Hi,
SDL uses the SDL_ttf library for font rendering. The engine of this lib is the freetype lib, which is fine until you have to cross-compile for Android. This freetype lib consists of a huge number of C files, that must be compiled apart from the Android NDK environment because no Android.mk files are provided.
There is an alternative. A clever guy called Sean Barrett has written a parser and renderer for truetype fonts. It consists of one file (http://nothings.org/stb/stb_truetype.h), containing everything you need: a manual, examples, header file and C code.
From the examples I created a small demo program, listed hereunder.
If you call it test-stbtt.c it can be compiled as follows:
gcc test-stbtt.c -o test-stbtt $(sdl2-config --cflags) $(sdl2-config --libs) -lm
It can be run with 0, 1, 2 or 3 options, and will display a black text in a white window. Notice that there is a hard-coded path to a ttf spec file, modify this as needed.
I did’nt use all provided refinements in this demo program. Notice that the SDL.h file is included after the stb_truetype.h, that’s because some big- and small endian magic occurs, which might get disturbed by #define statements in SDL.h. The characters that are displayed are not cached, so a big speed-up would still be possible.
wboe
Code:
#define STB_TRUETYPE_IMPLEMENTATION
#include “stb_truetype.h”
#include <SDL.h>
int main(int argc, char **argv) {
if (SDL_Init(SDL_INIT_VIDEO) < 0) { printf(“Init problem: %s\n”,SDL_GetError()); exit(1); }
SDL_Window *window = SDL_CreateWindow(“test-stbtt”, 100,100,200,100, SDL_WINDOW_SHOWN);
if (!window) { printf("%s\n",SDL_GetError()); SDL_Quit(); }
SDL_Renderer *renderer=SDL_CreateRenderer(window, -1,SDL_RENDERER_ACCELERATED);
SDL_SetRenderDrawColor(renderer,0xff,0xff,0xff,0xff);
SDL_RenderClear(renderer);
SDL_RenderPresent(renderer);
SDL_SetRenderDrawBlendMode(renderer,SDL_BLENDMODE_BLEND);
stbtt_fontinfo font;
unsigned char *bitmap=0;
const char *text=(argc > 1 ? argv[1] : “Hallo!”);
int s = (argc > 2 ? atoi(argv[2]) : 20);
FILE *ff=fopen(argc > 3 ? argv[3] : “/usr/share/fonts/google-droid/DroidSans.ttf”,“rb”);
if (!ff) { puts(“font file not found”); exit(1); }
fseek(ff,0,SEEK_END);
int fsize=ftell(ff);
rewind(ff);
char ttf_buffer[fsize];
fread(ttf_buffer, 1,fsize,ff);
stbtt_InitFont(&font, ttf_buffer, stbtt_GetFontOffsetForIndex(ttf_buffer,0));
float scale=stbtt_ScaleForPixelHeight(&font, s);
int ascent,
descent;
stbtt_GetFontVMetrics(&font,&ascent,&descent,0);
int ind,
advance,
x0,y0,
h,w,
xpos=10,
ypos=10+scaleascent;
printf(“ascent=%d descent=%d linedist=%d\n”,(int)(scaleascent),(int)(scale*descent),(int)(scale * (ascent-descent)));
for (ind=0;text[ind];++ind) {
bitmap = stbtt_GetCodepointBitmap(&font, 0,stbtt_ScaleForPixelHeight(&font, s), text[ind], &w, &h, 0,0);
stbtt_GetCodepointHMetrics(&font, text[ind], &advance, 0);
stbtt_GetCodepointBitmapBoxSubpixel(&font, text[ind], scale,scale,0,0, &x0,&y0,0,0);
int i,j,
x=xpos,
y=ypos;
for (j=0; j < h; ++j) {
for (i=0; i < w; ++i) {
if (bitmap[j*w+i]) {
SDL_SetRenderDrawColor(renderer,0,0,0,bitmap[j*w+i]);
SDL_RenderDrawPoint(renderer,x+x0,y+y0);
}
++x;
}
x=xpos;
++y;
}
stbtt_FreeBitmap(bitmap,0);
if (!text[ind+1]) break;
xpos += scale*advance;
}
SDL_RenderPresent(renderer);
SDL_Event event;
while (1)
while(SDL_PollEvent(&event))
if (event.type==SDL_QUIT) { SDL_Quit(); exit(0); }
return 0;
}
