[bmx] ASynchronous Input Function by Pantheon [ 1+ years ago ]

[BlitzBot]

Title : ASynchronous Input Function
Author : Pantheon
Posted : 1+ years ago

Description : I almost feel cheeky posting something so simple but i think you will find this solution is quite elegant. Its also something that everyone will have to write at some stage in there game, so...

This function will modify the input string based on the keyboard events. It will handle all case text, symbols and numbers. Anything it doesnt know it will return the ascii code of, usefull for mapping the escape or tab key.

I was writing this for the GUI im working and I like the idea of sharing code, have fun.

Code :

Code: BlitzMax

1. '/**
2. ' * ASYNCHRONOUS INPUT USING POLLED INPUT
3. ' *
4. ' *   this code will change the input string based
5. ' *   on the current keyboard events, and is usefull
6. ' *   for non blocking input
7. ' *   return codes to handle special events
8. ' *
9. ' *       these must be larger than a byte       
10. ' *
11. Const IAS_Normal        = $AAAAAAAA     'we're sweet
12. Const IAS_Return        = $BBBBBBBB     'carrage return hit
13. ' *
14. ' *   if anything else was returned then its the
15. ' *   ASCII value of the unknown key press
16. ' *
17. ' *       tab is at ascii <9>
18. ' *   escape is at ascii <27>
19. ' *
20. Function InputASync:Int( aStr:String Var )
21.         Local a:Int = GetChar( )
22.         ' loop hack :)
23.         Repeat
24.                 ' * space numbers symbols letters
25.                 If (a=>32 And a<=126) Then Exit
26.                 ' * pound symbol
27.                 If (a=163) Then Exit
28.                 ' * carrage return
29.                 If (a=13) Then Return IAS_Return
30.                 ' * backspace key
31.                 If (a=8)
32.                         Local b:Int = Len( aStr )
33.                         If (b>0) Then aStr = Left( aStr, b-1 )
34.                         Return IAS_Normal
35.                 EndIf
36.                 ' * no input entered
37.                 If (a=0) Then Return IAS_Normal
38.                 ' something else cought
39.                 Return a
40.         Forever
41.         aStr = aStr+Chr( a )
42.         Return IAS_Normal
43. End Function
44. ' *
45. ' */
46.  
47.  
48. '/**
49. ' * EXAMPLE CODE
50. ' *
51. ' *             just to show why its a bit different ;)
52. ' */
53. Local myString:String = "type 'exit' to close!"
54. Local cursor:String = ""
55. Local time = 0
56. Graphics 320, 240, 0
57. Repeat
58.         Cls
59.        
60.         Local ret:Int = InputASync( myString )
61.        
62.         ' what did we get back
63.         Select( ret )
64.         Case IAS_Normal
65.                 ' hack to warp between 1 and 360 for the sin wave
66.                 time :+ ( 1- (time > 360) *360 )
67.                
68.         Case IAS_Return
69.                 ' what have we got
70.                 If ( Lower( myString ) = "exit" ) Then Exit
71.                 ' no? well just erase
72.                 myString = ""
73.                
74.         Default
75.                 ' found an undisplayable ascii value
76.                 myString = "ASCII value <"+ret+"> not handled!"
77.                
78.                 ' is it the escape key
79.                 If (ret = 27) Then Exit
80.                
81.         End Select
82.        
83.         ' make a blinking cursor
84.         If ((time Mod 40) < 20)
85.                 cursor = "_"
86.         Else
87.                 cursor = ""
88.         EndIf
89.        
90.         ' draw our string plus cursor
91.         DrawText myString+cursor, 10, 40+Sin( time )*20
92.        
93.         Flip
94. Forever

Comments :


Pantheon(Posted 1+ years ago)

 I just realised that this will only handle one charictor every time its called but its not very hard to modify to deal with them all so i mite update it but if not then its a user exercise If its even necessary.