想用SDL的按键检测，网上找了半天都没找到SDL中按键的值的定义，索性自己去看头文件，在SDL_keysym.h中。
其实很多键的值和它们的ASCII码是相同的。
其他更多的用法，可以参考这篇博客：http://blog.chinaunix.net/uid-28482676-id-3444915.html/
typedef enum { /** @name ASCII mapped keysyms * The keyboard syms have been cleverly chosen to map to ASCII */ /*@{*/ SDLK_UNKNOWN = 0, SDLK_FIRST = 0, SDLK_BACKSPACE = 8, SDLK_TAB = 9, SDLK_CLEAR = 12, SDLK_RETURN = 13, SDLK_PAUSE = 19, SDLK_ESCAPE = 27, SDLK_SPACE = 32, SDLK_EXCLAIM = 33, SDLK_QUOTEDBL = 34, SDLK_HASH = 35, SDLK_DOLLAR = 36, SDLK_AMPERSAND = 38, SDLK_QUOTE = 39, SDLK_LEFTPAREN = 40, SDLK_RIGHTPAREN = 41, SDLK_ASTERISK = 42, SDLK_PLUS = 43, SDLK_COMMA = 44, SDLK_MINUS = 45, SDLK_PERIOD = 46, SDLK_SLASH = 47, SDLK_0 = 48, SDLK_1 = 49, SDLK_2 = 50, SDLK_3 = 51, SDLK_4 = 52, SDLK_5 = 53, SDLK_6 = 54, SDLK_7 = 55, SDLK_8 = 56, SDLK_9 = 57, SDLK_COLON = 58, SDLK_SEMICOLON = 59, SDLK_LESS = 60, SDLK_EQUALS = 61, SDLK_GREATER = 62, SDLK_QUESTION = 63, SDLK_AT = 64, /* Skip uppercase letters */ SDLK_LEFTBRACKET = 91, SDLK_BACKSLASH = 92, SDLK_RIGHTBRACKET = 93, SDLK_CARET = 94, SDLK_UNDERSCORE = 95, SDLK_BACKQUOTE = 96, SDLK_a = 97, SDLK_b = 98, SDLK_c = 99, SDLK_d = 100, SDLK_e = 101, SDLK_f = 102, SDLK_g = 103, SDLK_h = 104, SDLK_i = 105, SDLK_j = 106, SDLK_k = 107, SDLK_l = 108, SDLK_m = 109, SDLK_n = 110, SDLK_o = 111, SDLK_p = 112, SDLK_q = 113, SDLK_r = 114, SDLK_s = 115, SDLK_t = 116, SDLK_u = 117, SDLK_v = 118, SDLK_w = 119, SDLK_x = 120, SDLK_y = 121, SDLK_z = 122, SDLK_DELETE = 127, /* End of ASCII mapped keysyms */ /*@}*/ /** @name International keyboard syms */ /*@{*/ SDLK_WORLD_0 = 160, /* 0xA0 */ SDLK_WORLD_1 = 161, SDLK_WORLD_2 = 162, SDLK_WORLD_3 = 163, SDLK_WORLD_4 = 164, SDLK_WORLD_5 = 165, SDLK_WORLD_6 = 166, SDLK_WORLD_7 = 167, SDLK_WORLD_8 = 168, SDLK_WORLD_9 = 169, SDLK_WORLD_10 = 170, SDLK_WORLD_11 = 171, SDLK_WORLD_12 = 172, SDLK_WORLD_13 = 173, SDLK_WORLD_14 = 174, SDLK_WORLD_15 = 175, SDLK_WORLD_16 = 176, SDLK_WORLD_17 = 177, SDLK_WORLD_18 = 178, SDLK_WORLD_19 = 179, SDLK_WORLD_20 = 180, SDLK_WORLD_21 = 181, SDLK_WORLD_22 = 182, SDLK_WORLD_23 = 183, SDLK_WORLD_24 = 184, SDLK_WORLD_25 = 185, SDLK_WORLD_26 = 186, SDLK_WORLD_27 = 187, SDLK_WORLD_28 = 188, SDLK_WORLD_29 = 189, SDLK_WORLD_30 = 190, SDLK_WORLD_31 = 191, SDLK_WORLD_32 = 192, SDLK_WORLD_33 = 193, SDLK_WORLD_34 = 194, SDLK_WORLD_35 = 195, SDLK_WORLD_36 = 196, SDLK_WORLD_37 = 197, SDLK_WORLD_38 = 198, SDLK_WORLD_39 = 199, SDLK_WORLD_40 = 200, SDLK_WORLD_41 = 201, SDLK_WORLD_42 = 202, SDLK_WORLD_43 = 203, SDLK_WORLD_44 = 204, SDLK_WORLD_45 = 205, SDLK_WORLD_46 = 206, SDLK_WORLD_47 = 207, SDLK_WORLD_48 = 208, SDLK_WORLD_49 = 209, SDLK_WORLD_50 = 210, SDLK_WORLD_51 = 211, SDLK_WORLD_52 = 212, SDLK_WORLD_53 = 213, SDLK_WORLD_54 = 214, SDLK_WORLD_55 = 215, SDLK_WORLD_56 = 216, SDLK_WORLD_57 = 217, SDLK_WORLD_58 = 218, SDLK_WORLD_59 = 219, SDLK_WORLD_60 = 220, SDLK_WORLD_61 = 221, SDLK_WORLD_62 = 222, SDLK_WORLD_63 = 223, SDLK_WORLD_64 = 224, SDLK_WORLD_65 = 225, SDLK_WORLD_66 = 226, SDLK_WORLD_67 = 227, SDLK_WORLD_68 = 228, SDLK_WORLD_69 = 229, SDLK_WORLD_70 = 230, SDLK_WORLD_71 = 231, SDLK_WORLD_72 = 232, SDLK_WORLD_73 = 233, SDLK_WORLD_74 = 234, SDLK_WORLD_75 = 235, SDLK_WORLD_76 = 236, SDLK_WORLD_77 = 237, SDLK_WORLD_78 = 238, SDLK_WORLD_79 = 239, SDLK_WORLD_80 = 240, SDLK_WORLD_81 = 241, SDLK_WORLD_82 = 242, SDLK_WORLD_83 = 243, SDLK_WORLD_84 = 244, SDLK_WORLD_85 = 245, SDLK_WORLD_86 = 246, SDLK_WORLD_87 = 247, SDLK_WORLD_88 = 248, SDLK_WORLD_89 = 249, SDLK_WORLD_90 = 250, SDLK_WORLD_91 = 251, SDLK_WORLD_92 = 252, SDLK_WORLD_93 = 253, SDLK_WORLD_94 = 254, SDLK_WORLD_95 = 255, /* 0xFF */ /*@}*/ /** @name Numeric keypad */ /*@{*/ SDLK_KP0 = 256, SDLK_KP1 = 257, SDLK_KP2 = 258, SDLK_KP3 = 259, SDLK_KP4 = 260, SDLK_KP5 = 261, SDLK_KP6 = 262, SDLK_KP7 = 263, SDLK_KP8 = 264, SDLK_KP9 = 265, SDLK_KP_PERIOD = 266, SDLK_KP_DIVIDE = 267, SDLK_KP_MULTIPLY = 268, SDLK_KP_MINUS = 269, SDLK_KP_PLUS = 270, SDLK_KP_ENTER = 271, SDLK_KP_EQUALS = 272, /*@}*/ /** @name Arrows + Home/End pad */ /*@{*/ SDLK_UP = 273, SDLK_DOWN = 274, SDLK_RIGHT = 275, SDLK_LEFT = 276, SDLK_INSERT = 277, SDLK_HOME = 278, SDLK_END = 279, SDLK_PAGEUP = 280, SDLK_PAGEDOWN = 281, /*@}*/ /** @name Function keys */ /*@{*/ SDLK_F1 = 282, SDLK_F2 = 283, SDLK_F3 = 284, SDLK_F4 = 285, SDLK_F5 = 286, SDLK_F6 = 287, SDLK_F7 = 288, SDLK_F8 = 289, SDLK_F9 = 290, SDLK_F10 = 291, SDLK_F11 = 292, SDLK_F12 = 293, SDLK_F13 = 294, SDLK_F14 = 295, SDLK_F15 = 296, /*@}*/ /** @name Key state modifier keys */ /*@{*/ SDLK_NUMLOCK = 300, SDLK_CAPSLOCK = 301, SDLK_SCROLLOCK = 302, SDLK_RSHIFT = 303, SDLK_LSHIFT = 304, SDLK_RCTRL = 305, SDLK_LCTRL = 306, SDLK_RALT = 307, SDLK_LALT = 308, SDLK_RMETA = 309, SDLK_LMETA = 310, SDLK_LSUPER = 311, /**< Left "Windows" key */ SDLK_RSUPER = 312, /**< Right "Windows" key */ SDLK_MODE = 313, /**< "Alt Gr" key */ SDLK_COMPOSE = 314, /**< Multi-key compose key */ /*@}*/ /** @name Miscellaneous function keys */ /*@{*/ SDLK_HELP = 315, SDLK_PRINT = 316, SDLK_SYSREQ = 317, SDLK_BREAK = 318, SDLK_MENU = 319, SDLK_POWER = 320, /**< Power Macintosh power key */ SDLK_EURO = 321, /**< Some european keyboards */ SDLK_UNDO = 322, /**< Atari keyboard has Undo */ /*@}*/ /* Add any other keys here */ SDLK_LAST } SDLKey;