使用SDL记录键盘信息(一)
SDL（Simple DirectMedia Layer）是一套开放源代码的跨平台多媒体开发库，使用C语言写成。
为了熟悉SDL , 最近在写一些小的Demo , SDL的事件功能只是它的功能之一，而键盘事件是属于事件功能其中之一，还有鼠标事件、应用程序的可见度改变等等事件。
博主的环境是 wingw32 + eclipse CDT , 前面本来不想装wing32，想直接用cywin凑合着用，但是当把环境搭建好之后才发现，SDL中的头文件和cywin中的某个头文件中的某个宏冲突了，定义了相同的宏，所以会造成编译错误，最后没办法才安装了wing32.
先看看工程的目录结构：
src/include 代表头文件信息 , Debug下面的stdout.txt是wing32中编译器执行工程后的输出信息。当然，你也可以设置在当前eclipse的控制台输出，请参照http://blog.sina.com.cn/s/blog_5607cf010100vq2d.html.
SDL_init.h：
/* * SDL_init.h * * Created on: 2013-9-28 * Author: Christian */ #ifndef SDL_INIT_H_ #define SDL_INIT_H_ #include <iostream> #include <SDL/SDL.h> void createSDL(const char* title); void destorySDL(void); #endif /* SDL_INIT_H_ */
里面封装了两个函数，用于SDL的初始化和销毁,createSDL中的title指针参数代表当前窗口的名字。下面是两个函数的实现。
SDL_init.cpp：
/*
* SDL_init.cpp
*
* Created on: 2013-9-28
* Author: Christian
*/
#include "include/SDL_init.h"
void createSDL(const char* title) {
if (SDL_WasInit(SDL_INIT_EVERYTHING) != 0) {
std::cout << "SDL is already running.\n";
return;
}
if (SDL_Init(SDL_INIT_EVERYTHING) == -1) {
std::cout << "SDL_Init Failed:" << SDL_GetError() << std::endl;
SDL_ClearError();
return;
}
//设置窗口 caption
if (title != NULL) {
SDL_WM_SetCaption(title, NULL);
}
std::cout << "SDL is running successfully.\n";
return;
}
void destorySDL(void) {
if (SDL_WasInit(SDL_INIT_EVERYTHING) == 0) {
std::cout << "SDL was NOT running!\n";
return;
}
SDL_Quit();
std::cout << "SDL_Quit successfully.\n";
return;
}
这样初始化环境就搞定了，用起来会十分方便。
下面是主要代码，用于记录案件信息
SDL_demo.cpp:
//============================================================================
// Name : SDL_demo.cpp
// Author : Christian
// Version :
// Copyright : Copyright (c) Christian 2012/9/28
// Description : SDL Demo in C++
//============================================================================
#include "include/SDL_init.h"
using namespace std;
//读取按键的值
void readKeyboard() {
SDL_SetVideoMode(640, 480, 32, SDL_SWSURFACE);
//create a new event
SDL_Event event;
Uint8 type;
SDLKey history;
SDLKey current;
do {
SDL_PollEvent(&event);
type = event.type;
switch (type) {
case SDL_KEYDOWN:
case SDL_KEYUP:
current = event.key.keysym.sym;
if(history != current){
//print key name
std::cout << current << "\n";
history = current;
}
break;
default:
break;
}
} while (type != SDL_QUIT);
}
//entry
int main(int argc, char* args[]) {
createSDL("Christian Test");
readKeyboard();
atexit(destorySDL);
return EXIT_SUCCESS;
}
运行效果：
黑色屏幕对吧，看看标题，是咱们设置的Christian test.
在运行期间我按下了christian这些个字母，下面看看输出信息：
红色框里的代码按下的键盘码，在SDL的头文件SDL_keysym.h中有定义。
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 */ /*@}*/
................................................ SDLK_LAST
} SDLKey;
看到了吧，SDLKey这个枚举，就是SDL为我们定义的键盘码，每个码对应相应的按键。
很简单对吧，我也这样觉得，另外本人用SDL加载图片的时候会出现黑色闪屏，有高手能帮忙解决一下这个问题的可以和我联系一下。
这里是[email protected]，欢迎交流。
本人原创作品，转载请标明出处。