string
32 if(ASCII >= 32 && ASCII <= 126)
33 {
34 // add the new char, inserting or replacing as need be
35 if(insert || iter == edittext.end())
36 iter = edittext.insert(iter, ASCII);
37 else
38 edittext.replace(caret, 1, 1, ASCII);
39 
40 // increment both the caret and the iterator
41 caret++;
42 iter++;
43 }
44 // some other, "special" key was pressed; handle it here
45 else
46 switch(scancode)
47 {
48 case KEY_DEL:
49 if(iter != edittext.end()) iter = edittext.erase(iter);
50 break;
51 
52 case KEY_BACKSPACE:
53 if(iter != edittext.begin())
54 {
55 caret--;
56 iter--;
57 iter = edittext.erase(iter);
58 }
59 break;
60
61 case KEY_RIGHT:
62 if(iter != edittext.end()) caret++, iter++;
63 break;
64
65 case KEY_LEFT:
66 if(iter != edittext.begin()) caret--, iter--;
67 break;
68
69 case KEY_INSERT:
70 if(insert) insert = 0; else insert = 1;
71 break;
72 
73 default:
74 
75 break;
76 }
77 }
78
79 // clear screen
80 clear(buffer);
81 
82 // output the string to the screen
83 textout(buffer, font, edittext.c_str(), 0, 10, WHITE);
84 
85 // output some stats using Allegro's printf functions
86 textprintf(buffer, font, 0, 20, WHITE, "length: %d", edittext.length());
87 textprintf(buffer, font, 0, 30, WHITE, "capacity: %d", edittext.capacity());
88 textprintf(buffer, font, 0, 40, WHITE, "empty?: %d", edittext.empty());
89 if(insert)
90 textout(buffer, font, "Inserting", 0, 50, WHITE);
91 else
92 textout(buffer, font, "Replacing", 0, 50, WHITE);
93 
94 // draw the caret
95 vline(buffer, caret * 8, 8, 18, WHITE);
96 
97 // blit to screen
98 blit(buffer, screen, 0, 0, 0, 0, 320, 240);
99 
100 }while(!key[KEY_ESC]); // end of game loop
101
102 // clean up
103 destroy_bitmap(buffer);
104 set_gfx_mode(GFX_TEXT, 0, 0, 0, 0);
105
106 return 0;
107}
108END_OF_MAIN()

The C++ version has some extra functionality, I think (gotta love the string class). 8-)

]]> no-reply@allegro.cc (23yrold3yrold) Thu, 17 Jul 2003 20:36:04 +0000

Hmm... I smell an AMC library around the corner. This would make a fairly nice AMC module, so you don't have to reprogram input all of the time.

]]> no-reply@allegro.cc (Carrus85) Thu, 17 Jul 2003 20:38:47 +0000

I see a possible buffer overflow with 23's C code ;)

]]> no-reply@allegro.cc (MiquelFire) Thu, 17 Jul 2003 20:42:05 +0000

Yeah. In the C code. Stupid language. ;)

]]> no-reply@allegro.cc (23yrold3yrold) Thu, 17 Jul 2003 20:50:03 +0000

A simple check to see if you're at the end of the string buffer is all you need really to prevent it (both the beginning and the end :o, stick with C++ you! ;))

]]> no-reply@allegro.cc (MiquelFire) Thu, 17 Jul 2003 20:53:11 +0000

I know, I know ;) If your game stops gameplay long enough for me to enter 128 characters it probably sucks anyway ;)

]]> no-reply@allegro.cc (23yrold3yrold) Thu, 17 Jul 2003 20:55:33 +0000

If only it were that easy to rag on C.

Typically unless you provide the explicit checks on buffer size that you NEED in C, C++-style code unfortunately usually turns the problem from a buffer overflow exploit/crash into a process that runs and runs until it runs out of memory from a 1GB long string (causing a crash anyway and making the system slow in the process). One might say that C++ is more dangerous from taking too much data because it just makes the system slow and crashes softly, whereas in C you crash hard and fast and the system moves on. Although you do prevent root exploits which is the most important of all.

EDIT: haha 23 I like that line of reasoning!

]]> no-reply@allegro.cc (gillius) Thu, 17 Jul 2003 20:55:52 +0000

Here; is it fixed now? Might as well correct it since I post it a fair bit ;)

1// edittext.c
2#include <allegro.h>
3 
4#define BUFFERSIZE 128
5 
6int main()
7{
8 BITMAP* buffer = NULL;
9 char edittext[BUFFERSIZE];
10 int caret = 0;
11 
12 /* typical Allegro initialization */
13 allegro_init();
14 install_keyboard();
15 set_gfx_mode(GFX_AUTODETECT, 320, 240, 0, 0);
16 
17 buffer = create_bitmap(320, 240);
18 
19 do
20 {
21 if(keypressed())
22 {
23 int newkey = readkey();
24 char ASCII = newkey & 0xff;
25 char scancode = newkey >> 8;
26 
27 /* a character key was pressed; add it to the string */
28 if(ASCII >= 32 && ASCII <= 126)
29 {
30 if(caret < BUFFERSIZE - 1)
31 {
32 edittext[caret] = ASCII;
33 caret++;
34 edittext[caret] = '\0';
35 }
36 }
37 else if(scancode == KEY_BACKSPACE)
38 {
39 if (caret > 0) caret--;
40 edittext[caret] = '\0';
41 }
42 }
43
44 /* all drawing goes here */
45 clear(buffer);
46 textout(buffer, font, edittext, 0, 10, makecol(255, 255, 255));
47 vline(buffer, caret * 8, 8, 18, makecol(255, 255, 255));
48 blit(buffer, screen, 0, 0, 0, 0, 320, 240);
49 
50 }
51 while(!key[KEY_ESC]);
52
53 destroy_bitmap(buffer);
54 
55 return 0;
56}
57END_OF_MAIN()

]]> no-reply@allegro.cc (23yrold3yrold) Thu, 17 Jul 2003 21:01:12 +0000