src/bz/gfx/font.c

   1 #include <bz/gfx/font_internal.h>
   2
   3 #include <bz/memory/allocator.h>
   4 #include <bz/resources/resource.h>
   5 #include <bz/types/identifier_internal.h>
   6 #include <stb_image.h>
   7 #include <stb_truetype.h>
   8
   9 struct BZFontCodepoint {
  10         unsigned char sprite[32*32];
  11         int advanceWidth, leftSideBearing;
  12         int x0, y0;
  13         int x1, y1;
  14 };
  15 typedef struct BZFontCodepoint BZFontCodepoint;
  16
  17 struct BZFont {
  18         stbtt_fontinfo ttfFontInfo;
  19         float scale;
  20         int ascent;
  21         int descent;
  22         int lineGap;
  23         int baseline;
  24         BZFontCodepoint codepoints[256];
  25 };
  26
  27 BZFontID bzGfxLoadFont(BZMemoryArenaID arena, const char *identifierFmt, ...) {
  28         bzMakeIdentifier(identifier, identifierFmt);
  29
  30         BZResourceID handle = bzResourcesOpenResource("font", "assets/fonts/%s.ttf", identifier);
  31         size_t length = bzResourcesFileLength(handle);
  32         void *data = (uint8_t *)bzMemoryAlloc(arena, length);
  33         bzResourcesReadBytes(handle, data, length);
  34         bzResourcesCloseResource(handle);
  35
  36         BZFont *font = (BZFont *)bzMemoryAlloc(arena, sizeof(BZFont)); // FIXME
  37         stbtt_InitFont(&font->ttfFontInfo, data, stbtt_GetFontOffsetForIndex(data, 0));
  38         font->scale = stbtt_ScaleForPixelHeight(&font->ttfFontInfo, 20);
  39
  40         stbtt_GetFontVMetrics(&font->ttfFontInfo, &font->ascent, &font->descent, &font->lineGap);
  41
  42 //      int baselineX0, baselineY0, baselineX1, baselineY1;
  43 //      stbtt_GetFontBoundingBox(&font->ttfFontInfo, &baselineX0, &baselineY0, &baselineX1, &baselineY1);
  44         font->baseline = (float)font->ascent * font->scale;
  45
  46         for (int c = 0; c < 256; ++c) {
  47                 BZFontCodepoint *codepoint = &font->codepoints[c];
  48                 stbtt_MakeCodepointBitmap(&font->ttfFontInfo, codepoint->sprite, 32, 32, 32, font->scale, font->scale, c); // fixme, box size
  49                 stbtt_GetCodepointHMetrics(&font->ttfFontInfo, c, &codepoint->advanceWidth, &codepoint->leftSideBearing);
  50                 codepoint->advanceWidth *= font->scale;
  51                 stbtt_GetCodepointBitmapBox(&font->ttfFontInfo, c, font->scale, font->scale, &codepoint->x0, &codepoint->y0, &codepoint->x1, &codepoint->y1);
  52                 //stbtt_GetCodepointBox(&font->ttfFontInfo, c, &codepoint->x0, &codepoint->y0, &codepoint->x1, &codepoint->y1);
  53                 //codepoint->x0 = (float)codepoint->x0 * font->scale;
  54                 //codepoint->y0 = (float)codepoint->y0 * font->scale;
  55                 //codepoint->x1 = (float)codepoint->x1 * font->scale;
  56                 //codepoint->y1 = (float)codepoint->y1 * font->scale;
  57         }
  58
  59         return font;
  60 }
  61
  62 /*
  63
  64
  65
  66 //  Displaying a character:
  67 //    Compute the bounding box of the character. It will contain signed values
  68 //    relative to <current_point, baseline>. I.e. if it returns x0,y0,x1,y1,
  69 //    then the character should be displayed in the rectangle from
  70 //    <current_point+SF*x0, baseline+SF*y0> to <current_point+SF*x1,baseline+SF*y1).
  71 //
  72 //  Advancing for the next character:
  73 //    Call GlyphHMetrics, and compute 'current_point += SF * advance'.
  74
  75
  76
  77
  78
  79
  80 char buffer[24<<20];
  81 unsigned char screen[20][79];
  82
  83 int main(int arg, char **argv)
  84 {
  85    stbtt_fontinfo font;
  86    int i,j,ascent,baseline,ch=0;
  87    float scale, xpos=2; // leave a little padding in case the character extends left
  88    char *text = "Heljo World!"; // intentionally misspelled to show 'lj' brokenness
  89
  90    fread(buffer, 1, 1000000, fopen("c:/windows/fonts/arialbd.ttf", "rb"));
  91    stbtt_InitFont(&font, buffer, 0);
  92
  93    scale = stbtt_ScaleForPixelHeight(&font, 15);
  94    stbtt_GetFontVMetrics(&font, &ascent,0,0);
  95    baseline = (int) (ascent*scale);
  96
  97    while (text[ch]) {
  98       int advance,lsb,x0,y0,x1,y1;
  99       float x_shift = xpos - (float) floor(xpos);
 100       stbtt_GetCodepointHMetrics(&font, text[ch], &advance, &lsb);
 101       stbtt_GetCodepointBitmapBoxSubpixel(&font, text[ch], scale,scale,x_shift,0, &x0,&y0,&x1,&y1);
 102       stbtt_MakeCodepointBitmapSubpixel(&font, &screen[baseline + y0][(int) xpos + x0], x1-x0,y1-y0, 79, scale,scale,x_shift,0, text[ch]);
 103       // note that this stomps the old data, so where character boxes overlap (e.g. 'lj') it's wrong
 104       // because this API is really for baking character bitmaps into textures. if you want to render
 105       // a sequence of characters, you really need to render each bitmap to a temp buffer, then
 106       // "alpha blend" that into the working buffer
 107       xpos += (advance * scale);
 108       if (text[ch+1])
 109          xpos += scale*stbtt_GetCodepointKernAdvance(&font, text[ch],text[ch+1]);
 110       ++ch;
 111    }
 112
 113    for (j=0; j < 20; ++j) {
 114       for (i=0; i < 78; ++i)
 115          putchar(" .:ioVM@"[screen[j][i]>>5]);
 116       putchar('\n');
 117    }
 118
 119    return 0;
 120 }
 121 */
 122
 123
 124 void bzGfxRenderFont(BZFontRenderPixelSetFunction pixelSetFunction, int *xPosition, int *yPosition, BZFontID font, int color, const char *text) {
 125         for (const char *c = text; *c != '\0'; ++c) {
 126                 BZFontCodepoint *codepoint = &font->codepoints[*c];
 127
 128                 for (int y = 0, i = 0; y < 32; ++y) {
 129                         for (int x = 0; x < 32; ++x, ++i) {
 130                                 if (codepoint->sprite[i] > 100) {
 131                                         pixelSetFunction(*xPosition + x + codepoint->x0, *yPosition + font->baseline + y + codepoint->y0, color);
 132                                 }
 133                         }
 134                 }
 135
 136                 *xPosition += codepoint->advanceWidth;
 137         }
 138 }