6.SDL游戏开发：玩玩文字的游戏reading the fuck source code

TTF（TrueTypeFont）是一种字库名称。TTF（TrueTypeFont）是Apple公司和Microsoft公司共同推出的字体文件格式,随着windows的流行，已经变成最常用的一种字体文件表示方式。首先我们先看下windows下的字体在\WINDOWS\Fonts下面的字体，

   

标准的SDL是不支持TTF，通过扩展就可以了，有兴趣的同学，可以去看看关于字体方面的内容。TTF的扩展库在安装SDL的时候就已经完成了。本篇的目的就是显示reading the fuck source code！来了source code!

#include "SDL/SDL.h"
#include "SDL/SDL_image.h"
#include "SDL/SDL_ttf.h"
#include <string>

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
const int SCREEN_BPP = 32;

SDL_Surface *background = NULL;
SDL_Surface *message = NULL;
SDL_Surface *screen = NULL;

//The event structure
SDL_Event event;

//The font that's going to be used
TTF_Font *font = NULL;

//设置字体颜色
SDL_Color textColor = { 255, 255, 255 };

SDL_Surface *load_image( std::string filename )
{
    //The image that's loaded
    SDL_Surface* loadedImage = NULL;

    //The optimized surface that will be used
    SDL_Surface* optimizedImage = NULL;

    //Load the image
    loadedImage = IMG_Load( filename.c_str() );

    //If the image loaded
    if( loadedImage != NULL ） {
        //Create an optimized surface
        optimizedImage = SDL_DisplayFormat( loadedImage );

        //Free the old surface
        SDL_FreeSurface( loadedImage );

        //If the surface was optimized
        if( optimizedImage != NULL ) {
            //Color key surface
            SDL_SetColorKey( optimizedImage, SDL_SRCCOLORKEY, SDL_MapRGB( optimizedImage->format, 0, 0xFF, 0xFF ) );
        }
    }

    //Return the optimized surface
    return optimizedImage;
}

void apply_surface( int x, int y, SDL_Surface* source, SDL_Surface* destination, SDL_Rect* clip = NULL )
{
    //Holds offsets
    SDL_Rect offset;

    //Get offsets
    offset.x = x;
    offset.y = y;

    //Blit
    SDL_BlitSurface( source, clip, destination, &offset );
}

bool init()
{
    //Initialize all SDL subsystems
    if( SDL_Init( SDL_INIT_EVERYTHING ) == -1 ) {
        return false;
    }

    //Set up the screen
    screen = SDL_SetVideoMode( SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_BPP, SDL_SWSURFACE );

    //If there was an error in setting up the screen
    if( screen == NULL ) {
        return false;
    }

    //初始化TTF库
    if( TTF_Init() == -1 ) {
        return false;
    }

    //Set the window caption
    SDL_WM_SetCaption( "TTF Test", NULL );

    //If everything initialized fine
    return true;
}

bool load_files()
{
    //导入背景图片
    background = load_image( "background.png" );

    //打开字体
    font = TTF_OpenFont( "lazy.ttf", 28 );

    //If there was a problem in loading the background
    if( background == NULL ) {
        return false;
    }

    //If there was an error in loading the font
    if( font == NULL ) {
        return false;
    }

    //If everything loaded fine
    return true;
}

void clean_up()
{
    //Free the surfaces
    SDL_FreeSurface( background );
    SDL_FreeSurface( message );

    //关闭字体
    TTF_CloseFont( font );

    //释放 SDL_ttf
    TTF_Quit();

    //Quit SDL
    SDL_Quit();
}

int main( int argc, char* args[] )
{
    //Quit flag
    bool quit = false;

    //初始化
    if( init() == false ) {
        return 1;
    }

    //Load the files
    if( load_files() == false ) {
        return 1;
    }

    //Render the text
    message = TTF_RenderText_Solid( font, "reading the fuck source code", textColor );

    //If there was an error in rendering the text
    if( message == NULL ) {
        return 1;
    }

    //Apply the images to the screen
    apply_surface( 0, 0, background, screen );
    apply_surface( 0, 150, message, screen );

    //Update the screen
    if( SDL_Flip( screen ) == -1 ) {
        return 1;
    }

    //While the user hasn't quit
    while( quit == false ) {
        //While there's events to handle
        while( SDL_PollEvent( &event ) ) {
            //If the user has Xed out the window
            if( event.type == SDL_QUIT ) {
                //Quit the program
                quit = true;
            }
        }
    }

    //Free surfaces and font then quit SDL_ttf and SDL
    clean_up();

    return 0;
}

保存为sdl06.cpp 编译

g++ -o sdl06 sdl06.cpp -lSDL -lSDL_image -lSDL_ttf
./sdl06

上图片了喽！

如果深入Linux底层就得Reading the fuck source code! 不过现在这点代码算不上操蛋的，想想内核里三四百行的结构体（加注释），这就小巫见大巫了。不过还是认真看，发现有什么与众不同地方，多了一个头文件

＃include "SDL/SDL_ttf.h" 说明引SDL_ttf库，

 TTF_Init()； TTF_Quit(); TTF_OpenFont (); TTF_CloseFont();

这些多比较简单就细说了，要找更多与SDL_TTF相关的文档请点击这儿， 下面我们将详细解说下面这个函数

message = TTF_RenderText_Solid( font, "reading the fuck source code", textColor );

这才是关键所在，先说下TTF库的使用过程，－－>(1)初始化－－>(2)打开字体文件，并设置字体大小－－>（3）设置字体的其它属性（如着色）－－>（4）使用打开的字体将所要显示的文字“画”到内存里，有以下三个函数可用［根据不同的文字，选择不同的函数Text为普通字符串，UTF8为UTF8格式的字符串，UNICODE为UNIXCODE格式的字符串。

TTF_RenderText_Solid()

TTF_RenderUTF8_Solid()

TTF_RenderUNICODE_Solid()

－－>（5）将内存数据拷贝到当前显示设备环境－－>（6）显示－－>（7）释放销毁TTF

关于更多TTF相关的点这里有篇文章写得很好［这里］。

关于字体就用到这里，其中文的显示问题，及文字的其它属性（如下画线，斜体……）可以到SDL_TTF这里找函数.