Урок 4. Растрові шрифти

Lesson 4: Bitmap Fonts

Hi all! This lesson is about drawing bitmap fonts on a surface in SDL. They are called bitmap fonts because our fonts will be stored in one big bitmap that contains all of them. Here's what one of our font map looks like:

Our font system will consist of 2 files: font.cpp and font.h. The lesson itself will also have the file lesson4.cpp. I decided to put the font routines into seperate files because this way it's much easier to use the same code in many programs - just copy the 2 files to your new project, add an '#include "font.h"' line and you're all set.

Note: I won't talk about what code goes into which file. You can put all the code into one big file if you want (if you like to follow this tutorial while coding your font routines). I will only talk about the functions. If you want to look at the code in many files, look at the source. Also this code could really easilly be put into a class. I won't use classes this time.

All our fonts will be stored inside one structure called SDLFont. It looks like this:

// Structure to hold our font

struct SDLFont

{

SDL_Surface *font; // The SDL Surface for the font image

int width; // Width of the SDL Surface (=height)

int charWidth; // Width of one block character in the font

int *widths; // Real widths of all the fonts

unsigned char *data; // The raw font data

};

The SDL_Structure font will hold the font image map. Width is the width of the font (for easy access) and since the font image is a square, the width = height. charWidth is the with of one "character cell" on the font (width/16). Since mostly all of the characters in the font have different real widths, then the array widths will hold the widths of all the characters. Data will hold the raw image data for the SDL_Surface.

Now here's one function that you should remember from the previous lessons (if you have read them). It simply blits one part of a surface onto an other part of some other surface. It will be used when drawing the font.