6.SDL遊戲開發：玩玩文字的遊戲reading the fuck source code

TTF（TrueTypeFont）是一種字庫名稱。TTF（TrueTypeFont）是Apple公司和Microsoft公司共同推出的字體文件格式,隨着windows的流行，已經變成最經常使用的一種字體文件表示方式。首先咱們先看下windows下的字體在\WINDOWS\Fonts下面的字體，

   

標準的SDL是不支持TTF，經過擴展就能夠了，有興趣的同窗，能夠去看看關於字體方面的內容。TTF的擴展庫在安裝SDL的時候就已經完成了。本篇的目的就是顯示reading the fuck source code！來了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;

//設置字體顏色
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庫
    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()
{
    //導入背景圖片
    background = load_image( "background.png" );

    //打開字體
    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 );

    //關閉字體
    TTF_CloseFont( font );

    //釋放 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;
}

保存爲sdl06.cpp 編譯

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

上圖片了嘍！

若是深刻Linux底層就得Reading the fuck source code! 不過如今這點代碼算不上操蛋的，想一想內核裏三四百行的結構體（加註釋），這就小巫見大巫了。不過仍是認真看，發現有什麼不同凡響地方，多了一個頭文件

＃include "SDL/SDL_ttf.h" 說明引SDL_ttf庫，

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

這些多比較簡單就細說了，要找更多與SDL_TTF相關的文檔請點擊這兒， 下面咱們將詳細解說下面這個函數

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

這纔是關鍵所在，先說下TTF庫的使用過程，－－>(1)初始化－－>(2)打開字體文件，並設置字體大小－－>（3）設置字體的其它屬性（如着色）－－>（4）使用打開的字體將所要顯示的文字「畫」到內存裏，有如下三個函數可用［根據不一樣的文字，選擇不一樣的函數Text爲普通字符串，UTF8爲UTF8格式的字符串，UNICODE爲UNIXCODE格式的字符串。

TTF_RenderText_Solid()

TTF_RenderUTF8_Solid()

TTF_RenderUNICODE_Solid()

－－>（5）將內存數據拷貝到當前顯示設備環境－－>（6）顯示－－>（7）釋放銷燬TTF

關於更多TTF相關的點這裏有篇文章寫得很好［這裏］。

關於字體就用到這裏，其中文的顯示問題，及文字的其它屬性（以下畫線，斜體……）能夠到SDL_TTF這裏找函數.